WO2015015856A1

WO2015015856A1 - Restriction-time frame pattern estimation method, restriction-time frame pattern estimation device, and system and program for same

Info

Publication number: WO2015015856A1
Application number: PCT/JP2014/062427
Authority: WO
Inventors: 大輔太田; 信清　貴宏
Original assignee: 日本電気株式会社
Priority date: 2013-07-30
Filing date: 2014-05-09
Publication date: 2015-02-05
Also published as: JPWO2015015856A1

Abstract

In a situation in which, on the basis of a prescribed frame pattern, wireless communication is intermittently limited in a second area in which wireless communication is being carried out that interferes with the wireless communication of a first area, a restriction-time frame pattern estimation device calculates quality indicators for a plurality of frames by measuring, in the first area, at least the signal from the second area and estimates what type of frame pattern is being used as the prescribed frame pattern by comparing a calculated quality indicator calculated on the basis of the quality indicators calculated for the plurality of frames and the quality indicator of a frame from among the plurality of frames that is the current determination target.

Description

Time limit frame pattern estimation method, time limit frame pattern estimation device, system thereof, and program thereof

The present invention relates to a time limit frame pattern estimation method, a time limit frame pattern estimation device, a system thereof, and a program thereof for estimating a time limit frame pattern.

In a wireless communication system conforming to a standard such as LTE (Long Term Evolution) standardized in 3GPP (Third Generation Partnership Project), it is assumed that a plurality of base stations are arranged in the wireless communication system.

In these wireless communication systems, a cellular communication system is adopted. More specifically, each of these base stations arranged in the wireless communication system manages the communication area of the base station (hereinafter referred to as “cell” as appropriate). Each base station performs radio communication with a mobile station (hereinafter referred to as “terminal” as appropriate) located in a cell managed by the base station.

In addition, there is a case where a configuration called a sector configuration is further adopted. In this case, each base station divides one cell into a plurality of parts by giving the antenna directivity. This divided area is called a “sector cell”. In the following description, the term “cell” includes not only a cell but also a sector cell.

For example, in LTE, the same communication band is normally used between adjacent cells. Therefore, a terminal located at the boundary between adjacent cells (hereinafter referred to as “edge terminal” as appropriate) is adjacent to the cell in which it is located, regardless of whether it is an uplink or a downlink. It receives strong interference from neighboring cells.

Furthermore, as a countermeasure to the problem that traffic volume has increased in recent years, in addition to general macrocell base stations, it is possible to further introduce base stations with low transmission power in areas where terminals are concentrated such as hot spots. It is being advanced. In addition, although such a low transmission power base station is called by various names such as a nanocell base station, a picocell base station, a femto base station, and the like, for example, a cell smaller than a macrocell base station is managed in the following description. These are collectively referred to as base stations and are appropriately referred to as “small cell base stations”.

The cell form in which sector cells and small cell base stations are used as described above is called a heterogeneous network because cells of various sizes are mixed. And in heterogeneous networks, the area which becomes a boundary between cells expands with the increase in the number of cells, and interference between cells is especially regarded as a problem.

In order to address this problem, 3GPP Release 10 has standardized ABS (Almost Blank Blank Subframe) by eICIC (enhanced Inter Cell Cell Interference Coordination) as a management technology for inter-cell interference (non-patented). Reference 1). Subframe refers to a unit time of radio resource allocation. EICIC is also called time domain ICIC.

Here, ABS is one in which one or both of adjacent base stations (which may be either a macro cell base station or a small cell base station) intermittently stop transmission. In this way, in the subframe in which the interfering base station (aggressor) stops transmitting, the interfered base station (victim) does not need to receive interference, and thus the throughput of the terminals located in the interfered base station Will improve.

More specifically, for example, in the case of downlink, a base station that has set an ABS stops transmission of signals on a data channel (PDSCH: Physical Downlink Shared Channel) and a control channel (PDCCH: Physical Downlink Control Channel). To do.

Thereby, in the adjacent base station adjacent to the base station where the ABS is set, the reception quality of the terminal (for example, SINR: SignalSignTo Interference and Noise Ratio) is greatly improved. An increase in throughput can be expected for each terminal.

Subsequently, processing in a case where eICIC is applied to the downlink will be described in more detail with reference to a reference example shown in FIG. However, FIG. 18 and the following description referring to them are not directly described in publicly known documents including Non-Patent Document 1. However, it is a content generally understood by those skilled in the art who are in contact with these known documents.

FIG. 18 is a diagram illustrating an overview of a wireless communication system 1000 that is a configuration example of a wireless communication system that applies eICIC to a downlink and an operation procedure thereof.

The radio communication system 1000 includes two base stations, a macro cell base station 1001 and a small cell base station 1002, and five terminals 1011 to 1013 and 1021 to 1022.

The two base stations, the macro cell base station 1001 and the base station 1002, can communicate with each other via an inter-base station interface (X2 Interface). The macro cell base station 1001 is a base station that manages a macro cell. On the other hand, the small cell base station 1002 has a lower transmission power than the macro cell base station and is a base station that manages the small cell. Specifically, the macro cell base station 1001 manages the macro cell 1010, and the base station 1002, which is a small cell base station, manages the small cell 1020.

Terminals 1011 to 1013 are terminals located in the macro cell 1010 and connected to the base station 1001. In the following description, the terminals 1011 to 1013 are particularly referred to as macro cell terminals 1011 to 1013. On the other hand, the terminals 1021 to 1022 are terminals located in the small cell 1020 and connected to the base station 1002. In the following description, the terminals 1021 to 1022 are particularly referred to as small cell terminals 1021 to 1022.

First, the macro cell base station 1001 sets an ABS. FIG. 19 is a diagram illustrating an example of ABS setting. As illustrated in FIG. 19, the macro cell base station 1001 sets an ABS with 40 Subframe as one unit. In this 40 subframe, switching is performed at a predetermined cycle in which “Non-ABS”, which is a subframe other than ABS and ABS, is set.

Next, the macro cell base station 1001 notifies the small cell base station 1002 of the set ABS information (hereinafter referred to as “ABS Status” as appropriate) via the X2 Interface. In this regard, as described in Non-Patent Document 2, the ABS Status describes the ABS pattern in which ABS is set to 1 and Non-ABS is set to 0 for the ABS set by the base station, and the proportion of ABS in 40 Subframes. Has been.

Then, an initial state in which notification of ABS Status has not yet been made, and a case where an ABS Status in which all of the ABS patterns are 0 are notified from the macro cell base station 1001 will be described. In this case, the small cell base station 1002 measures the communication path quality and notifies the small cell terminal 1021 and the small cell terminal 1022 of CQI-ReportingConfig which is a notification for reporting CSI (Channel State information). To do. In response to this notification, the small cell terminal 1021 and the small cell terminal 1022 report the CS to the small cell base station 1001 (see Non-Patent Document 3).

Here, CQI-ReportingConfig distinguishes between ABS and Non-ABS, and reports that CSI is separately reported by ABS and Non-ABS and simply reports periodically without distinguishing between ABS and Non-ABS. There are two types of notifications: notifications. In this case, since the ABS Status notification has not yet been made or all of the ABS patterns are 0, it is not necessary to distinguish between ABS and Non-ABS, so the latter is notified.

The small cell terminal 1021 and the small cell terminal 1022 periodically measure the channel quality according to the CQI-Reporting Config notified from the small cell base station 1002, without distinguishing between the ABS and the Non-ABS, and the channel quality Is reported to the small cell base station 1002 as CSI. The small cell base station 1002 determines MCS (Modulation and Coding Scheme) based on the communication channel quality converted from CQI (Channel Quality and Indicator) included in the notified CSI. Here, the MCS is composed of, for example, a combination of a modulation scheme and a coding scheme ranked according to transmission rate.

On the other hand, a case where the ABS status including 1 in the ABS pattern is notified from the macro cell base station 1001 will be described. In this case, the small cell base station 1002 distinguishes the ABS and the Non-ABS from the small cell terminal 1021 and the small cell terminal 1022 in accordance with the notified ABS Status, and measures the CSI separately for the ABS and the Non-ABS. The CSI is reported to the small cell terminal 1021 and the small cell terminal 1022 by notifying the CQI-ReportingConfig to be performed. The small cell terminal 1021 and the small cell terminal 1022 measure the ABS channel quality and the Non-ABS channel quality according to the notified CQI-Reporting Config. Then, the small cell terminal 1021 and the small cell terminal 1022 report the measured channel quality information to the small cell base station 1002 as CSI for each ABS and Non-ABS.

The small cell base station 1002 determines the MCS based on the channel quality indicated by the CSI of the ABS when the ABS radio resource allocation is performed. Further, when non-ABS radio resource allocation is performed, the MCS is determined based on the channel quality indicated by the non-ABS CSI.

As a result, the ABS increases the transport block size (TBS) compared to the non-ABS, and thus the throughput of the small cell terminal 1021 and the small cell terminal 1022 is improved.

A specific application example of the technology related to the ABS as described above is described in Patent Document 1, for example. In the technique described in Patent Document 1, it is an object to provide a server device and an interference control method that suppress interference between cells and suppress a decrease in throughput of the entire network. Specifically, the ABS configuration determination unit of the OMC defines an ABS configuration table that is defined so as to reduce the frequency of stopping downlink transmission as the number of HeNBs decreases and to increase the frequency of stopping downlink transmission as the number of HeNBs increases. Prepare. Then, the ABS configuration determination unit acquires the number of HeNBs in the MeNB area, determines an ABS configuration corresponding to the acquired number of HeNBs from the ABS configuration table, and determines to apply to the MeNB.

International Publication No. 2012/108153

As described above, throughput can be improved by setting ABS.

However, in reality, there may be a case where the X2 Interface is not provided between the macro cell base station 1001 and the small cell base station 1002. For example, when the manufacturing vendors of the macro cell base station 1001 and the small cell base station 1002 are different from each other and the interconnection test is not performed in consideration of the working time, or because many small cell base stations 1002 are set, This is a case where a network for X2 cannot be installed. In such a case, if the macro cell base station 1001 sets the ABS, the throughput of the small cell terminal 1021 and the small cell terminal 1022 is not improved, and the throughput of the macro cell terminal 1011 to the macro cell terminal 1013 is nevertheless improved. The problem arises that only the deterioration occurs. This is not limited to the configuration shown in FIG. 18, and it is necessary to notify the ABS setting using the X2 Interface even in a general technique such as the configuration described in Patent Document 1, for example. Problems arise.

Here, the reason why such a problem occurs will be explained. When the X2 interface is not provided, the ABS status is not notified from the macro cell base station 1001 that has set the ABS to the small cell base station 1002. Therefore, the small cell base station 1002 distinguishes the ABS and the Non-ABS from the small cell terminal 1021 and the small cell terminal 1022, and describes the CQI that describes information for measuring the channel quality individually in the ABS and the Non-ABS. -Reporting Config cannot be notified.

Therefore, the small cell terminal 1021 and the small cell terminal 1022 measure the channel quality without distinguishing between the ABS and the Non-ABS, and notify the small cell base station of CSI, which is channel quality information.

As a result, there is a possibility that the estimated value of the channel quality converted from the CQI included in the reported CSI is greatly deviated from the actually measured value of the channel quality.

In order to explain this point, reference is made to FIG. 20, which represents an example of data in which an estimated value of channel quality converted from CQI and an actual value of channel quality at the time of user data transmission are arranged in time series. .

The small cell terminal (e.g., corresponding to the small cell terminal 1021 in the configuration of FIG. 18) measures the instantaneous value of 1 Subframe as the channel quality in 5 Subframe cycles, and the small cell base station (for example, the configuration of FIG. 18) after 4 Subframes of measurement. If so, it is reported to the small cell base station 1002). On the other hand, the small cell base station determines radio resource allocation such as MCS based on the estimated channel quality value converted from the CQI reported from the small cell terminal. That is, a certain 1 Subframe (for example, k-4 in FIG. 20) is an ABS, and an instantaneous value of the certain 1 Subframe is set to an ABS to a small base station after 4 Subframes of measurement (for example, k in FIG. 20). Time measurement results are reported. As a result, the estimated value in CQI conversion between 5 Subframes (for example, k to k + 4 in FIG. 20) until the next report is made is based on the measurement result at the time of ABS. On the other hand, a certain 1 subframe (for example, k + 1 in FIG. 20) in the next measurement period is a Non-ABS, and an instantaneous value of the certain 1 subframe is 4 Subframes after the measurement (for example, k + 5 in FIG. 20). The measurement result at Non-ABS is reported to the small base station. As a result, the estimated value in terms of CQI between 5 subframes (for example, k + 5 to k + 9 in FIG. 20) until the next report is made is based on the measurement result at Non-ABS.

Under such circumstances, when CQI measured by Non-ABS is used in radio resource allocation by Non-ABS, the correlation between the estimated value of channel quality and the actual measured value is high, and thus the expected transmission error rate. Transmission with (BLER: Block Error Rate) can be executed (see, for example, k-3 and k-4 indicated by (a) in FIG. 20). Similarly, when CQI measured by ABS is used in radio resource allocation by ABS, it becomes a factor for improving throughput by suppressing interference from the macro cell (see, for example, k and k + 2 shown in FIG. 20B).

However, when CQI measured by ABS is used in radio resource allocation by Non-ABS, the estimated value becomes significantly larger than the actually measured value (see, for example, k + 1 indicated by (1) in FIG. 20). For this reason, an MCS having an excessive number of transmission bits is selected for the channel quality, resulting in a problem that BLER increases.

Similarly, when CQI measured by Non-ABS is used in radio resource allocation at ABS, the estimated value is significantly higher than the channel quality (actually measured value) that can be achieved even if there is interference suppression from the macro cell. (For example, refer to k + 6 indicated by (2) in FIG. 20). Therefore, a large MCS cannot be selected, and the number of transmission bits of the small cell terminal does not become so large. As a result of the above, the increase in BLER greatly affects the throughput of the small cell terminal, and further, since the ABS setting is executed nevertheless, only the throughput of the macro cell terminal is deteriorated. Problems will arise.

For example, it is conceivable to average the interference power as a measure for mitigating the adverse effects caused by such a problem. That is, it is conceivable that the small cell terminal does not report the channel quality of a certain one subframe as CQI as described above, but reports the channel quality of a plurality of subframes as an average CQI.

However, even if this is done, the problem of increasing BLER in the above-described non-ABS radio resource allocation cannot be sufficiently improved. Moreover, since the estimated value of the channel quality at the ABS is smaller than the actual measurement value by averaging, the effect of improving the throughput of the small cell terminal by the ABS setting is also reduced. Further, by averaging, for example, the BLER at k-3 and k-4 in FIG. 20 where the correlation between the estimated value of the channel quality and the actual measurement value is high increases, and the throughput improvement effect at k and k + 2 in FIG. 20 is also reduced. .

