JP5058380B2 - Mobile communication system - Google Patents

Description

  The present invention relates to a mobile communication system.

  As shown in FIG. 8, 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. 8, 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 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 first relay node and a radio base station are connected via a radio bearer, and a second relay node and the radio base station are connected via a radio bearer. A state in which a mobile station sets up a radio bearer with the first relay node and performs communication via the first relay node and the radio base station, and the second relay node. Is configured to perform a handover process between the second relay node and a state in which communication is performed via the second base node and the radio base station. In the handover process, A control signal related to the handover process is transmitted / received via a radio bearer between the first relay node and the radio base station and a radio bearer between the second relay node and the radio base station. And gist that it is configured to.

  In the first aspect of the present invention, when the first relay node receives a measurement report from the mobile station, the first relay node transmits the radio base station via a radio bearer between the first relay node and the radio base station. The wireless base station starts handover processing from the first state to the second state of the mobile station based on the measurement report. If it is determined to do so, a handover request signal notifying that is sent as a control signal for the handover process via the radio bearer between the second relay node and the radio base station. It may be configured to transmit to the node.

  In the first feature of the present invention, when the first relay node decides to start a handover process from the first state to the second state of the mobile station, a handover request signal that notifies the fact Is transmitted to the radio base station via a radio bearer between the first relay node and the radio base station as a control signal related to the handover process, and the radio base station The received handover request signal may be transferred to the second relay node via a radio bearer between the second relay node and the radio base station.

  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 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 mobile communication system which concerns on the 2nd Embodiment of this invention. It is a sequence diagram which shows operation | movement of the mobile communication system which concerns on the 2nd Embodiment of this invention. It is a protocol stack figure in the mobile communication system which concerns on the 3rd Embodiment of this invention. It is a sequence diagram which shows operation | movement of the mobile communication system which concerns on the 3rd Embodiment of this 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)
With reference to FIG. 1 thru | or FIG. 3, the mobile communication system which concerns on the 1st Embodiment of this invention is demonstrated.

  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.

  In this mobile communication system, as shown in (4) of FIG. 1, the mobile station UE sets up a radio bearer with the relay node RN2 (first relay node), and the relay node RN2 and the radio base station DeNB2 A radio bearer is set between the state in which communication is performed via the (radio base station) and the relay node RN3 (second relay node), and communication is performed via the relay node RN2 and the radio base station DeNB2. It is configured to perform a handover process between states.

  In this handover process, the handover process is performed via the radio bearer (Un interface) between the relay node RN2 and the radio base station DeNB2 and the radio bearer (Un interface) between the relay node RN3 and the radio base station DeNB2. It is comprised so that the control signal (X2AP signal) which concerns on may be transmitted / received.

  In the present embodiment, a radio bearer (Un interface) is not set between the relay node RN2 and the relay node RN4.

  Specifically, as illustrated in FIG. 2, the relay node RN2 uses a physical (PHY) as an X2-C radio bearer function for setting up an X2-C radio bearer (Un interface) with the radio base station DeNB2. ) Layer function, MAC (Media Access Control) layer function provided as an upper layer function of the physical (PHY) layer function, and RLC (Radio Link Control) layer function provided as an upper layer function of the MAC layer function And a PDCP (Packet Data Convergence Protocol) layer function provided as an upper layer function of the RLC layer function.

  Note that the relay node RN2 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 is 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. And an SCTP layer function configured to perform keep-alive processing for the X2-C radio bearer as an upper layer function of the IP layer function.

  Further, the relay node RN2 may include an X2AP layer function configured to transmit and receive a control signal related to the handover process as an upper layer function of the SCTP layer function.

  Similarly, the relay node RN3 has a physical (PHY) layer function and a physical (PHY) as an X2-C radio bearer function for setting an X2-C radio bearer (Un interface) with the radio base station DeNB2. MAC layer function provided as an upper layer function of the layer function, RLC layer function provided as an upper layer function of the MAC layer function, and PDCP layer function provided as an upper layer function of the RLC layer function It has.

  Relay node RN3 may have an RRC layer function provided as an upper layer function of the PDCP layer function.

