JP7233181B2 - wireless communication system - Google Patents

Description

The present invention relates to a radio communication system including mobile terminals such as portable terminals, and more particularly to a radio communication system capable of improving individual cell throughput while reducing radio wave interference between adjacent cells.

Currently, various wireless communication systems are becoming popular, and frequency resources in the microwave band are in danger of being exhausted. In particular, technology for effective utilization of frequency resources in systems used in wide areas is an important technology for improving serviceability to users. Generally, in order to avoid inter-cell interference between cells formed by base stations, a plurality of channels are arranged repeatedly (frequency repetition). However, although a wide bandwidth is required for high-speed communication, it is difficult to prepare a sufficient number of channels because the bandwidth allocated to one business operator is limited. For example, in the case of 1-cell repetition, the band assigned to each cell can be operated in a wide band, but it is greatly affected by inter-cell interference, so there is a problem that the communication quality is greatly degraded especially near the cell boundary.

For example, FIG. 12 shows a method of performing frequency repetition in 3 cells for interference prevention. Frequency repetition avoids inter-cell interference and reduces its impact, but as shown in the schematic graph on the right side of FIG. Communication speed (throughput) cannot be secured. Therefore, a fractional frequency repetition technology as shown in FIG. 13 is used as a technology for providing large-capacity wireless access over a wide area while managing deterioration of communication quality due to interference and efficiently operating limited frequency resources. (Fractional Frequency Reuse: FFR) is attracting attention (Non-Patent Documents 1 and 2).

In this method, the entire band covered by three resource blocks (RB1, RB2, and RB3) is allocated for communication targeting the center area of the cell, and the three resource blocks are distributed to three cells in the edge area of the cell. assignment. In the cell edge region, the number of frequency repetitions is 3, that is, repetition by one resource block is performed with a large output that reaches the edge region as well. On the other hand, in the cell center area, three resource blocks are used simultaneously to widen the bandwidth, while the transmission power is lowered and the frequency repetition number is set to 1 so as not to affect the edge area. As a result, inter-cell interference due to frequency repetition is suppressed, and at the same time, the transmission frequency band is expanded and the cell throughput is improved.

Magazine FUJITSU Vol.63 No.4 pp.455-460 NTT Technical Journal, September 2012, pp.78-81

However, in the above scheme, as disclosed in Non-Patent Document 2, resource block allocation control for avoiding interference between adjacent cells is performed solely by cooperation between base stations. There is a problem that it tends to increase the processing load of In particular, the problem of inter-cell interference mentioned above should change depending on the connection status of mobile terminals within each cell, and further fine-grained control of resource block allocation in response to this would reduce the processing load on the base station. This leads to further acceleration of the increase. In addition, resource block allocation control processing is handled by the control/baseband unit of the base station in terms of hardware. This will also lead to an increase in the number of users, and the impact will be particularly large when constructing a small-scale communication network.

SUMMARY OF THE INVENTION An object of the present invention is to provide a wireless communication system that can inexpensively implement fine-tuned communication resource allocation control for preventing interference between adjacent cells while reducing the processing load on base stations.