Therefore, the present invention provides an ABS even when a time limit frame pattern such as an ABS pattern is not notified from a base station that manages a cell that has a time limit frame setting such as an ABS to a base station that manages its neighboring cells. It is an object of the present invention to provide a time limit frame pattern estimation method, a time limit frame pattern estimation apparatus, a system thereof, and a program thereof capable of estimating a time limit frame pattern such as a pattern.

According to the first aspect of the present invention, in a second area where radio communication that interferes with radio communication in the first area is performed, a frame in which radio communication is restricted based on a predetermined frame pattern The quality of each of the plurality of frames is measured by measuring a signal from at least the second area in the first area in a situation where the time frame is switched to a time frame other than the time limit frame. By calculating an index and comparing the calculated quality index calculated based on the calculated quality index of each of the plurality of frames and the quality index of the frame that is currently determined in any of the plurality of frames, The frame to be determined this time is either the time limit frame or a time frame other than the time limit frame. Or estimating the time limit frame pattern estimation apparatus and estimates what frame pattern as the predetermined frame pattern by performing the estimation for a plurality of frames is used is provided.

According to a second aspect of the present invention, there is provided a time limit frame pattern estimation method performed by a computer, wherein in a second area where radio communication that interferes with radio communication in the first area is performed, a predetermined area is used. Under the situation of switching between a time limit frame that is a frame for which wireless communication is restricted based on the frame pattern and a time frame other than the time limit frame, at least from the second area in the first area The quality index is calculated for each of a plurality of frames by measuring the signal, and the calculated quality index calculated based on the calculated quality index of each of the plurality of frames and any of the plurality of frames and the current determination target By comparing the quality index of the frame to be determined, the frame to be determined this time is And a frame other than the time limit frame is estimated, and the estimation is performed for a plurality of frames to estimate what frame pattern is used as the predetermined frame pattern. There is provided a time period frame pattern estimation method characterized in that:

According to the third aspect of the present invention, in the second area where radio communication that interferes with radio communication in each of the plurality of first areas is performed, the radio communication is limited based on a predetermined frame pattern. Each of the plurality of first area base stations measures a signal from at least the second area under the situation of switching between a time limit frame that is a frame to be transmitted and a time frame other than the time limit frame. By calculating the quality index for each of the plurality of frames, the calculated quality index calculated based on the calculated quality index of each of the plurality of frames, and the quality of any of the plurality of frames that are to be determined this time By comparing the index, the frame to be determined this time is determined to be the time limit frame and the time limit frame. The time frame other than the time frame is estimated, and by performing the estimation for a plurality of frames, it is estimated what frame pattern is used as the predetermined frame pattern. Each base station notifies each other of the estimated frame pattern and re-estimates the frame pattern based on both the frame pattern estimated by the base station itself and the frame pattern notified from the other base station. A featured limited time frame pattern estimation system is provided.

According to the fourth aspect of the present invention, in the second area where radio communication that interferes with radio communication in each of the plurality of first areas is performed, the radio communication is limited based on a predetermined frame pattern. In the situation of switching between a time limit frame that is a frame to be transmitted and a time frame other than the time limit frame, a plurality of frames are measured by measuring a signal from at least the second area in the first area. A quality index is calculated for each, and the calculated quality index calculated based on the calculated quality index of each of the plurality of frames is compared with the quality index of the frame that is the current determination target of any of the plurality of frames. Thus, the frame to be determined this time is the time frame other than the time limit frame and the time frame other than the time limit frame. The frame pattern estimated by each base station is estimated by performing the estimation on a plurality of frames to estimate what frame pattern is used as the predetermined frame pattern. To the master node, and the master node re-estimates the frame pattern based on the plurality of frame patterns reported from each base station, and notifies each base station of the re-estimated frame pattern. A featured master node is provided.

According to the fifth aspect of the present invention, in the second area in which wireless communication that interferes with wireless communication in the first area is performed, the frame in which wireless communication is restricted based on a predetermined frame pattern The server device determines the predetermined frame pattern that can be used in the second area under the situation of switching between the time limit frame that is and a time frame other than the time limit frame. A frame pattern is transmitted to the time limit frame pattern estimation device as a list, and the time limit frame pattern estimation device measures at least signals from the second area in each of the plurality of frames in the first area. A quality index is calculated, and a calculated quality index is calculated based on the calculated quality index of each of the plurality of frames. And the quality index of the frame that is the current determination target among any of the plurality of frames, and the frame that is the current determination target is the time frame other than the time limit frame and the time frame other than the time limit frame The frame pattern in the list is estimated based on a frame pattern that is used as the predetermined frame pattern by performing the estimation for a plurality of frames. By selecting, the server apparatus in the system is provided in which the frame pattern is estimated again.

According to the sixth aspect of the present invention, in the second area in which wireless communication that interferes with wireless communication in the first area is performed, the frame in which wireless communication is restricted based on a predetermined frame pattern The base station in the second area determines the predetermined frame pattern that can be used in the second area under the situation of switching between a time limit frame that is a time frame and a time frame other than the time limit frame. Then, the determined predetermined frame pattern is transmitted as a list to the time limit frame pattern estimation device, and the time limit frame pattern estimation device measures a signal from at least the second area in the first area. To calculate the quality index for each of the plurality of frames, and calculate based on the calculated quality index for each of the plurality of frames. By comparing the calculated quality index with the quality index of any of the plurality of frames that is the current determination target, the current determination target frame is the time limit frame and the time limit frame. The list is based on a frame pattern that is estimated as a frame pattern that is used as the predetermined frame pattern by estimating the time frame other than the time frame and performing the estimation for a plurality of frames. A base station of the second area in the system is provided, wherein the frame pattern is re-estimated by selecting a frame pattern within.

According to the seventh aspect of the present invention, in the second area in which radio communication that interferes with radio communication in the first area is performed, frames in which radio communication is restricted based on a predetermined frame pattern The quality of each of the plurality of frames is measured by measuring a signal from at least the second area in the first area in a situation where the time frame is switched to a time frame other than the time limit frame. By calculating an index and comparing the calculated quality index calculated based on the calculated quality index of each of the plurality of frames and the quality index of the frame that is the current determination target in any of the plurality of frames, The frame to be determined this time is either the time limit frame or a time frame other than the time limit frame. And a computer that functions as a time-limited frame pattern estimation device for estimating what frame pattern is used as the predetermined frame pattern by performing estimation for a plurality of frames. A time frame estimation program is provided.

According to the present invention, even when a base station that manages a cell in which a time limit frame is set such as an ABS is not notified of a time limit frame pattern such as an ABS pattern to the base station that manages the neighboring cell, the ABS A time limit frame pattern such as a pattern can be estimated.

1 is a block diagram illustrating a basic configuration of a wireless communication system according to a first embodiment of the present invention. It is a block diagram showing the basic composition of the small cell base station in the 1st Embodiment of this invention. It is a block diagram showing the basic composition of the terminal in a 1st embodiment of the present invention. It is a flowchart showing the transfer method to NLM in the 1st Embodiment of this invention. It is a flowchart showing the estimation method of the ABS pattern in the 1st Embodiment of this invention. 3 is a flowchart illustrating a method for notifying a CQI-ReportConfig to a terminal according to the first embodiment of the present invention. It is a block diagram showing the basic composition of the small cell base station in the 2nd Embodiment of this invention. It is a flowchart showing the transfer method to NLM in the 2nd Embodiment of this invention. It is a block diagram showing the basic composition of the small cell base station in the 3rd Embodiment of this invention. It is a flowchart showing the estimation method of the ABS pattern in the 3rd Embodiment of this invention. It is a flowchart showing the correction method of the ABS pattern in the 3rd Embodiment of this invention. It is a block diagram showing the basic composition of the radio | wireless communications system in the 4th Embodiment of this invention. It is a block diagram showing the basic composition of the small cell base station in the 4th Embodiment of this invention. It is a figure showing the ABS pattern candidate list | wrist in the 4th Embodiment of this invention. It is a block diagram showing the basic composition of the OAM server in the 4th Embodiment of this invention. It is a flowchart (1/2) showing the estimation method of the ABS pattern in the 4th Embodiment of this invention. It is a flowchart (2/2) showing the estimation method of the ABS pattern in the 4th Embodiment of this invention. It is a figure showing the estimation result of the ABS pattern in the 4th Embodiment of this invention. It is a block diagram showing the fundamental structure of the radio | wireless communications system in a general technique. It is a figure showing the setting method of the radio | wireless resource which restrict | limits use of the macrocell base station in a general technique. It is a figure showing the problem which should be solved which a general technique has.

10, 20 Wireless communication systems 100-1, 100-2, 400-1, 500-1, 500-2, 600-1, 700-1 Small cell base station 101 Base station operation unit 102 Reference

signal generation units

103, 403

NLM transition units

104, 504, 604 ABS pattern estimation units 104-1, 504-1, 604-1 DL quality index calculation units 104-2, 504-2, 604-2 ABS pattern estimation execution unit 105 transmission buffer 106 scheduler 200 -1, 200-2 Macrocell base stations 300-P1-1, 300-P1-2, 300-P2-1, 300-P2-2, 300-M1-1, 300-M1-2, 300-M2-1 300-M2-2 terminal 301 terminal operation unit 302 channel quality measurement unit 700 OAM server 900 communication line network

First, an outline of an embodiment of the present invention will be described.

According to the embodiment of the present invention, when the macro cell base station sets the ABS, the throughput of the small cell terminal can be improved even when the macro cell base station does not notify the small cell base station of the ABS status. The reason is that the small cell base station estimates the ABS pattern of the macro cell base station using the channel quality information measured by itself. Then, since the CQI report is instructed to the terminal based on the estimation result, the small cell base station can acquire an appropriate channel quality at the ABS and the Non-ABS, so that the MCS appropriate for the actual communication quality can be obtained. This is because it can be assigned.
The above is the outline of the embodiment of the present invention.

Next, embodiments of the present invention will be described in detail with reference to the drawings. Here, in this description, four embodiments will be described as an example of the embodiment of the present invention.

First, a first embodiment, which is an embodiment for directly estimating an ABS pattern, will be described with reference to FIG.

Referring to FIG. 1, a radio communication system 10 according to the present embodiment includes small cell base stations 100-1 and 100-2, macro cell base stations 200-1 and 200-2, a plurality of terminals 300-P1-1, 300-P1-2, 300-P2-1, 300-P2-2, 300-M1-1, 300-M1-2, 300-M2-1 and 300-M2-2. The same applies to the description of each embodiment below, but the configuration of each embodiment is merely an example for description. That is, each of the following embodiments is a preferred embodiment of the present invention, but the scope of the present invention is not limited only to the above-described embodiment, and various modifications are made without departing from the gist of the present invention. Implementation in the form is possible.

For example, FIG. 1 illustrates an example in which the wireless communication system 10 includes two macro cell base stations and two small cell base stations, but the wireless communication system 10 includes one or three of these base stations. It is good to include more than one unit. Further, the wireless communication system 10 may include more or fewer terminals than the terminals illustrated in FIG. In this description, the wireless communication system 10 is assumed to be applied to the downlink in the communication conforming to LTE, but the present embodiment may be realized in conformity with other communication methods.

Next, the explanation method and notation in this embodiment will be explained. In each figure and in the following description, the symbol of the terminal 300 includes the letter P or M. Here, M is an acronym for Macro, and P is an acronym for Pico. However, as described above, the pico cell is referred to as a small cell in the following description. A picocell base station is called a small cell base station.

For example, the notation “terminal 300-P1-X” means that the terminal 300 is the terminal 300 connected to the small cell base station 100-1. Similarly, terminal 300-M1-Y means that terminal 300 is terminal 300 connected to macro cell base station 200-1. Furthermore, X and Y are arbitrary indexes for identifying terminals in each base station.

Further, in the following description, items common to each small cell base station (for example, small cell base stations 100-1 and 100-2) and each macro cell base station (for example, macro cell base stations 200-1 and 200-2) are described. In the description, without describing the end of the code, “small cell base station 100 is” and “macro cell base station 200 is” are described. Similarly, for the terminal, each terminal connected to the small cell base station (for example, the terminals 300-P1-1, 300-P1-2, 300-P2-1 and 300-P2-2), the macro cell base station When the items common to the terminals (for example, 300-M1-1, 300-M1-2, 300-M2-1, and 300-M2-2) connected to the mobile terminal are described, -P is "," and "Macrocell terminal 300-M is". Further, when a common item is described regardless of the connected base station, “terminal 300 is” is described.

Subsequently, each device included in the wireless communication system 10 will be described in detail.

The small cell base stations 100-1 and 100-2 and the macro cell base stations 200-1 and 200-2 can communicate with each other via a communication line network 900 (denoted as NW900 in the figure). . However, it is assumed that there is no X2 interface between each small cell base station 100 and each macro cell base station 200. Therefore, in this embodiment, even if each macro cell base station 200 sets an ABS, it is not possible to notify the ABS Status from each macro cell base station 200 to each small cell base station 100.

Also, each small cell base station 100 and each macro cell base station 200 can manage cells that are a plurality of communication areas. However, in the following description, an example in which each small cell base station 100 and each macro cell base station 200 manages one communication area will be described in order to simplify the description and clarify the gist.

Each small cell base station 100 is a low transmission power base station and has a narrow communication area compared to each macro cell base station 200. In addition, it is assumed that at least part or all of the communication area of each small cell base station 100 is included in the communication area of each macro cell base station 200.

Each small cell base station 100 performs wireless communication with a terminal 300-P existing in a communication area managed by the base station 100. Each small cell base station 100 can simultaneously perform radio communication with each of the plurality of terminals 300-P.

Each macro cell base station 200 is a base station having a wider communication area than each small cell base station 100. Each macro cell base station 200 performs wireless communication with a terminal 300-M existing in a communication area excluding the communication area managed by each small cell base station 100 from the communication area managed by each macro cell base station 200 itself. I do. Similar to each small cell base station 100, each macro cell base station 200 can perform wireless communication simultaneously with each of the plurality of terminals 300-M.

The functions of each small cell base station 100 and each macro cell base station 200 are realized by an information processing device (not shown). The information processing apparatus includes a central processing unit (for example, CPU: Central Processing Unit) (not shown) and a storage device (memory and hard disk drive (for example, HDD: Hard Disk Drive)). In each small cell base station 100 and each macro cell base station 200, the central processing unit reads a program specific to the present embodiment which is software stored in the storage device, and according to the result of the arithmetic processing based on this program. This is realized by controlling each hardware.

Each terminal 300 can be realized by an arbitrary device, but in the present embodiment, it is assumed to be realized by a mobile phone. Here, an arbitrary device for realizing each terminal 300 is, for example, a personal computer, a PHS (Personal Handyphone System) terminal, a PDA (Personal Data Assistant, Personal Digital Assistant), a smartphone, a tablet terminal, a car navigation terminal, Or a game terminal etc. may be sufficient.

