JP5429077B2 - Mobile communication system, base station, and communication control method - Google Patents

Description

  The present invention relates to a technical field of a base station in a mobile communication system in which a plurality of different mobile communication systems share an antenna unit and a communication control method in the base station.

  As this type of base station, there is a shared base station that supports both mobile communication systems using different radio communication technologies (RAT) such as 3G (3rd Generation) and LTE (Long Term Evolution). is there. Since such a base station corresponds to each of a plurality of RATs and can communicate with a mobile network, it is expected to be introduced in a transition period between different RATs in terms of convenience and installation cost. It is.

  Under such a base station, there are cases where the service areas of the respective RATs are arranged so as to overlap the same range. At this time, in a mobile terminal corresponding to each RAT, a so-called system from one RAT to another RAT Inter-handover can be performed. By using such inter-system handover, the number of mobile terminals accommodated in the service area for each RAT in the base station can be adjusted, and a communication environment according to the service type required for the mobile terminals can be provided.

  In handover between different radio systems, a configuration for realizing seamless inter-system handover by using location information of a mobile terminal is known as seen in the following prior art documents.

JP 2009-212746 A JP 2003-87858 A

  In the inter-system handover that does not involve the positional movement of the mobile terminal, it is not always necessary to perform a wide-range path search. However, in the handover procedure in the conventional base station, it cannot be determined that the handover source base station and the handover destination base station are the same base station shared by different RATs. For this reason, there is a technical problem that it is impossible to distinguish between inter-system handover and normal inter-base station handover. Therefore, in the conventional base station, a wide range of path searches are performed even during inter-system handover. By performing such unnecessary processing, the amount of processing inside the base station increases, and in some cases, there is a possibility that reliable success of inter-system handover may be hindered.

  In view of the above-described problems, the present invention provides a base station and a communication control method capable of reducing an amount of processing at the time of inter-system handover in base stations shared by different RATs and realizing appropriate inter-system handover. The task is to do.

  In order to solve the above-described problem, the disclosed mobile communication system moves in a first communication system that shares an antenna capable of transmitting and receiving signals of a plurality of communication systems including the first communication system and the second communication system. A first base station that communicates with a terminal and a second base station that communicates with a mobile terminal using a second communication method are provided. The first communication method and the second communication method are typically intended to indicate different wireless communication technologies, and for example, indicate communication methods such as the LTE method and the 3G method.

  The first base station includes acquisition means for acquiring radio information indicating a relative distance from the mobile terminal accommodated in the first base station, and notification means for notifying the second base station of the radio information. Prepare.

  The acquisition means acquires radio information indicating a relative distance between the first base station and the mobile terminal, such as RTT (Round Trip Time) in a communication channel with the mobile terminal by, for example, path search processing. Also good. The acquired wireless information may be stored in a database or the like in such a manner that it can be identified for each channel.

  The notifying means notifies the second base station of the radio information acquired by the acquiring means. The notifying means transmits radio information to the second base station, for example, by communication via a CPRI link or IP connection that is communicably connected between the first base station and the second base station, or via a core network. To do.

  When the second base station starts communication with the mobile terminal accommodated in the first base station, the second base station sets communication with the mobile terminal based on the wireless information notified from the first base station. Communication control means for performing is provided.

  The communication control means is, for example, wireless information notified from the first base station in a so-called Inter-RAT handover process in which the mobile terminal accommodated in the first base station and the second base station start communication. May be used to determine the relative distance to the mobile terminal and set for establishing a wireless connection.

  The disclosed communication control method is a method of performing communication control in the above-described mobile communication system in order to solve the above problems. Specifically, the disclosed communication control method includes an acquisition step for performing processing similar to that performed by the acquisition unit included in the mobile communication system, a notification step for performing processing similar to that performed by the notification unit, and communication. A communication control step for performing processing similar to that performed by the control means.

  In order to solve the above-described problem, the disclosed first base station is a base station that is connected to the above-described mobile communication system and performs communication with the mobile terminal accommodated in the first base station. An acquisition unit configured to acquire radio information indicating a relative distance; and a notification unit configured to notify the radio information to another base station (for example, the above-described second base station).

  In order to solve the above-described problem, the disclosed second base station is a base station that is connected to the mobile communication system and performs communication, and starts communication with a mobile terminal accommodated in another base station. In this case, a communication control unit configured to set communication with the mobile terminal based on wireless information notified from another base station (for example, the first base station described above) is provided.

  According to the operation of the mobile communication system described above, the communication control means of the second base station that is the handover destination using the radio information acquired in the first base station that is the handover source during the Inter-RAT handover process. Can grasp the relative distance from the mobile terminal.

  Since the first base station and the second base station use the same shared antenna, the cells under the first base station and the cells under the second base station have the same physical cell range. May be. Therefore, by using the radio information acquired in the first base station, the second base station can estimate the positions of the mobile terminal and the second base station with a certain degree of accuracy. As a result, the second base station can easily detect the path of the dedicated channel set with the mobile terminal by performing a path search in a narrow range based on the estimated position of the mobile terminal. It becomes possible to do.

  For this reason, it is possible to shorten the time required for completing the path search by the communication setting performed in the second base station during the Inter-RAT handover process. This leads to an increase in the success rate of the handover process. Further, since the processing amount related to the path search process in the second base station is reduced, it leads to an increase in handover calls that can be simultaneously processed in parallel, and the efficiency of the entire system is improved.

It is a block diagram which shows the structure of a mobile communication system. 1 is a block diagram illustrating a configuration of an LTE radio control apparatus. FIG. It is a block diagram which shows the structure of the radio | wireless control apparatus of a 3G system. It is a block diagram which shows the hardware constitutions of a radio | wireless control apparatus. It is a figure which shows an example of the Phy information table stored in a memory | storage part. It is a figure which shows the aspect of sharing of a Phy information table. It is a figure which shows an example of the station data stored in a memory | storage part. It is a flowchart which shows the flow of the new acquisition and update process of Phy information. It is a flowchart which shows the flow of the sharing process of Phy information. It is a flowchart which shows the flow of a Phy information table invalid flag setting process. It is a sequence diagram concerning an Inter-RAT handover process. It is a flowchart which shows the flow of a process of eNB concerning an Inter-RAT handover process. It is a flowchart which shows the flow of a process of BTS concerning an Inter-RAT handover process. It is a flowchart which shows the flow of a process of RNC concerning an Inter-RAT handover process. It is a flowchart which shows the flow of the hand-over destination confirmation process in a hand-over process. It is a flowchart which shows the flow of the path search process in a handover process. It is a block diagram which shows the structure of the 1st modification of a mobile communication system. It is a block diagram which shows the structure of the 2nd modification of a mobile communication system. It is a block diagram which shows the structure of the 3rd modification of a mobile communication system. It is a block diagram which shows the structure of the 4th modification of a mobile communication system.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(1) Basic Configuration The configuration of a mobile communication system 1 that is an embodiment of the disclosed mobile communication system will be described with reference to the block diagram of FIG.

  The mobile communication system 1 includes a REC (eNB (enode B)) 10, a 3G REC (BTS (Base Transceiver Station)) 20, and a REC (eNB). ) 10 and REC (BTS) 20 are provided with a shared RE (Radio Equipment) 40 which is a radio device shared.

  The REC (eNB) 10 is an apparatus that configures an LTE base station (eNB) together with a shared RE 40 connected via a CPRI (Common Public Radio Interface) link # 1. The REC (eNB) 10 is connected to the core network CN and communicates with a UE (User Equipment: User Equipment) 50 accommodated in a cell under the shared RE 40.

