JP2012050152A - Mobile communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mobile communication system capable of achieving handover processing of a mobile station even if a relay node is connected.SOLUTION: The mobile communication system is configured in such a way that in handover processing, a control signal of the handover processing is transmitted and received via an X2-C radio bearer between a relay node RN2 and a radio base station DeNB2.

Description

  The present invention relates to a mobile communication system.

  As shown in FIG. 6, in the mobile communication system of the LTE scheme (Release.8) defined in 3GPP, a handover process of the mobile station UE from the radio base station eNB # 1 to the radio base station eNB # 2 is performed. In this case, handover processing is performed between the radio base station eNB # 1 and the radio base station eNB # 2 via the X2 bearer set between the radio base station eNB # 1 and the radio base station eNB # 2. It is comprised so that the control signal which concerns on may be transmitted / received.

  As illustrated in FIG. 6, the radio base station eNB # 1 and the radio base station # 2 have a network layer 1 (NW L1) function and a network layer 2 (NW L2) as an X2 bearer function for setting up an X2 bearer. And an IP (Internet Protocol) layer function and an SCTP (Stream Control Transmission Protocol) layer function.

3GPP TS 36.423, "Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Network (E-UTRAN); X2apAPAP

  In an LTE-Advanced mobile communication system, which is a successor to the LTE system, a “relay node (Relay Node) having a function similar to that of the radio base station eNB between the mobile station UE and the radio base station eNB. RN "can be connected.

  However, in the conventional mobile communication system, when the relay node RN is connected, there is a problem that it is not specified how to perform the handover process of the mobile station UE.

  Therefore, the present invention has been made in view of the above-described problems, and an object of the present invention is to provide a mobile communication system that can realize a handover process of a mobile station even when a relay node is connected. And

  A first feature of the present invention is a mobile communication system, in which a relay node and a radio base station are connected via a radio bearer, and the mobile station sets a radio bearer with the relay node. Between a state in which communication is performed via the relay node and the radio base station, and a state in which a radio bearer is set with the radio base station and communication is performed via the radio base station, It is configured to perform a handover process, and is configured to transmit and receive a control signal related to the handover process via a radio bearer between the relay node and the radio base station in the handover process. This is the gist.

  In the first aspect of the present invention, the relay node and the radio base station are configured to perform a keep alive process for the radio bearer as an upper layer function of the function for setting the radio bearer. A function may be provided.

  In the first aspect of the present invention, the relay node and the radio base station perform security processing between the relay node and the radio base station as an upper layer function of the function for setting the radio bearer. The first layer function configured as described above and the second layer function configured to perform keep alive processing on the radio bearer may be provided as an upper layer function of the first layer function.

  As described above, according to the present invention, it is possible to provide a mobile communication system capable of realizing a handover process of a mobile station even when a relay node is connected.

1 is an overall configuration diagram of a mobile communication system according to a first embodiment of the present invention. FIG. 3 is a protocol stack diagram in the mobile communication system according to the first embodiment of the present invention. FIG. 3 is a protocol stack diagram in the mobile communication system according to the first embodiment of the present invention. FIG. 3 is a protocol stack diagram in the mobile communication system according to the first embodiment of the present invention. FIG. 3 is a sequence diagram showing an operation of the mobile communication system according to the first embodiment of the present invention. It is a protocol stack figure in the present mobile communication system.

(Mobile communication system according to the first embodiment of the present invention)
A mobile communication system according to a first embodiment of the present invention will be described with reference to FIG. 1 to FIG.

  The mobile communication system according to the present invention is an LTE-Advanced mobile communication system, for example, as shown in FIG. 1, to which an exchange MME, relay nodes RN1 to RN4, and a relay node RN1 are connected. A radio base station DeNB (Donor eNB) 1, a radio base station DeNB 2 to which relay nodes RN 2 and RN 3 are connected, and a radio base station eNB 1 are provided.

  Here, the radio base station DeNB1 and the radio base station DeNB2 are connected via the X2-C interface, and the radio base station DeNB2 and the radio base station eNB1 are connected via the X2-C interface. .

  In addition, each of the radio base station DeNB1, the radio base station DeNB2, and the radio base station eNB1 is connected to the exchange MME via an S1-MME interface.

  In such a mobile communication system, the mobile station UE is configured to perform radio communication by setting a radio bearer between the radio base station eNB (DeNB) and the relay node RN.

  Further, in such a mobile communication system, as shown in FIG. 1 (1), the mobile station UE sets up a radio bearer with the relay node RN2, and performs communication via the relay node RN2 and the radio base station DeNB2. And a state in which a radio bearer is set up with the radio base station DeNB2 and a communication is performed via the radio base station DeNB2.

  Further, in the handover process, the control signal (X2AP signal) related to the handover process is configured to be transmitted and received via the X2-C radio bearer (radio bearer) between the relay node RN2 and the radio base station DeNB2. Yes.

  For example, as illustrated in FIG. 2 to FIG. 4, the relay node RN2 and the radio base station DeNB2 have a physical (PHY) layer function, a physical ( (PHY) layer function MAC (Media Access Control) layer function provided as an upper layer function, RLC (Radio Link Control) layer function provided as an MAC layer function upper layer function, and RLC layer function upper layer PDCP (Packet Data Convergence Protocol) layer function provided as a layer function.

  Note that the relay node RN2 and the radio base station DeNB2 may include an RRC (Radio Resource Control) layer function provided as an upper layer function of the PDCP layer function.

