Abstract:
The present invention relates to the radio communication field and discloses a method, an apparatus, and a system for handover between multi-carrier cells, so that a user equipment (UE) can be handed over to carriers of different cells on multiple target evolved NodeBs (eNBs). The handover method includes: after performing handover request acknowledge, receiving serial numbers (SNs) of data to be transferred and identifier information of target eNBs of other carriers to which the UE is handed over sent by a source eNB; and transferring scheduling information to the target eNBs of other carriers to which the UE is handed over.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Application No. PCT/CN2009/070337, filed on Feb. 2, 2009, which is hereby incorporated by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to the radio communication field, and in particular to a method, an apparatus, and a system for handover between multi-carrier cells. 
     BACKGROUND OF THE INVENTION 
     In an LTE-A (long-term evolution advanced, long-term evolution advanced) system, a user equipment (UE) in the LTE-A may use more than one carrier after the carrier aggregation (Carrier Aggregation, CA) technology is applied. Generally, conditions of aggregation may be categorized into three types: continuous CA, discontinuous CA within the same band, and discontinuous CA within different bands. 
     In the prior art, when a UE moves to the edge of a neighboring cell, the UE generally judges whether the RSRP (Reference Signal Received Power, reference signal received power) value of the neighboring cell is one offset better than the RSRP value of serving cell through measuring RSRP of the neighboring cell; if yes, triggers an A3 event, and submits a measurement report triggered by the event. After receiving the measurement report, the serving cell may start a handover determination procedure. 
     Usually, a source eNB preferentially selects an eNB with multiple carriers being in the same cell as a target eNB. Using multiple carriers by a UE generally means that the current service data rate of the UE is comparatively high. If the source eNB selects only a single eNB as the target eNB, only one carrier has better channel quality, and other carriers have worse channel quality. Therefore, only the single carrier can be used to support the current service. The current service of the UE may not be well supported, and the user experience of an end user may deteriorate. 
     In the network topology of the CA, if the UE reports a cell  1  (corresponding to a carrier with the best quality) and a cell  2  (corresponding to a carrier with better quality) as candidate cells in the measurement result, generally, the source eNB may use the cell  1  rather than the cell  2  as the final target cell of the UE, so that the UE is handed over to the target eNB  1  of the cell  1 . However, in this case, the UE can use only one carrier, so the data transmission rate is reduced. 
     SUMMARY OF THE INVENTION 
     Embodiments of the present invention provide a method, an apparatus, and a system for solving the problem that UE hands over to carriers of different cells of multiple target eNBs. The embodiments of the present invention employ the following technical solutions: 
     In embodiments of the present invention, a method for handover between multi-carrier cells includes: 
     receiving a measurement report triggered by an event submitted by a UE; 
     determining, according to the measurement report, to hand over the UE to corresponding carriers of different target eNBs; and 
     sending SNs of data to be transferred and identifier information of target eNBs of other carriers to which the UE is handed over to different target eNBs or a master target eNB of the different target eNBs. 
     In embodiments of the present invention, another method for handover between multi-carrier cells includes: 
     after performing handover request acknowledge, receiving SNs of data to be transferred and identifier information of target eNBs of other carriers to which the UE is handed over from a source eNB; and 
     transferring, according to the identifier information, scheduling information to the target eNBs of other carriers to which the UE is handed over. 
     In embodiments of the present invention, a handover apparatus includes: 
     a receiver, configured to receive a measurement report triggered by an event submitted by a UE; 
     a processor, configured to determine, according to the measurement report, to hand over the UE to corresponding carriers of different target eNBs; and 
     a transmitter, configured to send SNs of data to be transferred and identifier information of target eNBs of other carriers to which the UE is handed over to different target eNBs or a master target eNB of the different target eNBs. 
     In embodiments of the present invention, another handover apparatus includes: 
     a receiver, configured to receive SNs of data to be transferred and identifier information of target eNBs of other carriers to which the UE is handed over from a source eNB after performing handover request acknowledge; and 
     a transmitter, configured to transfer, according to the identifier information, scheduling information to the target eNBs of other carriers to which the UE is handed over. 
