WO2014010153A1

WO2014010153A1 - Wireless resource configuration method, base station, wireless communication system and non-temporary computer-readable medium with program stored therein

Info

Publication number: WO2014010153A1
Application number: PCT/JP2013/002535
Authority: WO
Inventors: 大輔太田; 信清　貴宏
Original assignee: 日本電気株式会社
Priority date: 2012-07-11
Filing date: 2013-04-15
Publication date: 2014-01-16
Also published as: JPWO2014010153A1

Abstract

In the present invention, a first base station (100-1) manages a first communications area, a second base station (200-1) manages a second communications area that encompasses at least a portion of the first communications area, and a third base station (200-2) manages a third communications area that is adjacent to the second communications area. If a first criteria, which is calculated from a first index relating to the load of the first communications area and a second index relating to the load of the second communications area, is satisfied, the second base station (200-1) restricts the wireless resources that can be used in the second communications area. If the first criteria is satisfied and a second criteria, calculated from a third index relating to the load of the third communications area, is satisfied, the third base station (200-2) restricts the wireless resources that can be used in the third communications area.

Description

Radio resource setting method, base station, radio communication system, and non-transitory computer-readable medium storing program

The present invention relates to a radio resource setting method, a base station, a radio communication system, and a non-transitory computer-readable medium storing a program, and more particularly, to an assigned radio resource setting technique for suppressing interference with neighboring cells.

In a wireless communication system such as LTE (Long Term Evolution) standardized in 3GPP (Third Generation Partnership Project), a plurality of base stations are arranged, and each base station has a communication area (hereinafter referred to as a communication area) allocated to the base station. Communication with a communication terminal (mobile station) located within a cell. In addition, a cell can be divided into a plurality of parts by imparting directivity to the antenna, and this divided area is called a sector cell. Hereinafter, the cell includes not only a normal cell but also a sector cell.

In LTE, the same communication band is used in each of a plurality of cells. Therefore, a communication terminal (hereinafter referred to as an edge terminal) located at the boundary between cells receives strong interference from adjacent cells regardless of uplink or downlink. In order to cope with such a problem, adjacent cells set different priority bands in advance, and each cell allocates a radio resource of the priority band of the own cell to a communication terminal in communication with the own cell, There is known an interference management technique called ICIC (Inter Cell Interference Coordination) that suppresses interference between adjacent cells by restricting allocation of radio resources in the priority band of adjacent cells. The restriction of the radio resource here may be, for example, excluding the priority band of an adjacent cell from the allocation target to the communication terminal or suppressing the transmission power.

As a method for setting the priority band, a technique called FFR (Fractional Frequency Reuse) is known (Non-patent Document 1) that prevents the priority band from overlapping between cells by performing partial frequency repetition. In addition, as a method of notifying a priority band to adjacent cells, LOAD INFORMATION is specified in LTE. For example, it is possible to use RNTP (relative narrowband TX power) in the downlink of LTE and HII (high interference indication) in the uplink (Non-patent Document 2).

Furthermore, in recent years, as a countermeasure against the increase in traffic volume, a heterogeneous network in which cells of various sizes are mixed, in which a base station (small cell base station) with low transmission power is introduced in addition to a conventional macro base station. (Heterogeneous Network) is drawing attention. However, in the heterogeneous network, the cell boundary area expands with an increase in the number of cells, and thus inter-cell interference becomes more problematic. In order to deal with this problem, 3GPP Release 10 standardized eICIC (enhanced ICIC) as interference management technology, and specified ABS (Almost Blank Subframe) (Non-patent Document 3). In addition, eICIC is also called time domain ICIC. If it is a downlink, the base station which set ABS will stop transmission of a data channel (PDSCH: Physical Data Shared Channel). Thereby, the SINR (Signal to Interference and Noise Ratio) of the communication terminal in the adjacent cell is greatly improved, and an increase in throughput of the communication terminal can be expected.

By the way, as a priority band notification condition in ICIC, Non-Patent Document 4 proposes “a case where there are a predetermined number or more of terminals whose communication path quality is equal to or lower than the required quality” (hereinafter, Conventional Technology 1). According to the prior art 1, when there is a communication terminal at the cell edge, the priority band can be notified to the adjacent cell. However, in the prior art 1, when the number of communication terminals in the cell to which the priority band is notified is large, the 5% value of the cumulative distribution of throughput of all communication terminals in the wireless communication system deteriorates. For this reason, there has been a problem that the fairness of throughput between communication terminals is lost. This problem occurs because, in a cell having a large number of communication terminals, the communication band allocated per communication terminal is small, and the radio resources allocated to the communication terminals are limited although the throughput of each communication terminal is originally low.

In order to solve this problem, Patent Document 1 restricts the allocation of radio resources to communication terminals only when the load defined by the number of communication terminals or the like is less than a threshold in a cell to which a priority band is notified. Has been proposed (hereinafter referred to as Prior Art 2). Thereby, in a cell having a large number of communication terminals and originally low throughput of the communication terminals, it is possible to avoid the limitation of the allocated radio resources.

In the prior art 2, when the number of edge terminals is equal to or greater than a predetermined value, the priority band is notified to the neighboring cell. Then, the notification destination cell restricts radio resource allocation only when the number of communication terminals is smaller than that of the notification source cell. For example, the threshold value is three. Under this condition, it is assumed that the wireless communication system includes a base station A that manages the pico cell A, a base station B that manages the macro cell B, and a base station C that manages the macro cell C adjacent to the macro cell B (see FIG. 13). Here, the base station A is a base station with low transmission power. Further, it is assumed that the pico cell A has five communication terminals, four of which are edge terminals located on the cell boundary. Further, it is assumed that the macro cell B and the macro cell C each have four communication terminals, one of which is an edge terminal. Since the number of terminals of the macro cell B and the macro cell C is the same four, the traffic between the macro cell B and the macro cell C is balanced, and there is no great difference between the number of terminals of the pico cell A, so each communication of the macro cell A Terminal throughput is not particularly high. Therefore, the edge terminal of the macro cell A is a dominant terminal with respect to the 5% value of the cumulative distribution of throughput of all communication terminals.

At this time, according to the prior art 2, since the number of edge terminals of the pico cell A is four, which is larger than the threshold value, the pico cell A notifies the macro cell B of the priority band. Since the number of terminals of the macro cell B is four, which is less than the number of five terminals of the pico cell A, the macro cell B performs radio resource allocation restriction such as reducing the transmission power to the notified priority band.

As a result, the channel quality of the terminal of the macro cell B deteriorates. Therefore, the traffic balance between the macro cell B and the macro cell C is lost. In particular, the edge terminal of the macro cell B has a relatively high interference level from the macro cell C, so that the channel quality is significantly degraded and the throughput is greatly degraded. Therefore, the 5% value of the cumulative distribution of throughput of all communication terminals deteriorates, and the fairness of throughput between communication terminals is lost.

Japanese Patent Application No. 2011-036659

As described above, when the related art 2 is applied to the heterogeneous network, the traffic load balance between the cells is lost, and the throughput of the communication terminal is excessively deteriorated in the cell in which the allocation of the radio resources is restricted. There was a problem that the fairness of the throughput of the communication terminal was lost.

The present invention has been made to solve such problems, and a radio resource setting method, a base station, a radio communication system, and a non-transitory computer storing a program capable of suppressing interference with adjacent cells. An object is to provide a readable medium.

A radio resource setting method according to the present invention is a radio resource setting method for a base station to perform radio communication with a communication terminal in a communication area of the base station, wherein the first base station Managing a communication area, a second base station managing a second communication area including at least a part of the first communication area, and a third base station managing a third communication area adjacent to the second communication area. Managing, obtaining a first indicator relating to the load of the first communication area, a second indicator relating to the load of the second communication area, and a third indicator relating to the load of the third communication area; Limiting radio resources that can be used in the second communication area on condition that the first criterion calculated from the first indicator and the second indicator is satisfied, and 1 standard Satisfied, and the condition that satisfies the second criterion is calculated from the third index, and a step of restricting the radio resource that can be used in the third communication area.

