JP6672445B2 - Mobile communication system - Google Patents

Description

  The present invention relates to a mobile communication system.

  Introduction of small cells (or phantom cells) in the LTE (Long Term Evolution) system for the purpose of effective use of high frequency (3.5 GHz or more) having poor propagation characteristics and realization of high-speed large-capacity communication utilizing wideband characteristics. Is being considered.

3GPP TS36.300

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

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

  However, in the existing LTE scheme, when the mobile station UE is communicating in the macro cell, there is no study on how to add the radio base station PhNB on the transmission path of the mobile station UE. There was a point.

  Similarly, in the existing LTE scheme, when the mobile station UE is communicating in the small cell, the radio base station PhNB that manages the small cell is deleted from the transmission path of the mobile station UE by any method. There was a problem that it was not considered what should be done.

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

  A first feature of the present invention is a mobile communication method, wherein when a mobile station is communicating in a macro cell under the control of a first radio base station, a small cell having coverage including a position where the mobile station exists is provided. When the second radio base station to be managed is selected as the transmission path of the user data of the mobile station, the first radio base station transmits the second radio base station to the transmission path of the user data of the mobile station. A step of initiating an additional process, wherein the second radio base station resets information related to header compression, security setting information, and management information of a sequence number in the additional process; Transferring the uplink user data of the mobile station to the second radio base station without transferring the uplink user data of the mobile station to the second radio base station. It is the gist of.

  A second feature of the present invention is a mobile communication method, which comprises a first radio base station that manages a macro cell on a transmission path of user data of a mobile station and a small coverage having a coverage including a position where the mobile station exists. A second radio base station that manages a cell is included, and when the mobile station is communicating in the small cell, the second radio base station is not used as a transmission path of user data of the mobile station In the case, the first radio base station starts a process of deleting the second radio base station from a transmission path of user data of the mobile station, and the first radio base station includes a header in the deletion process. Resetting information related to compression, security setting information, and management information of sequence number; and the second radio base station, in the deletion processing, transfers the transfer information to the first radio base station. 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, when adding or deleting a radio base station PhNB that manages a small cell, the mobile station while minimizing the impact on the radio base station eNB and the radio base station PhNB A mobile communication system capable of changing a transmission path of a UE can be provided.

FIG. 1 is an overall configuration diagram of a mobile communication system according to a first embodiment of the present invention. FIG. 2 is a functional block diagram of a radio base station eNB according to the first embodiment of the present invention. FIG. 4 is a sequence diagram showing an operation of the mobile communication system according to the first embodiment of the present invention. FIG. 4 is a sequence diagram showing an operation of the mobile communication system according to the first embodiment of the present invention.

(Mobile communication system according to the first embodiment of the present invention)
The mobile communication system according to the first embodiment of the present invention will be described with reference to FIGS.

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

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

  As shown in FIG. 1, when the mobile station UE is communicating in a macro cell under the control of the radio base station eNB, the radio base station PhNB that manages a small cell having coverage including the location where the mobile station UE is located is a mobile station When selected as the transmission path of the user data of the UE, the user data of the mobile station UE includes the U-plane bearer set between the gateway device S-GW and the radio base station eNB, the radio base station eNB and the radio base station eNB. The transmission is performed via a U-plane bearer set between the station PhNB and a U-plane bearer set between the radio base station PhNB and the mobile station UE.

  That is, in such a case, the transmission route of the user data of the mobile station UE changes from the route of the gateway device S-GW ← → the radio base station eNB ← → the mobile station UE to the gateway device S-GW ← → the radio base station eNB ← → The route is changed to the base station PhNB →→ 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 exists is included in the coverage area of the radio base station PhNB. Next, it is assumed that the radio base station PhNB is selected as a transmission path for 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 the control of the radio base station PhNB, and the radio base station PhNB is not used as a transmission path of user data of the mobile station UE, the mobile station UE moves. The user data of the station UE is a U-plane bearer set between the gateway device S-GW and the radio base station eNB, and a U-plane bearer set between the radio base station eNB and the mobile station UE. Will be transmitted via.

  That is, in such a case, the transmission route of the user data of the mobile station UE is changed from the route of the gateway device S-GW ← → the radio base station eNB ← → the radio base station PhNB ← → the mobile station UE to the gateway device S-GW ← → radio. The route is changed to the base station eNB ← → mobile station UE.

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

  With this configuration, the radio base station PhNB does not need to set a logical path with the gateway device S-GW, and only needs to guarantee the connection with the radio base station eNB. The processing load on the station PhNB can be reduced.

  Further, it is not necessary for the gateway device S-GW to have a function of identifying a small cell, 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 device 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 device S-GW, receives uplink user data of the mobile station from the radio base station PhNB or the mobile station UE, 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 and the uplink user data of the mobile station received by the reception unit 11 in a GTP (GPRS Tunneling Protocol) layer or a PDCP (Packet Data Convergence Protocol) layer. It is configured as follows.