Each terminal 300 includes a central processing unit (for example, a CPU), a storage device (for example, a memory), an input device (for example, a key button and a microphone), and an output unit (for example, a display and a speaker). Each terminal 300 is realized by the central processing unit reading a program specific to the present embodiment, which is software stored in the storage device, and controlling each hardware according to the result of the arithmetic processing based on this program Is done.

Next, functions of each small cell base station 100 will be described with reference to FIG. FIG. 2 is a block diagram showing functions of the small cell base station 100-1 in the wireless communication system 10 shown in FIG. Note that this time, the small cell base station 100-1 will be described as a representative of each small cell base station 100, but the functions of the other small cell base stations 100 (for example, the small cell base station 100-2) The function is the same as that of the cell base station 100-1.

The small cell base station 100-1 includes a base station operation unit 101, a reference signal generation unit 102, an NLM transition unit 103, an ABS pattern estimation unit 104, a transmission buffer 105, and a scheduler 106.

The base station operation unit 101 has various functions. Specifically, the base station operation unit 101 has a function of transmitting and receiving radio signals between the small cell base station 100-1 and each terminal 300-P1 that is connected. Further, the base station operation unit 101 has a function of notifying each terminal 300-P1 of an allocated band used for transmission / reception of a radio signal, scheduling information such as MCS Index, and transmission power setting information.

Furthermore, the base station operation unit 101 has a function of holding the ABS pattern of the macrocell base station 200-1 estimated by the ABS pattern estimation unit 104.

Furthermore, the base station operation unit 101 has a function of notifying each terminal 300-P1 of CQI-Reporting Config based on the ABS pattern. Here, in the present embodiment, when the ABS is included in the ABS pattern of the macro cell base station 200-1 estimated by the ABS pattern estimation unit 104, the CQI-ReportingConfig distinguishes between ABS and Non-ABS, and ABS and Non-ABS It is a notification that causes CSI to be reported individually by the ABS. In addition, when the ABS is not included in the ABS pattern of the macro cell base station 200-1 estimated by the ABS pattern estimation unit 104, the CQI-ReportingConfig is a notification for simply reporting periodically without distinguishing the ABS and the Non-ABS. .

Further, the base station operation unit 101 has a peripheral base station list in which information used for identifying the macro cell base station 200-1 and other peripheral macro cell base stations 200-k (k ≠ 1) is described. is doing. Then, the base station (hereinafter referred to as “peripheral base station”) described in the peripheral base station list and the report timing of each channel quality of the small cell base station 100-1 are transmitted to each terminal 300-P1. It has a function to notify.

Furthermore, the base station operation unit 101 has a function of receiving radio signals from neighboring base stations. Further, the base station operation unit 101 has a function of holding ABS setting information (ABS Status) of neighboring base stations.

Each function of these base station operation units 101 is a general function as a base station except for differences such as the estimated ABS pattern to be held. Are well known to those skilled in the art, and thus the description thereof is omitted.

The reference signal generation unit 102 has a function of generating a reference signal used by each terminal 300-P1 to measure the channel quality with the small cell base station 100-1. The reference signal generation unit 102 transmits the generated signal to each terminal 300-P1 via the base station operation unit 101.

The NLM transition unit 103 has a function of determining whether or not to shift the small cell base station 100-1 to NLM (Network Listen Mode). Here, NLM is a mode in which the base station itself receives a downlink signal. NLM is defined in detail in Non-Patent Document 4.

And when shifting to NLM, the NLM shifting unit 103 stops the operation of the base station operating unit 101 that transmits a radio signal to each terminal 300-P1. Further, when shifting to NLM, the NLM shifting unit 103 stops the operation of the scheduler 106 via the base station operation unit 101. Furthermore, when shifting to NLM, the NLM shifting unit 103 causes the base station operation unit 101 to start receiving radio signals from neighboring base stations.

The ABS pattern estimation unit 104 has a function of estimating the ABS pattern of the macrocell base station 200-1. Here, the ABS pattern estimation unit 104 includes a DL quality index calculation unit 104-1 and an ABS pattern estimation execution unit 104-2.

Also, the DL quality index calculation unit 104-1 refers to a list of neighboring base stations held by the base station operation unit 101, and is a “quality index” that is a standard for determining the interference level from the macro cell base station 200-1. ”Is measured.

In this regard, as described in Non-Patent Document 4, the base station applies the NLM, thereby referring to the list of neighboring base stations held by the base station operation unit 101 and RSRP (Reference Signal Received of the neighboring base stations. Power), RSRQ, RSSI (Received Signal Signal Strength) Indicator, etc. can be measured. In this embodiment, any one of these scales can be adopted as the quality index. However, in the following description, it is assumed that RSRQ (Reference Signal Received Quality) of the macrocell base station 200-1 is adopted as the quality indicator. .

Further, the DL quality index calculation unit 104-1 aggregates the measured quality index at the ABS setting period, and calculates the average quality index for all the subframes in the ABS setting period and the average quality index of each subframe in the ABS setting period. Has the function to calculate. In the present embodiment, the ABS setting cycle is 40 subframes. Each calculated average quality index is used by the ABS pattern estimation execution unit 104-2.

The ABS pattern estimation execution unit 104-2 has a function of estimating the ABS pattern of the macro cell base station 200-1 using each average quality index calculated by the DL quality index calculation unit 104-1. The estimation result is output to the base station operation unit 101, and the estimation result is managed by the base station operation unit 101. A specific estimation method will be described later as an explanation of the operation.

Furthermore, the ABS pattern estimation execution unit 104-2 has a function of terminating the NLM of the small cell base station 100-1 that has moved to the NLM. When ending the NLM, the ABS pattern estimation execution unit 104-2 stops the operation of the base station operation unit 101 that receives radio signals from the neighboring base stations. When the NLM is terminated, the ABS pattern estimation execution unit 104-2 causes the base station operation unit 101 to resume transmission of radio signals to each terminal 300-P1. Further, when the NLM is terminated, the ABS pattern estimation execution unit 104-2 restarts the operation of the scheduler 106 via the base station operation unit 101.

The transmission buffer 105 has a function of accumulating both transmission data addressed to each terminal 300-P1 arriving via the communication line network 900 and information used for transmitting the transmission data.

The scheduler 106 determines the transmission power, frequency band, and MCS index assigned to each terminal 300-P1, based on the accumulated transmission data addressed to each terminal 300-P1 and the CSI reported from each terminal 300-P1. To do. The scheduler 106 has a function of transmitting data to each terminal 300-P1 via the base station operation unit 101 according to the determination content.

In the present embodiment, when CSI is individually reported by the ABS and the Non-ABS from each terminal 300-P1, the scheduler 106 performs radio resource allocation by distinguishing between the ABS and the Non-ABS. That is, in this case, the ABS CSI is used for radio resource allocation in the ABS, and the Non-ABS CSI is used for radio resource allocation in the Non-ABS. On the other hand, when CSI that is not distinguished between ABS and Non-ABS is reported, the scheduler 106 uses CSI that is not distinguished between ABS and Non-ABS in radio resource allocation in ABS and Non-ABS.

Next, functions of each terminal 300 will be described with reference to FIG. FIG. 2 is a block diagram showing functions of the terminal 300-P1-1 in the wireless communication system 10 shown in FIG. In this example, the terminal 300-P1-1 is described as a representative of each terminal 300. However, the other terminals 300 (for example, the terminal 300-P1-2, the terminal 300-P2-1, the terminal 300-P2-2) are described. The functions of the terminal 300-M1-1 and the terminal 300-M1-2) are the same as those of the terminal 300-P1-1.

The terminal 300-P1-1 includes a terminal operation unit 301 and a channel quality measurement unit 302.

The terminal operation unit 301 is a part that realizes a general function for causing the terminal 300-P1-1 to function as a wireless communication terminal. Here, the general function is, for example, a function of determining a cell that requests connection when establishing a communication link from an idle state, or a connection with the terminal 300-P1-1 (a communication link has been established). This is a function of transmitting / receiving a radio signal to / from the small cell base station 100-1. The function of the terminal operation unit 301 is a well-known function in a general wireless communication system, and the configuration and operation related to the function are well known to those skilled in the art, and thus the description thereof is omitted.

The channel quality measuring unit 302 has a function for measuring channel quality with respect to a reference signal and information on the measured channel quality in accordance with the CQI-ReportingConfig notified from the small cell base station 100-1. It has the function to transmit to. In the present embodiment, the channel quality is CQI (Channel Quality Indicator) calculated from SINR with respect to the reference signal of the small cell base station 100-1.

Next, the operation procedure in which each small cell base station 100 described above estimates the ABS pattern of each macro cell base station 200 and notifies the small cell terminal 300-P of CQI-ReportingConfig based on the estimation result will be described with reference to FIGS. This will be described with reference to the flowchart of FIG. In the following description, the operation procedure of the small cell base station 100-1 will be described as an example, but the other small cell base stations 100 operate in the same manner as the small cell base station 100-1.

FIG. 4 shows an operation procedure in which the NLM transition unit 103 of the small cell base station 100-1 determines whether or not to move the small cell base station 100-1 to the NLM. When the small cell base station 100-1 is in a state other than the NLM, the NLM transition unit 103 performs the operation illustrated in FIG. 4 in each subframe.

First, the NLM transition unit 103 determines whether or not the current time (T [Subframe]) is a preset transition start time (T_start [Subframe]) to the NLM using Equation 1 below (step S11). ).

If the numerical formula 1 is satisfied (Yes in Step S11), the NLM transition unit 103 moves the small cell base station 100-1 to the NLM (Step S12). Thereafter, the NLM transition unit 103 ends the process of FIG.

On the other hand, when Expression 1 is not satisfied (NO in step S11), the NLM transition unit 103 ends the process of FIG. 4 without performing further processes.

FIG. 5 shows that the ABS pattern estimation unit 104 of the small cell base station 100-1 measures the RSRQ of the macro cell base station 200-1, calculates the average quality index by summing the RSRQ, and calculates the quality index. 10 is a flowchart showing a series of operation procedures for estimating an ABS pattern of the macrocell base station 200-1 by using it. The ABS pattern estimation unit 104 performs the operation illustrated in FIG. 5 in each subframe when the small cell base station 100-1 is an NLM.

Note that, as described above, the ABS pattern estimation unit 104 includes two functional blocks, a DL quality index calculation unit 104-1 and an ABS pattern estimation execution unit 104-2. In FIG. 5, the operations of steps S21 to S24 are performed by the DL quality index calculation unit 104-1, and the operations of steps S25 to S30 are performed by the ABS pattern estimation execution unit 104-2. However, in the following description, the DL quality index calculation unit 104-1 and the ABS pattern estimation execution unit 104-2 are not distinguished for each processing step, and only the operation of the ABS pattern estimation unit 104 will be described.

First, the ABS pattern estimation unit 104 measures the RSRQ (RSRQ (T)) of the macro cell base station 200-1 at the current time T (step S21). The unit of RSRQ_T to be measured is a true value. Here, RSRQ (reference signal reception quality) is an index of LTE signal quality, and is defined as the ratio of RSRP and the received signal strength indicator (RSSI) of the carrier.

Next, the ABS pattern estimation unit 104 uses the following Equation 2 to determine what subframe the RSRQ of the macro cell base station 200-1 measured in step S21 is the ABS setting period (Tp_abs [Subframe]). Is calculated (step S22). Here, i is a subframe number in the ABS setting cycle, and takes a value from 0 to Tp_abs-1. MOD (x, y) is a function that returns a remainder obtained by dividing x by y.

Next, the ABS pattern estimation unit 104 updates the RSRQ aggregate value (SUM_RSRQ (i)) of the i-th subframe in the ABS setting cycle using Equation 3 below (step S23). In Equation 3, SumRSRQ (i) is the sum of RSRQ and is totaled with a true value. The initial value is 0.

Subsequently, the ABS pattern estimation unit 104 updates the RSRQ count number (Num_measure (i)) of the i-th subframe in the ABS setting cycle by using Equation 4 below (step S24). In Equation 4, the initial value of Num_measure (i) is 0.

Next, the ABS pattern estimation unit 104 determines whether or not the current time T is the end time of the NLM, using Equation 5 below (step S25). In Equation 5, Tp_nlm [subframe] is the NLM duration of the small cell base station 100-1, and is set to 200 Subframe which is a multiple of the ABS setting period in this embodiment.

If Equation 5 is not satisfied (No in step S25), that is, if the current time T is not yet the end time of the NLM, the ABS pattern estimation unit 104 ends the process of FIG. And the ABS pattern estimation part 104 performs a process from step S21 again in the next subframe.

On the other hand, if Expression 5 is satisfied (Yes in step S25), that is, if the current time T is the NLM end time, the process proceeds to step S26. Then, in step S26, the ABS pattern estimation unit 104 calculates the average value (RSRQ_ave [dB]) of the RSRQ of the macrocell base station 200-1 in the ABS setting cycle using the following Equation 6 (step S26). In Equation 6, DB [x] is a function that returns a value obtained by converting the true value x into dB.

Next, the ABS pattern estimation unit 104 calculates the average value (RSRQ_ind (i) [dB]) of the RSRQ of the macro cell base station 200-1 in each subframe in the ABS setting cycle using the following Equation 7. (Step S27).

Next, the ABS pattern estimation unit 104 estimates the ABS pattern of the macrocell base station 200-1 using Equation 8 below (step S28). Specifically, when Expression 8 is satisfied, subframe i that is the i-th subframe is estimated as the ABS of the macrocell base station 200-1. On the other hand, when Expression 8 is not satisfied, subframe i is estimated as the Non-ABS of the macrocell base station 200-1.

This estimation process is performed for all subframes (that is, i = 0 to Tp_abs-1) included in the ABS setting cycle.

Here, the reason why the ABS pattern of the macro cell base station 200-1 is estimated in this process will be described. In the Non-ABS, transmission by the macro cell base station 200-1 is performed as usual, so that the small cell managed by the small cell base station 100-1 receives interference from the macro cell base station 200-1. However, in the ABS, interference from the macro cell base station 200-1 is reduced. The average value of RSRQ of macro cell base station 200-1 in the ABS setting cycle is the average of interference when both Non-ABS and ABS are repeated. Therefore, the RSRQ of the macro cell base station 200-1 in the ABS is expected to be higher than the average value of the RSRQ of the macro cell base station 200-1 in the ABS setting cycle. For this reason, it is determined whether or not the average RSRQ value in the subframe to be determined (corresponding to the “calculated quality index” of the present invention) is higher than the average RSRQ value of the macrocell base station 200-1 in the ABS setting cycle. If it is high, it can be estimated that the subframe to be determined is ABS. In addition, since the measurement value may be blurred depending on the circumstances such as the environment at the time of measurement, in Equation 8, the difference between the average values is not determined in advance by simply comparing the average values and determining whether or not there is a difference. Whether or not it is greater than or equal to the set ABS determination threshold is used as a determination criterion. Note that ΔThr_RSRQ in Equation 8 represents a preset ABS determination threshold. The ABS determination threshold can be arbitrarily set and changed.

