JP2014120782A - Method for controlling distributed radio communication base station system and centralized control station - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an increase in the transmission bandwidth of a PON section necessary to perform communication between base stations as the number of ONUs requesting CoMP and X2 handover increases in a backhaul form connecting between base stations by the PON.SOLUTION: An OLT side device with a PON configuration is used as a centralized control station, information on mobile stations belonging to all base stations is gathered at the centralized control station, and user data is transferred to a base station after determining the base station to which the user data should be sent. This eliminates necessity to transfer user data to a base station after transmitting it to another station.

Description

  The present invention relates to a communication method between base stations in a distributed radio communication base station system including a plurality of radio communication base stations and a PON (Passive Optical Network) transmission system.

  An area in which a base station provides services to a mobile station in a mobile communication system is called a cell. When the base station outputs radio signal radio waves with an omnidirectional antenna, the cell spreads concentrically around the base station, and the radius changes according to the level of the transmission output of the antenna. In order to efficiently use radio frequency bands, base stations are installed with high geographical density, cells that are the reach of radio waves are kept in a certain area, and the same frequency band is reused as much as possible spatially. It has been broken.

  FIG. 1 shows an example of a communication environment in a cellular system. When the mobile station moves in the cell and reaches the end region of the cell, the strength of the signal (solid line) from the communicating base station 103A is weakened, while the signal received from the adjacent base station 103B (broken line) ) Is relatively strong. As a result, as shown in FIG. 1, in the area where the cell 102A and the cell 102B overlap, it is more greatly affected by the interference signals of the adjacent base stations 103A and 103B in the downlink communication, and the downlink at the mobile station 101 Signal reception sensitivity decreases.

  Further, when the mobile station 101 moves and enters the area of the cell 102B of the adjacent base station 103B, the communication is continued by switching the belonging base station from 103A to 103B. This series of procedures is generally called handover. As the mobile station 101 moves between cells from 102A to 102B, there arises a problem that the transmission rate is remarkably lowered in the state before and after the handover, that is, in the state where the mobile station 101 is located at the cell edge. For this reason, there is a problem in realizing communication quality that is stable in terms of area.

  In order to solve the problem of communication quality degradation caused by signal interference between adjacent base stations, various measures have been studied so far. One of the measures is a method of suppressing deterioration in communication quality by allowing base stations adjacent to a mobile station located at a cell edge to communicate with each other in cooperation with each other. This method is generally called coordinated multi-point transmission / reception (CoMP) between base stations (cells) (Non-Patent Document 1).

  There are several implementation methods for CoMP, but there is a Joint Transmission (JT) system as one of implementation methods for CoMP for a downlink signal. The JT method is a method for improving the gain of a received signal of a terminal by transmitting the same downlink signal from an adjacent base station to a mobile station located at a cell edge. In JT, two methods of non-coherent transmission using soft combining (combining) reception of radio signals and coherent transmission for realizing in-phase combining of signals at reception points by performing precoding across cells are being studied. . Both cases are common in that the mobile station improves the gain by simultaneously receiving the same signal from two or more base stations, and as a result, the communication quality of the mobile station located at the cell edge is improved. An effect is obtained.

  In non-coherent transmission that is easier to implement among these two JT implementation methods, adjacent base stations transmit the same radio signal to a mobile station. However, a mobile core network (Evolved Packet Core: EPC) sends RAN ( It is necessary to transmit the same downlink signal to each base station via Radio Access Network). As the method, for example, in the LTE (Long Term Evolution) system standardized in 3GPP (Third Generation Partnership Project), there are roughly two procedures as shown in FIG. 2 (a) and FIG. 2 (b). That is, a method of transmitting a user plane signal from each EPC to each base station via the S1 interface (FIG. 2 (a)), and a signal received by the base station requesting JT once buffered. 2 is a method of copying the signal used in (1) and transmitting it to other base stations participating in JT via the X2 interface (FIG. 2B).

