JP2019071642A - Mobile communication system - Google Patents

Abstract

To change a transmission path of a mobile station UE while minimizing the impact on a radio base station eNB and a radio base station PhNB when adding or removing the wireless base station PhNB managing a small cell.SOLUTION: When a radio base station PhNB is selected as a transmission path of user data of a mobile station UE when the mobile station UE is in communication in a macro cell, a radio base station eNB starts additional processing of the radio base station PhNB to the transmission path of the user data of the mobile station UE. In the addition processing, the radio base station PhNB resets information on header compression, security setting information, and sequence number management information. In the addition processing, the radio base station eNB does not transfer uplink user data of the mobile station UE to the radio base station PhNB, but transfers downlink user data addressed to the mobile station UE.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a mobile communication system.

  Introduction of small cells (or phantom cells) for the purpose of realizing high-speed, large-capacity communication utilizing effective use of high frequency (3.5 GHz or more) inferior to propagation characteristics and wide bandwidth in LTE (Long Term Evolution) system Is being considered.

3GPP TS 36.300

  The radio base station PhNB that manages such a small cell is functionally limited, for example, does not have an RRC (Radio Resource Control) layer function as compared to the radio base station eNB that manages the macro cell.

  In view of this point, even if the mobile station UE is in communication in a small cell, a method of transmitting user data (U-plane data) of the mobile station UE via the radio base station eNB The introduction of is being considered.

  However, in the existing LTE system, when the mobile station UE is in communication in the macro cell, there is a problem that how to add the radio base station PhNB on the transmission path of the mobile station UE is not considered. There was a point.

  Similarly, in the existing LTE scheme, when the mobile station UE is in communication in a small cell, the radio base station PhNB that manages such a small cell is deleted from the transmission path of the mobile station UE by any method. There was a problem that it was not examined about what to do.

  Therefore, the present invention has been made in view of the above-described problems, and has minimal impact on the radio base station eNB and the radio base station PhNB when adding or deleting the radio base station PhNB that manages small cells. It is an object of the present invention to provide a mobile communication system capable of changing the transmission path of the mobile station UE while limiting the number.

  According to a first aspect of the present invention, there is provided a mobile communication method, wherein, when a mobile station is communicating in a macro cell under control of a first radio base station, a small cell having a coverage including a position where the mobile station is present. When the second radio base station to be managed is selected as a transmission path of user data of the mobile station, the first radio base station is configured to select the second radio base station on the transmission path of user data of the mobile station. A step of starting an addition process, a step of resetting information related to header compression, security setting information and sequence number management information in the addition process, and the first wireless base station And transmitting, in the additional processing, no uplink user data of the mobile station to the second radio base station, but transmitting downlink user data addressed to the mobile station. It is the gist of.

  A second aspect of the present invention is a mobile communication method, comprising: a small first radio base station for managing a macro cell and a small coverage including a position where the mobile station exists on a user data transmission path of the mobile station. When the second radio base station that manages the cell is included and the mobile station is in communication in the small cell, the second radio base station is not used as a transmission path for user data of the mobile station In this case, the first wireless base station may start the process of deleting the second wireless base station from the transmission path of user data of the mobile station, and the first wireless base station may use a header in the deletion process. Resetting the management information of information related to compression, security setting information, and sequence number; and in the deletion process, the second radio base station performs the transfer to the first radio base station in the deletion process. Without transferring for uplink user data of the station, and summarized in that a step of transferring the downlink user data of the mobile stations.

  As described above, according to the present invention, at the time of addition or deletion of a radio base station PhNB managing a small cell, a mobile station while minimizing the impact on the radio base station eNB and the radio base station PhNB. It is possible to provide a mobile communication system capable of changing the transmission path of the UE.

FIG. 1 is an overall configuration diagram of a mobile communication system according to a first embodiment of the present invention. It is a functional block diagram of radio base station eNB concerning a 1st embodiment of the present invention. It is a sequence diagram which shows operation | movement of the mobile communication system which concerns on the 1st Embodiment of this invention. It is a sequence diagram which shows operation | movement of the mobile communication system which concerns on the 1st Embodiment of this invention.