Next, the ABS pattern estimation unit 104 updates the transition start time T_start of the small cell base station 100-1 to the NLM using the following formula (9) (step S29). In Equation 9, T_next_nlm is a transition period of the small cell base station 100-1 to the NLM. In this description, as one example of setting the transition period to NLM, the transition period T_next_nlm is set to 600000 Subframe that is a multiple of the ABS setting period.

Subsequently, the ABS pattern estimation unit 104 ends the NLM of the small cell base station 100-1 (step S30). Thereafter, the ABS pattern estimation unit 104 ends the process of FIG. When the current time thereafter becomes the transition start time T_start updated in step S29, the result in step S12 is Yes, and the process in FIG. 5 is executed again.

FIG. 6 shows an operation procedure when the base station operation unit 101 notifies each small cell terminal 300-P1 of CQI-ReportingConfig based on the ABS pattern of the macro cell base station 200-1 estimated by the ABS pattern estimation unit 104. It is shown. When the ABS pattern estimation unit 104 does not estimate the ABS pattern of the macrocell base station 200-1, the base station operation unit 101 sends a CQI-ReportingConfig that periodically reports the channel quality to each small cell terminal. Notify 300-P1.

First, the base station operation unit 101 determines whether or not ABS is included in the ABS pattern of the macro cell base station 200-1 estimated by the ABS pattern estimation unit 104 (step S41).

When the ABS is included (Yes in step S41), the base station operation unit 101 determines that the ABS and Non-ABS are based on the ABS and Non-ABS of the macrocell base station 200-1 estimated by the ABS pattern estimation unit 104. The CQI-Reporting Config for reporting CSI individually is notified to each small cell terminal 300-P1 (step S42).

On the other hand, when the ABS is not included (No in step S41), the base station operation unit 101 does not distinguish between the ABS and the Non-ABS, and simply sends a CQI-ReportingConfig to each small cell terminal 300- P1 is notified (step S43).

As described above, according to the small cell base station 100-1 according to the first embodiment of the present invention, the macro cell base station 200-1 sets an ABS, and the macro cell base station 200 Even when no ABS status notification is received from -1, the small base station 100-1 can estimate the ABS pattern by itself.

Then, based on the estimation result, it is possible to instruct the small cell terminal 300-P1 to report CQI. Therefore, CSI can be reported separately for the ABS and the Non-ABS, and different appropriate MCSs can be determined for the ABS and the Non-ABS. Since data can be transmitted based on this appropriate MCS, there is an effect that the throughput of the small cell terminal 300-P1 can be improved.

As mentioned above, although this invention was demonstrated with reference to the said embodiment, this invention is not limited to embodiment mentioned above. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

For example, in the above description, the RSRQ of the macrocell base station 200-1 is used as the channel quality used for control, but a measure other than RSRQ may be used as the channel quality. For example, RSSI can be used as the channel quality. In this case, the ABS pattern estimation unit 104 of the small cell base station 100-1 does not perform estimation using Equation 8 in step S28, but estimates Subframe i satisfying Equation 10 below as ABS.

The basis for the estimation is the same as the estimation using Equation 8. That is, since the interference from the macro cell base station 200-1 is reduced in the ABS, the RSSI in the ABS is expected to be lower than the average value of the RSSI in the ABS setting period. Therefore, the following Equation 10 determines whether or not the average RSSI value in the subframe to be determined is lower than the average RSSI value of the macrocell base station 200-1 in the ABS setting cycle. It can be estimated that the subframe to be determined is ABS. The reason for using the ABS determination threshold is the same reason as the estimation using Equation 8.

In Equation 10 below, RSSI_ave (i) [dB] is the RSSI of the i-th subframe in the ABS setting cycle, RSSI_ave is the average value of RSSI in the ABS setting cycle, and ΔThr_RSRQ is the ABS determination threshold.

Other examples of changes are also possible. For example, in the present embodiment described above, the small cell base station 100-1 ends the NLM when a predetermined time has elapsed after shifting to the NLM, and then estimates the ABS pattern. However, after shifting to NLM, the ABS pattern may be periodically estimated to check whether the currently estimated ABS pattern matches the previously estimated (for example, the previous) ABS pattern. Then, the NLM may be terminated when the estimation results continuously match a predetermined number of times or more, for example. Thereby, the estimation accuracy of the ABS pattern can be improved.

Furthermore, other examples of changes are possible. In the above description, it is determined whether or not the average value of RSRQ in the subframe to be determined is higher than the average value of RSRQ of the macrocell base station 200-1 in the ABS setting cycle using Expression 8. Estimated that the subframe to be judged is ABS. By modifying this, when the average value of RSRQ in the subframe to be determined is lower than the average value of RSRQ of the macro cell base station 200-1 in the ABS setting period, it is estimated that the subframe of this determination target is Non-ABS You may make it do. In addition, when the average RSSI value in the subframe to be determined is higher than the average RSSI value of the macro cell base station 200-1 in the ABS setting cycle, it is estimated that the subframe in the determination target is Non-ABS. Anyway.

Note that a change in which the above-described estimation according to Equation 8 is replaced with an estimation according to Equation 10, a change in which the ABS pattern is matched, and a change in which the non-ABS is estimated are described in the present embodiment. In addition, the present invention can be similarly applied to each embodiment described below.

Next, a second embodiment obtained by modifying the above-described first embodiment will be described in detail with reference to the drawings. In the first embodiment, the small cell base station is periodically shifted to the NLM. In this embodiment, the start condition of the NLM is set, and the event condition trigger is changed to satisfy the start condition. The point is different. Although any condition can be adopted as the start condition, in this embodiment, a small divergence between the measured BLER value and the BLER target value in the small cell base station is used as an event trigger. The point which transfers a cell base station to NLM is different from 1st Embodiment.

Next, functions of each small cell base station 400 in the second embodiment will be described with reference to FIG. FIG. 7 is a block diagram showing functions of the small cell base station 400-1. The functions of the other small cell base stations 400 (for example, the small cell base station 400-2) are the same as the functions of the small cell base station 400-1.

The small cell base station 400-1 in the second embodiment is different from the small cell base station 100-1 in the first embodiment in that it includes an NLM transition unit 403 instead of the NLM transition unit 103. Different. Therefore, in the following description, only the NLM transition unit 403 that is the difference will be described, and description of other common functional blocks will be omitted.

The NLM transition unit 403 determines whether or not the small cell base station 400-1 should transition to NLM based on the average BLER of the small cell base station 400-1. In the present embodiment, the NLM transition unit 403 calculates the average BLER by counting the HARQ (Hybrid Automatic Repeat Request) response signals of TB (TransportBlock) reported from each terminal 300-P every predetermined period. Here, there are two types of HARQ response signals: ACK (Acknowledgement) reported when demodulation of transmitted TB is successful and NACK (Negative Acknowledgement) reported when demodulation fails.

However, in the present embodiment, in order to determine whether or not to shift to the NLM using the average BLER of the small cell base station 400-1, it is possible to return to the NLM performed in step S29 of the first embodiment. The transition start time is not set. Further, since the NLM transition unit 103 does not exist, the determination process in step S11 illustrated in FIG. 4 is not performed.

Subsequently, the operation procedure of the small cell base station 400-1 will be described with reference to FIG. FIG. 8 shows an operation procedure in which the NLM transition unit 403 of the small cell base station 400-1 determines whether or not to migrate the small cell base station 400-1 to the NLM. The operation procedure of each other small cell base station 400 (for example, the small cell base station 400-2) is the same as the operation procedure of the small cell base station 400-1. When the small cell base station 400-1 is in a state other than the NLM, the NLM transition unit 403 performs the operation illustrated in FIG. 8 in each subframe.

First, the NLM transition unit 403 uses the following formula 11 to count the number of first-time TB HARQ response signals (SumNum — 1stTx) notified to the small cell base station 400-1 (Step S51). In Equation 11, Num_1stTx (T) is the number of HARQ response signals of the first transmission TB reported to the small cell base station 400-1 between time T-1 [subframe] and time T [subframe]. The initial value of SumNum_1stTx is 0.

Subsequently, the NLM transition unit 403 adds up the number of NACKs (SumNum_1stTx_NACK) in the HARQ response signal of the first transmission TB notified to the small cell base station 400-1 using Equation 12 below (Step S52). ). In Equation 12, Num_1stTx_NACK (T) is the number of NACKs in Num_1stTx (T). Also, the initial value of SumNum_1stTx_NACK is 0.

Next, the NLM transition unit 403 determines whether or not the current time T has reached the time for calculating the BLER of the small cell base station 400-1 using the following Equation 13 (step S53). In Equation 13, Tp_bler is a BLER calculation period. Although the calculation cycle can be set arbitrarily, in this explanation, it is assumed that 200 Subframe, which is a multiple of the ABS setting cycle, is set.

Here, when Expression 13 is satisfied (Yes in Step S53), the NLM transition unit 403 calculates BLER (BLER_ave) of the small cell base station 400-1 using Expression 14 below (Step S54).

Subsequently, the NLM transition unit 403 determines whether or not to migrate the small cell base station 400-1 to the NLM using Equation 15 below (step S55). In Formula 15, ΔThr_BLER is a transition determination threshold value, and is set to a value larger than the target value of BLER by a predetermined value.

If Expression 15 is satisfied (Yes in step S55), the NLM transition unit 403 transitions the small cell base station 400-1 to the NLM (step S12). Here, the reason for shifting to the NLB when the BLER (BLER_ave) of the small cell base station 400-1 exceeds the shift determination threshold will be described. If the same ABS pattern is used without the macro cell base station 200-1 updating the ABS pattern, the accuracy of the ABS pattern estimation result of the macro cell base station 200-1 held by the small cell base station 400-1 is does not change. However, if the macro cell base station 200-1 updates the ABS pattern, the accuracy of the estimation result of the ABS pattern of the macro cell base station 200-1 held by the small cell base station 400-1 decreases, and the small cell base station 400-1 -1 BLER is expected to rise above the target value. Therefore, when the measured BLER exceeds a transition determination threshold value that is larger than the target value by a predetermined value, it is considered that the ABS pattern has been updated, and the macro cell base station 200-is used to infer a new ABS pattern after the change. 1 is transferred to NLB.

Next, the NLM transition unit 403 updates the transition start time to the NLM using the following formula 16 (step S56).

Next, the NLM transition unit 403 initializes SumNum_1stTx and SumNum_1stTx_NACK using Equation 17 below (step S57).

Thereafter, the NLM transition unit 403 ends the process of FIG.

On the other hand, when the formula 13 is not satisfied in the determination in step S53 (No in step S53), the NLM transition unit 403 ends the process of FIG.

On the other hand, if it is determined in step S55 that Expression 15 is not satisfied (No in step S55), the NLM transition unit 403 proceeds to step S57. Then, the NLM transition unit 403 initializes SumNum_1stTx and SumNum_1stTx_NACK using Equation 17 (step S57), and ends the process.

As described above, according to each small cell base station 400 according to the second embodiment of the present invention, each small base station 400 has a large discrepancy between the measured BLER value and the BLER target value in its own station. Only in this case, the ABS pattern of the macrocell base station 200 may be estimated. This is because when the ABS pattern of the macrocell base station 200-1 is updated, the divergence is considered to be large, and it is considered that it is sufficient to estimate the ABS pattern again only in this case.

Therefore, compared with the small cell base station 100-1 of the first embodiment, which periodically estimates the ABS pattern, the macro cell base station 200-1 updates the ABS pattern immediately after the ABS pattern is updated in the small cell. Estimation can be performed, and unnecessary transition to NLM can be avoided when the macro cell base station 200-1 does not update the ABS pattern. That is, there is an effect that it is possible to appropriately estimate the ABS pattern at a timing at which the ABS pattern is considered to be deformed.

For example, in the above description, each small cell base station 400 has been shifted to the NLM with an event trigger that the difference between the measured BLER value and the BLER target value in each small cell base station 400 has increased. Other conditions may be used as event triggers for shifting to NLM. For example, a case where the small cell terminal 300-P1 determines that the load on the macro cell base station 200-1 is high may be added to the event trigger.

The reason why the condition that the load on the macro cell base station 200-1 can be determined to be high is used as an event trigger will be described. When the load on the macro cell base station 200-1 is low, the improvement effect of the communication channel quality of the small cell terminal 300-P1 is small even if the macro cell base station 200-1 sets the ABS. That is, the throughput of the small cell terminal 300-P1 is not different from the ABS and the Non-ABS, and even when the CSI reported periodically is used, the CSI reported separately by the ABS and the Non-ABS. Even if it is used, there is almost no change in both. Therefore, when NLM is applied when the load on the macro cell base station 200-1 is low, the throughput of the small cell terminal 300-P1 deteriorates due to a decrease in data transmission opportunities to the small cell terminal due to the NLM application. There is a possibility that the problem that the effect of improving the communication channel quality of the small cell terminal 300-P1 is not accompanied even if the ABS is set as such.

Therefore, by adding that it has been determined that the load on the macro cell base station 200-1 described above is high to the condition for shifting to the NLM, the transition to the NLM that is not necessary when the load on the macro cell base station 200-1 is low is performed. Can be avoided.

Here, various methods are conceivable for determining the load of the macrocell base station 200-1. As an example, the small cell base station 400- calculated using the average SINR of Non-ABS reported from the small cell terminal 300-P1 and the RSRP of the neighboring base stations reported from the same small cell terminal 300-P1. A method of using a geometry of 1 and determining that the load on the macrocell base station 200-1 is high when the difference between the two is less than a threshold value can be considered.

Here, the geometry is the SINR with respect to the reference signal of the connected base station when receiving interference from all of the neighboring base stations. The reason why it can be determined that the load on the macro cell base station 200-1 is high when the difference between the SINR and the geometry is small is that interference from the macro cell generally increases as the load on the macro cell base station 200-1 increases. This is because the SINR of the non-ABS of the small cell terminal decreases, and the difference between the SINR and the geometry becomes small. This condition can also be added to the first embodiment that periodically shifts to the NLM.

Note that the change of adding or replacing the above-described event trigger can be performed not only in this embodiment but also in each embodiment described below.

Next, a third embodiment obtained by modifying the first embodiment described above will be described in detail with reference to the drawings. In the first embodiment, each small cell base station 100 independently estimates the ABS pattern of each macro cell base station 200, whereas in this embodiment, the estimation results of its own cell and neighboring cells are used. The difference is that the data is aggregated and the estimation result is determined. Specifically, in this embodiment, the estimation results at the small cell base stations and the estimation results at the neighboring small cell base stations are tabulated, and the ABS pattern estimation results of each macro cell base station 200 are determined.