A base station according to the present invention is a base station that manages a first communication area, wherein the first communication area is at least partially included in a second communication area managed by a second base station, and The communication area is adjacent to the third communication area managed by the third base station, and a load measuring unit that obtains a first index related to the load of the first communication area; and a second related to the load of the second communication area Priority to obtain an index and to notify the priority band to at least the third base station on condition that at least the first criterion calculated from the first index and the second index is satisfied A bandwidth setting unit.

A wireless communication system according to the present invention is a wireless communication system in which a base station performs wireless communication with a communication terminal in a communication area of the base station, and the first base station that manages the first communication area; A second base station that manages a second communication area that includes at least a part of the first communication area, and a third base station that manages a third communication area adjacent to the second communication area, The first base station acquires a first index related to the load of the first communication area and a second index related to the load of the second communication area, and at least the first index and the second index And a priority band is notified to at least the third base station on the condition that the first criterion calculated from the first index is satisfied, and the third base station transmits a third bandwidth related to a load in the third communication area. An index of the first base station If et priority bandwidth information is notified, the condition that satisfies the second criterion is calculated from the third index, restricting the radio resource that can be used in the third communication area. *

A non-transitory computer-readable medium in which a program according to the present invention is stored is a computer that performs wireless resource setting processing for a base station to perform wireless communication with a communication terminal in a communication area of the base station. The first base station manages the first communication area, the second base station manages the second communication area including at least a part of the first communication area, and the third base station. Manages a third communication area adjacent to the second communication area, a first index relating to the load of the first communication area, a second index relating to the load of the second communication area, and the third communication. Obtaining the third index relating to the load of the area, and satisfying a first criterion calculated from at least the first index and the second index, Communication A wireless resource that can be used in the third communication area, on the condition that the first criterion is satisfied and the second criterion calculated from the third indicator is satisfied. A non-transitory computer readable medium having stored thereon a program having the steps of limiting possible radio resources.

According to the present invention, it is possible to provide a non-transitory computer-readable medium storing a radio resource setting method, a base station, a radio communication system, and a program that can suppress interference with neighboring cells.

1 is a diagram illustrating a configuration of a wireless communication system 10 according to a first embodiment. 3 is a diagram illustrating a configuration of pico base station 100-1 and macro base station 200-1 in Embodiment 1. FIG. 3 is a diagram illustrating a configuration of a communication terminal 300-P1-1 in Embodiment 1. FIG. FIG. 6 is a diagram showing a method of setting a priority band of the pico base station 100-1 in the first embodiment. 6 is a diagram illustrating a method of determining whether to restrict allocation of radio resources of the macro base station 200-1 according to Embodiment 1. FIG. FIG. 10 is a diagram illustrating a configuration of pico base station 400-1 and macro base station 500-1 in the second embodiment. FIG. 11 is a diagram showing a method of setting a priority band of the pico base station 400-1 in the second embodiment. FIG. 11 is a diagram illustrating a method for determining whether to restrict allocation of radio resources of the macro base station 500-1 in the second embodiment. FIG. 11 is a diagram illustrating a method for determining whether to restrict allocation of radio resources of the macro base station 500-1 in the second embodiment. FIG. 11 is a diagram illustrating the configuration of pico base station 600-1 and macro base station 700-1 in Embodiment 3. It is a figure which shows the setting method of the interference suppression band with respect to pico base station 600-1 of macro base station 700-1 in embodiment. FIG. 10 is a diagram illustrating an implementation determination method for radio resource allocation restriction of the macro base station 700-1 according to Embodiment 3. It is a figure which shows the subject in a prior art.

Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings.

<Embodiment 1>
FIG. 1 shows the configuration of radio communication system 10 according to Embodiment 1 of the present invention.

The wireless communication system 10 applies the present invention to the LTE downlink.

The radio communication system 10 includes pico base stations 100-1 and 100-2, macro base stations 200-1 and 200-2, and a plurality of communication terminals 300-P1-1, 300-P1-2, 300-M1-. 1 and 300-M1-2. Here, communication terminal 300-P1-X is connected to pico base station 100-1. Communication terminal 300-M1-Y is connected to macro base station 200-1. X and Y are arbitrary indexes for identifying a terminal in each base station.

Note that the numbers of macro base stations, pico base stations, and communication terminals are not limited to those described above. Further, in the following description, items common to each pico base station and each macro base station are described as “pico base station 100 is” and “macro base station 200 is”, respectively. Similarly, regarding the communication terminal, when describing items common to each communication terminal connected to the pico base station and each communication terminal connected to the macro base station, “Pico communication terminal 300-P is "," Macro communication terminal 300-M is ... ". In addition, when a matter common to each communication terminal is described regardless of the base station to be connected, it is described as “communication terminal 300 is”.

The pico base stations 100-1 and 100-2 and the macro base stations 200-1 and 200-2 can communicate with each other via the communication line NW. Each pico base station 100 and each macro base station 200 can manage a plurality of communication areas (cells). In the present embodiment, each pico base station 100 and each macro base station 200 manage one communication area.

The pico base station 100 is a low transmission power base station and has a smaller communication area than the macro base station 200. The communication area of each pico base station 100 is assumed to include at least a part of the communication area in the communication area of each macro base station 200.

Each pico base station 100 performs wireless communication with the communication terminal 300-P existing in the communication area managed by the base station 100. Each pico base station 100 is configured to perform wireless communication simultaneously with each of the plurality of communication terminals 300-P.

Each macro base station 200 performs wireless communication with the communication terminal 300-M existing in the communication area excluding the communication area managed by the pico base station 100 from the communication area managed by the base station 200. Each macro base station 200 is configured to perform wireless communication simultaneously with each of the plurality of communication terminals 300-M.

Each pico base station 100 and each macro base station 200 includes an information processing device (not shown). The information processing apparatus includes a central processing unit (CPU: Central Processing Unit) and a storage device (for example, a memory and a hard disk drive (HDD)) (not shown). Each pico base station 100 and each macro base station 200 are configured to realize functions to be described later by a CPU executing a program stored in a storage device.

Each communication terminal 300 is, for example, a mobile phone terminal. Each communication terminal 300 may be a personal computer, PHS (Personal Handyphone System), PDA (Personal Data Assistance, Personal Digital Assistant), smart phone, car navigation terminal, game terminal, or the like.

Each communication terminal 300 includes a CPU, a storage device (memory), an input device (for example, a key button and a microphone), and an output device (for example, a display and a speaker). Each communication terminal 300 is configured to realize functions to be described later when the CPU executes a program stored in the storage device.

FIG. 2 is a block diagram showing functions of each pico base station 100 and each macro base station 200 in the wireless communication system 10.

Here, pico base station 100-1 will be described as a representative for the pico base station, and macro base station 200-1 will be described as a representative for the macro base station. Although not shown in FIG. 2, the function of the pico base station 100-2 is the same as the function of the pico base station 100-1. Similarly, the function of the macro base station 200-2 is the same as the function of the macro base station 200-1.

The pico base station 100-1 includes a base station operation unit 101, a reference signal generation unit 102, a load measurement unit 103, a priority band setting unit 104, and a scheduler 105.

The base station operation unit 101 has a function of transmitting / receiving a radio signal to / from each communication terminal 300-P1 connected to the pico base station 100-1, an allocated band used for transmitting / receiving the radio signal, and a TBS (Transport Block Size). A function for determining scheduling information such as Index and transmission power setting information for each communication terminal 300-P1 and notifying each communication terminal 300-P1, and at least the macro base station 200-1 and each adjacent macro base station 200-k It has a peripheral base station list in which information for identifying (k ≠ 1) is described, and has a function of performing communication with peripheral base stations via the communication line NW. In addition, since these functions are well-known functions employed in a general wireless communication system, detailed description is omitted.

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

The load measurement unit 103 measures the actual load of the pico base station 100-1, and notifies the measured base load information to the surrounding base stations including at least the macro base station 200-1 via the base station operation unit 101. It has the function to do. In the present embodiment, the actual load is a PRB (Physical Resource Block) usage rate. The PRB is disclosed in the following document, for example.