  The functional units included in the REC (eNB) 10 will be described with reference to the block diagram of FIG. FIG. 2 is a diagram illustrating the functions of the REC (eNB) 10 as independent functional units for convenience. Each functional unit is described in a program, for example, and does not have an independent entity. Also good. The REC (eNB) 10 includes a CPRI # 1 interface 11 that is a communication interface with the shared RE 40, a CPRI # 2 interface (eNB) 12 that is a communication interface with the REC (BTS) 20, and a CPRI multiplexer (MUX) 13. , Network transmission / reception unit (eNB) 14, storage unit (eNB) 15, baseband signal processing unit (eNB) 16, handover management unit (eNB) 17, call processing control unit (eNB) 18, clock ( eNB) 19.

  The CPRI # 1 interface 11 forms a CPRI link # 1 with the CPRI interface included in the shared RE 40, and transmits and receives data. The CPRI # 2 interface (eNB) 12 forms a CPRI link # 2 with the CPRI # 2 interface (BTS) 21 included in the REC (BTS) 20, and transmits and receives data. The CPRIMUX 13 multiplexes data transmitted and received via the CPRI # 1 interface 11 and the CPRI # 2 interface (eNB) 12. The network transmission / reception unit (eNB) 14 is connected to the core network CN and transmits / receives data.

  The storage unit (eNB) 15 is a memory for storing data, and stores, for example, a handover call identification ID, Phy information, and station data described later.

  The baseband signal processing unit (eNB) 16 performs radio resource management and transmission / reception data processing in communication via the shared RE 40. The baseband signal processing unit (eNB) 16 includes a path search processing unit (eNB) 161 that performs a path search for the UE 50 that performs communication, and Phy information for Inter-RAT handover stored in the storage unit (eNB) 15. A Phy information management unit (eNB) 162 that performs management is provided.

  The handover management unit (eNB) 17 determines whether or not the Inter-RAT handover is performed according to the load status of the REC (eNB) 10, the radio wave status of the shared RE 40, the capability of the UE 50, and the like. For example, the handover management unit (eNB) 17 determines the implementation of the Inter-RAT handover according to the number of UEs 50 accommodated in the cell of the shared RE 40, the service type requested by the UE 50, or the movement of the position of the UE 50. .

  The call processing control unit (eNB) 18 performs processing of calls from the core network CN to the UE 50 and resource management of dedicated channels. Further, the call processing control unit (eNB) 18 is a handover that is an ID for identification common to the REC (eNB) 10 and the REC (BTS) 20 for the dedicated channel used for the call processing at the time of Inter-RAT handover of the UE 50. The call identification ID is assigned for management.

  The clock (eNB) 19 generates a clock signal for latching the processing signal of each unit.

  Note that a mobility management entity (MME) is provided above the REC (eNB) 10 as a device arranged in the core network CN.

  Returning to FIG. 1, the description will be continued. The REC (BTS) 20 is connected to the connection REC (eNB) 10 via the CPRI link # 2, and together with the shared RE 40 connected via the REC (eNB) 10 via the CPRI # 1, the 3G base station (BTS) It is the apparatus which comprises. The REC (BTS) 20 is connected to the core network CN via an RNC (Radio Network Controller) 30 and communicates with the UE 50 accommodated in a cell under the shared RE 40.

  The functional units of the REC (BTS) 20 will be described with reference to the block diagram of FIG. FIG. 3 is a diagram showing the functions of the REC (BTS) 20 as independent functional units for convenience. Each functional unit is described in a program, for example, and does not have an independent entity. Also good. The REC (BTS) 20 includes a CPRI # 2 interface (BTS) 21 that is an interface for communicating with the shared RE 40 via the REC (eNB) 10 and a network transmission / reception unit (BTS) connected to the core network CN via the RNC 30. ) 22, a storage unit (BTS) 23, a baseband signal processing unit (BTS) 24, a call processing control unit (BTS) 25, and a clock (BTS) 26. The RNC 30 connected to the REC (BTS) 20 includes a handover management unit (RNC) 31.

  The CPRI # 2 interface (BTS) 21 forms a CPRI link # 2 with the CPRI # 2 interface (eNB) 12 included in the REC (eNB) 10, and data is transmitted between the REC (eNB) 10 and the shared RE 40. Send and receive. The network transmission / reception unit (BTS) 22 is connected to the core network CN via the RNC 30 and transmits / receives data.

  The storage unit (BTS) 23 is a memory for storing data, and stores, for example, a handover call identification ID, Phy information, and station data described later.

  The baseband signal processing unit (BTS) 24 performs management of radio resources in communication via the shared RE 40 and processing of transmission / reception data. The baseband signal processing unit (BTS) 24 includes a path search processing unit (BTS) 241 that performs a path search for the UE 50 that performs communication, and Phy information for Inter-RAT handover stored in the storage unit (BTS) 23. A Phy information management unit (BTS) 242 that performs management is provided.

  The call processing control unit (BTS) 25 performs processing of calls from the core network CN to the UE 50 and resource management of dedicated channels. Further, the call processing control unit (BTS) 25 is a handover that is an ID for identification common to the REC (eNB) 10 and the REC (BTS) 20 for the dedicated channel used for the call processing at the time of Inter-RAT handover of the UE 50. The call identification ID is assigned for management.

  The clock (BTS) 26 generates a clock signal for latching the processing signal of each unit.

  The handover manager (RNC) 31 determines whether or not the Inter-RAT handover is performed according to the load status of the REC (BTS) 20, the radio wave status of the shared RE 40, the capability of the UE 50, and the like. For example, the handover management unit (BTS) 31 determines whether to perform the Inter-RAT handover according to the number of UEs 50 accommodated in the cell of the shared RE 40, the service type required by the UE 50, or the movement of the position of the UE 50. .

  Returning to FIG. 1, the description will be continued. The shared RE 40 is a device having a radio unit as a part of the REC (eNB) 10 or the REC (BTS) 20, and a CPRI interface connected to the REC (REC (eNB) 10) via the CPRI link # 1. And a duplexer for processing transmission / reception signals and an antenna. In a portion that is not particularly described, the shared RE 40 may have a known configuration.

  The UE 50 is a so-called dual UE 50 that can communicate with the REC (eNB) 10 by the LTE method and can communicate with the RNC 30 by the 3G method. Therefore, the UE 50 can perform an Inter-RAT (Radio Access Technology) handover from the LTE cell to the 3G cell or from the 3G cell to the LTE cell.

  The REC (eNB) 10 and the REC (BTS) 20 are information related to a physical layer (Physical layer) of a dedicated channel (hereinafter referred to as a dedicated channel) set in a call of the UE 50 accommodated in a subordinate cell. (Hereinafter referred to as “Phy information”). The Phy information is, for example, RTT in communication via an individual channel set for a call of the UE 50. The database takes the form of a table (hereinafter, referred to as a Phy information table) having an identification ID for identifying a call for each UE 50 and Phy information such as RTT. FIG. 5 is a diagram illustrating an example of the Phy information table stored in the storage unit (eNB) 15 of the REC (eNB) 10 and the Phy information table stored in the storage unit (BTS) 23 of the REC (BTS) 20. .

  The REC (eNB) 10 and the REC (BTS) 20 that share the same shared RE 40 mutually notify and share the Phy information table of the individual channels set in their own cells. As shown in FIG. 6, the Phy information management unit (eNB) 162 of the REC (eNB) 10 stores the Phy information table of the individual ch set in the own cell stored in the storage unit (eNB) 15 as a CPRI link. Notify REC (BTS) 20 via # 2. In the storage unit (BTS) 23 of the REC (BTS) 20 that has received the notification, in addition to the Phy information table of the individual ch set in the own cell, the individual ch of the individual ch set in the cell under the REC (eNB) 10 A Phy information table is stored. On the other hand, the Phy information management unit (BTS) 242 of the REC (BTS) 20 stores the Phy information table of the individual ch set in the own cell stored in the storage unit (BTS) 23 via the CPRI link # 2. REC (eNB) 10 is notified. In response to the notification, the storage unit (eNB) 15 of the REC (eNB) 10 includes the individual channel configured in the cell under the REC (BTS) 20 in addition to the Phy information table of the individual channel configured in the own cell. A Phy information table is stored. The process for newly acquiring and notifying the Phy information table related to the individual channel set in each cell will be described in detail later.