Subsequently, functions of each small cell base station 500 in the third embodiment will be described with reference to FIG. FIG. 9 is a block diagram exclusively representing functions of the small cell base station 500-1. The functions of the other small cell base stations 500 (for example, the small cell base station 500-2) are the same as the functions of the small cell base station 500-1.

Here, the relationship between the small cell base station 500-1 and the small cell base station 500-2, which is a small cell base station around the small cell base station 500-1, will be described.

Each communication area (ie, each small cell) of small cell base station 500-1 and small cell base station 500-2 shown in FIG. 9 is at least one in the communication area (ie, macro cell) of macro cell base station 200-1. Part of the communication area is included.

In FIG. 9, only the small cell base station 500-1 and the small cell base station 500-2 are shown as the small cell base stations, but other than the small cell base station 500-1 and the small base station 500-2. There may be another small cell base station 500-k (k ≠ 1∧k ≠ 2) in which at least a part of the communication area is included in the communication area of the macrocell base station 200-1.

In addition, it is assumed that an X2 interface is established between the small cell base stations 500 and mutual communication between the small cell base stations 500 is possible.

The small cell base station 500-1 in the third embodiment is different from the small cell base station 100 in the first embodiment in that it includes an ABS pattern estimation unit 504 instead of the ABS pattern estimation unit 104. Different. Therefore, in the following description, the ABS pattern estimation unit 504, which is the difference, will be described exclusively, and description of other common functional blocks will be omitted.

The ABS pattern estimation unit 504 includes a DL quality index calculation unit 504-1 and an ABS pattern estimation execution unit 504-2.

In this regard, the function of the DL quality index calculation unit 504-1 is the same as that of the DL quality index calculation unit 104-1.

The ABS pattern estimation execution unit 504-2 estimates the ABS pattern of the macro cell base station 200-1 in the same manner as the ABS pattern estimation execution unit 104-2 of the ABS pattern estimation unit 104. In the description of the present embodiment, this estimation result is referred to as “primary estimation result” for convenience.

Also, the ABS pattern estimation execution unit 504-2 extracts the primary estimation result by referring to the neighboring base station list held by the base station operation unit 101 and the neighboring small cell base station 500-k (k ≠ It further has a function of notifying to 1).

Here, in the present embodiment, the peripheral base station list held by the base station operation unit 101 includes the peripheral small cell base station 500- in which at least a part of the communication area is included in the communication area of the macro cell base station 200-1. Assume that an identifier used for individually identifying k is described. This identifier is, for example, a cell ID.

The ABS pattern estimation execution unit 504-2 uses ABS Status for notification to the neighboring small cell base station 500-k. In addition, as the notification contents of the primary estimation result, the ABS pattern of the macrocell base station 200-1 and the ratio of the ABS are notified. Each of the ABS pattern estimation execution units 504-2 included in the neighboring small cell base station 500-k performs the same estimation, and the primary estimation result is included in the ABS pattern estimation execution unit included in the small cell base station 500-1. Notify 504-2.

Further, the ABS pattern estimation execution unit 504-2 included in the small cell base station 500-1 includes the macro cell base station 200-1 estimated by the ABS pattern estimation execution unit 504-2 included in the small cell base station 500-1. The primary estimation results of the ABS pattern and the primary estimation results of the ABS pattern of the macro cell base station 200-1 notified from the neighboring small cell base station 500-k are aggregated to estimate the ABS pattern of the macro cell base station 200-1. Has the function of determining the result. The determined ABS pattern of the macrocell base station 200-1 is managed by the base station operation unit 101.

Next, the operation of this embodiment will be described with reference to the flowchart of FIG. In FIG. 10, the ABS pattern estimation unit 504 of the small cell base station 500-1 measures the RSRQ of the macro cell base station 200-1, and includes the RSRQ received from the neighboring small cell base station 500-k. Then, the operation procedure of calculating the average channel quality and estimating the ABS pattern of the macrocell base station 200-1 using the channel quality is shown.

Referring to FIG. 10, the operation procedure shown in FIG. 10 is different from the operation procedure shown in FIG. 5 in that step S61 is added. However, processing in other steps is the same as the processing shown in FIG. Therefore, only the added operation of step S61 will be described below. The operation of step S61 is performed by the ABS pattern estimation execution unit 504-2 included in the ABS pattern estimation unit 504. Hereinafter, the operation of the ABS pattern estimation unit 504 will be described.

The ABS pattern estimation unit 504 notifies the estimated small ABS cell pattern of the macro cell base station 200-1 to the neighboring small cell base station 500-k through the base station operation unit 101 as a primary estimation result (step S61). Then, it progresses to step S29 and continues the process similar to the operation | movement procedure represented by FIG.

Next, FIG. 11 is a flowchart showing an operation procedure in which the ABS pattern estimation unit 504 of the small cell base station 500-1 determines the estimation result of the ABS pattern of the macrocell base station 200-1.

The ABS pattern estimation unit 504 uses the result of the primary estimation of the ABS pattern of the latest macro cell base station 200-1 notified to the small cell base station 500-1 after the processing of FIG. 11 is executed. The operation illustrated in FIG. 11 is performed by the ABS pattern estimation execution unit 504-2 of the ABS pattern estimation unit 504. Hereinafter, the operation will be described as the operation of the ABS pattern estimation unit 504.

First, the ABS pattern estimation unit 504 firstly estimates the ABS pattern of the macrocell base station 200-1 estimated by the ABS pattern estimation unit 504 itself included in the small cell base station 500-1, and the neighboring small cell base station 500-1. Summing up the primary estimation results of the ABS pattern of the macro cell base station 200-1 notified from -k. Based on the counting result, the number of times estimated to be ABS (SumNum_abs (i)) is counted for each subframe in the ABS setting cycle (step S71). That is, the number of primary estimation results that estimate Subframe i to be determined as an ABS is counted.

Next, the ABS pattern estimation unit 504 determines the estimation result of the ABS pattern of the macrocell base station 200-1 using the following Equation 18 (step S72). Specifically, if the mathematical formula 18 is satisfied, the subframe i estimation result is determined to be ABS, and if the mathematical formula 18 is not satisfied, the subframe i estimation result is determined to be Non-ABS. In Formula 18, ΔThr_SumNum_abs is a preset ABS determination threshold value.

As described above, according to the small cell base station 500-1 which is the third embodiment of the present invention, the macro cell base station estimated by the ABS pattern estimation unit 504 included in the small cell base station 500-1 itself. In addition to the ABS pattern of 200-1, the macro cell base station 200 estimated by the own station using the ABS pattern of the macro cell base station 200-1 estimated by the neighboring small cell base station 500-k (k ≠ 1) is also used. -1 ABS pattern can be estimated. Therefore, compared with the first embodiment in which the ABS pattern estimated by the own station is used as the ABS pattern estimation result of the macrocell base station 200-1, an effect equivalent to increasing statistical data used for estimation can be expected. . Therefore, the ABS pattern estimation accuracy of the macrocell base station 200-1 is improved.

For example, in this embodiment, the estimation result of the ABS pattern of the macro cell base station 200-1 is determined for each small cell base station 500 individually. That is, each small cell base station 500 performs totalization, and each small cell base station 500 performs the operation process described in FIG. However, by changing this, a master node is selected from the small cell base stations 500, the master node aggregates the primary estimation results from the neighboring small cell base stations 500, determines the estimation results, and the results are used as the neighboring small cells. You may notify to the cell base station 500. FIG. As a result, the partner to which the small cell base station 500 notifies the ABS Status is narrowed down to one master node, so that the amount of signaling between the base stations via the X2 Interface can be suppressed as compared with the above-described processing.

Also, any small cell base station 500 does not become a master node, but an OAM (Oracle Access Manager) server can be connected on the communication line network 900, and this OAM server can be used as the master node. Further, when the OAM server serves as a master node, the primary estimation results of the ABS pattern of the macro cell base station 200-1 notified from the neighboring small cell base station 500 are not counted in the same procedure as in this embodiment. Only the primary estimation results of the ABS pattern of the macro cell base station 200-1 notified from the small cell base station 500 with large interference from the macro cell base station 200-1 may be aggregated.

The reason for this is that the larger the interference from the macro cell base station 200-1, the greater the difference in channel quality between the ABS and the Non-ABS. This is because the estimation accuracy of the ABS pattern 200-1 becomes high. That is, it is possible to perform estimation with higher accuracy by counting only the primary estimation results with high estimation accuracy.

Here, the method of determining the small cell base station 500 with large interference from the macro cell base station 200-1 may be any method. As an example, it is conceivable to use the maximum RSRP among the RSRP of the macrocell base station 200-1 and the base stations other than the macrocell base station 200-1. Then, the determination condition is that the difference between the RSRP of the macrocell base station 200-1 and the maximum RSRP among base stations other than the macrocell base station 200-1 is equal to or greater than a threshold value. The RSRP of the macro cell base station 200-1 and the maximum RSRP among the base stations other than the macro cell base station 200-1 are measured by each small cell base station 500 when NLM is applied, and reported to the OAM server.

It should be noted that only the primary pattern estimation result of the macro cell base station 200-1 notified from the small cell base station 500 notified by the small cell base station 500 having a large interference and the change of determining the master node described above, the change of using the OAM server, and the like. Each of these changes can be made not only in the present embodiment but also in each embodiment described below.

Next, a fourth embodiment of the present invention, which is a modification of the above-described first embodiment, will be described in detail with reference to the drawings. In the first embodiment, the small cell base station directly estimates the ABS pattern of the macro cell base station. However, in this embodiment, the ABS pattern candidates notified in advance are selected. . Specifically, in this embodiment, the macro cell base station ABS pattern candidates are notified to the small cell base station in advance. Then, the small cell base station selects a pattern closest to the ABS pattern of the macro cell base station estimated by the small cell base station from the notified candidates.

Next, a radio communication system 20 according to the fourth embodiment will be described with reference to FIG. The configuration of the wireless communication system 20 is different from the configuration of the wireless communication system 10 of each embodiment described above in that an OAM server 700 is newly added on the communication line network 900 and each small cell base station 100 is small. The difference is that the cell base station 600 is replaced.

Next, functions of each small cell base station 600 according to the fourth embodiment will be described with reference to FIG. FIG. 13 is a block diagram showing the functions of small cell base station 600-1. The functions of the other small cell base stations 600 (for example, the small cell base station 600-2) are the same as the functions of the small cell base station 600-1.

The small cell base station 600-1 in the fourth embodiment includes an ABS pattern estimation unit 604 instead of the ABS pattern estimation unit 104, as compared with the small cell base station 100-1 in the first embodiment. The point is different. Therefore, in the following description, only the ABS pattern estimation unit 604 which is the difference will be described, and description of other common functional blocks will be omitted.

The ABS pattern estimation unit 604 includes a DL quality index calculation unit 604-1 and an ABS pattern estimation execution unit 604-2.

The function of the DL quality index calculation unit 604-1 is the same as that of the DL quality index calculation unit 104-1.

The ABS pattern estimation execution unit 604-2 has a function of estimating the ABS pattern of the macro cell base station 200-1 in the same manner as the ABS pattern estimation execution unit 104-2. In addition, the ABS pattern estimation execution unit 604-2 has a function of receiving and holding a candidate list of ABS patterns that can be set by the macro cell base station 200-1 notified from the OAM server 700. Then, the ABS pattern estimation execution unit 604-2 selects the estimation result of the ABS pattern of the macro cell base station 200-1 from the ABS pattern candidate list based on the ABS pattern of the macro cell base station 200-1 estimated by itself. It has the function to do. The estimation result is managed by the base station operation unit 101.

Here, a candidate list of ABS patterns that can be set by the macrocell base station 200-1 notified from the OAM server 700 will be described with reference to FIG. FIG. 14 shows an example of an ABS pattern candidate list. In FIG. 14, each numerical sequence is a bitmap representation of an ABS pattern, where 1 represents ABS and 0 represents Non-ABS. In this embodiment, there are six ABS pattern candidates for the macrocell base station 200-1 as shown in FIG.

FIG. 15 is a block diagram illustrating functions of the OAM server 700 according to the fourth embodiment. Referring to FIG. 15, the OAM server 700 includes a transmission / reception unit 701 and an information management unit 702.

The transmission / reception unit 701 has a peripheral base station list in which information used to individually identify each small cell base station 600 and each macro cell base station 200 is described. The transmission / reception unit 701 has a function of performing communication with each peripheral base station via the communication line network 900 while referring to the peripheral base station list.

The information management unit 702 has a function of determining the contents of an ABS pattern candidate list that can be set by each macrocell base station 200. Further, the information management unit 702 has a function of notifying each macro cell base station 200 of the determined settable ABS pattern candidate list.

Upon receiving the notification, the macro cell base station 200 selects an ABS pattern from the notified candidate list and sets the ABS.

Furthermore, the information management unit 702 has a function of notifying each small cell base station 600 of a candidate list of ABS patterns that can be set by the macro cell base station 200.

In this embodiment, the ABS pattern candidate list is notified by using ABS Status, with ABS set to 1, Non-ABS set to 0, and the ratio of ABS to 40 subframes in the pattern being described.

Next, an operation procedure in which the ABS pattern estimation unit 604 of the small cell base station 600-1 estimates the ABS pattern of the macro cell base station 200-1 will be described with reference to FIGS. 16-1 and 16-2.

Referring to FIGS. 16-1 and 16-2, compared with the operation procedure shown in FIG. 5, steps S81 to S83 are newly added in the operation procedure shown in FIG. 16-2. It is different in point. However, processing in other steps is the same as the processing shown in FIG. Therefore, in the following, only the operations of the added steps S81 to S83 will be described. The operations in steps S81 to S83 are performed by the ABS pattern estimation execution unit 604-2 of the ABS pattern estimation unit 604. Hereinafter, the operation will be described as the operation of the ABS pattern estimation unit 604.

First, the ABS pattern estimation unit 604 is self-contained for each subframe included in the ABS pattern candidate list of the macrocell base station 200-1 notified from the OAM server 700 and for each subframe in the ABS setting cycle. It is determined whether or not the estimation results match. Then, the number of times of coincidence (Num_True (j)) is counted for each candidate (step S81). Here, j is an identifier for identifying each ABS pattern candidate of the macrocell base station 200-1 notified from the OAM server.

The count in step S81 will be described with reference to a specific example shown in FIG. FIG. 17 shows an example of an ABS pattern estimation result of the macro cell base station 200-1 and an example of a bitmap display of the ABS pattern candidate list of the macro cell base station 200-1. Note that the ABS pattern candidate list of the macrocell base station 200-1 illustrated in FIG. 17 is the same as the candidate list example illustrated in FIG. In the example illustrated in FIG. 17, for example, Num_True of ABS pattern candidate 1, that is, Num_True (j) when j = 1 is 23.