3GPP TS 36.314 V9.1.0 (2010-06), 3GPP TSG RAN E-UTRA Layer 2-Measurements, pp. 6-7, June. 2010

Furthermore, the load measurement unit 103 measures the transmission load of the pico base station 101-1. In this embodiment, the transmission load is an instantaneous value of the number of Active UEs. Here, the instantaneous value of the number of active UEs is the number of connected communication terminals at the time of scheduling. The measured actual load and transmission load are input to the priority band setting unit 104 via the base station operation unit 101 and used.

The priority band setting unit 104 uses the actual load and the transmission load of the pico base station 100-1 measured by the load measuring unit 103 and the actual load notified from the macro base station 200-1, and uses the actual load notified from the macro base station 200-1. It is determined whether or not one priority band is to be set, and the determination result is referred to the neighboring base station list managed by the base station operation unit 101, and the macro base station 200-1 and each adjacent macro base station 200- It has a function of notifying k (k ≠ 1). In the present embodiment, the priority band is the system band, and RNTP (Relativate Narrowband TX Power) is used for notification of the determination result. RNTP is set to 1 for an RB (Resource Block) set as a priority band, and is set to 0 for an RB not set as a priority band. RB represents a frequency block, which is a radio band allocation unit. In the present embodiment, when the priority band setting unit 104 sets the priority band of the pico base station 100-1, the RNTP of all RBs is set to 1 and notified, and when not set, the RNTP of all RBs Set to 0 to notify.

The scheduler 105 has a transmission buffer for managing transmission data addressed to each communication terminal 300-P1 arriving via the communication line NW and information thereof. The scheduler 105 is based on the transmission data size addressed to each communication terminal 300-P1 remaining in the transmission buffer, and CSI (Channel State Information) information such as CQI (Channel Quality Indicator) reported from each communication terminal 300-P1. The communication terminal 300-P1 has a function of assigning transmission power and frequency band and transmitting data via the base station operation unit 101.

The macro base station 200-1 includes a base station operation unit 201, a reference signal generation unit 202, a load measurement unit 203, an allocated radio resource setting unit 204, and a scheduler 205.

The base station operation unit 201 has a function of transmitting / receiving a radio signal to / from each communication terminal 300-M1 connected to the macro base station 200-1, an allocated band used for transmitting / receiving a radio signal, and a TBS (Transport Block Size). A function of determining scheduling information such as Index and setting information of transmission power for each communication terminal 300-M1, and notifying each communication terminal 300-M1, and at least the pico base station 100-1 and each adjacent macro base station 200 A neighboring base station list in which information for identifying -k (k ≠ 1) and the pico base station 100-k installed in the communication area of each adjacent macro base station 200-k is described; Have functions to communicate with neighboring base stations via the communication line NW, but these functions are used in general wireless communication systems. Since it is known of the functionality, a detailed description thereof will be omitted.

The reference signal generation unit 202 has a function of generating a reference signal used by the communication terminal 300 to measure the channel quality with the macro base station 200-1. The generated signal is transmitted to each communication terminal 300 via the base station operation unit 201.

The load measurement unit 203 measures the actual load of the macro base station 200-1, and sends information on the measured actual load via the base station operation unit 201 to the pico base station 100-1 and the adjacent macro base station 200-k. It has a function to notify the surrounding base station including The measured actual load is input to the assigned radio resource setting unit 204 via the base station operation unit 201 and used.

The allocated radio resource setting unit 204 is configured such that the RNTP notified from the pico base station 100-1, the actual load of the macro base station 200-1 measured by the load measuring unit 202, and the actual result notified from the pico base station 100-1. Using the load information and the actual load information of each adjacent macro base station notified from each adjacent macro base station 200-k, the macro base station 200-1 transmits radio resource information to the communication terminal 300-M1. It has a function for determining whether or not to perform allocation restriction. In the present embodiment, when the allocated radio resource setting unit 203 determines to limit the allocation of radio resources to the communication terminal 300-M1, the band that can be allocated to the communication terminal 300-M1 is assigned to the system. The transmission power of PDSCH which is a data channel is set to a transmission power smaller than a preset reference transmission power. Further, when the allocation restriction execution determination unit 203 determines that the wireless resource allocation is not limited to the communication terminal 300-M1, the band that can be allocated to each communication terminal 300-M1 is set as the system band. Set the transmission power and set a reference transmission power that is set in advance.

The scheduler 205 has a transmission buffer for managing transmission data addressed to each communication terminal 300-M1 arriving via the communication line NW and information thereof. The scheduler 205 is based on the transmission data size addressed to each communication terminal 300-M1 remaining in the transmission buffer and CSI (Channel State Information) information such as CQI (Channel Quality Indicator) reported from each communication terminal 300-M1. The communication terminal 300-M1 has a function of allocating transmission power and frequency band and transmitting data via the base station operation unit 201.

FIG. 3 is a block diagram showing functions of the communication terminal 300-P1-1 in the wireless communication system 10.

Although not shown in FIG. 3, the functions of communication terminal 300-P1-1 are communication terminal 300-P1-2, communication terminal 300-P2-1, communication terminal 300-P2-2, and communication terminal 300. -The same function as that of M1-1 and communication terminal 300-M1-2.

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

The communication terminal operation unit 301 has a function of transmitting / receiving a radio signal to / from the pico base station 100-1 connected to the communication terminal 300 (a communication link has been established). In addition, since these functions are well-known functions employed in a general wireless communication system, detailed description is omitted.

The channel quality measuring unit 202 has a function of measuring channel quality with respect to the reference signal and transmitting information on the measured channel quality to the pico base station 100-1. In this embodiment, the channel quality is a CQI calculated from the SIRP for the RSRP and the reference signal.

Next, the operation of the wireless communication system 10 will be described using FIG. 4 and FIG.

FIG. 4 shows an operation procedure in which the priority band setting unit 104 of the pico base station 100-1 determines whether or not to set the priority band of the pico base station 100-1.

The priority band setting unit 104 executes the operation shown in FIG. 4 for each period in which the PRB usage rate is notified from the macro base station 200-1.

First, in order to determine whether or not there is a communication terminal 300-P1 connected to the pico base station 100-1 and the number of the communication terminal 300-P1 is large, the priority band setting unit 104 calculates the pico base calculated by the load measuring unit 103. It is determined whether or not the instantaneous value N_pue of the Active UE count of the station 100-1 is equal to or greater than the required value N_thr_p (step S101).

When the instantaneous value N_pue of the active UE number of the pico base station 100-1 is equal to or greater than the required value N_thr_p (Yes in step S101), the priority band setting unit 104 determines the communication terminal 300-P1 connected to the pico base station 100-1 It is determined that the number is large, and the relative load ΔU_p of the pico base station 100-1 is calculated according to Equation 1 (step S102). U_m represents the PRB usage rate of the macro base station 200-1.

Next, the priority band setting unit 104 determines whether or not the relative load ΔU_p of the pico base station 100-1 is equal to or greater than the required value ΔU_thr_p (step S103).

When the relative load ΔU of the pico base station 100-1 is equal to or greater than the required value ΔU_thr_p (S103, Yes), the priority band setting unit 104 sets the RNTP of all RBs to 1, and the macro base station The station 200-1 and each adjacent macro base station 200-k (k ≠ 1) are notified (step S104). Thereafter, the process of FIG. 4 is terminated.

On the other hand, when the relative load ΔU of the pico base station 100-1 is less than the required value ΔU_thr_p (S103, No), the priority band setting unit 104 sets the RNTP of all RBs to 0, The macro base station 200-1 and each adjacent macro base station 200-k are notified (step S105). Thereafter, the process of FIG. 4 is terminated.

On the other hand, if the instantaneous value N_pue of the number of active UEs of the pico base station 100-1 is less than the required value N_thr_p in step S101 (step S101, No), the priority band setting unit 104 communicates with the pico base station 100-1. It is determined that the number of terminals 300-P1 is small or does not exist, and the process proceeds to step 105.

FIG. 5 shows an operation procedure in which the allocated radio resource setting unit 204 of the macro base station 200-1 sets radio resources that can be allocated to each communication terminal 300-M1 connected to the macro base station 200-1. .

The allocated radio resource setting unit 204 executes the operation shown in FIG. 5 every time it receives an RNTP from the pico base station 100-1.