  Without being limited to the example shown in FIG. 6, when another REC is further connected to the shared RE 40, the configuration may be such that the Phy information of the individual channel is shared with the REC.

  In addition to the Phy information table, the storage unit (eNB) 15 of the REC (eNB) 10 and the storage unit (BTS) 23 of the REC (BTS) 20 are handover destination candidates during the handover process of the UE 50 accommodated in the subordinate cell. Stores station data for confirming. The station data is stored, for example, in the form of a handover destination candidate station table shown in FIG. As an example, in the handover destination candidate station table, the candidate station number (candidate station #), the node identifier for identifying the node of the candidate station, the carrier number of the candidate station, the sector number, and the sharing status of the RE of the candidate station are shown. The RE shared information shown is stored.

  With reference to FIG. 4, an example of a hardware configuration for realizing each functional unit included in the REC (eNB) 10, the REC (BTS) 20, and the shared RE 40 will be described. FIG. 4 is a block diagram illustrating the hardware that the REC (eNB) 10 or the REC (BTS) 20 has in common and the hardware that the shared RE 40 has.

  The inter-station network signal processing unit 110 is an example of the network transmission / reception units 14 and 22, and is a base station control station interface circuit 111 serving as an interface with a control station, and a large scale integration (LSI) or a field programmable gate (FPGA). And a signal processing circuit 112 including an array). The inter-station network signal processing unit 110 is connected to the bus 150 connected to each unit of the REC (eNB) 10 or the REC (BTS) 20 via the overhead interface circuit 113.

  The call processing signal processing unit 120 includes a signal processing circuit 121 for processing a signal related to call processing, and a built-in interface circuit 122 connected to a bus 150 connected to each unit of the REC (eNB) 10.

  The CPRI interface 130 is an example of the CPRI # 1 interface 11, the CPRI # 2 interfaces 12, 21 and the CPRIMUX 13, and includes a connection optical module 131 and a signal processing circuit 132 configured by an LSI or FPGA. The CPRI interface 130 is connected to the bus 150 connected to each part of the REC (eNB) 10 or the REC (BTS) 20 via the intra-building interface circuit 133.

  The call control / monitoring control unit 140 is configured to control or monitor the entire operation of the REC (eNB) 10 or the REC (BTS) 20, and includes a control CPU 141, a storage memory 142, an operation memory 143, and a storage An interface circuit 144 is included. The CPU 141 functions as an example of the handover management units 17 and 25 and the call processing control units 18 and 26 by executing a program stored in the storage memory 142. The operation memory 143 is a memory for temporarily developing programs and various data during the operation of the CPU 141. The storage memory 142 operates as an example of the storage units 15 and 23 that store the Phy information table and the station data. The call control / monitoring control unit 140 is connected to the bus 150 connected to each unit of the REC (eNB) 10 or the REC (BTS) 20 via the intra-building interface circuit 144.

The bus 150 is a bus for connecting each part of the REC (eNB) 10 or the REC (BTS) 20 to each other. The bus 150 is connected to a reference signal transmitter (not shown) as an example of the clocks 19 and 27 or an external reference signal input terminal to supply an input clock signal to each unit.
(2) Operation Example Hereinafter, each process performed by the mobile communication system 1 will be described.

(2-1) Acquisition and notification processing of Phy information In the REC (eNB) 10 or the REC (BTS) 20 of the mobile communication system 1, it is set for the call of the UE 50 accommodated in the subordinate cell as described above. Phy information such as RTT for each individual channel is stored in the Phy information table. The RTT may vary depending on the position of the UE 50 and the like, and appropriately updated information is acquired by a path search process performed periodically. For this reason, it is preferable that the Phy information is also periodically updated. A procedure for newly acquiring and updating the Phy information of the dedicated CH of the call of the UE 50 in the mobile communication system 1 will be described with reference to the flowchart of FIG. FIG. 8 illustrates a procedure for newly acquiring and updating the dedicated channel Phy information set for the call of the UE 50 implemented by the REC (eNB) 10 that accommodates the UE 50.

  The Phy information management unit (eNB) 162 of the REC (eNB) 10 receives the notification of the new individual channel setting related to the UE 50 from the call processing control unit (eNB) 18 (Step S101). The Phy information management unit (eNB) 162 sets a new identification ID for the new individual channel (step S102).

  The Phy information management unit (eNB) 162, when information related to the RTT of the individual CH of the call of the UE 50 is included in the setting parameter at the time of setting the new individual channel (step S103: Yes), the newly set identification ID and The RTT value based on the related information is added as a new item to the Phy information table in the storage unit (eNB) 15 (step S104). On the other hand, when the information related to the RTT of the individual CH of the call of the UE 50 is not included in the setting parameter at the time of setting the new individual channel (step S103: No), the Phy information management unit (eNB) 162 is newly set. A new item is added to the Phy information table in the storage unit (eNB) 15 for the identified ID. At this time, the Phy information management unit (eNB) 162 sets the RTT to a NULL value (step S105). Through the above operation, the Phy information of the individual ch with the UE 50 that is newly set is added as a new item to the Phy information table in the storage unit (eNB) 15.

  Subsequently, the Phy information management unit (eNB) 162 activates an internal information update cycle timer and prepares to update the Phy information of the newly set individual channel of the UE 50 (Step S106). The timer is set to a predetermined time of about 1.0 sec, for example. The set time of the timer at this time becomes the update period of the Phy information of the UE 50.

  When there is a request for releasing the dedicated ch resource allocated to the call of the UE 50, such as when the UE 50 is handed over to another base station during the update preparation before the timer expires (Step S107: Yes), the Phy information The management unit (eNB) 162 deletes the item related to the individual ch of the UE 50 from the Phy information table in the storage unit (eNB) 15 (step S109).

  If there is no request for releasing the dedicated ch resource allocated to the call of the UE 50 during update preparation (step S107: No) and the timer expires (step S108: Yes), the Phy information management unit (eNB) 162 Updates the Phy information of the UE 50 stored in the Phy information table in the storage unit (eNB) 15 (step S110). Specifically, the Phy information management unit (eNB) 162 receives the notification of the RTT related to the individual ch of the UE 50 measured by the path search periodically performed in the path search processing unit (eNB) 161, and receives the notification. The Phy information table is updated with the new RTT as a new value. Thereafter, the Phy information management unit (eNB) 162 starts an internal information update cycle timer, and repeatedly updates the Phy information of the individual channels of the UE 50 (Steps S106 to S110).

  With the above operation, the Phy information table in the storage unit (eNB) 15 is updated according to the measured value of the RTT of the UE 50 for each predetermined period. In addition, information in the Phy information table that is newly acquired and periodically updated in this way is notified from the REC (eNB) 10 that is the handover source to the REC (BTS) 20 and the RNC 30 that are the handover destination. Is preferred. A procedure for sharing the Phy information of the dedicated CH of the call of the UE 50 in the mobile communication system 1 will be described with reference to the flowchart of FIG. In FIG. 9, the UE 50 is accommodated and shared by notifying the REC (BTS) 20 that can be the handover destination of the UE 50 of the PHY (eNB) 10 that can be the handover source and notifying the PHY (PTS) 20 that can be the handover destination of the UE 50. The operation when doing this is described.