(Mobile Communication System According to 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 FIGS. 1 to 4.

  As shown in FIG. 1, the mobile communication system according to the present embodiment is a mobile communication system according to the LTE scheme, and includes a gateway apparatus P-GW (PDN Gateway) / S-GW (Serving Gateway), and a mobility management node MME. (Mobility Management Entity), a radio base station PhNB managing a small cell, and a radio base station eNB managing a macro cell are provided.

  Here, the coverage area of the macro cell and the coverage area of the small cell are arranged to at least partially overlap.

  As shown in FIG. 1, when the mobile station UE is in communication in the macro cell under control of the radio base station eNB, the radio base station PhNB managing a small cell having a coverage including the position where the mobile station UE exists is the mobile station When selected as a transmission path of user data of UE, the user data of the mobile station UE is a U-plane bearer set between the gateway apparatus S-GW and the radio base station eNB, the radio base station eNB and the radio base It will be transmitted via the U-plane bearer set up with the station PhNB and the U-plane bearer set up between the radio base station PhNB and the mobile station UE.

  That is, in this case, the transmission path of the user data of the mobile station UE is from the gateway apparatus S-GW →→ radio base station eNB ← → mobile station UE, the gateway apparatus S-GWGW → radio base station eNB ← → radio The route changes to base station PhNBNB → mobile station UE.

  For example, when the coverage area of the radio base station PhNB is included in the coverage area of the radio base station eNB, and the position where the mobile station UE is present is included in the coverage area of the radio base station PhNB. It is assumed that the radio base station PhNB is selected as a transmission path of user data of the mobile station UE.

  On the other hand, as shown in FIG. 1, when the mobile station UE is communicating in a small cell under control of the radio base station PhNB, if the radio base station PhNB is not used as a transmission path of user data of the mobile station UE, The user data of the station UE is a U-plane bearer configured between the gateway apparatus S-GW and the radio base station eNB, and a U-plane bearer configured between the radio base station eNB and the mobile station UE Will be transmitted via.

  That is, in this case, the transmission path of the user data of the mobile station UE is from the gateway apparatus S-GW →→ radio base station eNB ← → radio base station PhNB ← → mobile station UE, and the gateway apparatus S-GW ← → radio It is changed to a route of base station eNBeNB → mobile station UE.

  For example, when the mobile station UE leaves the coverage area of the radio base station PhNB, the radio base station PhNB is not used as a transmission path of user data of the mobile station UE.

  By configuring in this way, the radio base station PhNB does not need to set up a logical path with the gateway apparatus S-GW, and only needs to guarantee the connection with the radio base station eNB. The processing load of the station PhNB can be reduced.

  Also, the gateway device S-GW does not have to have a function to identify small cells, and the impact on the existing architecture can be minimized.

  As shown in FIG. 2, the radio base station eNB includes a reception unit 11, a storage unit 12, a management unit 13, and a transmission unit 14.

  The receiving unit 11 is configured to receive various signals from the gateway apparatus S-GW, the mobility management node MME, the radio base station PhNB, the mobile station UE, and the like.

  For example, the receiving unit 11 receives downlink user data addressed to the mobile station UE from the gateway apparatus S-GW, receives uplink user data of the mobile station from the radio base station PhNB or the mobile station UE, or the radio base It is configured to receive “E-RAB setup response” from the station PhNB.

  The storage unit 12 buffers the downlink user data addressed to the mobile station UE received by the reception unit 11 and the uplink user data of the mobile station in a GTP (GPRS Tunneling Protocol) layer or a PDCP (Packet Data Convergence Protocol) layer. Is configured as.

  The management unit 13 is information on U-plane bearer, security setting information, information on PDCP layer (PDCP Config), information on transfer mode and transmission state (RoHC context), and management information on sequence numbers. It is configured to manage about etc.

  Here, the information related to the U-plane bearer includes “E-RAB ID”, “QoS information (E-RAB Level QoS Parameters)”, and the like.

  Also, the security setting information includes UE's security capability (UE Security Capability), information on AS security (AS Security Information), and the like.