  In addition, the relay node RN3 includes an IP layer function configured to perform security processing between the relay node RN3 and the radio base station DeNB2, as an upper layer function of the X2-C radio bearer function. As an upper layer function of the function, an SCTP layer function configured to perform keep alive processing for the X2-C radio bearer may be provided.

  In addition, the relay node RN3 may include an X2AP layer function configured to transmit and receive a control signal related to the handover process as an upper layer function of the SCTP layer function.

  Further, the radio base station DeNB2 has an X2-C radio bearer function for setting an X2-C radio bearer (Un interface) between the relay node RN2 and the relay node RN3.

  The radio base station DeNB2 includes an IP layer function provided as an upper layer function of the X2-C radio bearer function, an SCTP function provided as an upper layer function of the IP layer function, and an upper layer of the SCTP layer function. And an X2AP layer function provided as a function.

  Hereinafter, with reference to FIG. 3, 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 to the relay node RN3 to a state in which communication is performed via the relay node RN3 and the radio base station DeNB2.

  As shown in FIG. 3, the relay node RN2 manages “UE Context” of the mobile station UE in step S1000. In step S1001, the relay node RN2 transmits the radio base station DeNB2 via the X2-C radio bearer. The mobile station UE transmits a “HO Request (handover request signal)” requesting a handover from the relay node RN2 to the relay node RN3.

  When receiving the “HO Request” in the X2AP layer function, the radio base station DeNB2 stores “UE Context” of the mobile station UE in Step S1002, and in Step S1003, stores the “HO Request” in the X2-C radio. The data is transferred to the relay node RN3 via the bearer.

  When receiving the “HO Request”, the relay node RN3 stores the “UE Context” of the mobile station UE in Step S1004. In Step S1005, the relay node RN3 receives the radio base station DeNB2 via the X2-C radio bearer. “HO Request Ack (handover request confirmation signal)” is transmitted.

  When receiving the “HO Request Ack” in the X2AP layer function, the radio base station DeNB2 transfers the “HO Request Ack” to the relay node RN2 via the X2-C radio bearer in Step S1006.

  In step S1007, the relay node RN2 transmits “HO Command (handover instruction signal)” instructing the mobile station UE to perform handover to the relay node RN3 by the RRC layer function.

  In step S1008, the mobile station UE transmits “HO Complete (handover completion signal)” to the relay node RN3 by the RRC layer function.

  In step S1009, the relay node RN3 transmits a “Path Switch Request (path switching request signal)” to the switching center MME via the S1-MME interface.

  In step S1010, the switching center MME transmits a “Path Switch Request Ack (path switching request confirmation signal)” to the relay node RN3 via the S1-MME interface and transfers a signal addressed to the mobile station UE. The destination is switched from relay node RN2 to relay node RN3.

  In step S1011, the relay node RN3 transmits “UE Context Release” to the radio base station DeNB2 via the X2-C radio bearer. In step S1012, the radio base station DeNB2 The “UE Context Release” is transferred to the relay node RN2 via the X2-C radio bearer, and the relay node RN2 manages the “UE Context” of the mobile station UE according to the “UE Context Release”. finish.

  In FIG. 3, relay node RN2 and relay node RN3 may be interchanged.

  As described above, the X2AP layer function in the radio base station DeNB2 is between the control signal (X2AP signal) related to the handover process between the relay note RN2 and the radio base station DeNB2, and between the relay note RN3 and the radio base station DeNB2. Is configured to convert a control signal (X2AP signal) related to the handover process in FIG.

  In addition, the X2AP layer function in the radio base station DeNB2 is a mobile station ID used between the relay note RN2 and the radio base station DeNB2, and a movement used between the relay note RN3 and the radio base station DeNB2. The station ID is managed in association with the station ID.

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.
(Mobile communication system according to the second embodiment of the present invention)
With reference to FIG.4 and FIG.5, the mobile communication system which concerns on the 2nd Embodiment of this invention is demonstrated. Hereinafter, the mobile communication system according to the second embodiment of the present invention will be described by focusing on differences from the above-described mobile communication system according to the first embodiment.