  The management unit 13 includes information on a U-plane bearer, security setting information, information on a PDCP layer (PDCP Config), information on a transfer mode and a transmission state (RoHC context), and management information on a sequence number. And so on.

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

  In addition, the security setting information includes UE Security Capability (UE Security Capability), information on AS Security (AS Security Information), and the like.

  The information on the PDCP layer includes the maximum length of the sequence number, information on header compression, and whether or not “PDCP Status Report” is necessary.

  Further, information relating to header compression includes “MAX_ID”, “PROFILES”, and the like.

  Here, “MAX_ID” is the maximum value of the context ID for identifying the 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 device S-GW, the mobility management node MME, the radio base station PhNB, the mobile station UE, and the like.

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

  Here, when the mobile station UE is communicating in a macro cell under the 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 is located is the user data of the mobile station UE. If the transmission path is selected as the transmission path, the transmitting unit 14 transmits “E-RAB setup request” to the radio base station PhNB, thereby transmitting the user data of the mobile station UE to the radio base station. It is configured to start a PhNB addition process.

  In addition, the radio base station eNB and the radio base station PhNB are included in the transmission path of the user data of the mobile station UE, and when the mobile station UE is communicating in a small cell, the radio base station PhNB becomes the mobile station. When the transmission section 14 is no longer used as the transmission path of the user data of the UE, the transmitting section 14 transmits “E-RAB release request” to the radio base station PhNB, thereby transmitting the transmission path of the user data of the mobile station UE. The radio base station PhNB is configured to start deletion processing.

  Further, in the above-described additional processing, the transmission unit 14 is configured not to transfer the uplink user data of the mobile station UE to the radio base station PhNB, but to transfer the downlink user data addressed to the mobile station UE. You may.

  Here, the transmitting unit 14 transmits the downlink user data addressed to the mobile station buffered in the PDCP layer, from the user data transmitted to the mobile station UE but not receiving the acknowledgment information (ACK) from the mobile station UE. , The radio base station PhNB.

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

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

  Hereinafter, the operation of the mobile communication system according to the present embodiment will be described with reference to FIG. 3 and FIG.

  First, with reference to FIG. 4, in the mobile communication system according to the present embodiment, when the mobile station UE is communicating in a macro cell under the control of the radio base station eNB, the coverage including the position where the mobile station UE is located The operation in the case where the radio base station PhNB that manages the small cell having the above is selected as the user data transmission path of the mobile station UE will be described.

  As illustrated in FIG. 3, the radio base station eNB selects the radio base station PhNB as a user data transmission path of the mobile station UE in a state where a DRB (Data Radio Bearer) is set with the mobile station UE. When the detection is performed, the transmission of the downlink user data addressed to the mobile station UE to the mobile station UE is stopped, and in step S1001, the communication between the radio base station eNB and the radio base station PhNB is performed with respect to 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 related to the U-plane bearer or the like 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 according to the “E-RAB setup request”, and also sets security setting information and information related to the PDCP layer. (PDCP Config), information on transfer mode and transmission state (RoHC context), management information on sequence number, and the like are reset, and in step S1002, “E-RAB setup response” is transmitted to the radio base station eNB. .

  In step S1003, the radio base station eNB transfers the 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 the 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 UE to the mobile station UE until the transmission of “RRC Connection Reconfiguration” in step S1005 is completed, or until the radio base station eNB receives “RRC Connection Reconfiguration Complete” in step S1006. It is assumed that downlink user data addressed to the UE is transmitted (see step S1004).

  In Step S1005, the radio base station eNB transmits “RRC Connection Reconfiguration” to the mobile station UE.

  The mobile station UE stops transmission of uplink user data to the radio base station eNB upon receiving 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 sets information on the U-plane bearer, security setting information, information on the PDCP layer (PDCP Config), and information on the transfer mode and transmission state (RoHC). Stop management such as context).

  Here, the DRB is set between the radio base station PhNB and the mobile station UE. In step S1007, the radio base station PhNB determines the mobile station from the downlink user data addressed to the mobile station UE having “sequence number = 0”. The transmission to the UE is restarted, and in step S1008, the mobile station UE transmits to the radio base station PhNB the uplink user data having a sequence number equal to or later than the sequence number of the uplink user data that has been transmitted to the radio base station eNB.

  Secondly, with reference to FIG. 4, in the mobile communication system according to the present embodiment, when the mobile station UE is communicating in a small cell under the control of the radio base station PhNB, the radio base station PhNB is connected to the mobile station UE. The operation in the case where the user data is no longer used as the transmission path of the user data will be described.

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

  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, releases the radio base station eNB to the radio base station eNB. Then, information and the like relating to the U-plane bearer are notified by “E-RAB release response”.

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

  In step S2003, the radio base station PhNB transfers the 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 the 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 transmits to 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 is assumed that downlink user data addressed to the mobile station UE is transmitted (see step S2004).

  In Step S2005, the radio base station eNB transmits “RRC Connection Reconfiguration” to the mobile station UE.