  In sharing the Phy information, the Phy information management unit (eNB) 162 of the REC (eNB) 10 activates an internal notification cycle timer and prepares for notification of the Phy information of the individual ch of the UE 50 (step S201). The timer is set to a predetermined time of about 10 seconds, for example. The set time of the timer at this time is a notification cycle for sharing the Phy information of the UE 50.

  When the notification cycle timer expires (step S202: Yes), the Phy information management unit (eNB) 162 of the REC (eNB) 10 transfers the information in the Phy information table in the storage unit (eNB) 15 to the REC (BTS) 20. Notice. At this time, the Phy information management unit (eNB) 162 transmits information to the REC (BTS) 20 via the CPRI link # 2.

  In the REC (BTS) 20 that has received the information in the Phy information table (step S204), the Phy information management unit (BTS) 242 updates the information in the Phy information table in the storage unit (BTS) 23 using the received information. I do. With the above operation, the Phy information table in the storage unit (BTS) 23 of the REC (BTS) 20 is updated to a value updated in the REC (eNB) 10 at every predetermined period.

  By periodically updating and sharing the Phy information table in this manner, statistics of Phy information such as RTT notified from the handover source REC (eNB) 10 on the REC (BTS) 20 side serving as the handover destination are aggregated. It becomes possible to do. It is also possible to determine the accuracy of RTT measurement in the handover source REC (eNB) 10 from the past handover record, and to determine whether or not the RTT in the Phy information table is applicable at the time of handover. Become.

(2-2) Phy Information Storage Table Invalid Flag Setting Process The Phy information table invalid flag setting process will be described with reference to FIG. Here, the process in the REC (BTS) 20 that has received the Phy information notification related to the dedicated ch set for the call of the UE 50 from the REC (eNB) 10 by the above-described Phy information notification process will be described.

  The Phy information management unit (BTS) 242 of the REC (BTS) 20 totals the path search success results at the time of handover performed in the past for the Phy information table stored in the storage unit (BTS) 23. The success rate of the path search is calculated from the total number of successful path searches, and the success rate of the path search is compared with a predetermined threshold success rate such as 80% (step S301).

  The Phy information management unit (BTS) 242 sets the invalid flag to on for the Phy information table when the success rate of the path search is below the threshold (Yes in Step S301) (Step S302). The Phy information management unit (BTS) 242 executes the same processing for all the Phy information tables stored in the storage unit (BTS) 23.

  The Phy information table in which the invalid flag is set to on is not used during handover of the UE 50 whose Phy information is included in the Phy information table, as will be described in detail later. Specifically, in the Inter-RAT handover process of the UE 50, the RTT is measured for the UE 50 by performing a wide range path search instead of using the RTT included in the Phy information table.

  Note that it is preferable that the initial value of the Phy information table invalid flag is set to off, and the invalid flag is set to on based on the success rate of handover that is aggregated with the operation of the mobile communication system 1. The invalid flag set to on may be initialized at a constant cycle such as every 24 hours, or may be set to off by some other process.

  In the mobile communication system 1, the call of the UE 50 located in the cell under one of the RECs between the REC (eNB) 10 and the REC (BTS) 20 sharing the shared RE 40 by the above-described Phy information acquisition and notification process. The Phy information of the individual channel set for is shared by the other REC. By using such Phy information, for example, during Inter-RAT handover processing from REC (eNB) 10 to REC (BTS) 20 described later, the handover destination REC (BTS) 20 performs path search for the call of UE 50. RTT can be acquired without depending on the above.

  However, if the shared Phy information does not have sufficient accuracy to realize an appropriate handover, it may lead to a handover failure.

  Therefore, as described above, it is possible to prevent such a handover failure by determining whether to use Phy information based on the path search success rate at the time of handover. Therefore, it is possible to reduce the time required for the path search in the handover process, and it is possible to guarantee a success rate of the handover process that is at least higher than that of the conventional Inter-RAT handover process.

(2-3) Inter-RAT handover process The Inter-RAT handover process in the mobile communication system 1 will be described with reference to FIGS. As for such Inter-RAT handover processing, FIG. 11 is a sequence showing messages transmitted / received in each unit, FIG. 12 is processing performed in the REC (eNB) 10, and FIG. 13 is processing performed in the REC (BTS) 20. FIG. 14 shows processing executed in the RNC 30. Hereinafter, the operation of each unit will be described with reference to FIGS. 12 to 14 as appropriate according to the time series in the Inter-RAT handover process. In the following, processing when UE 50 accommodated in a cell under REC (eNB) 10 moves to a cell under REC (BTS) 20 sharing the RE with REC (eNB) 10 by Inter-RAT handover. Will be described.

  The handover management unit (eNB) 17 of the REC (eNB) 10 performs the Inter-RAT handover of the UE 50 located in the LTE cell under the shared RE 40 based on the load status, radio wave status, terminal capability, and the like of the own system. It is decided to implement (FIG. 12, step S401).

  The call processing control unit (eNB) 18 of the REC (eNB) 10 performs handover destination confirmation processing (FIG. 12, step S402), and whether or not the handover destination cell of the UE 50 shares the shared RE 40 with the REC (eNB) 10 Is determined (FIG. 12, step S403).

  With reference to FIG. 15, the procedure of a handover destination confirmation process will be described. The call processing control unit (eNB) 18 of the REC (eNB) 10 acquires connected cell information such as a carrier number and a sector number for identifying the connected cell of the current call to the UE 50 (FIG. 15, step S701). Subsequently, the call processing control unit (eNB) 18 of the REC (eNB) 10 refers to station data indicating base station information including other RATs stored in the storage unit (eNB) 15, and performs a handover destination cell. RE information is acquired (FIG. 15, step S702).

  Based on the acquired connection cell information and the RE information of the handover destination cell, the handover manager (eNB) 17 of the REC (eNB) 10 includes the connection cell information of the current UE 50 in the RE information of the handover destination cell. Is detected (step S703 in FIG. 15).

  When the connected cell information of the current UE 50 is not included in the RE information of the handover destination cell, it is recognized that the handover destination of the UE 50 is not a cell sharing the same shared RE 40 (FIG. 15, step S704). That is, it is recognized that the handover process is not an Inter-RAT handover process. On the other hand, when the connected cell information of the current UE 50 is included in the RE information of the handover destination cell, the handover destination of the UE 50 is recognized as a cell sharing the same shared RE 40 (FIG. 15, Step S705). . That is, the handover process is recognized as an Inter-RAT handover process. With the above processing, it is determined whether or not the handover of the UE 50 is an Inter-RAT handover from the REC (eNB) 10 sharing the same shared RE 40 to the REC (BTS) 20.

  Returning to FIG. 12, the description will be continued. When it is recognized that the handover destination cell is not a cell of the same shared RE 40 (FIG. 12, Step S403: NO), the REC (eNB) 10 sends a handover request message “ m1 "is transmitted to the MME (FIG. 12, step S404). On the other hand, when it is recognized that the handover destination cell is a cell of the same shared RE 40 (FIG. 12, Step S403: Yes), the REC (eNB) 10 is generated by the call processing control unit (eNB) 18. An identification ID is assigned to the request message “m1” and transmitted to the MME (FIG. 12, step S405).

  In any case, the MME that has received the handover request message “m1” transmits the relocation request message “m2” to the core network CN (FIG. 12, steps S404 and S405). The core network CN that has received the relocation request message “m2” transmits the relocation request message “m3” to the RNC 30 under the handover destination REC (BTS) 20 (FIG. 12, steps S404 and S405).

  After receiving the relocation request message “m3” (FIG. 14, step S601), the RNC 30 checks whether or not an identification ID is given to the relocation request message “m3” (FIG. 14, step S602).