FIG. 3 shows an example of a flowchart when JT is performed via the related X2 interface. The operation procedure is described below.
Step S301: Data addressed to the mobile station X is transmitted from the MME / S-GW to the base station A.
Step S302: The base station A acquires information on neighboring cells based on information from the mobile station X. Specifically, information such as the signal reception level of the downlink signal from the adjacent cell and the signal-to-noise interference power ratio (SINR) reported from the mobile station X is used.
Step S303: When the reception level of the signal from the adjacent cell reaches a preset threshold value, the base station A determines that the mobile station X exists at the end of the cell with the adjacent cell. At the same time, the base station B subject to JT is specified. Base station A then issues a JT cooperation request to base station B. At this time, control information such as radio band allocation information related to the mobile station is also notified.
Step S304: The base station B determines whether or not cooperation with the base station A is possible. The case where the base station B determines that the cooperation is impossible occurs, for example, when a resource shortage occurs, for example, the radio band of the mobile station X transmitted from the base station A is not free due to the radio band allocation of the base station B. sell. In other cases, the base station B replies that cooperation is possible (cooperation response).
Step S305: The base station B returns to the base station A whether cooperation is possible.
Step S <b> 306: The base station A that has received the cooperable signal (cooperation response) transfers the data addressed to the mobile station X to the base station B.
Step S307: The same signal is transmitted from the base stations A and B to the mobile station X.

  After step S305, the channel gain information (CSI) between the base station A and the mobile station X and the CSI between the base station B and the mobile station X are collected in one place, and the precoding vector of each base station is calculated. You may be notified.

  When the mobile station moves and enters the cell area of the adjacent base station, communication is continued by switching the belonging base station. This series of procedures is generally called handover. A handover procedure will be described by taking the LTE (Long Term Evolution) method standardized by 3GPP (Third Generation Partnership Project) as an example. In the handover process, it is necessary to exchange control information regarding the mobile station such as which mobile station is connected to the base station and how far the data transmission / reception has been completed. For handover in LTE, two types of handover procedures, “S1 handover” and “X2 handover”, are defined.

  “S1 handover” is a method for exchanging control signals associated with handover between base stations via an S1 interface, which is an interface for connecting a base station apparatus (eNodeB) and a mobile core network (Evolved Packet Core: EPC). . On the other hand, “X2 handover” is a method in which a control signal associated with handover is directly exchanged between base stations using an X2 interface which is a communication interface between base stations.

  The procedure of X2 handover will be described with reference to FIG. Similar to the S1 handover, the source base station determines whether to execute the handover based on the report of the signal strength measurement results of the neighboring base stations from the mobile station. However, the handover request is transmitted directly to the destination base station, not the MME (Mobility Management Entity). The movement-destination base station confirms the availability of radio signal resources and determines whether or not to accept the handover (admission control). The destination base station transmits a notification of handover approval to the source base station. Based on this, the source base station instructs the mobile station to perform handover, and data that has not reached the mobile station (data that has not been transmitted to the mobile station, or data that has been transmitted but has not received an acknowledgment) ) To the destination base station. The mobile station performs synchronization processing with the destination base station, and transmits a handover completion notification to the destination base station. The destination base station transmits unreached data to the mobile station. In addition, the movement-destination base station transmits a path switching request to the MME, and the MME receives this and notifies the gateway device (S / P-GW) of the new base station. Based on this, the packet communication path is switched from the source base station to the destination base station, and the handover is completed.

  In X2 handover, since data that has not reached the mobile station is transferred from the source base station to the destination base station, signal loss is reduced compared to S1 handover, and a shorter time is required. Can be handed over.

  As one form of mobile backhaul, configurations as shown in FIGS. 5A and 5B have been proposed. This configuration is a configuration in which a representative base station is installed in an optical line terminator (OLT) inside the station, and a base station is installed in an optical network unit (ONU) on the subscriber side (non-patent document). Reference 2). That is, base stations are connected by a PON system, and signal division multiplexing methods for PON systems between base stations include TDM (Time Division Multiplex), WDM (Wavelength Division Multiplex), and FDM (Frequency Division Multiplex). It can be illustrated.