     In embodiments of the present invention, a system for handover between multi-carrier cells includes: 
     a first handover apparatus, configured on a source eNB and configured to: receive a measurement report triggered by an event submitted by a UE; determine, according to the measurement report, to hand over the UE to corresponding carriers of different target eNBs; and send SNs of data to be transferred and identifier information of target eNBs of other carriers to which the UE is handed over to a second handover apparatus on the different target eNBs or a master eNB of the different target eNBs; and 
     a second handover apparatus, configured on the target eNBs and configured to: after performing handover request acknowledge, receive the SNs of data to be transferred and the identifier information of the target eNBs of other carriers to which the UE is handed over sent by the first handover apparatus on the source eNB; and transfer, according to the identifier information, scheduling information to the target eNBs of other carriers to which the UE is handed over. 
     The method, apparatus, and system for handover between multi-carrier cells provided by the embodiments of the present invention make a handover determination according to a measurement report triggered by an event submitted by a UE; if the UE is determined to be handed over to corresponding carriers of different target eNBs, SNs of data to be transferred and identifier information of the target eNBs of other carriers to which the UE is handed over are sent to different target eNBs or a master target eNB of the different target eNBs; after receiving the SNs, the different target eNBs transfer scheduling information. It is realized that multiple eNBs perform data interactions with the UE through multiple carriers, so that the data throughput of the UE during the handover at a cell edge is increased, and the data transmission efficiency is improved. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       To make the embodiments of the present invent or the technical solution of the prior art clearer, the embodiments or the accompanying drawings for illustrating the prior art are described in the following. Obviously, the accompanying drawings are only exemplary embodiments of the present invent, and those skilled in the art may derive other drawings from such accompanying drawings without creative efforts. 
         FIG. 1  is a flowchart of a method for handover between multi-carrier cells according to an embodiment of the present invention; 
         FIG. 2  is a flowchart of another method for handover between multi-carrier cells according to an embodiment of the present invention; 
         FIG. 3  is a flowchart of a method for handover between multi-carrier cells according to a first embodiment of the present invention; 
         FIG. 4  is a flowchart of a method for handover between multi-carrier cells according to a second embodiment of the present invention; 
         FIG. 5  is a schematic diagram of an apparatus for handover between multi-carrier cells according to an embodiment of the present invention; 
         FIG. 6  is a schematic diagram of a determining unit according to an embodiment of the present invention; 
         FIG. 7  is a schematic diagram of another apparatus for handover between multi-carrier cells according to an embodiment of the present invention; and 
         FIG. 8  is a schematic diagram of a transferring unit according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     The method, apparatus, and system for handover between multi-carrier cells are hereinafter described in detail with reference to the accompanying drawings. 
     It should be definite that, the embodiments are only a part of embodiments of the present invention rather than all the embodiments. Based on the embodiments in the present invention, every other embodiment obtained by those skilled in the art without making creative labor also fall within the protection scope of the present invention. 
     As shown in  FIG. 1 , a method for handover between multi-carrier cells according to an embodiment of the present invention includes: 
     S 101 : Receive a measurement report triggered by an event submitted by a UE. 
     S 102 : Determine, according to the measurement report, to hand over the UE to corresponding carriers of different target eNBs. 
     S 103 : Send SNs of data to be transferred and identifier information of the target eNBs of other carriers to which the UE is handed over to the different target eNBs or a master target eNB of the different target eNBs. 
     Another method for handover between multi-carrier cells according to an embodiment of the present invention includes: 
     S 201 : Receive SNs of data to be transferred and identifier information of the target eNBs of other carriers to which the UE is handed over sent by a source eNB. 
     S 202 : Transfer scheduling information to the target eNBs of other carriers to which the UE is handed over according to the identifier information. 