  When the received relocation request message “m3” is not given an identification ID (FIG. 14, step S602: No), the call connection processing unit of the RNC 30 uses an NBAP (Node B Application Part) protocol for radio resource control. And a new individual channel setting request with the UE 50 is transmitted to the handover destination REC (BTS) 20. (FIG. 14, step S603). On the other hand, if the received relocation request message “m3” has been given an identification ID (FIG. 14, step S602: Yes), the call connection processing unit of the RNC 30 makes a request for setting a new individual channel with the UE 50. An identification ID for the UE 50 is assigned and transmitted to the REC (BTS) 20 at the handover destination. (FIG. 14, step S604).

  A request for setting a new individual channel transmitted from the RNC 30 is received at the signal termination unit in the call processing control unit (BTS) 25 via the network transmission / reception unit (BTS) 22 of the REC (BTS) 20 (FIG. 13, Step S501).

  After receiving the setting request for the new individual channel, the call processing control unit (BTS) 25 of the REC (BTS) 20 checks whether or not an identification ID is given to the setting request (FIG. 13, step S502). ). When it is confirmed that an identification ID is assigned to the setting request (FIG. 13, Step S502: Yes), the call processing control unit (BTS) 25 sets the invalid flag of the Phy information table including the identification ID to off. (Step S503 in FIG. 13).

  When an identification ID is not assigned to the new individual channel setting request (FIG. 13, step S502: No), or an identification ID is assigned to the new individual channel setting request (FIG. 13, step S502: Yes), and Phy When the information table invalid flag is on (FIG. 13, step S503: No), the call processing control unit (BTS) 25 of the REC (BTS) 20 secures an individual channel resource in the baseband signal processing unit (BTS) 24. (FIG. 13, step S504). Thereby, transmission of DL-DPCCH (Down-Link Dedicated Physical Data Channel) which is a downlink individual channel is started to UE50. After the individual channel setting is completed normally, the REC (BTS) 20 transmits an individual channel setting instruction response to the RNC (FIG. 13, step S505). Thereafter, the call processing control unit (BTS) 25 starts monitoring the uplink individual ch radio synchronization establishment in the individual ch set for the UE 50 (FIG. 13, step S510).

  On the other hand, when an identification ID is given to the request for setting a new individual channel (FIG. 13, step S502: Yes) and the Phy information table invalid flag is off (FIG. 13, step S503: Yes), REC (BTS) The 20 call processing control unit (BTS) 25 assigns an identification ID to the signal instructing to secure the individual ch resource and similarly transmits the signal to the baseband signal processing unit (BTS) 24 (FIG. 13, Step S506). After the individual channel setting is normally completed according to the instruction, the REC (BTS) 20 transmits an individual channel setting instruction response to the RNC 30 (FIG. 13, step S507).

  After transmitting the individual channel setting instruction response, the Phy information management unit (BTS) 242 in the baseband signal processing unit (BTS) 24 uses the cell information and the identification ID to store the Phy stored in the storage unit (BTS) 23. Refer to the information table. As a result of the reference, the Phy information management unit (BTS) 242 acquires the RTT value in the individual ch of the call of the UE 50 acquired in the REC (eNB) 10. The acquired RTT value is notified to the path search processing unit (BTS) 241 (FIG. 13, step S508).

  Upon receiving the notification of the RTT value, the path search processing unit (BTS) 241 performs setting for invalidating the execution of a wide range of path search in the subsequent path search process (FIG. 13, step S509). For example, the path search processing unit (BTS) 241 performs setting for invalidating the wide-range path search by setting the wide-range path search execution flag stored therein to off. Subsequently, the call processing control unit (BTS) 25 starts monitoring the uplink individual ch radio synchronization establishment in the individual ch set for the UE 50 (FIG. 13, step S510).

  The call processing control unit (BTS) 25 activates a built-in uplink individual channel radio synchronization establishment waiting timer when monitoring monitoring of uplink individual channel radio synchronization establishment is started (step S511 in FIG. 13).

  The call processing control unit (BTS) 25 of the REC (BTS) 20 starts monitoring the establishment of uplink individual ch radio synchronization, and then performs a path search of the uplink individual ch of the UE 50 to the path search processing unit (BTS) 241. The instructions are given. The path search processing unit (BTS) 241 instructed to perform the path search performs the path search process (FIG. 13, step S512).

  With reference to FIG. 16, the path search process of the uplink individual ch of UE 50 by the path search processing unit (BTS) 241 will be described. FIG. 16 is a flowchart showing the flow of the path search process. In the flow of the path search process, as shown in FIG. 16, there are cases where two types of path searches of a broad range and a narrow range are performed. Note that the two types of path searches are distinguished according to the relative breadth (in other words, the size) of the path search range.

  At the time of the path search process, the path search processing unit (BTS) 241 first determines whether or not to perform the wide range path search by referring to the wide range path search execution flag (FIG. 16, step S801). ). When it is set to perform a wide range path search (FIG. 16, step S801: Yes), the path search processing unit (BTS) 241 repeatedly executes a wide range path search until a path is detected (FIG. 16, step S801). S802). The path search processing unit (BTS) 241 recognizes the detection of the path by receiving the radio wave transmitted from the UE 50 via the uplink individual channel set for the UE 50.

  On the other hand, when it is set not to perform the wide range path search (FIG. 16, Step S801: No), the path search processing unit (BTS) 241 does not perform the wide range path search.

  When a path is detected by a wide range path search (FIG. 16, Step S803: Yes), or when a wide range path search is not performed, the path search processing unit (BTS) 241 performs a narrow range path search. It repeats until it is detected (FIG. 16, step S804). When a path is detected by narrow path search (FIG. 16, step S805: Yes), the path search processing unit (BTS) 241 recognizes that the path search has succeeded (FIG. 16, step S806), and passes The search process ends.

  14 again, on the other hand, the RNC 30 that has received the transmission of the individual channel setting instruction response (FIG. 13, step S507) from the REC (BTS) 20 sends the REC (eNB) 10 to the REC (eNB) 10 via the core network CN. A response to the handover request is transmitted (FIG. 14, step S605). Specifically, the RNC 30 first transmits a relocation request confirmation message “m4” to the core network CN. The core network CN that has received the relocation request confirmation message “m4” transmits a relocation response message “m5” to the MME. The MME that has received the relocation response message “m5” transmits a handover instruction message “m6” to the REC (eNB) 10.

After transmitting the response to the handover request, the resource management unit (RNC) of the RNC starts a built-in timer and notifies the radio switching completion message “m9” that notifies the UE 50 that the communication destination has been switched to the REC (BTS) 20. Is started to be received (FIG. 14, step S606).
A response to the handover request transmitted from the RNC via the core network CN is received by the handover manager (eNB) 17 of the REC (eNB) 10 (FIG. 12, step S406). Based on the content of the received handover instruction message “m6”, the handover manager (eNB) 17 of the REC (eNB) 10 confirms that the individual ch setting has been normally completed in the handover destination RNC (FIG. 12, Step S407).

  At this time, when the individual channel setting is not normally completed in the RNC (FIG. 12, Step S407: No), the REC (eNB) 10 determines that an abnormality has occurred during the handover process, and performs a predetermined process such as the end of the handover process. The abnormal termination procedure is executed (FIG. 12, step S416).

  When it is determined that the individual channel setting has been normally completed in the handover target RNC (FIG. 12, Step S407: Yes), the individual channel resource management unit (eNB) of the REC (eNB) 10 performs the Inter-RAT handover process. The UE 50 determines an “activation time” that is a timing for switching the communication destination from the REC (eNB) 10 to the REC (BTS) 20 (FIG. 12, step S408).

  In order to switch the communication destination to the REC (BTS) 20, it is necessary that the downlink individual ch and the uplink individual ch with the UE 50 be established in the REC (BTS) 20 that is the handover destination. Therefore, the “activation time” is preferably determined based on the time required for the individual channel setting process and the path search process in the REC (BTS) 20.