  Specifically, as illustrated in FIG. 4, the relay node RN2 uses a physical (PHY) as an X2-C radio bearer function for setting up an X2-C radio bearer (Un interface) with the radio base station DeNB2. ) Layer function, MAC layer function provided as upper layer function of physical (PHY) layer function, RLC layer function provided as upper layer function of MAC layer function, and upper layer function of RLC layer function And the provided PDCP layer function.

  Relay node RN2 may have an RRC layer function provided as an upper layer function of the PDCP layer function.

  Also, as shown in FIG. 4, the relay node RN2 is configured to operate as a proxy for the RRC layer function in the mobile station UE, and as a higher layer function of the X2-C radio bearer function, the relay node RN2 and the radio node IP layer function configured to perform security processing with the base station DeNB2, SCTP layer function configured to perform keep-alive processing for the X2-C radio bearer, and control signal related to handover processing Does not have an X2AP layer function configured to transmit and receive.

  Further, the protocol stack of the radio base station DeNB2 and the relay node RN3 is the same as the protocol stack of the mobile communication system according to the first embodiment shown in FIG.

  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 to the relay node RN3 to a state in which communication is performed via the relay node RN3 and the radio base station DeNB2.

  As illustrated in FIG. 5, when the relay node RN2 receives “Measurement Report (measurement report)” from the mobile station UE in step S2000, the relay node RN2 acquires “UE Context” of the managed mobile station UE in step S2001. Then, in Step S2002, the “Measurement Report” including the “UE Context” of the mobile station UE is transferred to the radio base station DeNB2 by the RRC layer function.

  Based on the received “Measurement Report”, the radio base station DeNB2 determines to perform a handover process from the relay node RN2 of the mobile station UE to the relay node RN3. In step S2003, the “UE Context” of the mobile station UE is determined. In step S2004, “HO Request (handover request signal)” for requesting handover of the mobile station UE from the relay node RN2 to the relay node RN3 is transmitted to the relay node RN3 via the X2-C radio bearer. To send.

  When receiving the “HO Request”, the relay node RN3 stores “UE Context” of the mobile station UE in Step S2005, and in Step S2006, the radio base station DeNB2 via the X2-C radio bearer, “HO Request Ack (handover request confirmation signal)” is transmitted.

  When the radio base station DeNB2 receives “HO Request Ack”, in step S2007, the radio base station DeNB2 instructs the relay node RN2 to perform handover to the relay node RN3 by the RRC layer function. “HO Command (handover instruction signal)” Send.

  In step S2008, the relay node RN2 transfers the received “HO Command” to the mobile station UE by the RRC layer function.

  In step S2009, the mobile station UE transmits “HO Complete (handover completion signal)” to the relay node RN3 by the RRC layer function.

  In step S2010, the relay node RN3 transmits a “Path Switch Request (path switching request signal)” to the switching center MME via the S1-MME interface.

  In step S2011, the switching center MME transmits a “Path Switch Request Ack (path switching request confirmation signal)” to the relay node RN3 via the S1-MME interface, and transfers a signal addressed to the mobile station UE. The destination is switched from relay node RN2 to relay node RN3.

  In step S2012, the relay node RN3 transmits “UE Context Release” to the radio base station DeNB2 via the X2-C radio bearer.

In step S2013, the radio base station DeNB2 transfers “RRC Connection Release” to the relay node RN2 in the RRC layer function, and the relay node RN2 responds to the “RRC Connection Release” according to the “RRC Connection Release”. Management of “UE Context” is terminated.
(Mobile communication system according to the third embodiment of the present invention)
With reference to FIG.6 and FIG.7, the mobile communication system which concerns on the 3rd Embodiment of this invention is demonstrated. Hereinafter, the mobile communication system according to the third embodiment of the present invention will be described by focusing on differences from the above-described mobile communication system according to the first embodiment.

  Specifically, as shown in FIG. 6, the radio base station DeNB2 has an X2-C radio bearer function for setting an X2-C radio bearer (Un interface) between the relay node RN2 and the relay node RN3. It has.