  The mobile station UE stops transmission of uplink user data to the radio base station PhNB upon receiving 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 sets information on the U-plane bearer, security setting information, information on the PDCP layer (PDCP Config), and information on the transfer mode and transmission state (RoHC). Stop management such as context).

  Here, the DRB is set between the radio base station eNB and the mobile station UE. In step S2007, the radio base station eNB determines the mobile station from the downlink user data addressed to the mobile station UE having “sequence number = 0”. The transmission to the UE is restarted, and in step S2008, the mobile station UE transmits to the radio base station eNB the uplink user data having a sequence number equal to or later than the sequence number of the uplink user data that has been completely transmitted to the radio base station PhNB.

  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 a mobile station UE is located in a macro cell under a radio base station eNB (first radio base station) and is in a position where the mobile station UE exists. When the radio base station PhNB (second radio base station) that manages the small cell having the coverage including is selected as the transmission path of the user data of the mobile station UE, the radio base station eNB transmits the user data of the mobile station UE. A step of starting a process of adding the radio base station PhNB to the transmission path; and a step of the radio base station PhNB resetting information related to header compression, security setting information, and management information of a sequence number in the addition process. In the additional processing, the radio base station eNB does not transfer the uplink user data of the mobile station UE to the radio base station PhNB. That a step of transferring the downlink user data addressed to the mobile station UE is summarized as.

  According to such a configuration, data loss may occur when the wireless base station PhNB is added. However, it is possible to simplify the processing in the wireless base station PhNB and the wireless base station eNB and change the user data transmission path. it can.

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

  According to such a configuration, retransmission is performed in the radio base station eNB until the setting of the radio base station PhNB is completed, so that the possibility of occurrence of data loss can be reduced.

  In the first feature of the present embodiment, the radio base station eNB determines, from among downlink user data destined for the mobile station UE that is buffered in the PDCP layer, data that has not been transmitted to the mobile station UE, The transfer may be performed to the station PhNB.

  According to such a configuration, the mobile station UE may receive downlink user data addressed to the mobile station UE redundantly, but can avoid loss of downlink user data addressed to the mobile station UE.

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

  According to this configuration, although there is a possibility of loss of downlink user data addressed to the mobile station UE, downlink user data transmitted from the radio base station PhNB to the mobile station UE to reset the PDCP layer is new. , And it is possible to prevent mismatching of downlink user data between the mobile station UE and the radio base station PhNB also in the upper layer.

  In the first feature of the present embodiment, the mobile station UE may transmit, to the radio base station PhNB, uplink user data having a sequence number after the sequence number of uplink user data that has been completely transmitted to the radio base station eNB. .

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

  According to this configuration, there is no need 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 can be performed.

  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 that manages a macro cell and a mobile station UE exist on a transmission path of user data of the mobile station UE. When the radio base station PhNB that manages the small cell is included, and the mobile station UE is communicating in the small cell, the radio base station PhNB is not used as a transmission path of user data of the mobile station UE. A step in which the base station eNB starts a process of deleting the radio base station PhNB from the transmission path of the user data of the mobile station UE, and a process in which the radio base station eNB performs information related to header compression and security setting information in the deletion process. Resetting the management information of the base station and the sequence number, and the radio base station PhNB executes 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, data loss may occur when the radio base station PhNB is deleted. However, it is possible to change the transmission path of user data while simplifying the processes in the radio base station PhNB and the radio base station eNB. it can.

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

  According to this configuration, the possibility of data loss can be reduced by retransmitting 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 determines, from among the downlink user data addressed to the mobile station UE buffered in the PDCP layer and not transmitted to the mobile station UE, the radio base station PhNB. The transfer may be performed to the station eNB.

  According to such a configuration, the mobile station UE may receive downlink user data addressed to the mobile station UE redundantly, but can avoid loss of downlink user data addressed to the mobile station UE.

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

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

  In the second feature of the present embodiment, the mobile station UE may transmit, to the radio base station eNB, uplink user data having a sequence number equal to or later than the sequence number of the uplink user data transmitted to the radio base station PhNB. .

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

  According to this configuration, there is no need 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 can be performed.

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

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

  The 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 a processor. Further, 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. The storage medium and the processor may be provided as discrete components 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 in detail with reference to the above 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 aspects without departing from the spirit and scope of the present invention defined by the description of the claims. Therefore, the description in the present specification is for the purpose of illustrative explanation, and has no restrictive meaning to the present invention.

S-GW gateway device 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 communicating in a cell under the 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 located is connected to the user data of the mobile station. When the first radio base station is selected as the transmission path of, the first radio base station starts the process of adding the second radio base station to the user data transmission path of the mobile station,
The second radio base station, in the addition process, the information relating to header compression, to reset the management information security setting information and the sequence number,
The first radio base station transfers, in the additional processing, downlink user data addressed to the mobile station to the second radio base station;
The second radio base station does not have an RRC layer function,
The mobile communication system, wherein the information related to the header compression is included in a PDCP Config.