First, the assigned radio resource setting unit 204 determines whether or not the RNTP notified from the pico base station 100-1 to the macro base station 200-1 is 1 (step S201).

When the RNTP notified from the pico base station 100-1 to the macro base station 200-1 is 1 (Yes in step S201), the allocated radio resource setting unit 204 transmits the PDSCH transmission power P_pdsch of the macro base station 200-1 Is smaller than the reference power P_rs by a value P_offset (> 0 dB) (step S202).

When the transmission power P_pdsch is a value smaller than the reference power P_rs by P_offset (step S202, Yes), the allocated radio resource setting unit 204 ends the process of FIG.

On the other hand, when the transmission power P_pdsch is not a value smaller than the reference power P_rs by P_offset (step S202, No), the allocated radio resource setting unit 204 updates the transmission power P_pdsch from P_rs to a value smaller than ΔP_offset (> 0 dB) (step S203). . The setting information of the transmission power P_pdsch is notified to each communication terminal 300-M1 via the base station operation unit 201. Thereby, interference from the macro base station 200-1 can be suppressed for each communication terminal 300-P1 of the pico base station 100-1.

On the other hand, when the RNTP notified from the pico base station 100-1 to the macro base station 200-1 is 0 (No in step S201), the allocated radio resource setting unit 204 sets each adjacent macro base station 200-k (k It is determined whether or not RNTP notified from at least one of the pico base stations 100-k installed in the communication area of ≠ 1) to the macro base station 200-1 is 1 (step S204).

The assigned radio resource setting unit 204 is connected to the macro base station 200-1 when all the RNTPs notified from each pico base station 100-k to the macro base station 200-1 are 0 (No in S204). It is determined whether or not the transmission power P_pdsch of each communication terminal 300-M1 is equal to the reference power P_rs (step S205).

The allocated radio resource setting unit 204 ends the process of FIG. 5 when the transmission power P_pdsch is the same value as the reference power P_rs (Yes in step S205).

On the other hand, when the transmission power P_pdsch is not the same value as the reference power P_rs (step S205, No), the allocated radio resource setting unit 204 updates the transmission power P_pdsch to P_rs (step S206).

On the other hand, when the RNTP notified from at least one station of each pico base station 100-k to the macro base station 200-1 is 1 (Yes in step S204), the allocated radio resource setting unit 204 sets the pico base station 100-k. It is determined whether the PRB usage rate U_p of 1 is greater than or equal to the threshold value U_thr_p (step S207).

If the PRB usage rate U_p of the pico base station 100-1 is less than the threshold value U_thr_p (No in step S207), the allocated radio resource setting unit 204 proceeds to step S205.

On the other hand, when the PRB usage rate U_p of the pico base station 100-1 is equal to or greater than the threshold value U_thr_p (step S207, Yes), the allocated radio resource setting unit 204 calculates the relative load ΔU_m of the macro base station 200-1 according to Equation 2. (Step S208). U_m represents the PRB usage rate of the macro base station 200-1, and U_nm (i) represents the PRB usage rate of the adjacent macro base station 200-i. Further, i is an index of the adjacent macro base station 200-k listed in the adjacent macro base station list of the macro base station 200-1, and Nn_m is the number of adjacent macro base stations of the macro base station 200.

Next, the allocated radio resource setting unit 204 determines whether or not the relative load ΔU_m of the macro base station 200-1 is equal to or less than the required value ΔU_thr_m (step S209).

When the relative load ΔU_m of the macro base station 200-1 is equal to or less than the required value ΔU_thr_m (step S209, No), the assigned radio resource setting unit 204 proceeds to step S202. On the other hand, when the relative load ΔU_m of the macro base station 200-1 is larger than the required value ΔU_thr_m (step S205, Yes), the process proceeds to step S205.

According to pico base station 100-1 and macro base station 200-1 according to the present embodiment, the number of communication terminals 300-P1 connected to pico base station 100-1 is large, and pico base station 100-1 When the traffic load of the macro base station 200-1 is higher than the traffic load of the macro base station 200-1, the macro base station 200 having a low load among the macro base station 200-1 and each adjacent macro base station 200-k (k ≠ 1) -K limits the allocated radio resources. Thereby, while maintaining the traffic load balance between the macro base stations, the channel quality of each pico terminal 300-P can be improved, and the throughput of the pico base station can be improved.

It should be noted that the first embodiment is not limited to the above-described configuration, and various changes can be made without departing from the scope of the present invention.

For example, the priority band setting unit 104 instead of calculating the difference between the PRB usage rate of the macro base station 200-1 and the PRB usage rate of the pico base station 100-1 as the relative load of the pico base station 100-1, The ratio of the PRB usage rate of the macro base station 100-1 to the PRB usage rate of the base station 200-1 may be calculated.

Further, the priority band setting unit 104 may omit the process of step S101 in FIG. 4 and start the operation from the process of step S102. The conditional expression in step S101 is used to determine whether or not there is a communication terminal 300-P1 connected to the pico base station 100-1 and the number thereof is large. Among these, the presence / absence of the communication terminal 300-P1 connected to the pico base station 100-1 can be replaced by the conditional expression in step S103. If the PRB usage rate U_P of the pico base station is at least ΔU_thr_P or more, it is determined that there is a communication terminal 300-P1 connected to the pico base station 100-1. By omitting step S101, the processing step of the pico base station 100-1 can be omitted.

Also, the assigned radio resource setting unit 204 sets the PRB usage rate of the macro base station 200-1 and the PRB usage rate of each adjacent macro base station 200-k (k ≠ 1) as the relative load of the macro base station 200-1. Instead of calculating the difference value from the average value, the ratio of the PRB usage rate of the macro base station 200-1 to the average value of the PRB usage rate of each adjacent macro base station 200-k (k ≠ 1) may be calculated. good. The average PRB usage rate of each adjacent macro base station 200-k (k ≠ 1) used in the calculation of the relative load of the macro base station 200-1 is the PRB of each adjacent macro base station 200-k (k ≠ 1). It may be a predetermined value in the cumulative distribution of usage rate. Alternatively, PRB usage of the macro base station 200-k (k ≠ 1) for the pico base station 100-k (k ≠ 1) that has notified the priority band from among the adjacent macro base stations 200-k (k ≠ 1) It is good as a rate. Further, the PRB usage rate of the macro base station 200-1 may be used as the relative load of the macro base station 200-1.

Also, the allocated radio resource setting unit 204 sets the transmission power to a transmission power smaller than a preset reference transmission power when it is determined to limit the allocation of radio resources to the communication terminal 300-M1. Thus, although the allocation is restricted, the present invention is not limited to this. For example, the allocation may be limited by setting a band that can be allocated to a band other than the notified priority band. In this case, the priority band is a partial band obtained by dividing the system band into a plurality. Alternatively, the allocation may be limited by setting the allocatable time to a time other than ABS. In this case, the macro base station 200-1 does not perform data transmission during the ABS time. Further, the above allocation restriction methods may be combined. Furthermore, the method for performing the allocation restriction may be changed for each terminal.

Also, as the actual load used in the present embodiment, the number of Active UEs can be used. When the number of Active UEs is used as the actual load, an OAM server is connected on the communication line NW. The OAM server has a function of counting the number of Active UEs from each pico base station 100 and each macro base station 200 connected to the communication line NW. The number of Active UEs can be used in each pico base station 100 and each macro base station 200 via the OAM server.

In addition, as a transmission load used in the present embodiment, an average value can be used instead of an instantaneous value of the number of Active UEs. As the average value, a simple addition average or a weighted average can be considered. Alternatively, the PRB usage rate can be used instead of the Active UE number.

In addition, the present invention is a case where no pico base station is installed in the communication area of the macro base station, or when the number of pico terminals connected to the pico base station where the communication area overlaps with the macro base station is constantly small It can also be applied to. In this case, the assigned radio resource setting unit 204 determines in step 204 that the RNTP notified from at least one of the pico base stations 100-k to the macro base station 200-1 is 1 (step S204). Yes), the process of step S208 is performed without performing the process of step S207. With this modification, even in a macro base station in which no pico base station is installed in the communication area of the own station, it is possible to limit the allocated radio resources in order to maintain the traffic load balance between the macro base stations.