Next, the ABS pattern estimation unit 604 uses the following Equation 19 to calculate the accuracy rate (RateTF (j)) of the estimation result of the ABS pattern candidate of the macro cell base station 200-1 notified from the OAM server 700. ) Is calculated (step S82). In Equation 19, Tp_abs [Subframe] is an ABS setting cycle. In this embodiment, the ABS setting cycle is 40 Subframe. When this is applied to the example shown in FIG. 17, RateTF of ABS pattern candidate 1, that is, RateTF (j) when j = 1 is 0.575 (= 23/40).

Next, the ABS pattern estimation unit 604 estimates the ABS pattern candidate having the highest accuracy rate as the ABS pattern of the macro cell base station 200-1 (step S83). In the example shown in FIG. 17, the ABS pattern of ABS pattern candidate 5 is estimated as the ABS pattern of macrocell base station 200-1.

If a candidate list is prepared in advance as in the present embodiment and selected from this candidate list, accurate estimation is performed for all subframes included in the ABS setting period when the selected candidate is appropriate. Is possible. In other words, if the estimation result of this time is used as it is, the estimation for 3 Subframe in 40 Subframe is wrong, but the candidate 5 can be selected and the accurate ABS pattern can be estimated for 40 Subframe in 40 Subframe. It has the advantageous effect of becoming.

For example, in the above description of the present embodiment, it is assumed that X2 Interface is not established between the small cell base station 600-1 and the macro cell base station 200-1. However, the present embodiment can also be applied to a wireless communication system in which X2 Interface is established. For example, although the X2 Interface is established between the small cell base station 600-1 and the macro cell base station 200-1, the present embodiment can be used even when frequent information exchange cannot be performed from the viewpoint of the amount of signaling between base stations. Similarly, there is a problem that the ABS pattern is not notified appropriately. However, this problem can be solved by applying this embodiment.

Further, if the X2 interface is established, the OAM server 700 determines ABS pattern candidates that can be set in the macro cell base station 200-1, and notifies the small cell base station 600-1 of the candidate list. It is also possible to modify the above-described operation. Specifically, instead of the OAM server 700, ABS pattern candidates that can be set by the macro cell base station 200-1 itself are determined, and the candidate list can be notified to the small cell base station 600-1. .

Although the four embodiments of the first to fourth embodiments have been described, these embodiments are not completely independent and can be combined without departing from the scope of the invention. is there.

For example, the NLB transition unit 103 included in the small cell base station 500 of the third embodiment or the small cell base station 600 of the fourth embodiment may be replaced with the NLB transition unit 403 included in the small cell base station 400 of the second embodiment. Is possible.

In addition, for example, different small cell base stations may be mixed in one wireless communication system. For example, the small cell base station 100 of the first embodiment and the small cell base station 400 of the second embodiment may be mixed in one wireless communication system 10.

Note that each device included in the wireless communication system can be realized by hardware, software, or a combination thereof. Moreover, the time limit frame pattern estimation method performed by each device included in the wireless communication system can also be realized by hardware, software, or a combination thereof. Here, “realized by software” means realized by a computer reading and executing a program.

The program can be stored using various types of non-transitory computer readable media and supplied to a computer. Non-transitory computer readable media include various types of tangible storage media. Examples of non-transitory computer readable media include magnetic recording media (eg, flexible disk, magnetic tape, hard disk drive), magneto-optical recording media (eg, magneto-optical disc), CD-ROM (Read Only Memory), CD- R, CD-R / W, semiconductor memory (for example, mask ROM, PROM (Programmable ROM), EPROM (Erasable ROM), flash ROM, RAM (random access memory)). The program may also be supplied to the computer by various types of temporary computer readable media. Examples of transitory computer readable media include electrical signals, optical signals, and electromagnetic waves. The temporary computer-readable medium can supply the program to the computer via a wired communication path such as an electric wire and an optical fiber, or a wireless communication path.

This application is based on Japanese Patent Application No. 2013-157873 (filed on July 30, 2013), and claims the priority of the Paris Convention based on Japanese Patent Application No. 2013-157873. The disclosure of Japanese Patent Application No. 2013-157873 is incorporated herein by reference to Japanese Patent Application No. 2013-157873.

Although exemplary embodiments of the present invention have been described in detail, various changes, substitutions and alternatives may be made without departing from the spirit and scope of the invention as defined in the claims. It should be understood that this is done. Moreover, even if the claim is amended in the application procedure, the inventor intends that the equivalent scope of the claimed invention is maintained.

Some or all of the above embodiments can be described as in the following supplementary notes, but are not limited thereto.

(Supplementary note 1) In a second area where radio communication that interferes with radio communication in the first area is performed, a time limit frame and a limit that are frames in which radio communication is restricted based on a predetermined frame pattern Under the situation of switching to a time frame other than the time frame, a quality index is calculated for each of a plurality of frames by measuring a signal from at least the second area in the first area, and the calculation By comparing the calculated quality index calculated based on the quality index of each of the plurality of frames and the quality index of the frame that is one of the plurality of frames that is the current determination target, the frame that is the current determination target Is estimated to be either the time limit frame or a time frame other than the time limit frame, Time limit frame pattern estimation apparatus and estimates what frame pattern is used as the predetermined frame pattern by performing constant for a plurality of frames.

(Appendix 2) Notifying the estimated frame pattern to the terminal in the first area, and distinguishing the time limit frame from time frames other than the time limit frame based on the notified frame pattern The time limit frame pattern estimation apparatus according to appendix 1, wherein the terminal in the first area is instructed to report channel quality information.

(Supplementary Note 3) Based on the communication channel quality information reported as a reply to the instruction, radio resources are distinguished from the time limit frame and time frames other than the time limit frame for the terminals in the first area. The time limit frame pattern estimation apparatus according to Supplementary Note 2, wherein:

(Additional remark 4) When the average value of the quality index of the frame to be determined is a value representing a communication state better than the average value of the quality indexes of the plurality of frames, the frame to be determined is the restriction The time limit frame pattern estimation apparatus according to any one of appendices 1 to 3, wherein the time frame pattern is estimated to be a time frame.

(Additional remark 5) The said quality parameter | index is RSRQ (Reference Signal Received Quality) measured in the said 1st area,
Estimating that the frame to be determined is the time limit frame when the average value of RSRQ of the frame to be determined is a predetermined value or more than the average value of RSRQ of the plurality of frames. The time limit frame pattern estimation apparatus according to Supplementary Note 4, which is a feature.

(Appendix 6) The quality indicator is an RSSI (Received Signal Strength Indicator) measured in the first area,
Estimating that the frame to be determined is the time limit frame when the average RSSI value of the frame to be determined is a predetermined value or less than the average value of RSSI of the plurality of frames. The time limit frame pattern estimation apparatus according to Supplementary Note 4, which is a feature.

(Supplementary Note 7) There is at least one third area that is subject to interference by wireless communication in the second area,
A device other than the time limit frame pattern estimation device calculates a quality index by measuring a signal from at least the second area in the third area, and calculates the calculated quality index from a plurality of frames. Estimating which frame pattern is used as the predetermined frame pattern by comparing the calculated quality index and the calculated quality index of any one of the plurality of frames to be determined this time,
The time limit frame pattern estimation device uses the frame pattern estimated by the other device as being used as the predetermined frame pattern, and the time limit frame pattern is used as the predetermined frame pattern. Any one of appendices 1 to 6, wherein what kind of frame pattern is used as the predetermined frame pattern is estimated again based on both the frame pattern estimated by the estimation device. Time frame pattern estimation apparatus.

(Appendix 8) Obtaining a list of the predetermined frame patterns that can be used in the second area, and selecting a frame pattern in the list based on the estimated frame pattern by the time limit frame pattern device The time limit frame pattern estimation device according to any one of appendices 1 to 6, wherein the frame pattern is estimated again by the following:

(Supplementary note 9) The communication status of a terminal that performs wireless communication in the first area is monitored, and the signal from the second area is measured when the monitored communication status is worse than a predetermined communication status. The time-limited frame pattern estimation apparatus according to any one of appendices 1 to 8, wherein a quality index is calculated and the frame pattern is estimated.

(Supplementary Note 10) When the communication load in wireless communication in the second area becomes higher than a predetermined standard, the calculation of the quality index by measuring the signal from the second area and the frame pattern The time limit frame pattern estimation apparatus according to any one of appendices 1 to 8, wherein estimation is executed.

(Supplementary Note 11) After starting the calculation of the quality index by measuring the signal from the second area, if the estimation of the frame pattern is executed a plurality of times, and the plurality of estimation results have the same content 11. The time limit frame pattern estimation device according to any one of appendices 1 to 10, wherein the calculation of the quality index by measuring the signal from the second area and the estimation of the frame pattern are terminated.

(Supplementary note 12) A time limit frame pattern estimation method performed by a computer,
In the second area in which radio communication that interferes with radio communication in the first area is performed, a time frame other than the time limit frame and the time limit frame that are frames for which radio communication is restricted based on a predetermined frame pattern Under the situation of switching between time frames, a quality index is calculated for each of a plurality of frames by measuring a signal from at least the second area in the first area, and the calculated plurality of frames By comparing the calculated quality index calculated based on each quality index with the quality index of the frame that is the current determination target among any of the plurality of frames, the frame that is the current determination target It is estimated whether it is a time frame or a time frame other than the time limit frame, and the estimation is applied to a plurality of frames. Time limit frame pattern estimation method characterized by estimating what frame pattern is used as the predetermined frame pattern by performing the over-time.

(Appendix 13) Notifying the estimated frame pattern to the terminal in the first area, and distinguishing the time limit frame from time frames other than the time limit frame based on the notified frame pattern The time limit frame pattern estimation method according to appendix 12, wherein the terminal in the first area is instructed to report channel quality information.

(Additional remark 14) Based on the communication path quality information reported as a reply with respect to the said instruction | indication, a radio | wireless resource distinguishing the said time limit frame and time frames other than the said time limit frame to the terminal in the said 1st area 14. The time limit frame pattern estimation method according to appendix 13, wherein

(Additional remark 15) When the average value of the quality index of the frame to be determined is a value representing a communication state better than the average value of the quality indexes of the plurality of frames, the frame to be determined is the restriction 15. The time limit frame pattern estimation method according to any one of appendices 12 to 14, wherein the time frame pattern is estimated to be a time frame.

(Supplementary Note 16) The quality index is RSRQ (Reference Signal Received Quality) measured in the first area,
Estimating that the frame to be determined is the time limit frame when the average value of RSRQ of the frame to be determined is a predetermined value or more than the average value of RSRQ of the plurality of frames. The time limit frame pattern estimation method according to Supplementary Note 15, which is a feature.

(Supplementary Note 17) The quality indicator is an RSSI (Received Signal Strength Indicator) measured in the first area,
Estimating that the frame to be determined is the time limit frame when the average RSSI value of the frame to be determined is a predetermined value or less than the average value of RSSI of the plurality of frames. The time limit frame pattern estimation method according to Supplementary Note 15, which is a feature.

(Supplementary Note 18) There is at least one third area that is subject to interference by wireless communication in the second area,
A device other than the computer that performs the time frame pattern estimation method calculates a quality index by measuring a signal from at least the second area in the third area, and calculates the quality of the calculated plurality of frames Estimating which frame pattern is used as the predetermined frame pattern by comparing the calculated quality index calculated from the index and the calculated quality index of any one of the plurality of frames to be determined this time And
The computer that performs the time frame pattern estimation method is used as the frame pattern estimated by the other apparatus and the predetermined frame pattern as being used as the predetermined frame pattern. Additional remark 12: It is estimated again what frame pattern is used as the predetermined frame pattern based on both the frame pattern estimated by the computer performing the time limit frame pattern estimation method. 18. The time limit frame pattern estimation method according to any one of 1 to 17.

(Supplementary Note 19) A frame pattern in the list is acquired based on the frame pattern estimated by the computer that acquires the list of the predetermined frame patterns that can be used in the second area and performs the time frame pattern method. 18. The time limit frame pattern estimation method according to any one of appendices 12 to 17, wherein the frame pattern is estimated again by selecting.

(Supplementary note 20) The communication status of a terminal that performs wireless communication in the first area is monitored, and when the monitored communication status is worse than a predetermined communication status, a signal from the second area is measured. 20. The time-limited frame pattern estimation method according to any one of appendices 12 to 19, wherein a quality index is calculated and the frame pattern is estimated.

(Supplementary Note 21) When the communication load in the wireless communication in the second area becomes higher than a predetermined standard, the calculation of the quality index by measuring the signal from the second area and the frame pattern 20. The time limit frame pattern estimation method according to any one of appendices 12 to 19, wherein estimation is performed.

(Supplementary note 22) After starting the calculation of the quality index by measuring the signal from the second area, if the estimation of the frame pattern is executed a plurality of times, and the plurality of estimation results have the same content The time limit frame pattern estimation method according to any one of appendices 12 to 21, wherein the calculation of the quality index by measuring the signal from the second area and the estimation of the frame pattern are terminated.

(Supplementary Note 23) In the second area in which wireless communication that interferes with wireless communication in each of the plurality of first areas is performed, a time limit that is a frame in which wireless communication is restricted based on a predetermined frame pattern Under the situation of switching between a frame and a time frame other than the time limit frame, each base station in the plurality of first areas measures at least a signal from the second area for each of the plurality of frames. By calculating a quality index and comparing the calculated quality index calculated based on the calculated quality index of each of the plurality of frames and the quality index of the frame that is the current determination target of any of the plurality of frames. The frame to be determined this time is a time other than the time limit frame and the time limit frame. Estimating which frame pattern is used, estimating the frame pattern used as the predetermined frame pattern by performing the estimation on a plurality of frames, and estimating between the base stations A restriction characterized by notifying each other of a frame pattern, and each base station re-estimates the frame pattern based on both the frame pattern estimated by the base station itself and the frame pattern notified by another base station. Time frame pattern estimation system.

(Supplementary Note 24) In a second area where radio communication that interferes with radio communication in each of the plurality of first areas is performed, a time limit that is a frame in which radio communication is restricted based on a predetermined frame pattern Under the condition of switching between a frame and a time frame other than the time limit frame, a quality index is calculated for each of a plurality of frames by measuring a signal from at least the second area in the first area. By comparing the calculated quality index calculated based on the calculated quality index of each of the plurality of frames and the quality index of the frame that is one of the plurality of frames that is the current determination target, Whether the time frame is the time limit frame or a time frame other than the time limit frame Estimate what frame pattern is used as the predetermined frame pattern by performing the estimation for a plurality of frames, and report the estimated frame pattern at each base station to the master node. And
The master node is configured to re-estimate the frame pattern based on a plurality of frame patterns reported from each base station, and notify each base station of the re-estimated frame pattern.