  After determining the “activation time”, the REC (eNB) 10 transmits a radio switching instruction message “m7” to the UE 50 instructing to switch the communication destination to the REC (BTS) 20 in the “activation time”. (FIG. 12, step S409). Specifically, radio switching for the UE 50 is instructed by “Mobility FROM EUTRA COMMAND” generated by the call processing control unit (eNB) 18 and instructing radio switching from the LTE scheme.

  After transmitting the radio switching instruction message “m7”, the individual ch resource management unit (eNB) of the REC (eNB) 10 starts a built-in timer and instructs a release related to the UE 50 to release a context. Is started to be received (step S410 in FIG. 12).

  In the UE 50, data processing of the radio switching instruction message “m7” received by the LTE signal processing unit is performed, and the message content is recognized by the signal termination unit.

  The device control unit of the UE 50 reads the “activation time” included in the radio switching instruction message “m7”. Then, in the “activation time”, the wireless switching completion message “m9” is started to be transmitted to the RNC 30 via the REC (BTS) 20 on the uplink individual channel. Specifically, the completion of the radio switching for the UE 50 is notified by a “DCCF Handover to UTRAN” message that notifies the completion of the radio switching to the 3G scheme, which is generated in the 3G signal processing unit in the UE 50. In the case of Inter-RAT handover, “activation time” = Now is set because frame synchronization of radio sections between RATs is difficult. That is, after receiving the radio switching instruction message “m7” message, the UE 50 immediately transmits a radio switching completion message “m9” if an uplink individual channel for the REC (BTS) 20 is established.

  In the REC (BTS) 20 that is performing the path search process (FIG. 13, step S512), the UE 50 detects that a signal is transmitted on the uplink individual ch, thereby succeeding in a wide range of path searches (FIG. 16, Step S803) and the success of the narrow-range path search (FIG. 16, step S805) are recognized.

  After the success of the path search is recognized, the baseband signal processing unit (BTS) 24 of the REC (BTS) 20 performs uplink radio frame timing synchronization processing (FIG. 13, step S513). After the frame timing synchronization processing, the baseband signal processing unit (BTS) 24 notifies the establishment of synchronization to the individual channel resource management unit (BTS).

  When the individual channel resource management unit (BTS) receives notification of establishment of frame timing synchronization before the timer started in step S511 of FIG. 13 expires (FIG. 13, step S514: Yes), the timer is set. Stop (FIG. 13, step S515). Thereafter, the data processing unit in the baseband signal processing unit (BTS) 24 of the REC (BTS) 20 starts uplink individual channel data processing from the UE 50 (FIG. 13, step S516). As a result, the UE 50 starts communication with the REC (BTS) 20.

  On the other hand, when the radio synchronization of the uplink individual channel is not established before the timer expires (FIG. 13, Steps S514: No and S517: Yes), the REC (BTS) 20 determines that an abnormality has occurred during the handover process, and the handover is performed. A predetermined abnormal termination procedure such as the termination of processing is performed (FIG. 13, step S518).

  When the RNC 30 receives the wireless switching completion message “m9” before expiration of the timer activated by the processing in step S606 of FIG. 14 (FIG. 14, step S607: Yes), the RNC 30 stops the timer (FIG. 14, Step S608). Thereafter, the RNC 30 transmits a relocation completion message “m10” to the REC (eNB) 10 via the core network CN. Specifically, first, the RNC 30 transmits a relocation completion message “m10” to the core network CN. The core network CN that has received the relocation completion message “m10” transmits a relocation completion message “m11” to the MME. The MME that has received the relocation completion message “m11” transmits a relocation completion confirmation message “m12” to the core network CN and transmits a context release instruction message “m13” to the REC (eNB) 10.

  On the other hand, if the wireless switching completion message “m9” is not received before the timer expires (FIG. 14, Steps S607: No and S610: Yes), the RNC 30 determines that an abnormality has occurred during the handover process, and ends the handover process. A predetermined abnormal termination procedure is performed (FIG. 14, step S611).

  When the REC (eNB) 10 receives the context release instruction message “m13” before expiration of the timer activated by the processing in step S410 in FIG. 12 (FIG. 12, step S411: Yes), the reception waiting timer is set. Stop (FIG. 12, step S412). Thereafter, the dedicated channel resource management unit (eNB) of the REC (eNB) 10 releases the dedicated channel resource of the handover source and ends the communication with the UE 50 (FIG. 12, step S411). Furthermore, the dedicated channel resource management unit (eNB) transmits a context release completion message “m14” to the core network CN, and ends the handover process of the UE 50.

  On the other hand, when the context release instruction message “m13” is not received before the timer expires (FIG. 12, Steps S411: No and S415: Yes), the REC (eNB) 10 determines that an abnormality has occurred during the handover process, A predetermined abnormal termination procedure such as termination of the handover process is performed (FIG. 12, step S416).

  In the mobile communication system 1, the handover of the UE 50 is realized by the series of processes described above. In the case of Inter-RAT handover in which the UE 50 performs handover from the LTE REC (eNB) 10 to the 3G REC (BTS) 20, in the mobile communication system 1, the handover source REC (eNB) via the core network CN 10 notifies the handover destination RNC 30 and REC (BTS) 20 of the handover call identification ID of the UE 50.

  In the mobile communication system 1, the REC (eNB) 10 and the REC (BTS) 20 of different RATs sharing the same RE share the identification ID and Phy information such as RTT for each of the received UE 50 calls. ing. Therefore, the handover destination RNC 30 and the REC (BTS) 20 that have received the notification of the identification ID of the handover call of the UE 50 can identify the corresponding UE 50 and can acquire the Phy information stored in the database. .

  When the RNC 30 and the REC (BTS) 20 as the handover destination can acquire the RTT of the UE 50, the required time from the signal transmission to the UE 50 until the reception of the response signal is known by the RTT. In the Inter-RAT handover of the UE 50, since it is determined that the UE 50 does not move in position before and after the handover, the Phy information shared by the REC (eNB) 10 is used, so that at least the UE 50 has a wide range. This eliminates the need to measure the RTT by the path search.

  By not performing the path search over a wide range, the processing amount in the path search processing unit (BTS) 241 in the REC (BTS) 20 is reduced. In particular, in a wide-range path search performed in the conventional handover process, since it is necessary to perform a path search for a relatively large area, the processing amount in the path search processing unit (BTS) 241 is also relatively large. The number of simultaneous handover processes in the entire system was limited. On the other hand, not performing a wide-range path search leads to a decrease in the processing amount for each baseband card, which is an example of the baseband signal processing unit (BTS) 24 of the REC (BTS) 20, and increases the number of simultaneous processes. It becomes possible. For this reason, in the entire mobile communication system 1, this leads to an increase in the number of calls that can simultaneously process Inter-RAT handover, leading to an improvement in the efficiency of the entire system. Further, in the handover process for one UE 50, the time required for the path search process can be shortened, leading to a reduction in the time of the entire handover process.

  Note that it is preferable that the UE 50 performs a certain amount of movement even during the Inter-RAT handover, so that a path search is performed for more detailed RTT measurement. However, since the RTT related to the call of the UE 50 is known to some extent by the Phy information shared by the REC (eNB) 10, the REC (BTS) 20 performs a path search in a narrow range based on the Phy information. The RTT of UE50 can be measured more accurately.

(2-4) Description of Effect The handover process of the UE 50 is performed between the REC (eNB) 10 and the REC (BTS) 20 having the shared RE 40 by the procedure described above.

  As shown in the flowcharts of FIGS. 12 to 14, one of the reasons why the handover process fails is that a timer that is set without receiving a signal in each device expires.