In order to solve the above problems, the radio communication system of the present invention is a radio unit provided in each cell of a communication area divided into a plurality of cells, wherein a mobile terminal in the own cell and pre-allocated radio resources are provided. and a control/baseband unit that performs digital baseband signal processing including modulation/demodulation processing of transmission/reception signals handled by the radio unit, and resource allocation control that allocates radio resources to each cell. The control/baseband unit of the base station monitors whether or not there is a mobile terminal (hereinafter referred to as an active terminal) communicating with the radio unit in the cell handled by each radio unit, and Based on the monitoring result, an active terminal monitoring unit for creating active terminal monitoring information indicating whether or not a mobile terminal communicating with the radio unit exists in the cell; When the active terminal monitoring information of the cell indicates that there is no active terminal, the resource allocation control unit is permitted to allocate the radio resource common to the cell to an adjacent cell, and the active terminal of the cell is obtained. and an allocation control command unit that prohibits the resource allocation control unit from allocating a radio resource common to the cell to an adjacent cell when the monitor information indicates that there is an active terminal. Each cell in the communication area is set as a repeating unit cell group by equiangularly arranging three cells around a node. It has three radio units that are associated with cells one-to-one and are in charge of transmission and reception with mobile terminals in the corresponding cells. The process of confirming whether or not it exists, creating active terminal monitoring information, and transmitting it to the allocation control command unit is repeatedly executed in a predetermined order. Then, the allocation control command unit instructs the resource allocation control unit, if the active terminal monitoring information indicates that there is an active terminal in all of a plurality of predetermined cells adjacent to each other, different radio While issuing a command to allocate resources, if the active terminal monitoring information for a part of a plurality of cells indicates that there are no active terminals, the allocation control command unit determines the radio resources to be allocated to the cell by active terminal monitoring. In the active terminal monitoring information, when a cell with no active terminals is switched to a cell with active terminals, a common It is characterized by commanding a resource allocation control unit to prohibit allocation of radio resources to adjacent cells .

In this specification, "radio resources" are various radio resources necessary for information transmission allocated to each data flow in radio communication, and the allocation for each data flow can be changed. means defined by frequency, code, space, or a combination thereof.

The control/baseband section of the base station that is in charge of connection control can easily grasp whether or not there is an active terminal connected to the base station in the cell that the base station is in charge of. In the radio communication system of the present invention, an active terminal monitoring section is provided in the control/baseband section to monitor the presence or absence of active terminals in the cell. As a result of the monitoring, if the active terminal monitoring information of "no active terminal" is obtained in a certain cell, it means that there is no active mobile terminal in the cell and the same communication resource as the cell is used by neighboring cells. This means that inter-cell interference is inherently less likely to occur even when allocated to . Therefore, the active terminal monitoring information is acquired by an allocation control command unit provided separately from the base station, and the radio resource common to the cell determined to have "no active terminal" is allocated to adjacent cells. Permission is given to the resource allocation control unit. As a result, the base station can easily determine whether or not it is permissible to share radio resources between adjacent cells with a simple processing load of referring to commands from the allocation control command unit. Then, the radio resources of cells with "no active terminals" can be effectively used in other cells while eliminating the concern of inter-cell interference, which can contribute to the improvement of cell throughput.

When a cell whose active terminal monitoring information is "with active terminals" is switched to "without active terminals", the allocation control command unit prohibits allocation of radio resources common to the cell to adjacent cells. It can be configured to instruct the resource allocation control unit. According to the present invention, whether or not a cell has switched from "with active terminals" to "without active terminals" can be easily grasped based on the active terminal monitoring information, and the common radio resource can be allocated to adjacent cells based on this information. can effectively prevent the occurrence of inter-cell interference.

The allocation control command unit instructs the resource allocation control unit to assign different radio resources to all of the cells when the active terminal monitoring information indicates "there is an active terminal" in all of a plurality of predetermined cells adjacent to each other. can be configured to issue a command to assign Thereby, interference between cells in which active terminals exist can be effectively prevented or suppressed. On the other hand, if the active terminal monitoring information indicates "no active terminals" for some of a plurality of cells, the radio resources to be allocated to the cell are set to "active terminals exist" in the active terminal monitoring information. It can be configured to command additional control assignments to cells that are already in use. If even one of the cells indicates "no active terminals", additional allocation of the allocated radio resources of that cell to other cells (with "active terminals") contributes to improving the throughput of those cells. can. At this time, the state of additional allocation of radio resources to a cell whose active terminal monitoring information is "with active terminals" is changed from "no active terminals" to " It is preferable to continue until it shifts to "with active terminal". As a result, the additional radio resource allocation state can be reasonably extended, and the improved throughput state can be continued for a longer period of time.

When radio communication particularly adopts the orthogonal frequency division multiplexing system, the radio resource is divided by the frequency axis divided by the subcarrier frequency interval and the time axis divided by the slot interval of the communication data frame. It can be a resource block defined on the time plane. In the orthogonal frequency division multiplexing system in which high throughput can be expected, a large number of resource blocks can be cut out from the frequency/time plane (two-dimensional resource division space) according to the subcarrier frequency interval and the slot interval. It contributes to the improvement of communication quality by flexibly allocating according to the position of the terminal and the communication state.