  The radio base station DeNB2 has an IP layer function as an upper layer function of the X2-C radio bearer function, but does not have an SCTP function or an X2AP layer function as an upper layer function of the IP layer function. .

  Note that the protocol stacks of the relay nodes RN2 and RN3 are the same as those of the mobile communication system according to the first embodiment shown in FIG.

  Hereinafter, with reference to FIG. 7, 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 to the relay node RN3 to a state in which communication is performed via the relay node RN3 and the radio base station DeNB2.

  As shown in FIG. 7, the relay node RN2 manages the “UE Context” of the mobile station UE in step S3000. In step S3001, the relay node RN2 transmits the radio base station DeNB2 via the X2-C radio bearer. The mobile station UE transmits a “HO Request (handover request signal)” requesting a handover from the relay node RN2 to the relay node RN3.

  When receiving the “HO Request” in Step S3002 by the IP layer function, the radio base station DeNB2 transfers the “HO Request” to the relay node RN3 via the X2-C radio bearer in Step S3003.

  When receiving the “HO Request”, the relay node RN3 stores “UE Context” of the mobile station UE in Step S3004, and in Step S3005, the radio base station DeNB2 via the X2-C radio bearer. “HO Request Ack (handover request confirmation signal)” is transmitted.

  When receiving the “HO Request Ack” by the IP layer function, the radio base station DeNB2 transfers the “HO Request Ack” to the relay node RN2 via the X2-C radio bearer in Step S3006.

  In step S3007, the relay node RN2 transmits “HO Command (handover instruction signal)” instructing the mobile station UE to perform handover to the relay node RN3 by the RRC layer function.

  In step S3008, the mobile station UE transmits “HO Complete (handover completion signal)” to the relay node RN3 by the RRC layer function.

  In Step S3009, the relay node RN3 transmits a “Path Switch Request (path switching request signal)” to the switching center MME via the S1-MME interface.

  In step S3010, the switching center MME transmits a “Path Switch Request Ack (path switching request confirmation signal)” to the relay node RN3 via the S1-MME interface and transfers a signal addressed to the mobile station UE. The destination is switched from relay node RN2 to relay node RN3.

  In step S3011, the relay node RN3 transmits “UE Context Release” to the radio base station DeNB2 via the X2-C radio bearer.

  When the radio base station DeNB2 receives “UE Context Release” in step S3012 by the I layer function, in step S3013, the radio base station DeNB2 sends “UE Context Release” to the relay node RN2 via the X2-C radio bearer. Then, the relay node RN2 ends the management of the “UE Context” of the mobile station UE according to the “UE Context Release”.

  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 Registered 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 (1)

  A mobile communication system in which a first relay node and a radio base station are connected via a radio bearer, and a second relay node and the radio base station are connected via a radio bearer,
  The first relay node and the second relay node are provided as a physical layer function and an upper layer function of the physical layer function as a radio bearer function for setting an Un interface with the radio base station. MAC layer function, RLC layer function provided as an upper layer function of the MAC layer function, PDCP layer function provided as an upper layer of the RLC layer function, and an upper layer function of the PDCP layer function With the RRC layer function provided,
  The first relay node and the second relay node have an IP layer function as an upper layer function of the radio bearer function, an SCTP layer function provided as an upper layer function of the IP layer function, and the SCTP layer function. X2AP layer function provided as an upper layer function of
  The radio base station is provided as a physical layer function and an upper layer function of the physical layer function as a radio bearer function for setting a Un interface between the first relay node and the second relay node. MAC layer function, RLC layer function provided as an upper layer function of the MAC layer function, PDCP layer function provided as an upper layer of the RLC layer function, and an upper layer function of the PDCP layer function With the RRC layer function provided,
  The radio base station is provided as an IP layer function as an upper layer function of the radio bearer function, an SCTP layer function provided as an upper layer function of the IP layer function, and an upper layer function of the SCTP layer function. X2AP layer function, and
  A control signal related to a handover process is configured to terminate between an X2AP layer function of the first relay node and the second relay node and an X2AP layer function of the radio base station. Communications system.

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