  In this form, the representative base station responds to EPC on behalf of each base station connected to the ONU. Communication between the EPC and the base station is performed via the representative base station. In addition, communication between base stations can be realized using a PON section. The configurations of FIGS. 5A and 5B are more economical because the fibers can be concentrated compared to the case where communication is performed by connecting the related base stations with a dedicated fiber.

  FIG. 5A shows a configuration in which the representative base station 110 is added with the function of the OLT 140, the base station 120 is added with the function of the ONU 150, and the representative base station and the base station are connected by the PON system 130. For example, when a TDM-PON system such as GE-PON (IEEE802.3ah), 10G-EPON (IEEE802.3av), etc. is applied as the PON system, the function of the OLT is that the representative base station outputs in the downlink. A function of mapping data to be transmitted to an Ethernet (registered trademark) frame and transmitting it at a predetermined timing, and a function of extracting data from an Ethernet (registered trademark) frame received in the uplink. On the other hand, the ONU function refers to a function of extracting data from an Ethernet (registered trademark) frame received in the downlink, or a predetermined timing by mapping data output from a base station in the uplink to an Ethernet (registered trademark) frame. Includes the ability to send in.

  In FIG. 5B, adapters 210 and 230 are added between the representative base station 110 and the OLT 140 and between the base station 120 and the ONU 150, respectively, and the representative base station and the base station are connected by the PON system. The function of the adapter between the representative base station and the OLT includes a function of converting a downlink signal output from the representative base station into a signal in a format that can be recognized by the input interface of the OLT, and an upstream signal output from the OLT as an input of the representative base station. Includes a function to convert the signal into a format that the interface can recognize. On the other hand, the adapter function between the ONU and the base station includes a function for converting a downstream signal output from the ONU into a signal in a format that can be recognized by the input interface of the base station, and an ONU input interface for converting the upstream signal output from the base station. Includes the ability to convert the signal into a recognizable format.

"MIMO and inter-cell cooperative transmission / reception technology in LTE-Advanced", NTT DOCOMO Technical Journal Vol. No. 18 2 p. 22-30 Chathurika Ranaweera et al. , “Next Generation Optical-Wireless Converged Network Architectures”, IEEE Network, pp22-27.

  When performing JT, it is necessary to transmit user data of a mobile station to be subjected to JT from one base station to another base station. When performing handover, it is necessary to transmit unreached data of the mobile station from the source base station to the destination base station.

  Here, in the configurations of FIGS. 5A and 5B, one fiber is shared by a plurality of ONUs. For this reason, as the number of base stations requesting JT and handover increases, the bandwidth of the PON section necessary for transferring user data increases, and the bandwidth for transmitting other user data is insufficient. There is.

  An object of the present invention is to prevent an increase in the bandwidth of a PON section necessary for transferring user data even if the number of base stations requesting JT or handover increases.

The central control station according to the present invention is:
A centralized control station provided in a distributed radio communication base station system in which a plurality of base stations that perform radio communication with mobile stations in a cell are connected to one representative base station by a PON (Passive Optical Network),
An information aggregating unit that aggregates the communication status of the mobile station with the base station from each base station;
A determination unit that determines a communication environment suitable for performing wireless communication with the mobile station based on the aggregated information;
A control unit that operates at least one of the base stations so as to be a communication environment determined by the determination unit;
Is provided.

The distributed radio communication base station system according to the present invention is:
Representative base station,
A plurality of base stations that communicate wirelessly with mobile stations in the cell;
A PON system that has an OLT on each of the representative base stations and an ONU on each of the base stations, and multiplex-transmits signals between the representative base station and the base station;
A central control station of the present invention;
Is provided.

A control method of a distributed radio communication base station system according to the present invention includes:
A control method of a distributed radio communication base station system in which a plurality of base stations that perform radio communication with a mobile station in a cell are connected to one representative base station by a PON,
Information aggregation procedure for aggregating the communication status of the mobile station with the base station from each base station,
A determination procedure for determining a communication environment suitable for performing wireless communication with the mobile station based on the aggregated information;
A control procedure for operating at least one of the base stations so as to be in the communication environment determined in the determination procedure;
Have

  The present invention provides a centralized control station on the representative base station side in the PON, collects information on mobile stations belonging to all base stations in the centralized control station, determines a base station to which user data is to be transmitted, Transferring data to the base station eliminates the need to transfer user data to one base station and then to another base station. Therefore, the present invention can prevent an increase in the bandwidth of the PON section necessary for transferring user data even if the number of base stations requesting JT or handover increases.

In the central control station according to the present invention,
The determining unit identifies a mobile station having a poor communication status based on the communication status aggregated by the information aggregating unit, and performs coordinated transmission / reception between base stations for the base station in which the mobile station exists in the cell of the own station. Decide to do,
The control unit transmits information necessary for performing coordinated transmission / reception between base stations including information on the mobile station together with a command for performing coordinated transmission / reception between base stations, to a base where the mobile station exists in the cell of the own station. You may notify the station.

In the central control station according to the present invention,
The determining unit identifies a mobile station having a poor communication status based on the communication status aggregated by the information aggregating unit, and the base station that is the handover destination from among the base stations that are present in the cell of the mobile station. Determine the station,
The control unit may notify the handover destination base station of information necessary for wireless communication with the mobile station including information on the mobile station together with a command to perform handover.

  In the centralized control station according to the present invention, the control unit may notify each base station of the command and the information of the mobile station by multicast.

  The above inventions can be combined as much as possible.

  According to the present invention, after the PON-configured OLT side device is used as a centralized control station, information on mobile stations belonging to all base stations is aggregated in the centralized control station, and the base station to which user data is to be sent is determined. Thus, by transferring the user data to the base station, it is not necessary to transfer the user data to another base station after sending the user data to a certain base station.

An example of the communication environment in a cellular system is shown. It is a schematic diagram which shows the 1st example of cooperation transmission / reception between base stations. It is a schematic diagram which shows the 2nd example of cooperation transmission / reception between base stations. An example of the sequence of the coordinated transmission / reception between base stations is shown. An example of the sequence of X2 handover is shown. The 1st example of the structure which connects between a representative base station and base stations by a PON system is shown. The 2nd example of the structure which connects between a representative base station and base stations by a PON system is shown. An example of the structure of the centralized control station which concerns on embodiment of this invention is shown. An example of a sequence when a related JT procedure is applied to a distributed radio communication base station system in which a representative base station and a base station are connected by a PON is shown. An example of the JT procedure according to the second embodiment will be shown. An example of a sequence when a related handover procedure is applied to a distributed radio communication base station system in which a representative base station and a base station are connected by a PON is shown. An example of the handover procedure according to the second embodiment is shown.

  Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to the following embodiments. In the present specification and drawings, the same reference numerals denote the same components.

  In the distributed radio communication base station system according to the embodiment of the present invention, a plurality of base stations 103A and 103B that perform radio communication with a mobile station 101 in a cell are connected by one representative base station 110 and a PON system 130. . As a signal multiplexing method of the PON, TDM (Time Division Multiplex), WDM (Wavelength Division Multiplex), FDM (Frequency Division Multiplex), or the like can be selected.

  The configuration in which the representative base station 110 and the base stations 103A and 103B are connected by the PON system is arbitrary. For example, the configuration shown in FIG. 5A is the configuration shown in FIG. Also good. Although the number of base stations connected by the PON can be an arbitrary number of 2 or more, in this embodiment, a case where there are two base stations will be described for easy understanding.

  The representative base station 110 includes a central control station. The central control station is provided closer to the representative base station 110 than the optical signal branch circuit 135 in the PON. For example, the central control station may be provided in the representative base station 110 illustrated in FIG. 5A or may be included in the adapter 210 or the OLT 140 illustrated in FIG.

  FIG. 6 shows an example of the configuration of the centralized control station according to the embodiment of the present invention. The centralized control station 160 includes an information aggregating unit 161, a determining unit 162, and a control unit 163. The control method of the distributed radio communication base station system according to the embodiment of the present invention includes an information aggregation procedure, a determination procedure, and a control procedure in order.

In the information aggregation procedure, the information aggregating unit 161 aggregates the communication status of the mobile station 101 with the base stations 103A and 103B from each base station 103. The communication status is, for example, a measurement result of the peripheral base station of the mobile station 101.
In the determination procedure, the determination unit 162 determines a communication environment suitable for performing wireless communication with the mobile station 101 based on the collected information. The communication environment is, for example, JT or handover.
In the control procedure, the control unit 163 operates at least one of the base stations 103A and 103B so that the communication environment determined by the determination unit 162 is obtained. At this time, the command may be notified only to the base station that needs to be operated, but the command may be notified to all base stations connected by the PON using the multicast function.

  Thus, in the present invention, the multicast function of PON can also be used. That is, after a representative base station or adapter or OLT having a PON configuration is used as a central control station, information on mobile stations belonging to all base stations is aggregated in the central control station, and a base station to which user data is to be sent is determined The user data is transferred to all base stations by the multicast function. This eliminates the need to transfer user data to one base station and then to another base station.

(Embodiment 1)
In Embodiment 1, the information regarding the mobile station which each base station hold | maintains is once transmitted to the centralized control station 160. FIG. The central control station 160 determines a base station that performs JT from the collected data. Thereafter, the centralized control station 160 transmits the data of the mobile station 101 by multicast to the base stations 103A and 103B participating in JT.

FIG. 8 shows an example of the JT procedure according to this embodiment.
Step S701: The base station A acquires information on neighboring cells based on information from the mobile station X. Specifically, peripheral base station information (peripheral base station measurement result) such as the signal reception level of the downlink signal from the adjacent cell and the signal-to-noise interference power ratio (SINR) reported from the mobile station X is used. The mobile station X may periodically transmit this information, or may transmit only when an information transmission request is received from the base station.
Step S702: All base stations transmit cooperation information to the centralized control station. The cooperation information includes the CSI information of the mobile station belonging to itself and the neighboring base station information obtained in step S701.
Step S703: The central control station specifies a mobile station that has poor communication conditions and needs to use JT based on the cooperation information, and simultaneously specifies a base station that transmits a signal to the mobile station using this JT. Here, it is assumed that JT is required for signal transmission to the mobile station X from the base stations A and B.
Step S704: The central control station transmits the data of the mobile station X to the base station A and the base station B using the multicast function. At this time, the central control station determines and notifies the base station A and the base station B of the radio band used for data transmission of the mobile station X (S705).
Step S706: The same signal is transmitted from the base stations A and B to the mobile station X.

  After step S703, the precoding vector of each base station is calculated from the channel gain information between the base station A and the mobile station X and the channel gain information between the base station B and the mobile station X. You may notify the station.

  When determining the base station that performs JT in step S703, it can also be determined in view of the availability of the radio band of each base station. That is, a base station with a small available radio band is not a target for JT cooperation. The availability of the radio band can be acquired by sending the radio band allocation information or the CSI information and data amount of other mobile stations to the central control station in step S702.

FIG. 7 shows a sequence when the related JT procedure is applied to the configuration of FIG.
Step S601: Data addressed to the mobile station X is transmitted from the representative base station to the base station A.
Step S602: The base station A acquires information on neighboring cells based on information from the mobile station X.
Step S603: The base station A transmits a cooperation request to the representative base station, and the representative base station transmits a cooperation request from the base station A to the base station B.
Step S604: The base station B performs resource confirmation.
Step S605: The base station B responds to the representative base station as to whether or not cooperation is possible, and the representative base station notifies the base station A of the base station that is the cooperation possible response (cooperation response).
Step S606: The base station A transmits the data of the mobile station X to the representative base station, and the representative base station transmits the data of the mobile station X to the base station B.
Step S607: The same signal is transmitted from the base stations A and B to the mobile station X.

  In the JT procedure shown in FIG. 8 of the first embodiment, it can be seen that the number of times of transmitting data addressed to the mobile station X is reduced compared to the JT procedure shown in FIG. Therefore, the present invention can prevent an increase in the bandwidth of the PON section necessary for transferring user data even if the number of base stations requesting JT or handover increases.

Further, the first embodiment can be applied even when the number of base stations participating in JT is set to an arbitrary value as well as two.
Further, not only the representative base station 110 but also the adapter 210 or the OLT 140 can become the central control station 160.

(Embodiment 2)
In the second embodiment, information regarding the mobile station 101 held by each of the base stations 103A and 103B is once transmitted to the centralized control station 160. The centralized control station 160 determines the handover destination of the mobile station 101 from the collected data, and transmits the mobile station data only to the handover destination.

FIG. 10 shows an example of a handover procedure according to this embodiment.
Step S901: Data addressed to the mobile station X is transmitted from the S / P-GW to the representative base station.
Steps S902 and S903: The base station A acquires information on neighboring cells based on information from the mobile station X. Specifically, peripheral base station information (peripheral base station measurement result) such as the signal reception level of the downlink signal from the adjacent cell and the signal-to-noise interference power ratio (SINR) reported from the mobile station X is used.
Step S904: All base stations transmit the CSI information of the mobile stations belonging to them and the information of the neighboring base stations obtained in step S902 to the centralized control station provided in the representative base station. At this time, the base stations A and B as the movement source transmit user data such as CSI information of the mobile station X to the central control station.
Step S905: The central control station provided in the representative base station specifies a mobile station having a poor communication condition and using a handover (H / O) based on these data, and simultaneously transmits a signal to the mobile station. Is specified as a handover destination base station. Here, it is assumed that the handover destination of the mobile station X from the base station A is the base station B.

Step S906: The centralized control station provided in the representative base station transmits a handover (H / O) instruction to the base station A. Thereby, the base station A notifies the mobile station X that the handover (H / O) is performed.
Step S907: The central control station provided in the representative base station transmits data addressed to the mobile station X to the base station B. At this time, the central control station may determine and notify the base station B of the radio band used for data transmission of the mobile station X.
Step S908: The base station B performs synchronization processing with the mobile station X. When the synchronization process is completed, the handover of the mobile station X from the base station A to the base station B is completed (S909). When the handover is completed, data addressed to the mobile station X is transmitted from the base station B to the mobile station X.

Step S910: When the handover is completed, the base station B makes a path switching request to the representative base station. Then, the MME is notified of a path switching request.
Step S911: The MME notifies the S / P-GW that the base station of the mobile station X is the base station B. Then, the path for the S / P-GW to communicate with the mobile station X is switched to the base station B (S912).
Step S912: The MME notifies the base station A of a resource release instruction for the mobile station X via the representative base station. As a result, the base station A discards the information held for communication with the mobile station X.

  In this embodiment, when the connection cell of the mobile station X is switched from the base station A to the base station B, the base station A transmits, but the channel gain between the base station A and the mobile station X changes, and the mobile station X There is a possibility that the base station A has unreached data that has not been delivered. For this time, in step S904 of the above procedure, all the base stations transmit information on the unreached data of each mobile station to the centralized control station, and the centralized control station includes the unreached data of the base station A. It may be possible to transmit to the base station B. As another method, when the connection cell is switched, data may be additionally transferred from the base station A to the base station B only when unreachable data exists in the base station A.