     The method for handover between multi-carrier cells provided by this embodiment of the present invention makes a handover determination according to a measurement report triggered by an event submitted by a UE; if the UE is determined to be handed over to corresponding carriers of different target eNBs, SNs of data to be transferred and identifier information of the target eNBs of other carriers to which the UE is handed over are sent to different target eNBs or a master target eNB of the different target eNBs; after receiving the SNs, the different target eNBs transfer scheduling information. It is realized that different target eNBs perform data interactions with the UE through multiple carriers, so that the data throughput of the UE during the handover at a cell edge is increased, and the data transmission efficiency is improved. 
     The embodiment 1 hereinafter takes that a UE is handed over to a target eNB 1  of a neighboring cell  1  and a target eNB 2  of a neighboring cell  2  when the UE moves to the edges of the neighboring cell  1  and the neighboring cell  2  as example to describe the embodiment of the present invention in detail. 
     In this embodiment, a parallel relationship exists between the target eNB 1  and the target eNB 2 . 
     As shown in  FIG. 3 , this embodiment may include the following steps: 
     S 301 : a UE submits a measurement report triggered by an event. 
     A source eNB may deliver some measured frequencies and control information to the UE. In this embodiment, when the UE moves to the edges of the neighboring cell  1  and the neighboring cell  2 , the UE returns a measurement report (measurement reports) to the source eNB after measuring the cells. The measurement report may include identifier information of an event that triggers the measurement report, carrier information of the neighboring cell  1  and the neighboring cell  2  measured by the UE and corresponding measured values, and identifier information of the neighboring cell  1  and neighboring cell  2 . 
     S 302 : After receiving the measurement report from the UE, the source eNB makes a handover determination. 
     Specifically, according to the measurement report, obtain related information about candidate cells of the UE, and judge whether the candidate cells are different cells of different eNBs. If not, determine to hand over the UE to corresponding carriers of different target eNBs. In this embodiment, the source eNB determinesto hand over the UE to the carriers of the target eNB 1  of the neighboring cell  1  and the target eNB 2  of the neighboring cell  2 . 
     S 303   a ˜S 303   b : The source eNB sends handover requests (handover request), a handover request  1  and a handover request  2  as shown in  FIG. 3 , to the target eNB  1  and target eNB 2 . 
     S 304   a ˜S 304   b : The target eNB 1  and target eNB 2  return handover request acknowledges, a handover request acknowledge  1  and a handover request acknowledge  2 , as shown in  FIG. 3 . 
     S 305 : The source eNB performs downlink allocation (DL allocation) on the UE and sends a handover command (handover command) to the UE so that the UE submits measurement reports on the allocated downlink resource, and notifies the UE to be handed over to the target cell. 
     S 303 ˜S 305  are all the prior art, and are not detailed described herein. 
     S 306   a ˜S 306   b : The source eNB performs SN status transfer (SN Status Transfer) including an SN status transfer  1  and an SN status transfer  2  as shown in  FIG. 3  to the target eNB. 
     The SN status transfer includes SNs of data to be transferred and identifier information of the target eNBs of other carriers to which the UE is handed over. Specifically, the SN status transfer  1  includes SNs of data to be transferred and identifier information of the target eNB 2 , and the SN status transfer  2  includes SNs of data to be transferred and identifier information of the target eNB 1 . 
     If the corresponding carriers of the different target eNBs carry the same service, multiple target eNBs need to serve the same service of the UE, and the source eNB needs to send a proper SN to multiple target eNBs. In this embodiment. It is preferred in this embodiment of the invention that the SNs of data to be transferred are sent to different target eNBs separately. For example, the SNs of data packets of a video service include odd and even, and the odd SN (SN Status Transfer  1 ) of data to be transferred is sent to the target eNB  1  by the source eNB, and the even SN (SN Status Transfer  2 ) of data to be transferred is sent to the target eNB 2  by the source eNB. This embodiment of the invention is not limited to this mode. When the corresponding carriers of different target eNBs carry the same service, the source eNB may also send the same SN to each of the different target eNBs. 
     If the corresponding carriers of different target eNBs carry different services, different SNs of data to be transferred may be sent to different target eNBs by the source eNB according to the QoS requirements of different services. For example, according to the different QoS requirements of different services, the source eNB may preferably allocate services with higher QoS requirements (for example, real-time video services) to carriers that have stable channel status and more available resources. 