The above changes can also be made in the second and third embodiments described later.

<Embodiment 2>
FIG. 6 is a block diagram showing functions of each pico base station 400 and each macro base station 500 according to Embodiment 2 of the present invention.

Here, pico base station 400-1 will be described as a representative for a pico base station, and macro base station 500-1 will be described as a representative for a macro base station. Although not shown in FIG. 2, the function of the pico base station 400-2 is the same as the function of the pico base station 400-1. Similarly, the function of the macro base station 500-2 is the same as the function of the macro base station 500-1.

The pico base station 400-1 in the second embodiment is characterized by having a priority band setting unit 404 in place of the priority band setting unit 104, as compared to the pico base station 100-1 in the first embodiment. Also, the macro base station 500-1 in the second embodiment has an allocated radio resource setting unit 504 in place of the allocated radio resource setting unit 204, compared to the macro base station 200-1 in the first embodiment. Has characteristics. Other configurations may be the same as those in the first embodiment unless otherwise specified. Hereinafter, the priority band setting unit 404 and the assigned radio resource setting unit 504 will be described.

The priority band setting unit 404 includes the actual load and transmission load of the pico base station 400-1 measured by the load measuring unit 103, the actual load information notified from the macro base station 500-1, and each communication terminal 300-P1. And the communication channel quality information reported from the terminal, it is determined whether or not to set the priority band of the pico base station 400, and the determination result is notified to the macro base station 500-1. Further, the priority band setting unit 404 receives the actual load information of the neighboring macro base station 500-k notified from each neighboring macro base station 500-k (k ≠ 1) and the pico base of each neighboring macro base station 500-k. Using the actual load information of the pico base station 400-k notified from the station 400-k, the adjacent macro base station notifying the determination result is selected from the adjacent macro base stations 500-k, and the selected adjacent The macro base station has a function of notifying the determination result. In the present embodiment, the actual load and the transmission load are both PRB usage rates, and the channel quality is RSRP (Reference Signal Received Power). In the present embodiment, when the priority band setting unit 404 sets the priority band of the pico base station 400, the RNTP of all RBs is set to 1 for notification, and when it is not set, the notification is not performed.

The allocated radio resource setting unit 504 notifies the RNTP notified from the pico base station 400-1 and the pico base station 400-k installed in the communication area of each adjacent macro base station 200-k (k ≠ 1). The macro base station 500-1 has a function of determining whether or not to restrict the allocation of radio resources to the communication terminal 300-M1, using the RNTP. In the present embodiment, when allocated radio resource setting section 504 determines to limit the allocation of radio resources to communication terminal 300-M1, communication terminal 300 until a predetermined time elapses after receiving the notification. -For M1, set the band that can be allocated to the system band, and set the transmission power to a transmission power smaller than the preset reference transmission power. Further, after a predetermined time has elapsed, for the communication terminal 300-M1, an assignable bandwidth is set as a system bandwidth, and a transmission power is set to a preset reference transmission power.

FIG. 7 shows an operation procedure in which the priority band setting unit 404 determines whether or not to set the priority band of the pico base station 400-1.

The priority band setting unit 404 executes the operation shown in FIG. 7 for each period in which the PRB usage rate is notified from the macro base station 500-1.

First, the priority band setting unit 404 determines whether or not the PRB usage rate U_p of the pico base station 400-1 calculated by the load measuring unit 103 is equal to or greater than the required value U_thr_p (step S301).

When the PRB usage rate U_p of the pico base station 400-1 is less than the required value U_thr_p (No in step S301), the priority band setting unit 404 ends the process of FIG.

On the other hand, when the PRB usage rate U_p of the pico base station 400-1 is equal to or greater than the required value U_thr_p (step S301, Yes), the priority band setting unit 404 calculates the relative load ΔU_p of the pico base station 400-1 according to Equation 1. (Step S302), it is determined whether or not ΔU_p is equal to or greater than the required value ΔU_thr_p (Step S303).

If the relative load ΔU of the pico base station 400-1 is less than the required value ΔU_thr_p (No at Step S303), the priority band setting unit 404 ends the process of FIG.

On the other hand, when the relative load ΔU of the pico base station 400-1 is equal to or greater than the required value ΔU_thr_p (S303, Yes), the priority band setting unit 404 calculates the ratio R_p of the edge terminals of the pico base station 400-1 according to Equation 3. (Step S304). N_epue represents the number of edge terminals of the pico base station 400-1, and N_pue represents the number of terminals of the pico base station 400-1. The edge terminal is a terminal satisfying Equation 4 among the terminals of the pico base station 400. When the difference between the received power from the pico base station 400-1 and the received power from the macro base station 500-1 is small, the interference with other cells becomes large, and the edge terminal is determined. RSRP_p represents the RSRP of the pico base station 400-1, and RSRP_m represents the RSRP of the macro base station 500-1. ΔRSRP_thr is a threshold value.

Next, the priority band setting unit 404 determines whether the ratio R_p of the edge terminals of the pico base station 400-1 is equal to or greater than the required value R_thr_p (step S305).

If the ratio R_p of edge terminals of the pico base station 400-1 is less than the required value ΔU_thr_p (No in step S305), the priority band setting unit 404 ends the process of FIG.

On the other hand, when the ratio R_p of edge terminals of the pico base station 400-1 is equal to or greater than the required value ΔU_thr_p (S305, Yes), the priority band setting unit 404 sets the RNTP of all RBs to 1, and the macro base station 500- 1 is notified (step S306).

Next, the priority band setting unit 404 extracts the neighboring macro base station 500-k (k ≠ 1) of the macro base station 500-1 described in the neighboring base station list of the base station operation unit 101 (step 1). S307), it is determined whether or not the PRB usage rate U_p (k) of the pico base station 400-k installed in the communication area of the extracted adjacent macro base station 500-k is equal to or greater than the required value U_thr_p (step S308).

When the PRB usage rate U_p (k) of the pico base station 400-k is equal to or greater than the required value U_thr_p (step S308, Yes), the priority band setting unit 404 determines the relative load ΔU_m (k) of the adjacent macro base station 500-k. Calculation is performed according to Equation 5 (step S309). U_m (k) represents the PRB usage rate of the adjacent macro base station 500-k, and U_nm (j) represents the PRB usage rate of the adjacent macro base station 500-j (j ≠ k) in the adjacent macro base station 500-k. . Nn_m (k) is the number of adjacent macro base stations in the adjacent macro base station 500-k.

Next, the priority band setting unit 404 determines whether or not the relative load ΔU_m (k) of the adjacent macro base station 500-k is less than the required value ΔU_thr_m (step S310).

When the relative load ΔU_m (k) of the adjacent macro base station 500-k is less than the required value ΔU_thr_m (step S310, Yes), the priority band setting unit 404 sets the RNTP of all RBs to 1 and sets the adjacent macro base station 500-k is notified (step S311).

Thereafter, the priority band setting unit 404 repeats the processing from step S307 to step S311 for all adjacent macro base stations included in the neighboring base station list (step S312).

When the relative load ΔU_m (k) of the adjacent macro base station 500-k is larger than the required value ΔU_thr_m (No at Step S310), the process proceeds to Step S312.

If the relative load U_p (k) of the pico base station 400-k is less than the required value U_thr_p (step S308, No), the process proceeds to step S312.

When the priority band setting unit 404 executes the processing from step S307 to step S311 for all adjacent macro base stations 500-k included in the neighboring base station list of the base station operation unit 101 (step S312, Yes) ), The process of FIG.

In FIG. 8, the allocated radio resource setting unit 504 determines whether to limit radio resources that can be allocated to the communication terminal 300-M1 connected to the macro base station 500-1, and based on the determination result. The operation | movement procedure which sets the radio | wireless resource which can be allocated to communication terminal 300-M1 is shown.

The assigned radio resource setting unit 504 executes the operation shown in FIG. 8 at predetermined intervals.

First, the assigned radio resource setting unit 504 determines whether or not the macro base station 500-1 has received a notification that RNTP is 1 from at least one of the pico base stations 400 (step S401).