Also, the radio communication system of the present invention effectively contributes to the simplification of the construction of the above-described fractional frequency repetition system. In this case, the radio unit of the base station is in an edge communication mode in which resource blocks with different contents are allocated between adjacent cells and communication is performed with mobile terminals existing in the edge area of the cell at the first transmission power. and a center communication mode in which communication is performed with a mobile terminal existing in the center area of a cell with a second transmission power lower than the first transmission power while receiving common resource block allocation between adjacent cells. It is configured to wirelessly communicate with mobile terminals in the cell while switching. Then, in the edge communication mode, when the active terminal monitoring information in at least one of the adjacent cells indicates "no active terminal", the allocation control command unit allocates resource blocks common to the cell to the adjacent cells. is configured to allow the resource allocation control unit to do so. As a result, even in the edge communication mode in which the number of resource blocks allocated to each cell is reduced and the bandwidth is reduced, the temporarily redundant resource blocks of cells with "no active terminals" can be replaced with cells with "active terminals". can be additionally allocated in the form of contributing to the cell, thereby improving the throughput to mobile terminals existing near the edge of the cell and, in turn, improving the communication quality.

Also, in order to implement frequency repetition, the communication area can be divided into repeating unit cells consisting of adjacent cells with a fixed number of cells and cell placement. In the edge communication mode, the resource allocation control unit allocates a single unique resource block different from each other to each of the plurality of cells forming the repeating unit cell group, while in the center communication mode forming the repeating unit cell group. Each of the plurality of cells can be configured to additively allocate all of the unique resource blocks each allocated in the edge communication mode. The assignment control command unit assigns a cell having active terminal monitoring information "with active terminal" among the cells forming the repeating unit cell group in the edge communication mode to a cell having "no active terminal". It can be configured to instruct the resource allocation control unit to additionally allocate the specific resource blocks that are already specified.

In the center area where inter-cell interference is less likely to occur, the cell throughput in the center communication mode is significantly increased by additively allocating each cell's unique resource blocks for the edge communication mode to each cell in the center communication mode. can be done. In the edge communication mode, by additionally allocating specific resource blocks of cells with "no active terminals" to cells with "active terminals", in a communication environment with few active terminals, concentration terminals exist. The number of allocated resource blocks of the cell and thus the frequency bandwidth can be expanded, and the cell throughput can be similarly increased even in the edge communication mode.

Further, if there are a plurality of cells in which the active terminal monitoring information is "no active terminal" among the plurality of cells constituting the repeating unit cell group in the edge communication mode, the allocation control commanding unit It can be configured to instruct the resource allocation control unit to additively allocate the allocated specific resource blocks to cells that are "with active terminals". By additively allocating unique resource blocks of multiple "no active" cells to "active" cells, the throughput of "active" cells in edge communication mode can be further increased.

Since the details of the action and effect of the present invention have already been described in the column of "Means for Solving the Problems", they will not be repeated here.

1 is a block diagram of a wireless communication system that is an embodiment of the present invention; FIG. Block diagram of a base station. FIG. 3 is a schematic diagram showing an arrangement example of base stations; FIG. 4 is an explanatory diagram showing the resource block allocation status of each cell when there are active terminals in all cells in the radio communication system of the present invention; Conceptual diagram of a resource block. 4 is a flowchart showing a first example of the processing flow of an allocation control command unit; FIG. 11 is a flowchart showing a second example of the flow of processing by the allocation control command unit; FIG. 2 is a timing chart showing the flow of communication processing between units in the wireless communication system of FIG. 1; FIG. 4 is an explanatory diagram showing how resource blocks of cell A are additionally allocated to cells B and C when there are no active terminals in cell A in the radio communication system of the present invention; FIG. 4 is an explanatory diagram showing changes in resource block allocation state when cell A shifts to a state with active terminals in the wireless communication system of the present invention; FIG. 4 is an explanatory diagram showing how resource blocks of cell A and cell B are additionally allocated to cell C when there are no active terminals in cell A and cell B in the radio communication system of the present invention; FIG. 3 is an explanatory diagram of a scheme in which the number of frequency repetitions is 3 and resource blocks are assigned to each cell; FIG. 4 is an explanatory diagram showing how resource blocks are allocated to each cell by the fractional frequency repetition method, with the frequency repetition number in the edge region being 3 and the frequency repetition number in the center region being 1;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a block diagram showing the overall configuration of a radio communication system that is one embodiment of the present invention. The wireless communication system 1 includes a plurality of base stations 30 and an allocation control command section 10 connected to the base stations 30 as main parts. The base station 30 wirelessly communicates with a plurality of mobile terminals 40 (portable terminals, mobile devices, etc.) in the cell it serves. The switching device 20 will be described later.