     This embodiment is not limited to the preceding two SN transfer modes. Other modes may be used to transfer the same SN or different SNs to different eNBs. 
     In addition, in the embodiment of the invention, the source eNB may also send identifier information of the target eNBs of other carriers to which the UE is handed over by using other modes. For example, the source eNB sends identifier information of the target eNBs of other carriers to which the UE is handed over through an additional signaling message. 
     S 307   a  to S 307   b : The UE sends a synchronization signal (Synchronization)  1  and a synchronization signal  2  to the target eNB 1  and the target eNB 2 . 
     This step is the prior art, and is not detailedly described. 
     S 308   a  to S 308   c : After receiving the SN status transfer message, the target eNB 1  and target eNB 2  deliver scheduling information, and send uplink allocation and timing advance to the UE respectively. 
     Specifically, the target eNB 1  may send uplink allocation and timing advance (UL allocation+TA)  1  to the UE. Meanwhile, the target eNB 1  sends scheduling information to the target eNB 2 , so that the target eNB 2  can cooperate with the target eNB 1  in scheduling and send proper uplink allocation and timing advance  2  to the UE. 
     The scheduling information includes scheduling rules, continuous scheduling or discontinuous scheduling for example, and scheduling results and so on. 
     The invention is not limited to the preceding mode. The target eNB 2  may also send uplink allocation and timing advance information to the UE firstly, and send scheduling information to the target eNB 1 , so that the target eNB 1  can cooperate with the target eNB 2  in scheduling and send proper uplink allocation and timing advance information to the UE. 
     The transmission of scheduling information between the eNB 1  and the eNB 2  may be negotiated between the eNB 1  and the eNB 2 , and is not limited in the embodiment of the invention. 
     S 309   a  to S 309   b : After receiving the uplink allocation and timing advance information, the UE instructs the target eNBs to get ready to transfer data through a handover confirm (handover confirm) including a handover confirm  1  sent to the target eNB 1  and a handover confirm  2  sent to the target eNB 2 . 
     After the UE finished the handover confirm, the eNB 1  and the eNB 2  may continue to transfer data to be transferred to the UE according to the SNs of data to be transferred. Accordingly, it is realized that the UE is handed over from the source eNB to the target eNB 1  and the target eNB 2 , and realized handover between multi-carrier cells. 
     As an embodiment of the present invention, the handover between the source cell and the target cell is via an X2 interface between the source eNB and target eNB, or via a mobility management entity (MME) connected to the source eNB and the target eNB respectively. 
     The second embodiment takes a UE is handed over to a master target eNB of a neighboring cell  1  and a slave target eNB of a neighboring cell  2  when the UE moves to the edges of the neighboring cell  1  and the neighboring cell  2  as example to describe the embodiment of the present invention in detail. 
     In this embodiment, the target eNBs include a master target eNB and a slave target eNB. 
     As shown in  FIG. 4 , this embodiment may include the following steps: 
     S 401  to  5405  are the same as S 301  to S 305  in the first embodiment, where, the eNB 1  refers to the master target eNB in this embodiment, and the eNB 2  refers to the slave target eNB in this embodiment. The detailed steps are not described. 
     S 406   a  to S 406   b : The source eNB sends an SN status transfer (SN Status Transfer) to the master target eNB and sends identifier information of the slave target eNB of other carriers to which the UE is handed over to the master target eNB. The SN status transfer includes SNs of data to be transferred. 
     If there is more than one slave target eNB, the source eNB sends identifier information of all the slave target eNBs to the master target eNB. 
     In the embodiment of the invention, the source eNB may also send identifier information of the slave target eNB of other carriers to which the UE is handed over by using other modes. For example, the SN status transfer may include identifier information of the slave target eNB. That is, in the embodiment of the invention, whether the SN status transfer includes identifier information of the slave target eNB is not limited. Identifier information of other target eNBs may be sent to the source target eNB by using multiple modes. 
     S 407 : The master target eNB sends an SN status transfer, including the SNs of data to be transferred, to the slave target eNB according to the received identifier information of the slave target eNB. 