The assigned radio resource setting unit 504 ends the process of FIG. 8 when the macro base station 500-1 has not received any RNTP 1 notification from any pico base station 400 (No in step S401).

When the macro base station 500-1 receives a notification that RNTP is 1 from at least one of the pico base stations 400 (step S401, Yes), the allocated radio resource setting unit 504 calculates T_end calculated according to Equation 6 500-1 is set as the time for releasing the suppression of the transmission power of PDSCH (step S402). T represents the current time, and T_icic represents the time for the macro base station 500-1 to suppress the transmission power of the PDSCH.

Next, the allocated radio resource setting unit 504 determines whether or not the PDSCH transmission power P_pdsch of the communication terminal 300-M1 connected to the macro base station 500-1 is smaller than the reference power P_rs by P_offset (> 0 dB). (Step S403).

Allocated radio resource setting unit 504 updates transmission power P_pdsch from P_rs to a value smaller than ΔP_offset (> 0 dB) when transmission power P_pdsch is not a value smaller than reference power P_rs (No in step S403) (step S404).

On the other hand, when the transmission power P_pdsch is a value smaller than the reference power P_rs by P_offset (Yes in step S403), the allocated radio resource setting unit 504 ends the process.

Subsequently, in FIG. 9, the allocated radio resource setting unit 504 determines whether or not to cancel the limitation of radio resources that can be allocated to the communication terminal 300-M1 connected to the macro base station 500-1, An operation procedure for setting a radio resource that can be allocated to the communication terminal 300-M1 based on the determination result is shown.

The assigned radio resource setting unit 504 executes the operation shown in FIG. 9 for each hour frame.

First, the allocated radio resource setting unit 504 determines whether or not the current time T is after the time T_end when the macro base station 500 cancels the transmission power suppression (step S501).

The assigned radio resource setting unit 504 ends the process of FIG. 9 when the current time T is before the time T_end when the macro base station 500-1 cancels the transmission power suppression (No in step S501).

On the other hand, the assigned radio resource setting unit 504 connects to the macro base station 500-1 when the current time T is after the time T_end when the macro base station 500-1 cancels the transmission power suppression (Yes in step S501). It is determined whether or not the transmission power P_pdsch of each communication terminal 300-M1 is equal to the reference power P_rs (step S502).

The assigned radio resource setting unit 504 ends the process of FIG. 9 when the transmission power P_pdsch is the same value as the reference power P_rs (Yes in step S502).

On the other hand, when the transmission power P_pdsch is not the same value as the reference power P_rs (No in step S502), the allocated radio resource setting unit 504 updates the transmission power P_pdsch to P_rs (step S503). Then, the process of FIG. 9 is complete | finished.

According to the present embodiment, in the pico base station 400-1, only when the proportion of the communication terminal 300-P1 whose channel quality is degraded due to interference from the macro base station 500-1 is large, the communication terminal 300- Interference from the macro base station 500-1 with respect to P1 is suppressed. Therefore, the macro base station 500-1 and each of the adjacent macro base stations 500-k (k ≠ 1) are compared only when the improvement effect of the communication channel quality of the communication terminal 300-P1 is large compared to the first embodiment. It is possible to limit the allocated radio resources of the macro base station having a low load.

Furthermore, according to the present embodiment, the RNTP is notified only to the macro base station that restricts the allocated radio resources. Therefore, compared with Embodiment 1, the amount of signaling between base stations via the communication line NW can be suppressed.

It should be noted that the second embodiment is not limited to the above-described configuration, and it is needless to say that various modifications can be made without departing from the gist of the present invention.

For example, the priority band setting unit 404 may determine an edge terminal using RSRQ (Reference Signal Received Quality). In step S304, the priority band setting unit 404 determines that a terminal satisfying Equation 7 is an edge terminal. RSRQ_p represents the RSRQ of the pico base station 400, and RSRQ_m represents the RSRQ of the macro base station 500. ΔRSRQ_thr is a threshold value.

Alternatively, the priority band setting unit 404 may determine the edge terminal using the ABS CQI and the Non-ABS CQI. Since the edge terminal has a large amount of interference from the macro base station 700-1, there is a difference between the channel quality at the ABS that does not receive interference from the macro base station 700-1 and the channel quality at the non-ABS. This is because it becomes larger. In step S304, the priority band setting unit 404 determines that a terminal satisfying Equation 8 is an edge terminal. SINR_ABS represents the SINR calculated from the CQI of the ABS, and SINR_NonABS represents the SINR calculated from the CQI of the Non-ABS. ΔSINR_thr is a threshold value. By using Expression 8, it is possible to determine an edge terminal having a large SINR difference between ABS and Non-ABS.

Note that the determination of the edge terminal described above can also be performed in the first embodiment.

Also, the allocated radio resource setting unit 504 in the present embodiment releases the radio resource restriction when a predetermined time has elapsed since the start of radio resource restriction, but is the same as in the first embodiment. In addition, the restriction may be released when any one of the criteria for implementing the restriction of the radio resource cannot be satisfied. Or in Embodiment 1, like this Embodiment, you may cancel | release, if predetermined | prescribed time passes after starting a restriction | limiting.

The above changes can also be made in the third embodiment to be described later.

<Embodiment 3>
FIG. 10 is a block diagram showing the functions of each pico base station 600 and each macro base station 700 in the third embodiment.

Here, a pico base station 600-1 will be described as a representative for a pico base station, and a macro base station 700-1 will be described as a representative for a macro base station. Although not shown in FIG. 10, the function of pico base station 600-2 is the same as the function of pico base station 600-1. Similarly, the function of the macro base station 700-2 is the same as the function of the macro base station 700-1.

Compared to pico base station 100-1 in the first embodiment, pico base station 600-1 in the third embodiment has a load measurement unit 603 instead of load measurement unit 103, and priority band setting unit 104 This is characterized in that is omitted. Also, the macro base station 700-1 in the third embodiment has a load measurement unit 703 instead of the load measurement unit 203 as compared with the macro base station 200-1 in the first embodiment, and a new interference It is characterized in that it has a suppression band setting unit 706 and in that it has an assigned radio resource setting unit 704 instead of the assigned radio resource setting unit 204.

The load measuring unit 603 measures the actual load of the pico base station 600-1, and notifies the information of the measured actual load to the neighboring base stations including at least the macro base station 700-1 via the base station operation unit 101. It has the function to do. In the present embodiment, the actual load is the PRB usage rate.

The load measuring unit 703 measures the actual load of the macro base station 700-1, and uses the measured actual load information via the base station operation unit 201 to connect the pico base station 600-1 and the adjacent macro base station 700-k. It has a function to notify the surrounding base station including Further, the load measurement unit 703 measures the transmission load of the pico base station 701-1. In this embodiment, the transmission load is the PRB usage rate. The PRB usage rate of the pico base station 701-1 is notified from the pico base station 701-1. The measured actual load and transmission load are input to the interference suppression band setting unit 706 via the base station operation unit 201 and used.

The interference suppression band setting unit 706 measures the actual load of the macro base station 700-1, the transmission load of the pico base station 600-1, and the base station notified from the pico base station 600-1 measured by the load measuring unit 702. A function to determine whether to set an interference suppression band for the pico base station 600-1 and to notify the adjacent macro base station 700-k (k ≠ 1) of the determination result. Have In the present embodiment, when interference suppression band setting section 706 sets an interference suppression band for pico base station 600-1, RNTP of all RBs is set to 1 and notified, and when not set, all RBs The RNTP is set to 0 and notified. The determination result is input to the assigned radio resource setting unit 704 via the base station operation unit 101 and used.

The allocated radio resource setting unit 704 includes the determination result of the interference suppression band setting unit 706, the RNTP notified from each adjacent macro base station 700-k, and the actual load of the macro base station 700-1 measured by the load measurement unit 703. And the actual load information of the base station notified from the pico base station 600-1 and the actual load information of each adjacent macro base station notified from each adjacent macro base station 700-k. The base station 700-1 has a function of determining whether or not to restrict allocation of radio resources to the communication terminal 300-M1. In the present embodiment, when the allocated radio resource setting unit 704 determines to limit the allocation of radio resources to the communication terminal 300-M1, the band that can be allocated to the communication terminal 300-M1 is assigned to the system. The bandwidth is set, and the transmission power is set to a transmission power smaller than a preset reference transmission power. Also, if the allocated radio resource setting unit 704 determines not to limit the allocation of radio resources to the communication terminal 300-M1, it sets the band that can be allocated to the communication terminal 300 as the system band, A reference transmission power with a preset transmission power is set.