FIG. 2 shows an example of the configuration of the base station 30. As shown in FIG. The base station 30 is configured as an LTE (Long Term Evolution) system base station device, and includes two radio units (RRH: Remote Radio Head) 31A to 31C and a control/baseband unit (BBU: Base Band Unit) 32. Consists of large hardware blocks. In this embodiment, one base station 30 is provided with three radio units 31A to 31C, which are similarly indicated by reference numerals 31A to 31C. The reason for this will be described later. These three radio units are also simply referred to as radio unit 31 when collectively referred to. The radio unit 31 performs radio communication with mobile terminals in its own cell based on pre-assigned radio resources. The control/baseband unit 32 is responsible for digital baseband signal processing including modulation/demodulation processing of transmission/reception signals handled by the radio unit.

The control/baseband unit 32 specifically has the following components.
Control unit (CNT) 322: Performs overall control of the base station 30, protocols for call control, and control and monitoring. In addition, a transmission line interface unit that connects a transmission line such as Ethernet, processes protocols such as IPsec and IPv6, and exchanges IP packets. A timing control unit that generates various clocks used internally is also incorporated here.
Baseband unit (BB) 321: Performs modulation/demodulation of IP packets sent and received through the transmission line interface and baseband signals carried on the radio. In LTE, a baseband signal is a signal of an orthogonal frequency-division multiplexing (OFDM) system, and is exchanged with the radio section 31 . This baseband section covers various modulation schemes (QPSK, 16QAM, 64QAM, etc.) adopted for LTE adaptive modulation.

Also, the radio unit 31 has the following components.
Quadrature modulation/demodulation unit 313: Quadrature modulation/demodulation of the OFDM signal processed by the baseband unit 321, and conversion into an analog RF signal.
Transmitting/receiving unit 312: converts the RF signal generated by the quadrature modulation/demodulation unit 313 into a frequency for transmission as radio waves. Also, the received radio wave is converted into a frequency to be processed by the orthogonal modulation/demodulation section 313 .
Amplifier 311 : Amplifies the power of the RF signal generated by the transmitting/receiving section 312 in order to transmit it from the antenna 313 . On the other hand, weak radio waves received by the antenna 313 are amplified and transferred to the transmitting/receiving section 312 .

In this embodiment, the communication area is divided into repeating unit cell groups consisting of adjacent cells having a fixed number of cells and a fixed cell arrangement. Specifically, as shown in FIG. 3, three cells (A, B, C) equiangularly arranged around a node are set as a repeating unit cell group. The base station 30 is arranged at this node, and the three radio units 31A to 31C are associated one-to-one with each cell (A, B, C) belonging to the repeating unit cell group. It is in charge of transmission and reception with mobile terminals in the cell.

In the LTE system, mobile terminals in each cell wirelessly connect to the base station 30 by OFDM access (OFDMA). The OFDM access scheme is characterized as a two-dimensional multiplexed access scheme that combines frequency division multiplexing and time division multiplexing. Specifically, channels (subcarriers) on the orthogonal frequency axis and time axis are divided and assigned to users (mobile terminals currently connected), and the frequency axis is adjusted so that the signal of each subcarrier becomes zero (0 points). Divide the orthogonal subcarriers above. By dividing and allocating subcarriers, even if one subcarrier is affected by fading, it is possible to select another subcarrier that is not affected, so users can use better subcarriers according to the radio environment. There is an advantage that the radio quality can be maintained.

In the OFDM modulation scheme, resource blocks defined on a virtual plane formed by the frequency axis and the time axis are adopted as radio resources. As shown in FIG. 5, a resource block is defined as a block in which the above plane is divided into a matrix at 180 kHz/0.5 msec, and each block divides 12 subcarriers adjacent to each other at intervals of 15 kHz on the frequency axis, on the time axis. contains 1 slot (7 symbols) of the frame. These resource blocks are assigned to the user terminals as a set of two adjacent resource blocks (1 msec) on the time axis.

In this embodiment, allocation of resource blocks to each cell forming a repetition unit cell group is performed according to the principle of fractional frequency repetition. Specifically, as shown in FIG. 4, the radio units 31A to 31C of the base station 30 in FIG. 3 perform radio communication with mobile terminals in their own cells while switching between the following two modes by time division. .
- Edge communication mode: First transmission power between mobile terminals existing in the edge area of the cell while receiving allocation of resource blocks with different contents between adjacent cells (specifically, while covering the cell edge, Communication is performed at a high output that does not penetrate deeply into the center area of the adjacent cell. Specifically, three types of single resource blocks (RB 1 to 3: specific resource blocks) with different frequency bands are prepared in advance for each of the three cells A to C forming the repeating unit cell group. The allocation resource blocks are periodically changed within the three cells A to C according to a defined schedule. In order to avoid interference in the edge region, the three specific resource blocks are a plurality of resource blocks with different slot extraction positions on the time axis if the frequency bands to which the subcarrier groups in the blocks belong are mutually different. , and such a group of resource blocks is also considered to belong to the concept of "single unique resource block".

· Center communication mode: second transmission power lower than first transmission power between mobile terminals existing in the center area of the cell while receiving common resource block allocation between adjacent cells (specifically, Communication is performed with a low output that does not penetrate deeply into the edge region of the own cell. Specifically, to each of the three cells A to C, all of the unique resource blocks RB1 to 3 respectively allocated in the edge communication mode are additively allocated (ie, RB1+RB2+RB3).

Note that resource block allocation control for each cell is performed by scheduling processing of resource block allocation through cooperation between base stations when base stations are placed separately for each cell. However, in this embodiment, three cells A to C are covered by one base station 30 in which the control/baseband unit 32 is shared by the three radio units 31A to 31C. Scheduling is also autonomously performed by the shared control/baseband unit 32 . As a result, it can be said that the communication processing load is reduced in the repeating unit cell group compared to the case of cooperative communication between three individual base stations.

Returning to FIG. 2, the control unit 322 in the control/baseband unit 32 of the base station 30 is loaded with application software 322a for realizing communication processing and monitoring processing of the base station 30. FIG. The resource block allocation scheduling processing function described above is also realized by executing the application software 322a. That is, the control/baseband unit functions as a resource allocation control unit that allocates radio resources to each cell.

Also, by executing this application software 322a, it is possible to easily grasp whether or not there is a mobile terminal in communication connection in each cell. In this embodiment, the application software 322a includes mobile terminals ("active An active terminal monitoring unit 322b (function realizing program thereof) that monitors whether or not a terminal") exists and creates active terminal monitoring information based on the monitoring results is incorporated. The active terminal monitoring information consists of specific information of the corresponding cell and bit information indicating whether or not there is an active terminal in that cell.

Next, the plurality of base stations 30 in FIG. 2 are connected to the assignment control command unit 10 by wire or wirelessly via a switching device 20 (which may be the Internet 21). The allocation control command unit 10 is composed of an EMS (Environmental Monitoring System) server or the like, and its hardware structure has the same concept as a general computer. In FIG. 1, as an example, a CPU 11 as a processing body, a ROM 12 loaded with a control program at a level close to the physical layer such as BIOS, a RAM 13 as a program execution area, communication software 14a and management software 14b are rewritably installed. A hard disk drive (HDD) 14 and a communication unit 15 for performing external communication with a base station 30 or the like are connected by a bus 16 .

The management software 14b incorporates an allocation control instruction program 14c. This assignment control command program 14c acquires the active terminal monitoring information of each cell A to C shown in FIG. , to realize the main function of the allocation control commanding unit 10, which permits the resource allocation control unit to allocate the radio resources common to the cell in question to adjacent cells.

The operation of the radio communication system 1 will be described below. FIG. 6 is a flow chart showing a first example of the processing flow of the allocation control command program 14c in the allocation control command unit 10. As shown in FIG. The cell number i ranges from 1 to 3, i=1 means cell A, i=2 means cell B, and i=3 means cell C (see FIG. 3).

First, in S110, the cell number i is initialized (=1). At S120, the base station 30 is requested to transmit the active terminal monitoring information of the cell corresponding to the number i, and the information is received from the base station 30 at S130. If the cell number i is 1, the base station 30 grasps the presence of active terminals in cell A, if 2 in cell B, and if 3 in cell C. bit content (e.g. "1") indicating "no active terminal" if not present (e.g. "0"), cell specific information (e.g. at least 2 bits if covering 3 cells) information) to the allocation control command unit 10.

In S140, the active terminal monitoring information acquired by the active terminal is checked, and if "there is no active terminal" ("0"), the process proceeds to S150. It transmits to the base station 30 information about the neighboring cells that it permits. As shown in FIG. 3, in the repeating unit cell group bundled by the base station 30, three cells A to C are adjacent to each other. When i=2, cell B is selected, cells C and A are adjacent cells, and when i=3, cell C is selected, cells A and B are adjacent cells.

In the base station 30, when permission for additional allocation of resource blocks is received for cells adjacent to the cell with the number i, since the two cells other than the number i are adjacent cells, the control unit 322 of the control/baseband unit 32 The installed application software controls the additional allocation of the specific resource block allocated to the cell numbered i in the edge communication mode to the other two cells.

FIG. 9 schematically shows the exchange of processing at this time. Cell A has "no active terminals (abbreviated as AUE in the figure)", and the other two (B and C) have "active terminals". shows the situation. For example, in a certain edge communication mode, when RB1 is assigned to cell A, RB2 is assigned to cell B, and RB3 is assigned to cell C, cells B and C, which correspond to adjacent cells of cell A, have RB2 to RB3, respectively. In addition, as a result of the additional allocation of RB1 of cell A, resource blocks are additively allocated such that RB2+R1 for cell B and R3+R1 for cell C are obtained. As a result, cell B and cell C, which have active terminals, can allocate and acquire two resource blocks with different frequency bands, and can improve the cell throughput by expanding the bandwidth.

Returning to FIG. 6, if "there is an active terminal" ("1") in S140, the process proceeds to S160. to the base station 30. At S170, the cell number i is incremented. At S180, if the processing up to the third cell (C) is not completed and i≤3, the process returns to S120, and the processing up to S160 is repeated for the next cell. . On the other hand, if i>3 in S180, the process returns to S110, initializes the cell number, and repeats the above process (if there is an instruction to end in S190, the repeat process is completed there and the program is executed). finish).

For example, in the previous processing, cell A was "no active terminals" as shown in FIG. Since additional allocation of the resource block (RB1 in the figure) allocated to A to cells B and C is not permitted, a process of giving up is performed. As a result, as shown on the right side of FIG. 10, the state before the additional allocation is restored.

On the other hand, in the subsequent processing from the state of FIG. 9, when cell B also shifts to "no active terminals" as shown in FIG. , both RB1 assigned to cell A and RB2 assigned to cell B are additively assigned. As a result, the allocated bandwidth of cell C is further expanded and the throughput is further improved. In addition, in cell B, which has newly become "no active terminals", the additional allocation state of RB1 of cell A, which maintains the "no active terminals" state, continues. The additional allocation state of RB1 in cell B continues until cell A transitions to the "with active terminals" state.

FIG. 8 is a timing chart showing the flow of communication processing between the allocation control command unit and each cell. What the assignment control command unit executes is that it receives the information of "active terminal presence/absence" from each cell, and according to the content, determines "active terminal presence/absence" of the cell of interest as described above. , it is a very simple process of mechanically notifying neighboring cells of the use permission/non-permission of the resource block of the cell. On the other hand, on the base station side, according to the notification from the allocation control command unit, additional resource block allocation processing may be uniformly executed for neighboring cells of the designated cell, so the processing load is also very small. However, by repeating this simple operation, flexible resource block allocation operation to each cell can be realized smoothly, as shown in FIGS. I understand.

In summary, in FIGS. 9 and 11, in the edge communication mode, the resource blocks common to the cell (A) with “no active terminals” are allocated to at least one of the adjacent cells (B, C). RB1 (unique resource block of cell A) is additionally allocated to both adjacent cells B and C. Further, in FIG. 11, the unique resource blocks (RB1, RB2) assigned to the plurality of cells (A, B) with "no active terminals" are assigned to the cells with "active terminals". The function additively assigned to (C) is realized by repeating the processing according to the timing chart of FIG.

Next, in FIG. 1, the assignment control command unit 10 is connected to a plurality of base stations 30 via a switching device 20. FIG. Therefore, the above processing can be sequentially executed in the same manner while switching the connection destination base station 30 by the switching device 20 . As a result, the above-described resource block allocation control based on the present invention can be similarly applied to a plurality of repeating unit cell groups covering a communication area.

In FIG. 9, it is also possible to additionally allocate RB1 to only one of B and C in consideration of the status of the latest mobile terminals in the cell. Even if there is a permission command from the base station, the additional allocation of RB1 can be temporarily not performed in the relevant cycle based on the judgment of the base station based on the mobile terminal presence situation in the cell.

Also, in the above embodiment, the allocation control command unit 10 requests the base station 30 to transmit the active terminal monitoring information. Terminal monitoring information may be transmitted. For example, in FIG. 1, when active terminal monitoring information is exchanged via the Internet 21, the processing in the assignment control command unit 10 can be performed as shown in FIG. 7, for example. First, in S210, the system waits for a transmission notification of active terminal monitoring information from the base station 30, and if there is a transmission notification in S220, the process proceeds to S230, and the base station 30 sends the transmission of the active terminal monitoring information of the notified cell. (if there is no notification, return from S220 to S210 and continue the standby state).

Then, if the active terminal monitoring information is received in S240, the processing of S250-S270 becomes the same as that of S140-S160 in FIG. In this case, repetition of the routine across cells A to C as shown in FIG. 6 is unnecessary.

Although resource blocks are used as radio resources in this embodiment, the radio resources are not limited to resource blocks. For example, when a communication scheme is adopted in which a single radio resource is constantly allocated within a cell without adopting fractional frequency repetition, as shown in FIG. Can be configured.

Although the embodiment of the present invention has been described above, it is merely an example, and the present invention is not limited to this.

1 wireless communication system 10 allocation control command unit 11 CPU
12 ROMs
13 RAM
14 Hard disk drive 14a Communication software 14b Management software 14c Allocation control command program 15 Communication unit 16 Bus 20 Switching device 21 Internet 30 Base station 31 Radio unit 311 Amplifier 312 Radio signal processing unit 313 Antenna 32 Control/baseband unit 321 Baseband unit 322 Device control unit 322a Application 322b Active terminal monitoring unit 40 Mobile terminal

Claims (6)

A radio unit provided in each cell of a communication area divided into a plurality of cells, the radio unit performing radio communication with a mobile terminal in the own cell based on pre-assigned radio resources, and transmission/reception signals handled by the radio unit. a base station comprising a control/baseband unit that performs digital baseband signal processing including modulation/demodulation processing of
A resource allocation control unit that allocates the radio resource to each cell,
The control/baseband unit of the base station monitors whether or not there is a mobile terminal (hereinafter referred to as an active terminal) communicating with the radio unit in the cell handled by each radio unit. an active terminal monitoring unit for creating active terminal monitoring information indicating whether or not a mobile terminal communicating with the radio unit exists in the cell based on the result ;
Acquiring the active terminal monitoring information of the cell from the base station, and allocating the radio resource common to the cell to an adjacent cell when the active terminal monitoring information of the cell indicates that there is no active terminal. and if the active terminal monitoring information of the cell indicates that there is an active terminal, the resource allocation control unit allocates the radio resource common to the cell to an adjacent cell. an allocation control command unit that prohibits the allocation control unit,
Each cell in the communication area is set as a repeating unit cell group by equiangularly arranging three cells around a node;
The base station is arranged at the node and has three radio units that are associated one-to-one with each cell belonging to the repeating unit cell group and that are in charge of transmitting and receiving to and from mobile terminals in the corresponding cells. ,
The active terminal monitoring unit confirms whether or not the active terminal exists in the three cells forming the repeating unit cell group, creates the active terminal monitoring information, and transmits the active terminal monitoring information to the allocation control command unit. is repeatedly executed in a predetermined order,
The allocation control command unit instructs the resource allocation control unit, when the active terminal monitoring information indicates that there is an active terminal in all of a plurality of predetermined cells adjacent to each other, different While issuing a command to allocate radio resources, if the active terminal monitoring information for some of the plurality of cells indicates that there are no active terminals, the allocation control command unit allocates radio resources to the cell. , when the active terminal monitoring information indicates control for additional allocation to the cell in which there are active terminals, and on the other hand, when the cell in which the active terminal monitoring information indicates that there are no active terminals is switched to the presence of active terminals, , instructing the resource allocation control unit to prohibit allocation of the radio resource common to the cell to the adjacent cell;
A wireless communication system characterized by: The additional allocation state of the radio resource to the cell in which the active terminal monitoring information indicates that there are active terminals is such that the active terminal monitoring information of the cell that is the source of the additional allocation of the radio resources is changed from having no active terminals to having active terminals. 2. The wireless communication system of claim 1 , continued until the The radio communication employs an orthogonal frequency division multiplexing method, and the radio resource is a frequency/frequency defined by a frequency axis partitioned by subcarrier frequency intervals and a time axis partitioned by communication data frame slot intervals. 3. The radio communication system according to claim 1, wherein the resource block is defined on a time plane. The radio unit of the base station performs edge communication with a mobile terminal existing in an edge region of the cell at a first transmission power while being allocated the resource blocks with different content between the adjacent cells. a communication mode and a second transmission power lower than the first transmission power between mobile terminals existing in the center area of the cell while being allocated the resource blocks common to the adjacent cells; wireless communication with the mobile terminal in the cell while switching between the center communication mode and the center communication mode;
In the edge communication mode, when the active terminal monitoring information in at least one of the adjacent cells indicates that there is no active terminal, the allocation control command unit assigns the resource blocks common to the cell to the adjacent cell. 4. The radio communication system according to claim 3 , wherein said resource allocation control unit is permitted to allocate to said resource allocation control unit. The communication area is divided into repeating unit cell groups consisting of the cells adjacent to each other with a fixed number of cells and a constant cell arrangement,
The resource allocation control unit allocates single unique resource blocks different from each other to each of the plurality of cells constituting the repetition unit cell group in the edge communication mode, while in the center communication mode, the repetition unit All of the unique resource blocks allocated in the edge communication mode are additively allocated to each of a plurality of cells constituting a cell group,
The assignment control command unit assigns a cell having active terminal monitoring information indicating that there is an active terminal among the cells forming the repeating unit cell group in the edge communication mode to a cell having no active terminal. 5. The radio communication system according to claim 4 , further instructing said resource allocation control unit to additionally allocate said unique resource block. When there are a plurality of cells in which the active terminal monitoring information indicates no active terminal among a plurality of cells constituting the repeating unit cell group in the edge communication mode, the allocation control command unit allocates 6. The radio communication system according to claim 5 , wherein the resource allocation control unit is instructed to additively allocate the specific resource blocks to the cell in which an active terminal is present.

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