  Also, the information related to the PDCP layer includes the maximum length of the sequence number, the information related to header compression, the necessity of “PDCP Status Report”, and the like.

  Furthermore, the information related to header compression includes “MAX_ID”, “PROFILES”, and the like.

  Here, “MAX_ID” is the maximum value of context ID for identifying a flow, and “PROFILES” is information indicating which header is to be compressed.

  The transmission unit 14 is configured to transmit various signals to the gateway apparatus S-GW, the mobility management node MME, the radio base station PhNB, the mobile station UE, and the like.

  For example, the transmitting unit 14 transmits uplink user data of the mobile station UE to the gateway apparatus S-GW, or transmits downlink user data addressed to the mobile station to the radio base station PhNB or the mobile station UE. Also, it is configured to transmit “RRC Connection Reconfiguration” to the mobile station UE, and transmit “E-RAB setup request” to the radio base station PhNB.

  Here, when the mobile station UE is in communication in the macro cell under control of the radio base station eNB, the radio base station PhNB that manages the small cell having the coverage including the position where the mobile station UE exists is the user data of the mobile station UE When the transmission unit 14 is selected as the transmission path of the mobile station, the radio base station on the transmission path of the user data of the mobile station UE is transmitted by transmitting "E-RAB setup request" to the radio base station PhNB. It is configured to start additional processing of PhNB.

  Further, when the radio base station eNB and the radio base station PhNB are included in the user data transmission path of the mobile station UE, and the mobile station UE is in communication in the small cell, the radio base station PhNB is a mobile station When not being used as a transmission path of user data of the UE, the transmission unit 14 transmits an “E-RAB release request” to the radio base station PhNB to transmit from the transmission path of the user data of the mobile station UE. The radio base station PhNB is configured to start deletion processing.

  In addition, in the above-described addition process, the transmission unit 14 is configured not to transfer uplink user data of the mobile station UE to the radio base station PhNB, but to transfer downlink user data addressed to the mobile station UE. May be

  Here, from the downlink user data addressed to the mobile station buffered in the PDCP layer, the transmission unit 14 transmits to the mobile station UE but has not received the delivery confirmation information (ACK) from the mobile station UE. , And may be configured to transfer to the radio base station PhNB.

  In addition, the transmission unit 14 transfers downlink user data addressed to the mobile station UE buffered in the PDCP layer to the radio base station PhNB from data not transmitted to the mobile station UE. It may be configured.

  Furthermore, the radio base station eNB transmits, to the radio base station PhNB, downlink user data addressed to the mobile station UE that has been transmitted from the gateway apparatus S-GW via the S1-U interface and has not been buffered in the PDCP layer. It may be configured to forward.

  The operation of the mobile communication system according to the present embodiment will be described below with reference to FIGS. 3 and 4.

  First, referring to FIG. 4, in the mobile communication system according to the present embodiment, when the mobile station UE is in communication in the macro cell under control of the radio base station eNB, coverage including the position where the mobile station UE is present The operation in the case where the radio base station PhNB which manages the small cell having the < ' >

  As shown in FIG. 3, the radio base station PhNB selects the radio base station PhNB as a transmission path of user data of the mobile station UE in a state where a DRB (Data Radio Bearer) is set between the radio base station eNB and the mobile station UE. When it is detected, the transmission of downlink user data addressed to the mobile station UE to the mobile station UE is stopped, and in step S1001, between the radio base station eNB and the radio base station PhNB for the radio base station PhNB. Send "E-RAB setup request" requesting to create a U-plane bearer.

  Here, the radio base station eNB notifies the radio base station PhNB of information and the like related to the U-plane bearer by “E-RAB setup request”.

  The radio base station PhNB generates a U-plane bearer between the radio base station eNB and the radio base station PhNB in response to the “E-RAB setup request”, and also performs security setting information and information related to the PDCP layer. (PDCP Config), information on transfer mode and transmission state (RoHC context), management information of sequence numbers, etc. are reset, and "E-RAB setup response" is transmitted to the radio base station eNB in step S1002. .