     The master target eNB may send the received SNs of data to be transferred to each slave target eNB. Obviously, the master target eNB may also send the received SNs of data to be transferred to different slave target eNBs separately; or if multiple target eNBs carry different services, the master target eNB sends different SNs to different slave target eNBs according to the QoS requirements of different services. 
     S 408   a  to S 408   b : The UE sends a synchronization signal (Synchronization)  1  and a synchronization signal  2  to the master target eNB and the slave target eNB. 
     This step is prior art, and is not detailedly described. 
     S 409   a  to S 409   c : After receiving the SN status, the master target eNB and the slave target eNB transfer scheduling information, and send uplink allocation and timing advance to the UE respectively. 
     Specifically, the master target eNB may send uplink allocation and timing advance (UL allocation+TA)  1  to the UE. Meanwhile, the master target eNB sends scheduling information to the slave target eNB, so that the slave target eNB can cooperate with the master target eNB in scheduling and send proper uplink allocation and timing advance  2  to the UE. 
     The scheduling information includes scheduling rules, for example, continuous scheduling or discontinuous scheduling, and scheduling results and so on. 
     S 410   a  to S 410   b : After receiving the uplink allocation and timing advance, the UE instructs the target eNBs to get ready to transfer data through a handover confirm (handover confirm) including a handover confirm  1  sent to the master target eNB and a handover confirm  2  sent to the slave target eNB. 
     After the UE finished the handover confirm, the master target eNB and the slave target eNB may continue to transfer data to be transferred to the UE according to the SNs of data to be transferred. It is realized that the UE is handed over from the source eNB to the master target eNB and the slave target eNB, and handover between multi-carrier cells is realized. 
     For eNBs with a master-slave relationship, only a link between the core network (Core Network) and the master eNB is needed; for eNBs with a parallel relationship, there is a link between core network and each eNB. 
     By using the method for handover between multi-carrier cells provided in the embodiment of the present invention, after making a handover determination, the source eNB determines to hand over the UE to multiple carriers of different target eNBs, and then sends the same or different SNs and identifier information of the target eNBs of other carriers to which the UE is handed over to each target eNB or the master target eNB of each target eNB according to the requirements; after receiving the SNs, the target eNBs can transfer scheduling information between different eNBs, so as to cooperate with the UE in data transmission between different eNBs. Multi-carrier data transmission is implemented on different eNBs, and the data throughput of the UE is increased. 
     As shown in  FIG. 5 , a handover apparatus provided in an embodiment of the present invention includes: 
     a receiving unit  51 , configured to receive a measurement report triggered by an event submitted by a UE; 
     a determining unit  52 , configured to determine, according to the measurement report, to hand over the UE to corresponding carriers of different target eNBs; and 
     a sending unit  53 , configured to send SNs of data to be transferred and identifier information of target eNBs of other carriers to which the UE is handed over to the different target eNBs or a master target eNB of the different target eNBs. 
     As shown in  FIG. 6 , in an exemplary embodiment of the present invention, further, the determining unit  52  includes: 
     an obtaining module  521 , configured to obtain related information about candidate cells of the UE according to the measurement report; and 
     a judging module  522 , configured to instruct the sending unit to send the SNs of data to be transferred to different target eNBs when determining that the candidate cells are different cells of different target eNBs. 
     In this embodiment, the handover apparatus may be configured on the eNB. On the basis of the preceding embodiment, where, the SNs of data to be transferred that are sent to the different target eNBs may be different. 
     In addition, in this embodiment, the UE may be handed over to carriers of different target eNBs with reference to the operation of the source eNB in the method for handover between multi-carrier cells shown in  FIG. 3 . 
     As shown in  FIG. 7 , another handover apparatus provided in an embodiment of the present invention includes: 
     a receiving unit  71 , configured to receive SNs of data to be transferred and identifier information of target eNBs of other carriers to which the UE is handed over sent by a source eNB; and 
     a transferring unit  72 , configured to transfer scheduling information to the target eNBs of other carriers to which the UE is handed over according to the identifier information. 