(Supplementary note 25) The master node according to supplementary note 24, wherein the master node is any one of the base stations selected from the base stations.

(Supplementary note 26) The master node according to supplementary note 24, wherein the master node is a server device provided separately from the base station.

(Supplementary Note 27) In a second area where radio communication that interferes with radio communication in the first area is performed, a time limit frame that is a frame in which radio communication is restricted based on a predetermined frame pattern and a restriction Under the situation of switching between time frames other than the time frame,
The server device determines the predetermined frame pattern that can be used in the second area, transmits the determined predetermined frame pattern as a list to the time limit frame pattern estimation device,
The time limit frame pattern estimation device calculates a quality index for each of a plurality of frames by measuring a signal from at least the second area in the first area, and each quality of the calculated plurality of frames By comparing the calculated quality index calculated based on the index and the quality index of the frame that is one of the plurality of frames that is the current determination target, the frame that is the current determination target is the time limit frame A frame pattern in which a frame other than the time limit frame is estimated and a frame pattern used as the predetermined frame pattern is estimated by performing the estimation on a plurality of frames. By selecting a frame pattern in the list based on Said server apparatus in a system and estimates the serial frames pattern again.

(Supplementary Note 28) In a second area where radio communication that interferes with radio communication in the first area is performed, a time limit frame and a limit that are frames in which radio communication is restricted based on a predetermined frame pattern Under the situation of switching between time frames other than the time frame,
The base station of the second area determines the predetermined frame pattern that can be used in the second area, and transmits the determined predetermined frame pattern as a list to the time limit frame pattern estimation device,
The time limit frame pattern estimation device calculates a quality index for each of a plurality of frames by measuring a signal from at least the second area in the first area, and each quality of the calculated plurality of frames By comparing the calculated quality index calculated based on the index and the quality index of the frame that is one of the plurality of frames that is the current determination target, the frame that is the current determination target is the time limit frame A frame pattern in which a frame other than the time limit frame is estimated and a frame pattern used as the predetermined frame pattern is estimated by performing the estimation on a plurality of frames. By selecting a frame pattern in the list based on The base station of the second area in the system and estimates the serial frame pattern again.

(Supplementary Note 29) In a second area where radio communication that interferes with radio communication in the first area is performed, a time limit frame and a limit that are frames in which radio communication is restricted based on a predetermined frame pattern Under the situation of switching to a time frame other than the time frame, a quality index is calculated for each of a plurality of frames by measuring a signal from at least the second area in the first area, and the calculation By comparing the calculated quality index calculated based on the quality index of each of the plurality of frames and the quality index of the frame that is one of the plurality of frames that is the current determination target, the frame that is the current determination target is , Estimating whether the time limit frame or a time frame other than the time limit frame, Limiting the time frame estimation program for causing a computer to function as the time limit frame pattern estimating device for estimating what frame pattern is used as the predetermined frame pattern by performing constant for a plurality of frames.

(Supplementary Note 30) In a second area where radio communication that interferes with radio communication in each of the plurality of first areas is performed, a time limit that is a frame in which radio communication is restricted based on a predetermined frame pattern A time limit frame pattern estimation method performed by the base stations in the plurality of first areas under the situation of switching between a frame and a time frame other than the time limit frame,
Each of the base stations of the plurality of first areas calculates a quality index for each of a plurality of frames by measuring at least a signal from the second area, and is calculated based on the calculated quality index of each of the plurality of frames. The calculated quality index is compared with the quality index of the frame that is the current determination target among any of the plurality of frames, so that the current determination target frame is the time limit frame and the time limit frame. Is estimated for a plurality of frames to estimate what frame pattern is used as the predetermined frame pattern, and between the base stations. Each of the base stations notifies the frame pattern estimated by the base station itself. Time limit frame pattern estimation method characterized by re-estimating the frame pattern based on both the turn and the other notified frame pattern from the base station.

(Supplementary Note 31) A first base station (small cell base station) manages a first communication area (small cell), and a second base station (macro cell base station) includes at least a part of the first communication area. A time limit frame pattern estimation method for managing two communication areas (macro cells) and estimating a time limit frame in which wireless communication with a terminal is restricted in the second communication area,
A quality index for measuring a quality index including a signal of the second communication area in the first base station and calculating an average quality index for all time frames related to the quality index and an average quality index for each time frame in a predetermined period. A calculation step;
A time limit frame pattern estimation step for estimating a combination of the time limit frame and a time frame other than the time limit frame using an average quality index of the all time frames and an average quality index of each time frame;
A method for estimating a time-limited frame pattern, comprising:

(Supplementary Note 32) On the basis of the estimated time limit frame pattern, channel quality information (CQI: Channel Quality Indicator) is transmitted to the terminals in the first communication area at times other than the time limit frame and the time limit frame. A channel quality information reporting instruction step for instructing to report separately from a frame;
The time limit frame pattern estimation method according to supplementary note 31, further comprising:

(Supplementary Note 33) The quality indicator is RSRQ (Reference Signal Received Quality) of the second communication area,
The step of estimating the time limit frame pattern is
32. The time limit frame pattern estimation method according to supplementary note 31, wherein a time frame in which an average quality index of each time frame is equal to or greater than a predetermined value of an average quality index of all time frames is estimated as the time limit frame.

(Supplementary Note 34) The quality indicator is RSSI (Received Signal Strength Indicator),
The step of estimating the time limit frame pattern is
32. The time limit frame pattern estimation method according to supplementary note 31, wherein a time frame in which an average quality index of each time frame is equal to or less than a predetermined value of an average quality index of all time frames is estimated as the time limit frame.

(Supplementary Note 35) There is a third base station group that manages a third communication area group that includes the first communication area that is at least partially included in the second communication area.
Further comprising the step of acquiring information on the limited time frame pattern estimated using a quality indicator including a signal of the second communication area measured in the third base station group,
The step of estimating the time limit frame pattern is
32. The time limit frame pattern estimation method according to supplementary note 31, wherein the time limit frame pattern information determined by the third base station group is aggregated to determine the time limit frame pattern.

(Supplementary Note 36) The method further comprises a time limit frame pattern candidate list acquisition step of acquiring the time limit frame pattern candidate list set in a time frame of a predetermined period,
The step of estimating the time limit frame pattern is
32. The time limit frame pattern according to appendix 31, wherein the time limit frame pattern is selected from the candidate list based on the time limit frame pattern estimated from the measurement result of the first base station. Estimation method.

(Appendix 37)
A transmission error rate measuring step of measuring a user data transmission error rate (BLER: Block Error Rate) in the first communication area;
Starting the measurement of the quality index when the difference between the measurement value of the transmission error rate and the target value of the transmission error rate is equal to or greater than a transmission error rate threshold;
32. The time limit frame pattern estimation method according to supplementary note 31, characterized by:

(Supplementary Note 38) An SINR calculation step of calculating an SINR (Signal To Interference and Noise Ratio) of a data channel in the first communication area;
A geometry calculation step of calculating the geometry of the first communication area;
Starting the measurement of the quality indicator when the difference between the SINR and the geometry is greater than or equal to a SINR threshold;
32. The time limit frame pattern estimation method according to supplementary note 31, characterized by:

(Supplementary Note 39) Estimating a limited time frame pattern in which wireless communication in the second communication area is limited every predetermined period after the measurement of the quality index is started,
Ending the measurement of the quality indicator when the estimation results are the same multiple times,
32. The time limit frame pattern estimation method according to supplementary note 31, characterized by:

(Supplementary Note 40) A first base station (small cell base station) manages a first communication area (small cell), and a second base station (macro cell base station) includes at least a part of the first communication area. A time limit frame pattern estimation device for managing two communication areas (macro cells) and estimating a time limit frame in which wireless communication with a terminal is limited in the second communication area,
A quality index for measuring a quality index including a signal of the second communication area in the first base station and calculating an average quality index for all time frames related to the quality index and an average quality index for each time frame in a predetermined period. A calculation unit;
A time limit frame pattern estimator that estimates a combination of the time frame other than the time limit frame and the time limit frame using an average quality index of the all time frames and an average quality index of each time frame;
An apparatus for estimating a time-limited frame pattern, comprising:

(Supplementary Note 41) Based on the estimated time limit frame pattern, channel quality information (CQI: Channel Quality Indicator) is transmitted to the terminals in the first communication area for a time other than the time limit frame and the time limit frame. A report instruction unit for channel quality information for instructing to report separately from a frame;
42. The time limit frame pattern estimation apparatus according to appendix 40, further comprising:

(Additional remark 42) The said quality parameter | index is RSRQ (Reference Signal Received Quality) of the said 2nd communication area,
The time limit frame pattern estimation unit is:
41. The time limit frame pattern estimation apparatus according to appendix 40, wherein a time frame in which an average quality index of each time frame is equal to or greater than a predetermined value of an average quality index of all time frames is estimated as the time limit frame.

(Supplementary Note 43) The quality indicator is RSSI (Received Signal Strength Indicator),
The time limit frame pattern estimation unit is:
41. The time limit frame pattern estimation apparatus according to appendix 40, wherein a time frame in which an average quality index of each time frame is equal to or less than a predetermined value of an average quality index of all time frames is estimated as the time limit frame.

(Supplementary Note 44) There is a third base station group that manages a third communication area group that includes the first communication area that is at least partially included in the second communication area.
A time-limit frame pattern information acquisition unit for acquiring information on the time-limit frame pattern estimated using a quality index including a signal of the second communication area measured in the third base station group;
The time limit frame pattern estimation unit is:
41. The time limit frame pattern estimation apparatus according to appendix 40, wherein the time limit frame pattern information estimated by the third base station group is aggregated to determine the time limit frame pattern.

(Supplementary Note 45) A time limit frame pattern candidate list acquiring unit that acquires the time limit frame pattern candidate list set in a time frame of a predetermined period,
The time limit frame pattern estimation unit is:
41. The time limit frame pattern selection unit that selects the time limit frame pattern from the candidate list based on the time limit frame pattern estimated from the measurement result of the first base station. Time limit frame pattern estimation device.

(Additional remark 46) It further has the transmission error rate measurement part which measures the transmission error rate (BLER: Block Error Rate) of the user data in the said 1st communication area,
Starting the measurement of the quality index when the difference between the measurement value of the transmission error rate and the target value of the transmission error rate is equal to or greater than a transmission error rate threshold;
41. The time limit frame pattern estimation apparatus according to appendix 40, characterized by:

(Supplementary Note 47) An SINR calculation unit that calculates SINR (Signal To Interference and Noise Ratio) of a data channel in the first communication area;
A geometry calculation unit for calculating the geometry of the first communication area;
Starting the measurement of the quality indicator when the difference between the SINR and the geometry is greater than or equal to a SINR threshold;
41. The time limit frame pattern estimation apparatus according to appendix 40, characterized by:

(Supplementary Note 48) Estimating a limited time frame pattern in which wireless communication in the second communication area is limited every predetermined period after the measurement of the quality index is started,
Ending the measurement of the quality indicator when the estimation results are the same multiple times,
41. The time limit frame pattern estimation apparatus according to appendix 40, characterized by:

(Supplementary Note 49) The first base station (small cell base station) manages the first communication area (small cell), and the second base station (macro cell base station) includes at least a part of the first communication area. The first base station for managing two communication areas (macrocells) and estimating a time limit frame in which wireless communication with a terminal is restricted in the second communication area,
A quality index for measuring a quality index including a signal of the second communication area in the first base station and calculating an average quality index for all time frames related to the quality index and an average quality index for each time frame in a predetermined period. A calculation unit;
A time limit frame pattern estimator that estimates a combination of the time frame other than the time limit frame and the time limit frame using an average quality index of the all time frames and an average quality index of each time frame;
Have
There is a third base station group for managing a third communication area group including the first communication area, at least a part of which is included in the second communication area,
A time-limit frame pattern information acquisition unit for acquiring information on the time-limit frame pattern estimated using a quality index including a signal of the second communication area measured in the third base station group;
The time limit frame pattern estimation unit is:
The first base station characterized in that the time limit frame pattern is determined by aggregating information on the time limit frame patterns estimated by the third base station group.

(Supplementary Note 50) A first base station (small cell base station) manages a first communication area (small cell), and a second base station (macro cell base station) includes at least a part of the first communication area. 2 is a master node for managing a communication area (macro cell) and estimating a time limit frame in which wireless communication with a terminal is limited in the second communication area,
In the first base station, measure a quality index including a signal of the second communication area, calculate an average quality index of all time frames related to the quality index and an average quality index of each time frame in a predetermined period,
A time limit frame pattern estimator that estimates a combination of the time frame other than the time limit frame and the time limit frame using an average quality index of the all time frames and an average quality index of each time frame;
Have
There is a third base station group for managing a third communication area group including the first communication area, at least a part of which is included in the second communication area,
A time-limit frame pattern information acquisition unit for acquiring information on the time-limit frame pattern estimated using a quality index including a signal of the second communication area measured in the third base station group;
The time limit frame pattern estimation unit is:
A master node characterized in that the time limit frame pattern is determined by aggregating information on the time limit frame pattern estimated by the third base station group.

(Supplementary Note 51) The master node according to Supplementary Note 50, wherein the master node is any one of the first base stations.

(Supplementary Note 52) The master node according to Supplementary Note 50, wherein the master node is an OAM server.

(Supplementary Note 53) A first base station (small cell base station) manages a first communication area (small cell), and a second base station (macro cell base station) includes at least a part of the first communication area. An OAM server that manages two communication areas (macro cells) and estimates a time limit frame in which wireless communication with a terminal is restricted in the second communication area,
In the first base station, measure a quality index including a signal of the second communication area, calculate an average quality index of all time frames related to the quality index and an average quality index of each time frame in a predetermined period,
A time limit frame pattern estimator that estimates a combination of the time frame other than the time limit frame and the time limit frame using an average quality index of the all time frames and an average quality index of each time frame;
Have
A time limit frame pattern candidate list acquisition unit for acquiring a time limit frame pattern candidate list set in a time frame of a predetermined period;
The time limit frame pattern estimation unit is:
An OAM server, comprising: a time limit frame pattern selection unit that selects the time limit frame pattern from the candidate list based on the time limit frame pattern estimated from the measurement result of the first base station.

(Supplementary Note 54) A first base station (small cell base station) manages a first communication area (small cell), and a second base station (macro cell base station) includes at least a part of the first communication area. Two second base stations that manage two communication areas (macro cells) and estimate a time limit frame in which wireless communication with a terminal is restricted in the second communication area,
In the first base station, measure a quality index including a signal of the second communication area, calculate an average quality index of all time frames related to the quality index and an average quality index of each time frame in a predetermined period,
A time limit frame pattern estimator that estimates a combination of the time frame other than the time limit frame and the time limit frame using an average quality index of the all time frames and an average quality index of each time frame;
Have
A time limit frame pattern candidate list acquisition unit for acquiring a time limit frame pattern candidate list set in a time frame of a predetermined period;
The time limit frame pattern estimation unit is:
A second base station, wherein the second base station is a time limit frame pattern selection unit that selects the time limit frame pattern from the candidate list based on the time limit frame pattern estimated from the measurement result of the first base station. .