FIG. 11 shows an operation procedure in which the interference suppression band setting unit 706 determines whether to set an interference suppression band for the pico base station 600-1.

The interference suppression band setting unit 706 performs the operation shown in FIG. 11 for each period in which the PRB usage rate is notified from the pico base station 600-1.

First, the interference suppression band setting unit 706 determines whether or not the PRB usage rate U_p of the base station notified from the pico base station 600-1 is equal to or greater than the required value U_thr_p (step S601).

When the PRB usage rate U_p of the pico base station 600-1 is equal to or greater than the required value U_thr_p (step S601, Yes), the interference suppression band setting unit 706 calculates the relative load ΔU_p of the pico base station 600-1 according to Equation 1 ( Step S602).

Next, the interference suppression band setting unit 706 determines whether or not the relative load ΔU_p of the pico base station 600-1 is equal to or greater than the required value ΔU_thr_p (step S603).

When the relative load ΔU of the pico base station 600-1 is equal to or greater than the required value ΔU_thr_p (S603, Yes), the interference suppression band setting unit 706 sets the RNTP of all RBs to 1, The neighboring macro base station 700-k (k ≠ 1) is notified (step S604). Then, the process of FIG. 11 is complete | finished.

On the other hand, when the relative load ΔU of the pico base station 600-1 is less than the required value ΔU_thr_p (No in S603), the interference suppression band setting unit 706 sets the RNTP of all RBs to 0. Then, the neighboring macro base station 700-k (k ≠ 1) is notified (step S505). Then, the process of FIG. 11 is complete | finished.

In addition, when the PRB usage rate U_p of the pico base station 600 is less than the required value U_thr_p in step S601 (step S601, No), the interference suppression band setting unit 706 proceeds to step 605.

FIG. 12 shows an operation procedure in which the allocated radio resource setting unit 704 sets radio resources that can be allocated to the communication terminal 300-M1 connected to the macro base station 700-1.

The assigned radio resource setting unit 704 executes the operation shown in FIG. 12 after the macro base station 700-1 executes the operation shown in FIG.

In comparison with FIG. 5, in FIG. 12, step S201 is changed to step S701, and step S204 is changed to step S704. Further, Steps S702 to S703 in FIG. 12 are the same as Steps S202 to S203 in FIG. 5, and Steps S705 to S706 in FIG. 12 are the same as Steps S205 to S206 in FIG. Hereinafter, only the operations in step S701 and step S704 changed from FIG. 5 will be described.

First, the allocated radio resource setting unit 704 determines whether or not the macro base station 700-1 has notified the adjacent macro base station 700-k (k ≠ 1) as RNTP as 1 (step S701).

When the macro base station 700-1 notifies the adjacent macro base station 700-k that RNTP is 1 (Yes in step S701), the allocated radio resource setting unit 704 is a communication terminal connected to the macro base station 700-1. It is determined whether or not the transmission power P_pdsch of the 300-M1 PDSCH is smaller than the reference power P_rs by P_offset (> 0 dB) (step S702).

On the other hand, when the macro base station 700-1 notifies the adjacent macro base station 700-k that RNTP is set to 0 (No in step S701), the allocated radio resource setting unit 704 at least of each adjacent macro base station 700-k) It is determined whether or not the RNTP notified from one station to the macro base station 700-1 is 1 (step 704).

The assigned radio resource setting unit 704 connects to the macro base station 700-1 when all the RNTPs notified from each adjacent macro base station 700-k to the macro base station 700-1 are 0 (No in S704). It is determined whether or not the transmission power P_pdsch of the existing communication terminal 300-M1 is equal to the reference power P_rs (step S705).

On the other hand, when the RNTP notified from at least one of the adjacent macro base stations 700-k to the macro base station 700-1 is 1 (Yes in step S704), the allocated radio resource setting unit 704 determines that the pico base station 700 It is determined whether the PRB usage rate U_p of −1 is equal to or greater than the threshold value U_thr_p (step S707).

Note that the third embodiment is not limited to the above-described configuration, and various modifications can be made without departing from the scope of the present invention.

For example, the macro base station 700-1 determines whether or not to restrict the allocation of radio resources to the communication terminal 300-Mk of the adjacent macro base station 700-k (k ≠ 1), and sets the determination result to the adjacent The macro base station 700-k can also be notified using RNTP. In this case, the assigned radio resource setting unit 703 determines in step S704 that RNTP notified from at least one of the adjacent macro base stations 700-k to the macro base station 700-1 is 1 (step S704). (S704, Yes), the process proceeds to step S702.

<Other embodiments>
It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

For example, in the above-described embodiment, the present invention has been mainly described as a hardware configuration. However, the present invention is not limited to this, and allows a CPU (Central Processing Unit) to execute a computer program for arbitrary processing. Can also be realized. In this case, the computer program can be stored using various types of non-transitory computer readable media and supplied to the computer. Non-transitory computer readable media include various types of tangible storage media. Examples of non-transitory computer-readable media include magnetic recording media (for example, flexible disks, magnetic tapes, hard disk drives), magneto-optical recording media (for example, magneto-optical disks), CD-ROMs (Read Only Memory), CD-Rs, CD-R / W, semiconductor memory (for example, mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, RAM (Random access memory)). In addition, the program may 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.

The present invention has been described above with reference to the embodiment, but the present invention is not limited to the 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 invention.

This application claims priority based on Japanese Patent Application No. 2012-155908 filed on July 11, 2012, the entire disclosure of which is incorporated herein.

The present invention relates to a radio resource setting method, a base station, a radio communication system, and a non-transitory computer readable medium storing a program.

10 wireless communication system 100-1 pico base station 100-2 pico base station 101 base station operating unit 102 reference signal generating unit 103 load measuring unit 104 priority band setting unit 105 scheduler 200-1 macro base station 200-2 macro base station 201 Base station operation unit 202 Reference signal generation unit 203 Load measurement unit 204 Assigned radio resource setting unit 205 Scheduler 300-P1-1 Communication terminal 300-P1-2 Communication terminal 300-P2-1 Communication terminal 300-P2-2 Communication terminal 300 -M1-1 communication terminal 300-M1-2 communication terminal 300-M2-1 communication terminal 300-M2-2 communication terminal 301 communication terminal operation unit 302 communication path quality measurement unit 400-1 pico base station 400-2 pico base station 404 Priority band setting section 500-1 Macro base station 500-2 Mac Base station 504 Allocation radio resource setting unit 600-1 Pico base station 600-2 Pico base station 603 Load measurement unit 700-1 Macro base station 700-2 Macro base station 703 Load measurement unit 704 Allocation radio resource setting unit 706 Interference suppression band Setting section