FIG. 9 shows a sequence when the related handover procedure is applied to the configuration of FIG.
Step S801: Data addressed to the mobile station X is transmitted from the S / P-GW to the base station A via the representative base station.
Steps S802 and S803: Base station A acquires information on neighboring cells based on information from mobile station X.
Step S804: The base station A determines to perform a handover (H / O).
Step S805: The base station A makes a handover request to the representative base station, and the representative base station makes a handover request to the base station B.
Step S806: The base station B confirms the resource and performs admission control.
Step S807: The base station B approves the handover to the representative base station. The representative base station notifies the base station A that the base station B has approved the handover. Thereby, the base station A notifies the mobile station X that the handover (H / O) is performed (S808).
Step S809: The base station A transfers the unachieved data of the mobile station X and the terminal information of the mobile station X to the base station B via the representative base station.
Step S810: The base station B performs synchronization processing with the mobile station X. When the synchronization process is completed, the handover of the mobile station X from the base station A to the base station B is completed (S811). When the handover is completed, data addressed to the mobile station X is transmitted from the base station B to the mobile station X.
Step S812: The base station B makes a path switching request to the representative base station. Then, the MME is notified of a path switching request. The MME notifies the S / P-GW that the base station of the mobile station X is the base station B. Then, the path for the S / P-GW to communicate with the mobile station X is switched to the base station B (S813).
Step S814: The MME notifies the base station A of a resource release instruction for the mobile station X via the representative base station. As a result, the base station A discards the information held for communication with the mobile station X.

  In the handover procedure shown in FIG. 10 of the second embodiment, it can be seen that the number of times the PON band is used for transferring user data is reduced compared to the handover procedure shown in FIG. Therefore, the present invention can prevent an increase in the bandwidth of the PON section necessary for transferring user data even if the number of base stations requesting JT or handover increases.

  The present invention can be applied to the information communication industry.

10, 11: Representative base station device 12: Adapter 13: OLT
20, 21: ONU
22: Adapter 23: Base station apparatus 40A, 40B, 40C: Mobile station 50A, 50B: Base station 60: EPC
101: Mobile stations 102A, 102B: Cells 103A, 103B: Base station 110: Representative base station 120: Base station 130: PON system 135: Optical signal branch circuit 140: OLT
150: ONU
160: Central control station 161: Information aggregation unit 162: Determination unit 163: Control unit 210, 230: Adapter

Claims (6)

A centralized control station provided in a distributed radio communication base station system in which a plurality of base stations that perform radio communication with mobile stations in a cell are connected to one representative base station by a PON (Passive Optical Network),
An information aggregating unit that aggregates the communication status of the mobile station with the base station from each base station;
A determination unit that determines a communication environment suitable for performing wireless communication with the mobile station based on the aggregated information;
A control unit that operates at least one of the base stations so as to be a communication environment determined by the determination unit;
Centralized control station with The determining unit identifies a mobile station having a poor communication status based on the communication status aggregated by the information aggregating unit, and performs coordinated transmission / reception between base stations for the base station in which the mobile station exists in the cell of the own station. Decide to do,
The control unit transmits information necessary for performing coordinated transmission / reception between base stations including information on the mobile station together with a command for performing coordinated transmission / reception between base stations, to a base where the mobile station exists in the cell of the own station. The central control station according to claim 1, wherein the central control station is notified to the station.   The central control station according to claim 2, wherein the control unit notifies each base station of the command and the information of the mobile station by multicast. The determining unit identifies a mobile station having a poor communication status based on the communication status aggregated by the information aggregating unit, and the base station that is the handover destination from among the base stations that are present in the cell of the mobile station. Determine the station,
The control unit notifies a handover destination base station of information necessary for performing wireless communication with the mobile station including information on the mobile station together with a command to perform handover. 4 to 4. The central control station according to any one of 1 to 3. Representative base station,
A plurality of base stations that communicate wirelessly with mobile stations in the cell;
A PON system that has an OLT on each of the representative base stations and an ONU on each of the base stations, and multiplex-transmits signals between the representative base station and the base station;
A centralized control station according to any one of claims 1 to 4,
A distributed wireless communication base station system. A control method of a distributed radio communication base station system in which a plurality of base stations that perform radio communication with a mobile station in a cell are connected to one representative base station by a PON,
Information aggregation procedure for aggregating the communication status of the mobile station with the base station from each base station,
A determination procedure for determining a communication environment suitable for performing wireless communication with the mobile station based on the aggregated information;
A control procedure for operating at least one of the base stations so as to be in the communication environment determined in the determination procedure;
A control method for a distributed radio communication base station system.

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