  One of the timers is a timer for establishing uplink individual channel radio synchronization in the REC (BTS) 20. By providing the uplink individual channel radio synchronization establishment wait timer, particularly in the Inter-RAT handover process, when switching the base station with which the UE 50 communicates, the switching does not end properly, and the UE 50 does not end with the REC (eNB) 10 and the REC. It can suppress that the transient state which communicates with both (BTS) 20 is continued. Thereby, the continuation of the degradation time of the communication quality in the UE 50 can be suppressed, and the radio resources can be prevented from being occupied more than necessary in both base stations.

  By spending time for establishing synchronization of the uplink individual ch radio, the user may feel a momentary break especially in a voice call. For this reason, the timer setting value T indicating the allowable time until the synchronization of the uplink individual channel radio is established, for example, 2.0 sec so as to suppress the deterioration of the communication quality and enable appropriate handover processing. Set in second order. The breakdown of the set value T of the timer is indicated by T = T1 + T2 + T3.

  In T1, after the REC (eNB) 10 receives the handover instruction message “m6” (FIG. 12, step S406), the UE 50 receives the radio switching instruction message “m7” including the activation time (FIG. 12, step S409). ). At this time, the time required for signal transmission between the devices is also included in T1, but since each signal transmission path is a set path, there is no significant delay, and the setting of the mobile communication system 1 It can be said that T1 does not increase more than the value estimated from the information.

  T2 is a time required for the UE 50 that has received the radio switching instruction message “m7” to transmit the radio switching completion message “m9” at a timing according to the activation time. In the 3GPP standard, the maximum allowable time of T2 is standardized. For example, in 3GPPTS05.10V8.12.0 (2003-08), in the case of a cell unknown to the UE 50, such as Inter-RAT handover processing, T2 Is defined as within 320 ms.

  T3 is a period from when the path search processing unit (BTS) 241 of the REC (BTS) 20 starts the path search process until the signal transmitted from the UE 50 through the individual uplink channel is received and the path search is completed (FIG. 13). , The allowable time in step S512).

  As described above, a certain prediction value is set for T1 and T2 depending on the system design and standards. Therefore, the success rate of the handover process is increased by completing the path search process within T3 = T−T1−T2 obtained by subtracting T1 and T2 from the set value T.

  As described above, in the REC (BTS) 20 of the mobile communication system 1, during the Inter-RAT handover process of the UE 50, notification of PHY information such as RTT for the individual channel of the UE 50 from the handover source REC (eNB) 10 Receive. The Phy information is information related to the distance between the REC (eNB) 10 and the UE 50. For this reason, by using the Phy information, the REC (BTS) 20 having the same physical cell range as the REC (eNB) 10 can acquire or easily estimate the path position of the individual ch with the UE 50. It becomes possible.

  In the absence of any information regarding the distance between the REC (BTS) 20 and the UE 50, the path search processing unit (BTS) 241 of the REC (BTS) 20 It is required to perform a wide-range path search with a large amount of processing.

  For this reason, the REC (BTS) 20 that receives notification of Phy information does not need to perform a wide-range path search, and the time required to complete the path search is shortened. For this reason, it becomes easy to complete the path search process within the allowable time T3. As a result, the success rate of the Inter-RAT handover process is increased.

  In the above example, the LTE system and the 3G system are presented and described as examples of different communication systems, but the present invention can also be applied to other communication systems. Even in that case, as described above, the Phy information set in the handover call is shared between the systems, so that the time required for the path search can be shortened while ensuring a favorable handover success rate.

  In addition, sharing of Phy information is implemented by regularly reporting the Phy information table between the REC (eNB) 10 and the REC (BTS) 20. For this reason, in the sequence of the Inter-RAT handover process, only the identification ID for identifying Phy information is notified from the handover source REC (eNB) 10 to the handover destination REC (BTS) 20, so that REC (BTS ) 20, the Phy information acquired in the REC (eNB) 10 can be referred to. Therefore, by assigning an identification ID having a relatively small amount of information, the above-described effects can be applied without affecting the sequence during the Inter-RAT handover process.

(3) First Modification A configuration of a mobile communication system 2 that is a first modification of the mobile communication system 1 will be described with reference to the block diagram of FIG. The mobile communication system 2 includes a shared REC 60 that supports both LTE and 3G RATs, and a shared RE 40 that is shared by the LTE and 3G systems.

  The shared REC 60 performs processing common to the LTE method and the 3G method, the eNB function unit 61 that performs signal processing related to the LTE method communication, the BTS function unit 62 that performs signal processing related to the 3G method communication, And a common function unit 63 to be implemented. The eNB functional unit 61 is configured in accordance with the REC (eNB) 10 and stores a call processing control unit (eNB) 18 that processes an LTE call and a Phy information table of an individual channel set in the own cell. Storage unit (eNB) 15 is provided. The BTS function unit 62 is configured in accordance with the REC (BTS) 20, and stores a call processing control unit (eNB) 18 that processes 3G calls and a Phy information table for individual channels set in the own cell. Storage unit (BTS) 23. The common function unit 63 includes a power supply monitoring unit, a monitoring control unit, station data holding, and a clock.

  In the shared REC 60, the eNB functional unit 61 and the BTS functional unit 62 are connected by an in-house signal such as ATM (Asynchronous Transfer mode) or IP (Internet Protocol) transfer. The eNB functional unit 61 and the BTS functional unit 62 notify the Phy information table by this in-house signal in accordance with the in-house switch.

  According to the above configuration, it is possible to enjoy the effects related to the Inter-RAT handover process described above even if the device configuration uses the shared REC 60 for different communication methods. In addition, the part which is not especially demonstrated about the structure of each part, operation | movement, a processing sequence, etc. may be the structure similar to the mobile communication system 1 mentioned above.

(4) Second Modification A configuration of a mobile communication system 3 that is a second modification of the mobile communication system 1 will be described with reference to the block diagrams of FIGS. 18 and 19. The mobile communication system 3 includes LTE-type REC (eNB) 10, 3G-type REC (BTS) 20, REC (eNB) 10 and LTE-type RE 40 a, REC (BTS) 20 and CPRI # connected to CREC # 1. 1 includes a shared antenna 70 that is connected to and shared with the RE 40b, RE 40a, and RE 40B of the 3G system connected at 1.

  In the configuration of the mobile communication system 3, there is no existing connection line such as a CPRI link that can communicate signals between the REC (eNB) 10 and the REC (BTS) 20. For this reason, as shown in FIG. 18, an IP connection constituted by Ether or the like is provided between the REC (eNB) 10 and the REC (BTS) 20. The REC (eNB) 10 and the REC (BTS) 20 notify the Phy information table through this IP connection.

  Further, in the configuration of the mobile communication system 3, when the line on the core network CN side implements the IP connection, as shown in FIG. 19, the Phy information table is notified by this IP connection. Good.

  According to the above configuration, it is possible to enjoy the effects related to the above-described Inter-RAT handover process even in a device configuration in which different communication methods share only the shared antenna 70. In addition, the part which is not especially demonstrated about the structure of each part, operation | movement, a processing sequence, etc. may be the structure similar to the mobile communication system 1 mentioned above.

(5) Third Modification A configuration of a mobile communication system 4 that is a third modification of the mobile communication system 1 will be described with reference to FIG. The mobile communication system 4 includes LTE-based REC (eNB) 10, 3G-based REC (BTS) 20, REC (eNB) 10 and LTE-based RE 40 a, REC (BTS) 20 and CPRI # connected to CREC # 1. 1 includes a shared antenna 70 that is connected to and shared with the RE 40b, RE 40a, and RE 40B of the 3G system connected at 1.