  In step S1003, the radio base station eNB transfers downlink user data addressed to the mobile station UE buffered in the PDCP layer to the radio base station PhNB.

  Here, the radio base station eNB does not transfer uplink user data of the mobile station UE buffered in the PDCP layer to the radio base station PhNB.

  Note that the radio base station eNB transmits the mobile station to the mobile station UE until the transmission of “RRC Connection Reconfiguration” in step S1005 is completed, or until the “RRC Connection Reconfiguration Complete” in step S1006 is received. It shall transmit about downlink user data addressed to UE (refer to step S1004).

  In step S1005, the radio base station eNB transmits "RRC Connection Reconfiguration" to the mobile station UE.

  The mobile station UE stops the transmission of uplink user data to the radio base station eNB in response to the reception of the “RRC Connection Reconfiguration”.

  In step S1006, the mobile station UE transmits "RRC Connection Reconfiguration Complete" to the radio base station eNB.

  In response to the “RRC Connection Reconfiguration Complete”, the radio base station eNB performs information related to the U-plane bearer, security setting information, information related to the PDCP layer (PDCP Config), information related to the transfer mode and transmission state (RoHC Stop management of context etc.

  Here, DRB is set between the radio base station PhNB and the mobile station UE, and in step S1007, the radio base station PhNB is the mobile station from downlink user data addressed to the mobile station UE in which “sequence number = 0”. The transmission to the UE is resumed, and in step S1008, the mobile station UE transmits, to the radio base station PhNB, uplink user data having a sequence number after the sequence number of the uplink user data for which transmission to the radio base station eNB is completed.

  Second, referring to FIG. 4, in the mobile communication system according to the present embodiment, when the mobile station UE is in communication in a small cell under the radio base station PhNB, the radio base station PhNB is the mobile station UE. The operation when it is not used as the user data transmission path of

  As shown in FIG. 4, the radio base station PhNB uses the radio base station PhNB as a transmission path for user data of the mobile station UE, with the DRB set between the radio base station PhNB and the mobile station UE. When it is detected that it is no longer possible, the transmission of downlink user data for the mobile station UE to the radio base station PhNB is stopped, and in step S2001, the radio base station PhNB is transmitted between the radio base station eNB and the radio base station PhNB. Send "E-RAB release request" requesting to release the U-plane bearer of

  In response to the "E-RAB release request", the radio base station PhNB releases the U-plane bearer between the radio base station eNB and the radio base station PhNB, and in step S2002, the radio base station eNB sends the U-plane bearer to the radio base station eNB. The information related to the U-plane bearer etc. is notified by "E-RAB release response".

  The radio base station eNB starts management of information and the like related to the U-plane bearer, information on security setting information, information on the PDCP layer (PDCP Config), information on transfer mode and transmission state (RoHC context), and a sequence number Reset the management information of

  In step S2003, the radio base station PhNB transfers downlink user data addressed to the mobile station UE buffered in the PDCP layer to the radio base station eNB.

  Here, the radio base station PhNB does not transfer uplink user data of the mobile station UE buffered in the PDCP layer to the radio base station eNB.

  Note that the radio base station PhNB sends the mobile station UE until the transmission of “RRC Connection Reconfiguration” in step S2005 is completed, or until the transmission of “RRC Connection Reconfiguration Complete” in step S2006 is completed. It shall transmit about the downlink user data addressed to the mobile station UE (refer step S2004).

  In step S2005, the radio base station eNB transmits "RRC Connection Reconfiguration" to the mobile station UE.

  The mobile station UE stops the transmission of the uplink user data to the radio base station PhNB in response to the reception of the “RRC Connection Reconfiguration”.

  In step S2006, the mobile station UE transmits "RRC Connection Reconfiguration Complete" to the radio base station eNB.

  In response to the “RRC Connection Reconfiguration Complete”, the radio base station eNB performs information related to the U-plane bearer, security setting information, information related to the PDCP layer (PDCP Config), information related to the transfer mode and transmission state (RoHC Stop management of context etc.