Claims

A base station is a radio resource setting method for performing radio communication with a communication terminal in a communication area of the base station,
The first base station manages the first communication area,
A second base station manages a second communication area including at least a part of the first communication area;
The third base station manages a third communication area adjacent to the second communication area,
Obtaining a first indicator relating to the load of the first communication area, a second indicator relating to the load of the second communication area, and a third indicator relating to the load of the third communication area;
Limiting radio resources that can be used in the second communication area on condition that at least a first criterion calculated from the first index and the second index is satisfied;
Limiting radio resources that can be used in the third communication area on condition that the first criterion is satisfied and the second criterion calculated from the third index is satisfied;
A radio resource setting method comprising:
The first criterion is:
The radio resource setting method according to claim 1, wherein a difference or ratio of the second index with respect to the first index is equal to or greater than a first threshold value.
Further comprising obtaining a fourth index relating to the load of the first communication area;
The first criterion is:
The difference or ratio of the second index to the first index is greater than or equal to the first threshold;
And the said 4th parameter | index is more than a 2nd threshold value, The radio | wireless resource setting method of Claim 1 characterized by the above-mentioned.
The second criterion is:
The radio resource setting method according to claim 1, wherein the third index is less than a third threshold value.
The second criterion is:
The radio resource setting method according to claim 1, wherein a difference between the third index and the second index is less than the third threshold value.
Obtaining a fifth indicator relating to a load in a communication area adjacent to the third communication area;
Calculating an average value of the fifth index,
The second criterion is:
The radio resource setting method according to claim 1, wherein a difference between the third index and the average value is less than the third threshold value.
The radio resource setting method according to any one of claims 1 to 6, wherein the first index, the second index, and the third index are bandwidth usage rates.
The radio resource setting method according to any one of claims 1 to 6, wherein the first index, the second index, and the third index are connected terminals.
The radio resource setting method according to claim 3, wherein the fourth index is a bandwidth usage rate.
The radio resource setting method according to claim 3, wherein the fourth index is a connected terminal.
The radio resource setting method according to claim 3, wherein the fourth index is the first index.
The radio resource setting method according to claim 6, wherein the fifth index is the third index.
There is further a fourth communication area that is at least partially included in the third communication area, and in which a fourth base station can communicate with the communication terminal,
Further comprising obtaining a sixth index relating to the load of the fourth communication area;
Radio resources that can be used in the third communication area on condition that the first criterion is satisfied, the second criterion is satisfied, and the sixth index is equal to or greater than a fourth threshold value The radio resource setting method according to any one of claims 1 to 12, wherein the radio resource setting method is limited.
The radio resource setting method according to claim 13, wherein the sixth index is a bandwidth usage rate.
The radio resource setting method according to claim 13, wherein the sixth index is a connected terminal.
Further comprising the step of obtaining channel quality between the first base station and the second base station in the communication terminal in communication with the first base station;
On condition that the first criterion and a third criterion calculated from the channel quality with the first base station and the channel quality with the second base station are satisfied. The radio resource setting method according to any one of claims 1 to 15, wherein radio resources usable in the second communication area are limited.
The channel quality is RSRP (Reference Signal Response Power),
The third standard is that, in the first communication area, the ratio of the communication terminals in which the difference between the RSRP of the first communication area and the RSRP of the second communication area is less than the RSRP threshold is fifth. The radio resource setting method according to claim 16, wherein the radio resource setting method is equal to or greater than a threshold value.
The channel quality is RSRQ (Reference Signal Response Quality),
The third criterion is that, in the first communication area, the ratio of the communication terminals in which the difference between the RSRQ in the first communication area and the RSRQ in the second communication area is less than the RSRQ threshold is sixth. The radio resource setting method according to claim 16, wherein the radio resource setting method is equal to or greater than a threshold value.
The second base station further comprising obtaining time frame information for restricting data transmission;
The channel quality is SINR (Signal to Interference and noise rate),
The third criterion is communication in which, in the first communication area, a difference between an SINR of a time frame that restricts transmission and an SINR of a time frame other than the time frame that restricts transmission is equal to or greater than an SINR threshold value. The radio resource setting method according to claim 16, wherein the ratio of terminals is equal to or greater than a seventh threshold value.
The first base station determines whether the first criterion is satisfied, notifies the determination result to at least the third base station,
The radio resource setting method according to any one of claims 1 to 19, wherein the third base station determines whether or not the second reference is satisfied when the first reference is satisfied.
The first base station determines whether both the first criterion and the second criterion are satisfied, and notifies at least the third base station of the determination result. The radio resource setting method according to claim 1.
The second base station determines whether the first criterion is satisfied, notifies at least the third base station of a determination result,
The radio resource setting method according to any one of claims 1 to 19, wherein the third base station determines whether or not the second reference is satisfied when the first reference is satisfied.
The second base station determines whether the second reference is satisfied when the first reference is satisfied, and notifies the determination result to at least the third base station. The radio | wireless resource setting method of any one of items.
The step of limiting the available radio resources is:
As a radio resource that can be used by the base station to perform radio communication with the communication terminal in the communication area,
Make the transmission power smaller than the reference power,
Limiting a time frame that the base station can use for wireless communication with the communication terminal in the communication area;
Or limiting at least one of frequency blocks that can be used by the base station to perform wireless communication with the communication terminal within the communication area. The radio resource setting method according to any one of 1 to 23.
The radio resource according to any one of claims 1 to 24, wherein when any one of the first criterion and the second criterion cannot be satisfied, the limitation of the usable radio resource is terminated. Setting method.
The radio resource according to any one of claims 1 to 24, wherein when a predetermined time has elapsed since the restriction of the usable radio resource is implemented, the restriction of the usable radio resource is terminated. Setting method.
A base station that manages the first communication area,
The first communication area is at least partially included in a second communication area managed by a second base station,
The second communication area is adjacent to a third communication area managed by a third base station,
Load measuring means for obtaining a first index relating to the load of the first communication area;
Obtaining a second index relating to the load of the second communication area, and satisfying at least a first criterion calculated from the first index and the second index; Priority band setting means for notifying the third base station of the priority band;
A base station characterized by comprising:
A base station managing a third communication area,
The third communication area is adjacent to the second communication area managed by the second base station,
The second communication area includes at least a part of the first communication area managed by the first base station,
Load measuring means for obtaining a third index relating to the load of the third communication area;
Assigned radio that restricts radio resources that can be used in the third communication area on condition that the second criterion calculated from the third index is satisfied when priority band information is notified from the first base station Resource setting means;
A base station characterized by comprising:
A base station managing a third communication area,
The third communication area is adjacent to the second communication area managed by the second base station,
The second communication area includes at least a part of the first communication area managed by the first base station,
The first base station measures a first indicator relating to a load of the first communication area;
The second base station measures a second indicator relating to a load of the second communication area;
Load measurement means for obtaining a third index related to the load of the third communication area and notifying at least one of the first base station and the second base station of the third index;
At least when the first criterion calculated from the first index and the second index is satisfied and the second criterion calculated from the third index is satisfied, the first index is satisfied. An assigned radio resource setting means for restricting radio resources that can be used in the third communication area when priority band information notified from either one of the base station or the second base station is received;
A base station characterized by comprising:
A base station is a wireless communication system that performs wireless communication with a communication terminal in a communication area of the base station,
A first base station managing a first communication area;
A second base station that manages a second communication area including at least a part of the first communication area;
A third base station that manages a third communication area adjacent to the second communication area,
The first base station is
Obtaining a first indicator relating to the load of the first communication area and a second indicator relating to the load of the second communication area;
At least notifying the priority band to the third base station on condition that the first criterion calculated from the first index and the second index is satisfied,
The third base station is
Obtaining a third indicator relating to the load of the third communication area;
When priority band information is notified from the first base station, radio resources that can be used in the third communication area are limited on condition that the second criterion calculated from the third index is satisfied. system.
A base station is a wireless communication system that performs wireless communication with a communication terminal in a communication area of the base station,
A first base station managing a first communication area;
A second base station that manages a second communication area including at least a part of the first communication area;
A third base station that manages a third communication area adjacent to the second communication area,
The first base station is
Obtaining a first indicator relating to the load of the first communication area, a second indicator relating to the load of the second communication area, and a third indicator relating to the load of the third communication area;
At least on the condition that the first criterion calculated from the first index and the second index is satisfied and the second criterion calculated from the third index is satisfied. Informs the third base station of the priority band,
The third base station is
A radio communication system that limits radio resources that can be used in the third communication area when priority band information is notified from the first base station.
A non-transitory computer-readable medium storing a program that causes a base station to perform a wireless resource setting process for performing wireless communication with a communication terminal in a communication area of the base station. ,
The first base station manages the first communication area,
A second base station manages a second communication area including at least a part of the first communication area;
The third base station manages a third communication area adjacent to the second communication area,
Obtaining a first indicator relating to the load of the first communication area, a second indicator relating to the load of the second communication area, and a third indicator relating to the load of the third communication area;
Limiting radio resources that can be used in the second communication area on condition that at least a first criterion calculated from the first index and the second index is satisfied;
Limiting radio resources that can be used in the third communication area on condition that the first criterion is satisfied and the second criterion calculated from the third index is satisfied;
A non-transitory computer-readable medium storing a program characterized by comprising: