JP2009219010A - Base station control apparatus and base station control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless base station control apparatus and a wireless base station control method for controlling user throughput in a wireless communication system which performs downstream (a direction from a base station to a wireless terminal) simultaneous communication between a plurality of base stations and one wireless terminal by cooperation of the plurality of base stations. <P>SOLUTION: A base station control apparatus 1 includes: a base station cooperation determination part 13 that determines whether or not a plurality of base stations cooperate with each other based on a wireless reception environment in a wireless terminal; and a base station controller 14 that controls a base station based on the determination of the base station determination part. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a base station control device and a base station control method.

In a wireless communication system that expands a wireless communication area by cell or sector, wireless terminals that are located between cells or between sectors may deteriorate in communication quality due to interference from multiple base stations or multiple sectors and obtain high user throughput. Can not.
Conventionally, MIMO (Multi Input Multi Output) is known as a technique for solving such a problem. MIMO is a technique for increasing user throughput by transmitting separate data signals at the same frequency from a plurality of transmitting antennas, and receiving and restoring them by a plurality of receiving antennas. In the conventional MIMO wireless communication system described in Patent Document 1, simultaneous communication is performed by MIMO between a plurality of base stations and one wireless terminal (hereinafter referred to as cooperation between multiple base stations). When a plurality of base stations are linked, the user throughput of wireless terminals between cells or between sectors can be improved.
JP 2007-134844 A

  However, in the conventional MIMO wireless communication system described in Patent Document 1 described above, if there are wireless terminals between cells, a large amount of wireless resources are spent on the wireless terminals. For this reason, a large amount of radio resources cannot be allocated to radio terminals that are not located between cells, and the cell throughput, which is the sum of the user throughputs of the entire cell, is reduced compared to the case where multiple base station cooperation is not performed. Therefore, there is a problem that the frequency utilization efficiency is lowered.

  The present invention has been made in view of such circumstances, and the object thereof is the downlink direction (the direction from the base station to the wireless terminal) by cooperation of the plurality of base stations between the plurality of base stations and one wireless terminal. It is an object of the present invention to provide a radio base station control device and a radio base station control method capable of controlling user throughput in a radio communication system in a radio communication system that performs simultaneous communication.

  The present invention has been made to solve the above-described problem, and one aspect of the present invention is a wireless communication that performs simultaneous downlink communication between a plurality of base stations and one wireless terminal by cooperation of the plurality of base stations. In the base station control apparatus in the system, based on the determination of the base station determination unit, a base station cooperation determination unit that determines whether or not to perform multiple base station cooperation based on the distribution of the radio reception environment in the wireless terminal, And a base station controller that controls the station.

  One embodiment of the present invention is characterized in that, in the base station control apparatus, the radio reception environment is represented by CINR, user throughput, or a position of a radio terminal.

  One embodiment of the present invention is characterized in that, in the above-described base station control apparatus, wireless terminals having an RSSI of a certain value or more are targeted for the distribution.

  In addition, according to an aspect of the present invention, the above base station control device further includes a cumulative distribution generation unit that generates a cumulative distribution of a radio reception environment in the radio terminal.

  One embodiment of the present invention is a base station control method in a wireless communication system that performs simultaneous downlink communication between a plurality of base stations and one wireless terminal by cooperation of the plurality of base stations, and wireless reception in the wireless terminal A base station cooperation determination step for determining whether or not to perform base station cooperation based on an environment distribution, and a step of controlling a base station based on the determination in the base station determination step, This is a base station control method.

  One embodiment of the present invention is characterized in that, in the above-described base station control method, the radio reception environment is represented by CINR, user throughput, or a position of a radio terminal.

  One embodiment of the present invention is characterized in that, in the above-described base station control method, wireless terminals having an RSSI of a certain value or more are targeted for the distribution.

  Further, one aspect of the present invention is characterized in that, in the above-described base station control method, the method further includes a step of generating a cumulative distribution of a radio reception environment in the radio terminal.

  According to the present invention, it is determined whether or not to cooperate with a plurality of base stations based on the distribution of the wireless reception environment in the wireless terminal, and the plurality of base stations are controlled based on the determination result. In a wireless communication system that performs downlink simultaneous communication by cooperation of a plurality of base stations between one wireless terminal, user throughput in the wireless communication system can be controlled.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic diagram illustrating a configuration of a wireless communication system according to an embodiment of the present invention. In this figure, a plurality of base stations 2A and 2B are connected to a base station control device 1 by communication lines. The wireless terminal 3 performs wireless communication with the base stations 2A and 2B.

  In the following description, a configuration related to wireless communication in the downlink direction (direction from the base stations 2A and 2B to the wireless terminal 3) according to the present invention will be described. The wireless terminal 3 (# 1 in the example in the figure) within the communicable range (cell) of the base station 2A performs downlink wireless communication with the base station 2A. In addition, between the base station 2A and the base station 2B, between the wireless terminal 3 (# 2 in the example in the figure) and the plurality of base stations 2A and 2B, the base station 2A and the base station Simultaneous communication in the downlink direction is performed by cooperation of a plurality of base stations coordinated by 2B.

  In the present embodiment, the base stations 2A and 2B controlled by the base station control device 1 are two stations, but three or more base stations may be controlled.

  The base station control device 1 of the present invention controls the base stations 2A and 2B based on reception environment information representing the radio reception environment of the radio terminal 3 existing in the cells of the base stations 2A and 2B. In the present embodiment, the base station control device 1 determines to perform multi-base station cooperation when there are many wireless terminals 3 that increase user throughput by performing multi-base station cooperation. In the present embodiment, the following determination method is used.

  (Determination Method 1) CINR (Carrier to Interference Noise Ratio) or user throughput information is used as reception environment information. For example, when there are many wireless terminals 3 having a low CINR, it is determined that there are many wireless terminals 3 that have a high user throughput by performing cooperation with a plurality of base stations.

  (Determination method 2) Position information of the wireless terminal 3 is used as reception environment information. When there are many wireless terminals 3 between cells, it is determined that there are many wireless terminals 3 that increase the user throughput by performing cooperation with a plurality of base stations.

[First Embodiment]
The present embodiment is an embodiment of the determination method 1.
FIG. 2 is a block diagram showing the configuration of the base station control device 1 in the present embodiment. The base station control device 1 includes a reception environment information receiving unit 11, a distribution generation unit 12, a base station cooperation determination unit 13, and a base station control unit 14.

  The reception environment information receiving unit 11 receives the reception environment information of the wireless terminal 3 in the cell of each base station 2A, 2B and outputs it to the distribution generation unit 12. In this embodiment, the reception environment information is CINR.

  The distribution generation unit 12 generates a cumulative distribution of the input reception environment information and outputs the cumulative distribution to the base station cooperation determination unit 13. The base station cooperation determination unit 13 determines whether or not to perform multiple base station cooperation based on the input cumulative distribution. The base station control unit 14 controls the base stations 2A and 2B based on the determination result of the base station cooperation determination unit 13.

FIG. 3 is a flowchart showing a flow of determination processing of the base station control device 1 in the present embodiment.
First, the distribution generation unit 12 generates a cumulative distribution from the received CINR (step S1). Subsequently, the base station cooperation determination unit 13 determines whether or not the 10% value of the generated cumulative distribution is greater than or equal to a predetermined threshold value x (step S2). If the base station cooperation determination unit 13 is equal to or greater than the threshold value x, the base station cooperation determination unit 13 determines that the base station cooperation is to be performed (step S3), and ends the process. Moreover, the base station cooperation determination part 13 determines not to perform multiple base station cooperation, when smaller than the threshold value x (step S4), and complete | finishes a process.

  FIG. 4 is a graph showing an example of the cumulative distribution of CINR in the present embodiment. In this graph, the vertical axis represents the percentage value and the horizontal axis represents the CINR value. In this figure, the 10% value of the distribution A is smaller than the threshold value x. For this reason, in the case of distribution A, the base station cooperation determination unit 13 determines not to perform multiple base station cooperation. On the other hand, the 10% value of the distribution B is larger than the threshold value x. For this reason, in the case of the distribution B, the base station cooperation determination unit 13 determines to perform a plurality of base station cooperations. In the present embodiment, the 10% value is referred to, but the present invention is not limited to this example. For example, a 15% value or a 50% value may be referred to.

FIG. 5 is a sequence diagram showing an example of a processing flow in the wireless communication system of the present embodiment.
First, the radio terminal 3 existing in the cells of the base stations 2A and 2B measures its own CINR and notifies the base stations 2A and 2B of the measurement result (step S11). Next, the base stations 2A and 2B transmit the CINR notified from each wireless terminal 3 to the base station control device 1 (step S12).

  Next, the base station control device 1 generates a cumulative distribution of CINRs received from the base stations 2A and 2B (step S13). Next, the base station control device 1 determines whether or not to cooperate with a plurality of base stations from the generated cumulative distribution (step S14). Subsequently, when the base station control device 1 determines to cooperate with a plurality of base stations, the base station control device 1 controls the base stations 2A and 2B to perform the cooperation with the plurality of base stations (step S15).

  If comprised in this way, the base station control apparatus 1 will perform multiple base station cooperation, when there are many radio | wireless terminals 3 with low communication quality. That is, when it is determined that there are many wireless terminals 3 whose user throughput is improved by performing the cooperation of the plurality of base stations, the cooperation of the plurality of base stations is performed. As a result, it is possible to provide wireless communication with fairness with little variation in user throughput of the wireless terminal 3 in the entire wireless communication system.

  As described above, according to the present embodiment, since it is determined whether or not to cooperate with a plurality of base stations based on the CINR cumulative distribution of the wireless terminal 3, a wireless terminal whose user throughput is improved by performing the cooperation with a plurality of base stations. The base stations 2A and 2B can be controlled so that a plurality of base station linkages are performed only when there are three. Thereby, variation in user throughput in the wireless communication system can be suppressed.

  In this embodiment, it is determined whether or not to cooperate with a plurality of base stations based on the CINR cumulative distribution. However, based on the cumulative distribution of the user throughput of the wireless terminal 3, the threshold determination similar to FIG. Also good. At this time, the user throughput is acquired from the radio terminal 3 by the base stations 2A and 2B, and transmitted from the base stations 2A and 2B to the base station controller 1.

[Second Embodiment]
Next explained is a base station control apparatus 1 according to the second embodiment of the invention. In the base station control apparatus 1 according to the first embodiment, it is determined whether or not to perform multiple base station cooperation based on the CINR cumulative distribution of all the wireless terminals 3 in the cells of the base stations 2A and 2B. In the embodiment, a plurality of base stations cooperate with each other based on the CINR cumulative distribution of the wireless terminal 3 whose RSSI (Received Signal Strength Indicator) is a predetermined value or more. This is because the wireless terminal 3 whose user throughput is not improved even when a plurality of base stations cooperate is excluded.

  FIG. 6 is a flowchart illustrating an example of the flow of determination processing of the base station control device 1 in the present embodiment. The base station control device 1 acquires the CINR and RSSI of the wireless terminal 3 from the base stations 2A and 2B in advance. The base stations 2A and 2B obtain CINR and RSSI from the wireless terminal 3 in its own cell.

  First, the base station control device 1 selects a radio terminal 3 whose RSSI is equal to or greater than a predetermined value (step S21). Next, the cumulative distribution of the CINR of the selected wireless terminal 3 is generated by the distribution generation unit 12 (step S22).

  Next, the base station cooperation determination unit 13 determines whether or not the 10% value of the generated cumulative distribution is greater than or equal to a predetermined threshold value x (step S23). The base station cooperation determination unit 13 determines that multiple base station cooperation is performed if the threshold value is equal to or greater than the threshold value x (step S24), and ends the process. Moreover, the base station cooperation determination part 13 determines not to perform multiple base station cooperation, when smaller than the threshold value x (step S25), and complete | finishes a process. Since other configurations are the same as those of the first embodiment, description thereof is omitted.

  As described above, according to the present embodiment, it is determined whether or not to perform multi-base station cooperation based on the CINR cumulative distribution of the wireless terminal 3 having an RSSI of a predetermined value or more. As a result, it is possible to exclude wireless terminals 3 whose user throughput does not improve even if they cooperate with a plurality of base stations, and the distribution of wireless terminals 3 that improve the user throughput by performing cooperation between multiple base stations more accurately. I can grasp it.

[Third Embodiment]
The present embodiment is an embodiment of the determination method 2.
The base station control device 1 determines the wireless terminal 3 located at a predetermined position (between cells) from the position information of the wireless terminal 3 and the position information of the base stations 2A and 2B. The base station control device 1 determines to perform cooperation with a plurality of base stations when the number of wireless terminals 3 between cells exceeds a predetermined threshold value y.

  FIG. 7 is a flowchart showing an example of the flow of determination processing of the base station control device 1 in the present embodiment. The base station control device 1 acquires position information of the wireless terminal 3 from the base stations 2A and 2B in advance. The base stations 2A and 2B acquire location information from the wireless terminal 3 in its own cell.

  First, the distribution generation unit 12 generates a position distribution of the wireless terminal 3 from the received position information (step S31). Next, the base station cooperation determination unit 13 calculates the number of wireless terminals 3 located between the cells from the position distribution, and determines whether the calculated number of wireless terminals is equal to or greater than a predetermined threshold y (step S32). If the base station cooperation determination unit 13 is equal to or greater than the threshold value y, the base station cooperation determination unit 13 determines that the base station cooperation is performed (step S33), and ends the process. Moreover, the base station cooperation determination part 13 determines not to perform multiple base station cooperation, when smaller than the threshold value y (step S34), and complete | finishes a process. Since other configurations are the same as those of the first or second embodiment, description thereof is omitted.

  As described above, according to the present embodiment, since it is determined whether or not to cooperate with a plurality of base stations based on the position distribution of the wireless terminals 3, there are many wireless terminals 3 whose user throughput is improved by the cooperation of several base stations. It is possible to control the base stations 2A and 2B so that only a plurality of base stations cooperate with each other. Thereby, variation in user throughput in the wireless communication system can be suppressed.

  As described above, the embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to the above, and various design changes and the like can be made without departing from the scope of the present invention. It is possible to

  For example, in this embodiment, the base station control device 1 is configured to perform multiple base station cooperation when there are many wireless terminals 3 that improve user throughput by performing multiple base station cooperation. When there are few wireless terminals 3 whose user throughput is improved by cooperation, a plurality of base stations may be linked. When configured in this way, variations in user throughput for each wireless terminal 3 remain, but the utilization efficiency of wireless resources increases, so that the cell throughput increases. In the present invention, the operator can select which policy to use.

  Further, in this embodiment, the base station control device 1 determines that the multi-base station cooperation is performed as soon as the number of wireless terminals 3 that improve the user throughput by performing the multi-base station cooperation increases. When the state where there are many wireless terminals 3 whose user throughput is improved for a period or more continues, it may be determined that the multiple base station cooperation is performed.

  Further, in the present embodiment, the radio communication system in which the radio communication area is expanded by the cell has been described, but the present invention can be similarly applied to a radio communication system in which the radio communication area is expanded by the sector.

  In the present embodiment, the base station control device 1 creates a cumulative distribution. However, the base stations 2A and 2B may create a cumulative distribution and transmit it to the base station control device 1. At this time, the base station control device 1 determines to perform cooperation with a plurality of base stations when the distributions of the base station 2A and the base station 2B are both low.

It is the schematic which shows the structure of the radio | wireless communications system of this invention. It is a block diagram which shows the structure of the base station control apparatus in 1st Embodiment. It is a flowchart which shows the flow of the determination process of the base station control apparatus in this embodiment. It is the graph which showed the example of CINR cumulative distribution in this embodiment. It is a sequence diagram which shows the flow of a process in the radio | wireless communications system of this embodiment. It is a flowchart which shows the flow of the determination process of the base station control apparatus in 2nd Embodiment. It is a flowchart which shows the flow of the determination process of the base station control apparatus in 3rd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Base station control apparatus 2A, 2B ... Base station 3 ... Wireless terminal 11 ... Reception environment information receiving part 12 ... Distribution generation part 13 ... Base station cooperation determination part 14 ... Base station control part

Claims (8)

In a base station control apparatus in a wireless communication system that performs simultaneous downlink communication by cooperation of a plurality of base stations between a plurality of base stations and one wireless terminal,
A base station cooperation determination unit that determines whether or not to perform multiple base station cooperation based on the distribution of wireless reception environments in wireless terminals;
Based on the determination of the base station determination unit, a base station control unit that controls the base station,
A base station control device comprising:   The base station control apparatus according to claim 1, wherein the radio reception environment is represented by CINR, user throughput, or position of a radio terminal.   The base station control apparatus according to claim 1, wherein a wireless terminal having an RSSI of a certain value or more is targeted for the distribution.   The base station control apparatus according to claim 2, further comprising a cumulative distribution generation unit that generates a cumulative distribution of a wireless reception environment in the wireless terminal. A base station control method in a wireless communication system for performing simultaneous downlink communication by cooperation of a plurality of base stations between a plurality of base stations and one wireless terminal,
Base station cooperation determination step for determining whether or not to perform multiple base station cooperation based on the distribution of the wireless reception environment in the wireless terminal,
Controlling a base station based on the determination in the base station determination step;
A base station control method comprising:   The base station control method according to claim 5, wherein the radio reception environment is represented by CINR, user throughput, or position of a radio terminal.   The base station control method according to claim 5 or 6, wherein a radio terminal having an RSSI of a certain value or more is targeted for the distribution.   The base station control method according to claim 6, further comprising a step of generating a cumulative distribution of a radio reception environment in the radio terminal.

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