     On the basis of the preceding solution, the handover apparatus may further include a first sending unit, configured to send the SNs of data to be transferred to the target eNBs of other carriers to which the UE is handed over according to the identifier information after the receiving unit receives the SNs of data to be transferred and the identifier information. 
     The apparatus solution provided in this embodiment may refer to the operations of the master target eNB in the method for handover between multi-carrier cells of embodiment shown in  FIG. 4 , so as to realize handing over the UE to the carriers of the different target eNBs. 
     On the basis of the preceding solution, the handover apparatus further includes a second sending unit, configured to send uplink allocation and timing advance information to the UE. 
     In addition, the transferring unit  72  further includes: 
     a first transferring module, configured to send scheduling information to the target eNBs of other carriers to which the UE is handed over after the second sending unit sends the first uplink allocation and timing advance information to the UE, the scheduling information is used for enabling the target eNBs of other carriers to send the second uplink allocation and timing advance information to the UE according to the scheduling information; or 
     a second transferring module, configured to receive the scheduling information sent by the target eNBs of other carriers to which the UE is handed over, and after the receiving, instruct the sending unit to send uplink allocation and timing advance information to the UE according to the scheduling information. 
     This solution may refer to the operations of the target eNB in method for handover between multi-carrier cells of embodiment shown in  FIG. 3  or  FIG. 4 , so as to realize handing over the UE to the carriers of the different target eNBs. 
     The handover apparatus provided in this embodiment may be configured on the eNB. 
     As shown in  FIG. 8 , a system for handover between multi-carrier cells provided in an embodiment of the present invention includes: 
     a first handover apparatus  81 , configured on the source eNB and configured to: receive a measurement report triggered by an event submitted by a UE; determine, according to the measurement report, to hand over the UE to corresponding carriers of different target eNBs; and send SNs of data to be transferred and identifier information of the target eNBs of other carriers to which the UE is handed over to a second handover apparatus  82  on the different target eNBs or the master target eNB of the different target eNBs; and 
     the second handover apparatus  82 , configured on the target eNBs and configured to: after performing handover request acknowledge, receive SNs of data to be transferred and identifier information of the target eNBs of other carriers to which the UE is handed over sent by the first handover apparatus  81  on the source eNB; and transfer scheduling information to the target eNBs of other carriers to which the UE is handed over according to the identifier information. 
     On the basis of the preceding solution, in this embodiment, the first handover apparatus  81  preferably sends different SNs of data to be transferred to different target eNBs. 
     The system for handover between multi-carrier cells of this embodiment may refer to the operations of the source eNB and the target eNB in method for handover between multi-carrier cells of embodiment shown in  FIG. 3  and  FIG. 4 , so as to realize handing over the UE to the carriers of the different target eNBs. 
     The handover apparatus and system provided in embodiments of the present invention make a handover determination according to a measurement report triggered by an event submitted by a UE; if the UE is determined to be handed over to corresponding carriers of different target eNBs, SNs of data to be transferred and identifier information of the target eNBs of other carriers to which the UE is handed over are sent to different target eNBs or the master target eNB of the different target eNBs; after receiving the SNs, the different target eNBs transfer scheduling information. It is realized that multiple eNBs perform data interactions with the UE through multiple carriers, so that the data throughput of the UE during the handover at a cell edge is increased, and the data transmission efficiency is improved. 
     It is understandable to those skilled in the art that all or part of the processes in the preceding embodiments may be implemented by related hardware instructed by a computer program. The program may be stored in a computer readable storage medium. When the program runs, the processes of the preceding methods are carried out. The preceding storage medium may be a magnetic disk, a compact disk, a read only memory (Read-Only Memory, ROM), or a random access memory (Random Access Memory, RAM) and so on. 
     The preceding descriptions are merely exemplary embodiments of the present invention, but not intended to limit the scope of the present invention. Any modification or variation made without departing from the spirit and principle of the present invention should fall within the protection scope of the present invention. Therefore, the protection scope of the present invention is subject to the appended claims.