  Further, as shown in FIG. 2, the relay node RN2 and the radio base station DeNB2 are configured to perform security processing between the relay node RN2 and the radio base station DeNB2 as an upper layer function of the X2-C radio bearer function. SCTP layer function (second layer function) configured to perform keep-alive processing for the X2-C radio bearer as an upper layer function of the IP layer function. ).

  Or, as shown in FIG. 3, the relay node RN2 and the radio base station DeNB2 are configured to perform a keep-alive process for the X2-C radio bearer as an upper layer function of the X2-C radio bearer function. A function may be provided. In the example of FIG. 3, the relay node RN2 and the radio base station DeNB2 do not have an IP layer function configured to perform security processing between the relay node RN2 and the radio base station DeNB2.

  Furthermore, as shown in FIG. 4, the relay node RN2 and the radio base station DeNB2 are configured to perform a keep-alive process for the X2-C radio bearer as an upper layer function of the X2-C radio bearer function. The function and the IP layer function configured to perform the security process between the relay node RN2 and the radio base station DeNB2 may not be provided.

  Hereinafter, with reference to FIG. 5, in the mobile communication system according to the present embodiment, the mobile station UE sets up a radio bearer with the relay node RN2, and performs communication via the relay node RN2 and the radio base station DeNB2. A description will be given of an operation for performing a handover from a state in which a radio bearer is set with the radio base station DeNB2 to a state in which communication is performed via the radio base station DeNB2.

  As shown in FIG. 5, the relay node RN2 manages the “UE Context” of the mobile station UE in step S1000. In step S1001, the relay node RN2 manages the radio base station DeNB2 via the X2-C radio bearer. The mobile station UE transmits a “HO Request (handover request signal)” requesting handover from the relay node RN2 of the mobile station UE to the radio base station DeNB2.

  When receiving the “HO Request”, the radio base station DeNB2 stores “UE Context” of the mobile station UE in Step S1002, and in Step S1003, to the relay node RN2 via the X2-C radio bearer, “HO Request Ack (handover request confirmation signal)” is transmitted.

  In step S1004, the relay node RN2 transmits “HO Command (handover instruction signal)” instructing the mobile station UE to perform handover to the radio base station DeNB2 by the RRC layer function.

  In step S1005, the mobile station UE transmits “HO Complete (handover completion signal)” to the radio base station DeNB2 by the RRC layer function.

  In step S1006, the radio base station DeNB2 transmits a “Path Switch Request (path switching request signal)” to the switching center MME via the S1-MME interface.

  In step S1007, the switching center MME transmits a “Path Switch Request Ack (path switching request confirmation signal)” to the radio base station DeNB2 via the S1-MME interface, and transmits a signal addressed to the mobile station UE. The transfer destination is switched from the relay node RN2 to the radio base station DeNB2.

  In step S1008, the radio base station DeNB2 transmits “UE Context Release” to the relay node RN2 via the X2-C radio bearer, and the relay node RN2 moves according to the “UE Context Release”. Management of the “UE Context” of the station UE is terminated.

  In FIG. 5, the relay node RN2 and the radio base station DeNB2 may be interchanged.

  According to the mobile communication system according to the present embodiment, the handover process related to the relay node RN is realized without significantly modifying the protocol stack of each device used in the LTE mobile communication system. be able to.

  Further, according to the mobile communication system according to the present embodiment, it is not necessary to set up an X2-C radio bearer between the radio base station DeNB2 and the relay node RN2 during the handover process of the mobile station UE. The handover process can be performed quickly.

  Note that the operations of the mobile station UE, the relay node RN, the radio base station eNB, and the switching center MME described above may be performed by hardware, may be performed by a software module executed by a processor, or both. It may be implemented by a combination of

  The software module includes a RAM (Random Access Memory), a flash memory, a ROM (Read Only Memory), an EPROM (Erasable Programmable ROM), an EEPROM (Electronically Erasable and Programmable ROM, a hard disk, a registerable ROM, a hard disk). Alternatively, it may be provided in a storage medium of an arbitrary format such as a CD-ROM.

  Such a storage medium is connected to the processor so that the processor can read and write information from and to the storage medium. Further, such a storage medium may be integrated in the processor. Such a storage medium and processor may be provided in the ASIC. Such an ASIC may be provided in the mobile station UE, the relay node RN, the radio base station eNB, or the exchange MME. Further, the storage medium and the processor may be provided as a discrete component in the mobile station UE, the relay node RN, the radio base station eNB, or the exchange MME.

  Although the present invention has been described in detail using the above-described embodiments, it is obvious to those skilled in the art that the present invention is not limited to the embodiments described in this specification. The present invention can be implemented as modified and changed modes without departing from the spirit and scope of the present invention defined by the description of the scope of claims. Therefore, the description of the present specification is for illustrative purposes and does not have any limiting meaning to the present invention.

UE ... mobile station RN ... relay node eNB ... radio base station MME ... switching station

Claims (3)

The relay node and the radio base station are connected via a radio bearer,
The mobile station sets up a radio bearer with the relay node and communicates via the relay node and the radio base station, and sets up a radio bearer with the radio base station It is configured to perform handover processing with the state in which communication is performed via the base station,
In the handover process, a mobile communication system configured to transmit and receive a control signal related to the handover process via a radio bearer between the relay node and the radio base station.   The relay node and the radio base station have a layer function configured to perform a keep alive process for the radio bearer as an upper layer function of the function for setting the radio bearer. The mobile communication system according to claim 1. The relay node and the radio base station are
A first layer function configured to perform security processing between the relay node and the radio base station as an upper layer function of the function for setting the radio bearer;
The mobile communication system according to claim 1, further comprising: a second layer function configured to perform a keep alive process for the radio bearer as an upper layer function of the first layer function.

Images