  Here, DRB is set between the radio base station eNB and the mobile station UE, and in step S2007, the radio base station eNB is the mobile station from downlink user data addressed to the mobile station UE in which “sequence number = 0”. The transmission to the UE is resumed, and in step S2008, the mobile station UE transmits, to the radio base station eNB, uplink user data having a sequence number subsequent to that of the uplink user data for which transmission to the radio base station PhNB is completed.

  The features of the present embodiment described above may be expressed as follows.

  A first feature of the present embodiment is a mobile communication method, in which the mobile station UE is located when the mobile station UE is in communication in a macro cell under control of a radio base station eNB (first radio base station). If a radio base station PhNB (second radio base station) managing a small cell having a coverage including the following is selected as a transmission path of user data of the mobile station UE, the radio base station eNB selects user data of the mobile station UE. Step of starting addition processing of the radio base station PhNB on the transmission path, and step of resetting management information of header compression, security setting information and sequence number in the addition processing. The radio base station eNB does not transfer uplink user data of the mobile station UE to the radio base station PhNB in the additional process. That a step of transferring the downlink user data addressed to the mobile station UE is summarized as.

  According to this configuration, there is a possibility that data loss may occur when the radio base station PhNB is added, but it is possible to change the transmission path of user data while simplifying the processing in the radio base station PhNB and the radio base station eNB. it can.

  In the first feature of the present embodiment, the radio base station eNB transmits to the mobile station UE among downlink user data addressed to the mobile station buffered in the PDCP layer, but transmission confirmation information (ACK from the mobile station UE) ) May be transferred to the radio base station PhNB from the one that has not received.

  According to this configuration, the possibility of occurrence of data loss can be reduced by performing retransmission at the radio base station eNB until the setting of the radio base station PhNB is completed.

  In the first feature of the present embodiment, since the radio base station eNB is not transmitting to the mobile station UE among the downlink user data addressed to the mobile station UE buffered in the PDCP layer, the radio base station eNB It may be transferred to the station PhNB.

  According to this configuration, in the mobile station UE, although there is a possibility of redundantly receiving downlink user data for the mobile station UE, loss of downlink user data for the mobile station UE can be avoided.

  In the first feature of the present embodiment, the radio base station eNB may transfer, to the radio base station PhNB, downlink user data addressed to the mobile station UE not yet buffered in the PDCP layer.

  According to this configuration, although there is a possibility of loss of downlink user data for the mobile station UE, the downlink user data transmitted from the radio base station PhNB to the mobile station UE is new because the PDCP layer is reset. In the upper layer, it is possible to prevent the mismatch of the downlink user data between the mobile station UE and the radio base station PhNB.

  In the first feature of the present embodiment, the mobile station UE may transmit uplink user data having a sequence number subsequent to the sequence number of uplink user data for which transmission to the radio base station eNB is completed to the radio base station PhNB. .

  In addition, in the first feature of this embodiment, the mobile station UE may reset the sequence number of uplink user data to be transmitted to the radio base station PhNB in order to reset the PDCP layer.

  According to this configuration, it is not necessary to exchange the management state of the sequence number of the uplink user data between the radio base station eNB and the radio base station PhNB, and simple processing is possible.

  A second feature of the present embodiment is a mobile communication method, which has a coverage including a position where a radio base station eNB managing a macro cell and a mobile station UE exist on a user data transmission path of the mobile station UE. When the radio base station PhNB which manages the small cell is included and the mobile station UE is in communication in the small cell, the radio base station PhNB is not used as a transmission path of user data of the mobile station UE, the radio The process in which the base station eNB starts the process of deleting the radio base station PhNB from the transmission path of the user data of the mobile station UE, and the radio base station eNB performs information related to header compression in the deletion process, setting information of security And a process of resetting management information of the sequence number, and the radio base station PhNB, in the deletion process, the radio base station. Against NB, without transferring for uplink user data of the mobile station UE, and summarized in that and a step of transferring the downlink user data addressed to the mobile station UE.

  According to this configuration, there is a possibility that data loss may occur when the radio base station PhNB is deleted, but the transmission path of user data may be changed while simplifying the processing in the radio base station PhNB and the radio base station eNB. it can.

  In the second feature of the present embodiment, the radio base station PhNB transmits to the mobile station UE among downlink user data addressed to the mobile station UE buffered in the PDCP layer, but transmission confirmation information from the mobile station UE ( ACK may be transferred to the radio base station eNB from the one that has not received ACK.

  According to this configuration, the possibility of occurrence of data loss can be reduced by performing retransmission in the radio base station PhNB until the setting of the radio base station eNB is completed.

  In the second feature of the present embodiment, the radio base station PhNB does not transmit to the mobile station UE among the downlink user data for the mobile station UE buffered in the PDCP layer, the radio base station It may be transferred to the station eNB.

  According to this configuration, in the mobile station UE, although there is a possibility of redundantly receiving downlink user data for the mobile station UE, loss of downlink user data for the mobile station UE can be avoided.

  In the second feature of this embodiment, the radio base station PhNB may transfer, to the radio base station eNB, downlink user data addressed to the mobile station UE that has not been buffered in the PDCP layer.

  According to this configuration, although there is a possibility of loss of downlink user data for the mobile station UE, the downlink user data transmitted from the radio base station eNB to the mobile station UE is new because the PDCP layer is reset. In the upper layer, it is possible to prevent the mismatch of the downlink user data between the mobile station UE and the radio base station eNB.

  In the second feature of this embodiment, the mobile station UE may transmit, to the radio base station eNB, uplink user data having a sequence number subsequent to that of the uplink user data for which transmission to the radio base station PhNB is completed. .

  In addition, in the second feature of the present embodiment, the mobile station UE may reset the sequence number of uplink user data to be transmitted to the radio base station eNB in order to reset the PDCP layer.

  According to this configuration, it is not necessary to exchange the management state of the sequence number of the uplink user data between the radio base station eNB and the radio base station PhNB, and simple processing is possible.

  The above-described operations of the mobile station UE, the radio base station eNB / PhNB, the mobility management node MME, and the gateway device S-GW may be implemented by hardware or implemented by a software module executed by a processor. It may be implemented by the combination of both.

  The software modules include RAM (Random Access Memory), flash memory, ROM (Read Only Memory), EPROM (Erasable Programmable ROM), EEPROM (Electronically Erasable and Programmable ROM), registers, hard disks, removable disks. It may be provided in an arbitrary type of storage medium such as a CD-ROM.

  Such a storage medium is connected to the processor such that the processor can read and write information on the storage medium. Also, such a storage medium may be integrated into a processor. Also, the storage medium and the processor may be provided in an ASIC. Such an ASIC may be provided in the mobile station UE, the radio base station eNB / PhNB, the mobility management node MME, or the gateway device S-GW. Moreover, such a storage medium and processor may be provided as a discrete component in the mobile station UE, the radio base station eNB / PhNB, the mobility management node MME, and the gateway device S-GW.

  Although the present invention has been described above in detail using the above embodiments, it is obvious for those skilled in the art that the present invention is not limited to the embodiments described herein. The present invention can be embodied as modifications and alterations without departing from the spirit and scope of the present invention defined by the description of the claims. Accordingly, the description in the present specification is for the purpose of illustration and does not have any limiting meaning on the present invention.

S-GW: Gateway apparatus MME: Mobility management node eNB / PhNB: Radio base station UE: Mobile station 11: Reception unit 12: Storage unit 13: Management unit 14: Transmission unit

Claims (1)

A mobile station, a first radio base station, and a second radio base station;
When the mobile station is in communication in a cell under control of the first radio base station, the second radio base station having a cell having a coverage including a position where the mobile station is present is user data of the mobile station When the first radio base station is selected as the transmission path of the second radio base station, the process of adding the second radio base station to the transmission path of the user data of the mobile station is started.
In the additional process, the second wireless base station sets information related to header compression, security setting information, and management information of a sequence number,
The first wireless base station transfers downlink user data addressed to the mobile station to the second wireless base station in the addition process,
The second radio base station does not have an RRC layer function,
The information related to the header compression is included in PDCP Config.