(Supplementary Note 55) A first base station (small cell base station) manages a first communication area (small cell), and a second base station (macro cell base station) includes at least a part of the first communication area. A time limit frame pattern estimation system that manages two communication areas (macro cells) and estimates a time limit frame in which wireless communication with a terminal is limited in the second communication area,
A quality index for measuring a quality index including a signal of the second communication area in the first base station and calculating an average quality index for all time frames related to the quality index and an average quality index for each time frame in a predetermined period. A calculation unit;
A time limit frame pattern estimator that estimates a combination of the time frame other than the time limit frame and the time limit frame using an average quality index of the all time frames and an average quality index of each time frame;
A time-limited frame pattern estimation system comprising:

(Supplementary Note 56) The first base station (small cell base station) manages the first communication area (small cell), and the second base station (macro cell base station) includes at least a part of the first communication area. For managing two communication areas (macrocells) and causing a computer to function as a time limit frame pattern estimation device for estimating a time limit frame in which wireless communication with a terminal is limited in the second communication area A time limit frame pattern estimation program,
A quality index for measuring a quality index including a signal of the second communication area in the first base station and calculating an average quality index for all time frames related to the quality index and an average quality index for each time frame in a predetermined period. A calculation unit;
A time limit frame pattern estimator that estimates a combination of the time frame other than the time limit frame and the time limit frame using an average quality index of the all time frames and an average quality index of each time frame;
A time-limit frame pattern estimation program characterized by comprising:

The present invention is widely suitable for use in estimating a period in which wireless communication is limited.

Claims

In the second area in which radio communication that interferes with radio communication in the first area is performed, a time frame other than the time limit frame and the time limit frame that are frames for which radio communication is restricted based on a predetermined frame pattern Under the situation of switching between time frames, a quality index is calculated for each of a plurality of frames by measuring a signal from at least the second area in the first area, and the calculated plurality of frames By comparing the calculated quality index calculated based on each quality index with the quality index of the frame that is the current determination target among any of the plurality of frames, the frame that is the current determination target Estimating whether the time frame is a time frame other than the time limit frame, and Time limit frame pattern estimation apparatus and estimates what frame pattern is used as the predetermined frame pattern by performing the frame.
The estimated frame pattern is notified to the terminals in the first area, and based on the notified frame pattern, the limited time frame and a time frame other than the limited time frame are distinguished from each other to determine channel quality information. 2. The time limit frame pattern estimation apparatus according to claim 1, wherein a terminal in the first area is instructed to report
Based on the channel quality information reported as a reply to the instruction, the radio resources are allocated to the terminals in the first area by distinguishing the time limit frame and a time frame other than the time limit frame. The time limit frame pattern estimation apparatus according to claim 2, wherein:
When the average value of the quality index of the frame to be determined is a value representing a communication state better than the average value of the quality indexes of the plurality of frames, the frame to be determined is the time limit frame The time-limited frame pattern estimation apparatus according to claim 1, wherein
The quality index is RSRQ (Reference Signal Received Quality) measured in the first area,
Estimating that the frame to be determined is the time limit frame when the average value of RSRQ of the frame to be determined is a predetermined value or more than the average value of RSRQ of the plurality of frames. The time limit frame pattern estimation apparatus according to claim 4,
The quality indicator is RSSI (Received Signal Strength Indicator) measured in the first area,
Estimating that the frame to be determined is the time limit frame when the average RSSI value of the frame to be determined is a predetermined value or less than the average value of RSSI of the plurality of frames. The time limit frame pattern estimation apparatus according to claim 4,
There is at least one third area that is subject to interference by wireless communication in the second area;
A device other than the time limit frame pattern estimation device calculates a quality index by measuring a signal from at least the second area in the third area, and calculates the calculated quality index from a plurality of frames. Estimating which frame pattern is used as the predetermined frame pattern by comparing the calculated quality index and the calculated quality index of any one of the plurality of frames to be determined this time,
The time limit frame pattern estimation device uses the frame pattern estimated by the other device as being used as the predetermined frame pattern, and the time limit frame pattern is used as the predetermined frame pattern. 7. The method according to claim 1, further comprising reestimating what frame pattern is used as the predetermined frame pattern based on both the frame pattern estimated by the estimation device. The time-limited frame pattern estimation apparatus described in 1.
Obtaining the list of the predetermined frame patterns that can be used in the second area, and selecting the frame pattern in the list based on the estimated frame pattern by the time limit frame pattern device; The time limit frame pattern estimation apparatus according to claim 1, wherein the pattern is estimated again.
A quality index obtained by monitoring a communication status of a terminal that performs wireless communication in the first area, and measuring a signal from the second area when the monitored communication status is worse than a predetermined communication status. The time limit frame pattern estimation apparatus according to any one of claims 1 to 8, wherein the calculation of the frame length and the estimation of the frame pattern are executed.
When a communication load in wireless communication in the second area becomes higher than a predetermined reference, a quality index is calculated and a frame pattern is estimated by measuring a signal from the second area. The time limit frame pattern estimation apparatus according to any one of claims 1 to 8, wherein:
After starting the calculation of the quality index by measuring the signal from the second area, the frame pattern is estimated a plurality of times, and when the plurality of estimation results have the same content, The time limit frame pattern estimation apparatus according to any one of claims 1 to 10, wherein calculation of a quality index by measuring a signal from an area and estimation of the frame pattern are terminated.
A time limit frame pattern estimation method performed by a computer,
In the second area in which radio communication that interferes with radio communication in the first area is performed, a time frame other than the time limit frame and the time limit frame that are frames for which radio communication is restricted based on a predetermined frame pattern Under the situation of switching between time frames, a quality index is calculated for each of a plurality of frames by measuring a signal from at least the second area in the first area, and the calculated plurality of frames By comparing the calculated quality index calculated based on each quality index with the quality index of the frame that is the current determination target among any of the plurality of frames, the frame that is the current determination target It is estimated whether it is a time frame or a time frame other than the time limit frame, and the estimation is applied to a plurality of frames. Time limit frame pattern estimation method characterized by estimating what frame pattern is used as the predetermined frame pattern by performing the over-time.
The estimated frame pattern is notified to the terminals in the first area, and based on the notified frame pattern, the limited time frame and a time frame other than the limited time frame are distinguished from each other to determine channel quality information. The time limit frame pattern estimation method according to claim 12, wherein the terminal in the first area is instructed to report
Based on the channel quality information reported as a reply to the instruction, the radio resources are allocated to the terminals in the first area by distinguishing the time limit frame and a time frame other than the time limit frame. The time limit frame pattern estimation method according to claim 13, wherein:
When the average value of the quality index of the frame to be determined is a value representing a communication state better than the average value of the quality indexes of the plurality of frames, the frame to be determined is the time limit frame The time limit frame pattern estimation method according to any one of claims 12 to 14, characterized by:
The quality index is RSRQ (Reference Signal Received Quality) measured in the first area,
Estimating that the frame to be determined is the time limit frame when the average value of RSRQ of the frame to be determined is a predetermined value or more than the average value of RSRQ of the plurality of frames. The time limit frame pattern estimation method according to claim 15, wherein:
The quality indicator is RSSI (Received Signal Strength Indicator) measured in the first area,
Estimating that the frame to be determined is the time limit frame when the average RSSI value of the frame to be determined is a predetermined value or less than the average value of RSSI of the plurality of frames. The time limit frame pattern estimation method according to claim 15, wherein:
There is at least one third area that is subject to interference by wireless communication in the second area;
A device other than the computer that performs the time frame pattern estimation method calculates a quality index by measuring a signal from at least the second area in the third area, and calculates the quality of the calculated plurality of frames Estimating which frame pattern is used as the predetermined frame pattern by comparing the calculated quality index calculated from the index and the calculated quality index of any one of the plurality of frames to be determined this time And
The computer that performs the time frame pattern estimation method is used as the frame pattern estimated by the other apparatus and the predetermined frame pattern as being used as the predetermined frame pattern. The frame pattern estimated by the computer performing the time frame pattern estimation method is estimated again based on what frame pattern is used as the predetermined frame pattern. The time limit frame pattern estimation method according to any one of 12 to 17.
Obtaining a list of the predetermined frame patterns that can be used in the second area, and selecting the frame pattern in the list based on the estimated frame pattern by the computer performing the time-limited frame pattern method; The time frame pattern estimation method according to any one of claims 12 to 17, wherein the frame pattern is estimated again by the following.
A quality index obtained by monitoring a communication status of a terminal that performs wireless communication in the first area, and measuring a signal from the second area when the monitored communication status is worse than a predetermined communication status. The time limit frame pattern estimation method according to any one of claims 12 to 19, wherein the calculation of the frame length and the estimation of the frame pattern are executed.
When a communication load in wireless communication in the second area becomes higher than a predetermined reference, a quality index is calculated and a frame pattern is estimated by measuring a signal from the second area. The time limit frame pattern estimation method according to any one of claims 12 to 19, wherein:
After starting the calculation of the quality index by measuring the signal from the second area, the frame pattern is estimated a plurality of times, and when the plurality of estimation results have the same content, The time limit frame pattern estimation method according to any one of claims 12 to 21, wherein the calculation of the quality index by measuring a signal from the area and the estimation of the frame pattern are terminated.
In a second area where radio communication that interferes with radio communication in each of the plurality of first areas is performed, a time limit frame and a time limit that are frames in which the radio communication is restricted based on a predetermined frame pattern Under the condition of switching to a time frame other than a frame, each base station in the plurality of first areas calculates a quality index for each of the plurality of frames by measuring at least a signal from the second area. The current determination is performed by comparing the calculated quality index calculated based on the calculated quality index of each of the plurality of frames and the quality index of any one of the plurality of frames that is the current determination target. What is the target frame between the time limit frame and a time frame other than the time limit frame? Is estimated for a plurality of frames to estimate what frame pattern is used as the predetermined frame pattern and notifies the estimated frame pattern between the base stations. However, each base station reestimates the frame pattern based on both the frame pattern estimated by the base station itself and the frame pattern notified from the other base station. system.
In a second area where radio communication that interferes with radio communication in each of the plurality of first areas is performed, a time limit frame and a time limit that are frames in which the radio communication is restricted based on a predetermined frame pattern Under the situation of switching to a time frame other than a frame, a quality index is calculated for each of a plurality of frames by measuring a signal from at least the second area in the first area, and the calculated By comparing the calculated quality index calculated based on the quality index of each of the plurality of frames and the quality index of the frame that is the current determination target of any of the plurality of frames, the frame that is the current determination target , Estimating whether the time limit frame or a time frame other than the time limit frame, Estimating what frame pattern as the predetermined frame pattern by performing constant for a plurality of frames are used, the frame pattern estimated at each base station reported to the master node,
The master node is configured to re-estimate the frame pattern based on a plurality of frame patterns reported from each base station, and notify each base station of the re-estimated frame pattern.
The master node according to claim 24, wherein the master node is any one of the base stations selected from the base stations.
25. The master node according to claim 24, wherein the master node is a server device provided separately from the base station.
In the second area in which radio communication that interferes with radio communication in the first area is performed, a time frame other than the time limit frame and the time limit frame that are frames for which radio communication is restricted based on a predetermined frame pattern In the situation of switching between time frames,
The server device determines the predetermined frame pattern that can be used in the second area, transmits the determined predetermined frame pattern as a list to the time limit frame pattern estimation device,
The time limit frame pattern estimation device calculates a quality index for each of a plurality of frames by measuring a signal from at least the second area in the first area, and each quality of the calculated plurality of frames By comparing the calculated quality index calculated based on the index and the quality index of the frame that is one of the plurality of frames that is the current determination target, the frame that is the current determination target is the time limit frame A frame pattern in which a frame other than the time limit frame is estimated and a frame pattern used as the predetermined frame pattern is estimated by performing the estimation on a plurality of frames. By selecting a frame pattern in the list based on It said server apparatus in a system and estimates the serial frame pattern again.
In the second area in which radio communication that interferes with radio communication in the first area is performed, a time frame other than the time limit frame and the time limit frame that are frames for which radio communication is restricted based on a predetermined frame pattern In the situation of switching between time frames,
The base station of the second area determines the predetermined frame pattern that can be used in the second area, and transmits the determined predetermined frame pattern as a list to the time limit frame pattern estimation device,
The time limit frame pattern estimation device calculates a quality index for each of a plurality of frames by measuring a signal from at least the second area in the first area, and each quality of the calculated plurality of frames By comparing the calculated quality index calculated based on the index and the quality index of the frame that is one of the plurality of frames that is the current determination target, the frame that is the current determination target is the time limit frame A frame pattern in which a frame other than the time limit frame is estimated and a frame pattern used as the predetermined frame pattern is estimated by performing the estimation on a plurality of frames. By selecting a frame pattern in the list based on The base station of the second area in the system and estimates the serial frame pattern again.
In the second area in which radio communication that interferes with radio communication in the first area is performed, a time frame other than the time limit frame and the time limit frame that are frames for which radio communication is restricted based on a predetermined frame pattern Under the situation of switching between time frames, a quality index is calculated for each of a plurality of frames by measuring a signal from at least the second area in the first area, and each of the calculated plurality of frames By comparing the calculated quality index calculated based on the quality index of the frame and the quality index of the frame that is the current determination target among any of the plurality of frames, the frame that is the current determination target It is estimated whether the frame is a time frame other than the time limit frame, and the estimation is performed on a plurality of frames. Said predetermined what time limit frame estimation program frame pattern is characterized by causing a computer to function as the time limit frame pattern estimating device for estimating or being used as a frame pattern by performing the over-time.
In a second area where radio communication that interferes with radio communication in each of the plurality of first areas is performed, a time limit frame and a time limit that are frames in which the radio communication is restricted based on a predetermined frame pattern A time limit frame pattern estimation method performed by the base stations in the plurality of first areas under the situation of switching between time frames other than frames,
Each of the base stations of the plurality of first areas calculates a quality index for each of a plurality of frames by measuring at least a signal from the second area, and is calculated based on the calculated quality index of each of the plurality of frames. The calculated quality index is compared with the quality index of the frame that is the current determination target among any of the plurality of frames, so that the current determination target frame is the time limit frame and the time limit frame. Is estimated for a plurality of frames to estimate what frame pattern is used as the predetermined frame pattern, and between the base stations. Each of the base stations notifies the frame pattern estimated by the base station itself. Time limit frame pattern estimation method characterized by re-estimating the frame pattern based on both the turn and the other notified frame pattern from the base station.