  In the mobile communication system 4, the REC (eNB) 10 and the REC (BTS) 20 share Phy information with respect to the call handover sequence instead of sharing the Phy information table using the CPRI link and IP connection that connect each other. Is provided to share the Phy information of the handover call with each other. For example, the handover source REC (eNB) 10 adds Phy information to the handover request message “m1” transmitted via the core network CN in the Inter-RAT handover process instead of the corresponding identification ID. Send. At this time, the MME and the core network CN add the Phy information to the relocation request messages “m2” and “m3” and transmit the messages to the RNC 30.

  As a result, even if the PHY information table of the individual ch is not shared between the REC (eNB) 10 and the REC (BTS) 20 prior to the handover, the corresponding call can be performed in the Inter-RAT handover destination system. The Phy information before the handover can be referred to. Therefore, it is possible to enjoy the effects related to the Inter-RAT handover process described above. The method is not limited to the configuration in which the REC (eNB) 10 and the REC (BTS) 20 share only the antenna as shown in FIG. 20, but, for example, the mobile communication system 1 that shares the RE shown in FIG. Alternatively, the present invention can also be implemented in the mobile communication system 2 that shares the RE and REC shown in FIG. In addition, the part which is not especially demonstrated about the structure of each part, operation | movement, a processing sequence, etc. may be the structure similar to the mobile communication system 1 mentioned above.

  The present invention is not limited to the above-described embodiments, and can be appropriately changed without departing from the spirit or concept of the invention that can be read from the claims and the entire specification, and mobile communication involving such changes. A system, a base station, a communication control method, and the like are also included in the technical scope of the present invention.

  The following additional notes are further described with respect to the embodiment described above.

(Appendix 1)
A first base station that communicates with a mobile terminal using the first communication method, and that shares an antenna capable of transmitting and receiving signals of a plurality of communication methods including the first communication method and the second communication method, and the second A mobile communication system comprising a second base station that communicates with the mobile terminal using the communication method of:
The first base station is
Obtaining means for obtaining radio information indicating a relative distance from the mobile terminal accommodated in the first base station;
Notification means for notifying the radio information to the second base station,
The second base station is
Communication for setting communication with the mobile terminal based on the radio information notified from the first base station when starting communication with the mobile terminal accommodated in the first base station A mobile communication system comprising control means.

(Appendix 2)
The mobile communication system according to supplementary note 1, wherein the first base station and the second base station share a wireless device that performs communication with the mobile terminal via the antenna.

(Appendix 3)
The first base station and the second base station have a first functional unit for performing communication using the first communication method and a second function unit for performing communication using the second communication method. The mobile communication system according to appendix 1 or 2, wherein a radio control device including a functional unit is shared.

(Appendix 4)
The first base station and the second base station have communication means capable of transmitting / receiving signals to / from each other without going through a core network,
The mobile communication system according to any one of appendices 1 to 3, wherein the notifying unit notifies the second base station of the wireless information via the communication unit.

(Appendix 5)
The notification means is transmitted from the first base station to the second base station when the second base station starts communication with the mobile terminal accommodated in the first base station. The mobile communication system according to any one of appendices 1 to 3, wherein notification is performed by adding the radio information to a control signal for handover processing.

(Appendix 6)
The acquisition means acquires the radio information when the first base station sets an individual channel for the mobile terminal, and acquires the radio information at a predetermined period after the setting of the individual channel. Update
The mobile communication system according to any one of appendices 1 to 5, wherein the notification unit periodically notifies the second base station of the updated wireless information.

(Appendix 7)
Sharing an antenna capable of transmitting and receiving signals of a plurality of communication schemes including a first communication scheme and a second communication scheme with another base station communicating with the mobile terminal in the second communication scheme; A base station that communicates with a mobile terminal using the communication method of
Obtaining means for obtaining radio information indicating a relative distance from the mobile terminal accommodated in the base station;
A base station comprising: notification means for notifying the radio information to the other base station.

(Appendix 8)
Sharing an antenna capable of transmitting and receiving signals of a plurality of communication methods including the first communication method and the second communication method with another base station that communicates with the mobile terminal in the first communication method, A base station that communicates with a mobile terminal using the communication method of
When starting communication with the mobile terminal accommodated in the other base station, radio information indicating a relative distance between the mobile terminal and the other base station notified from the other base station. A base station comprising communication control means for setting communication with the mobile terminal based on the base station.

(Appendix 9)
A first base station that communicates with a mobile terminal using the first communication method, and that shares an antenna capable of transmitting and receiving signals of a plurality of communication methods including the first communication method and the second communication method, and the second A communication control method in a mobile communication system comprising a second base station that communicates with the mobile terminal using the communication method of:
An acquisition step of acquiring radio information indicating a relative distance from the mobile terminal accommodated in the first base station;
A notification step of notifying the wireless information to the second base station;
When the second base station starts communication with the mobile terminal accommodated in the first base station, based on the radio information notified from the first base station, A communication control step for setting the communication of the communication control method.

1 mobile communication system,
10 REC (eNB),
11 CPRI # 1 interface (eNB),
12 CPRI # 2 interface (eNB),
14 Network transceiver (eNB),
15 storage unit (eNB),
16 Baseband signal processor (eNB),
161 Path search processing unit (eNB),
162 Phy information management unit (eNB),
17 handover manager (eNB),
18 Call processing control unit (eNB),
20 REC (BTS),
21 CPRI # 2 interface (BTS),
22 Network transceiver (BTS),
23 storage unit (BTS),
24 Baseband signal processor (BTS),
241 Path search processing unit (BTS),
242 Phy Information Management Unit (BTS),
25 Call processing control unit (BTS),
30 RNC,
31 Handover Manager (RNC),
40 Shared RE,
50 Mobile terminal (UE).

Claims (5)

A first base station that communicates with a mobile terminal using the first communication method, and that shares an antenna capable of transmitting and receiving signals of a plurality of communication methods including the first communication method and the second communication method, and the second A mobile communication system comprising a second base station that communicates with the mobile terminal using the communication method of:
The first base station is
Obtaining means for obtaining radio information indicating a relative distance from the mobile terminal accommodated in the first base station;
Notification means for notifying the radio information to the second base station,
The second base station is
Communication for setting communication with the mobile terminal based on the radio information notified from the first base station when starting communication with the mobile terminal accommodated in the first base station A mobile communication system comprising control means.   The notification means is transmitted from the first base station to the second base station when the second base station starts communication with the mobile terminal accommodated in the first base station. The mobile communication system according to claim 1, wherein notification is performed by adding the radio information to a control signal for handover processing. Sharing an antenna capable of transmitting and receiving signals of a plurality of communication schemes including a first communication scheme and a second communication scheme with another base station communicating with the mobile terminal in the second communication scheme; A base station that communicates with a mobile terminal using the communication method of
Obtaining means for obtaining radio information indicating a relative distance from the mobile terminal accommodated in the base station;
A base station comprising: notification means for notifying the radio information to the other base station. Sharing an antenna capable of transmitting and receiving signals of a plurality of communication methods including the first communication method and the second communication method with another base station that communicates with the mobile terminal in the first communication method, A base station that communicates with a mobile terminal using the communication method of
When starting communication with the mobile terminal accommodated in the other base station, radio information indicating a relative distance between the mobile terminal and the other base station notified from the other base station. A base station comprising communication control means for setting communication with the mobile terminal based on the base station. A first base station that communicates with a mobile terminal using the first communication method, and that shares an antenna capable of transmitting and receiving signals of a plurality of communication methods including the first communication method and the second communication method, and the second A communication control method in a mobile communication system comprising a second base station that communicates with the mobile terminal using the communication method of:
An acquisition step of acquiring radio information indicating a relative distance from the mobile terminal accommodated in the first base station;
A notification step of notifying the wireless information to the second base station;
When the second base station starts communication with the mobile terminal accommodated in the first base station, based on the radio information notified from the first base station, A communication control step for setting the communication of the communication control method.

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