WO2013109063A1

WO2013109063A1 - Method for establishing user plane after relay node moves

Info

Publication number: WO2013109063A1
Application number: PCT/KR2013/000367
Authority: WO
Inventors: Hong Wang; Lixiang Xu
Original assignee: Samsung Electronics Co., Ltd.
Priority date: 2012-01-18
Filing date: 2013-01-17
Publication date: 2013-07-25
Also published as: CN103220735A

Abstract

The present invention discloses a method for establishing a user plane after a RN moving, in a switching procedure of S1 or X2 or after the switching is finished, the tunnel between the destination DeNB of the moving RN and the gateway serving the RN is established; after the switching is finished and the S1 interface is established, the tunnel between the moving RN and the destination DeNB is established. By using the method for establishing the user plane, the user plane is established when the RN moves to a new DeNB, the switching procedure is transparent to the UE and the data is transmitted continually.

Description

METHOD FOR ESTABLISHING USER PLANE AFTER RELAY NODE MOVES

The present invention relates to wireless communication technologies, and more particularly to, a method for establishing a user plane after a Relay Node (RN) moves.

Figure 1 is a schematic diagram illustrating the structure of a Long Term Evolution (LTE) supporting a RN in the prior art. As shown in Figure 1, in a wireless access network of the LTE system, the wireless resource management entity includes evolved Node B (eNB) 101 and RN 102, the RN accesses a core network via another Donor NodeB (DeNB) 103. The eNBs 101 connect with each other via an X2 interface, each eNB 101 connects to a Mobile Management Entity (MME) and Serving GateWay (S-GW) 104 in the core network via anS1interface respectively; RN 102 accesses DeNB 103 via a Un interface. DeNB 103 provides an X2 proxy function between RN 102 and other eNB. DeNB 103 provides a S1 proxy function between RN 102 and MME/S-GW 104. The S1 and X2 proxy functions include transmitting X2 or S1 signalingspecially used by the UE between RN 102 and eNB 101 and between RN 102 and MME 104, and transmission between RN 102 the S-GW 104.

Figure 1 shows the structure of a conventional fixed RN. The S1, X2 and Un interfaces are terminated on the fixed RN. The DeNB provides the S1 and X2 proxy functions between the RN and DeNB, RN and other node, e.g. MME, other eNB. The proxy functions include: transmitting S1 and X2 messages specially used by the UE, transmitting GTP data packets between the RN and DeNB, between RN and other network nodes. Based on the proxy functions, for the RN, the DeNB is a combination of the functions of the MME, other eNB and S-GW.

There are two phases in the procedure of connecting the RN to the DeNB.

The first phase is a pre-configuration phase of the RN.

The RN attaches to E-UTRAN/EPC as a UE, and the attachment procedure of the RN is the same as that of a common UE, and the MME regards the RN as the common UE and selects an S-GW and a P-GW for the RN. The MME serving the RN is called RN-MME, an original configuration parameters are obtained from the operation and maintaining of the RN, and the configuration parameters at least include a list of DeNB cells that the RN can connect to. After the procedure is finished, the RN leaves the network via a de-attachment procedure, and enters to the second phase.

The second phase is a work phase of the RN.

The RN selects one DeNB from the pre-configured list of the DeNB cells, and starts to enter a work state. After the DeNB initiates a S1/X2 bear establishing procedure, the RN initiates a S1/X2 bear establishing procedure between the RN and the DeNB. The DeNB may initiate a RRC re-configuration procedure of the RN to update parameters of the RN.

After the S1 interface is established, if the configuration parameter is changed, the DeNB initiates an eNB configuration update procedure of the S1. After the X2 interface is established, the DeNB initiates an eNB configuration update procedure of the X2 to update configuration information of cell. In this phase, a cell identifier of the RN, ECGI is configured by the RN OAM.

In the second phase, the DeNB provides S-GW/P-GWfunctions of the RN which include: establishing a session and management bear for the RN, providing a function of S11. Thefunctions of the P-GW on the DeNB also include assigning an IP address for the RN which is used when the RN communicates with the OAM. The IP address may be different from the IP address of the DeNB.

The RN and the DeNB need to map the signaling and data to an EPS bear established for the RN. The mapping mechanism is based on a currently defined Qos mechanism between the UE and the P-GW.

Figure 2 is a flowchart illustrating an attachment procedure of a RN. The procedure is basically similar as the attachment procedure of a common UE, and the differences include:

1. in the procedure of establishing the S1 interface with the MME, the DeNB know the MME that supporting the RN function via the S1 establishing response message;

2. in step 1, in the procedure of establishing the RRC connection between the RN and the DeNB, the RN sends a RN instruction to the DeNB;

3. in step 4b, in the initial UE message in the procedure of establishing the S1 interface UE context, the DeNB needs to send the RNinstruction and an IP address of the S-GW/P-GW to the MME

4. in the attachment procedure, the EPC check whether the RN is authenticated. Only if the RN is authenticated, the EPC accepts the attachment procedure and establishesthe context between the DeNB and the EPC; otherwise, the EPC refuses the attachment procedure. The UE attaches the network via the RN, the MME serving the UE is called UE-MME, the RN-MME and UE-MME may be the same MME or different MMEs. The GW of the RN includes SGW and PGW which are located on the same entity as the DeNB currently. The SGW and PGW implement different functions. For simple descriptions, the SGW and PGW are called as the GW of the RN, but they have different functions.

The RN currently defined is used in fixed location and does not support the movement of the RN between different cells. The current mechanism is inapplicable for scenes of a train moving at high speed. The high speed train is developing fast, and the moving speed of the train is high, e.g. 250-350 kilometer per hour. The wireless environmentof the high speed train is special, e.g. high noise, high penetration loss and serious Doppler shift etc. The service quality of the conventional RN can not satisfy the requirements of operators, and a moving RN is to solve the above problems of the fixed RN, so as to improve service quality provided by the high speed train and satisfy the requirementsof users.

The difference betweenthe moving RN and the fixed RN includes that the DeNB of the moving RN will change in the moving procedure, and when the switching is performed, the bear, context and users of the moving RN need to switchto the destination DeNB to ensure data continuity. How to support this aspect is not discussed in the current protocols. It is necessary to establish a user plane for transmitting UE information between the DeNB and the RN-GW, establish a S1 interface between the moving RN and the destination DeNB, and establish a user plane between the moving RN and the destination DeNB, so as to ensure that the switchingprocedure of the RN is transparent to the UE as much as possible.

The present invention relates to, when the RN moves, how to perform switching between DeNBs by the RN, how to switch to the destination DeNB together with the RN by the UE, how to establish a connection between the new and the DeNB, and how to ensure data is received continually, how to reduce information interaction in the switching procedure, and how to make the switching procedure transparent to the UE and the core network as much as possible.

The present invention provides a method for supporting group switch and receiving data continually, to reduce unnecessary signaling procedure and network congestion in high speed circumstance.

The present invention provides the following technical solutions:

A method for establishing a tunnel between a Donor NodeB (DeNB) of a moving Relay Node (RN) and a gateway of the moving RN, when the moving RN switches to a new DeNB via an S1 interface, comprising:

A. a source DeNB of the moving RN sending a switching need message to an Mobile Management Entity serving the moving RN (RN-MME), the message comprising an identifier of each UE served by the moving RN, and upstream tunnel information assigned for the UE by a gateway of the moving RN (RN-GW);

B. the RN-MME sending a switching request message to the destination DeNB of the moving RN, the message comprising the identifier of each UE served by the moving RN, and the upstream tunnel information assigned for the UE by the RN-GW;

C. the destination DeNB sending a switching response message to the RN-MME, the message comprising a new identifier on the S1 interface of each UE served by the moving RN and downstream tunnel information assigned by the destination DeNB;

D. the RN-MME or the destination DeNB sending the new identifier on the S1 interface of each UE served by the moving RN and the downstream tunnel information assigned by the destination DeNB to the RN-GW.

Thestep D comprises: the RN-MME sending a changing bear establishing request message to the RN-GW, the message comprising the new identifier on the S1 interface of each UE served by the moving RN and the downstream tunnel information assigned by the destination DeNB to the RN-GW;

Or,

the destination DeNB sending a path updating message to the RN-GW, the message comprising the new identifier on the S1 interface of each UE served by the moving RN and the downstream tunnel information assigned by the destination DeNB to the RN-GW.

The method further comprises a step E after the step D: the RN-MME sending a UE context release command message to the source DeNB, the message comprising identifiers of all UEs served by the moving RN; after receiving the UE context release command message, the source DeNB releasing context information of the moving RN and context information of all UEs served by the moving RN.

After the step E, the method further comprises: establishing an S1 interface between the moving RN and the destination DeNB, maintaining the context information of all UEs served by the moving RN unchanged.

After an S1 switching is finished, the method further comprises:

for each UE served by the moving RN, the destination DeNB sending the identifier of the UE and the new identifier of the UE on the S1 interface assigned by the destination DeNB to a UE-MME serving the UE, to update UE information on the UE-MME; the UE-MME assigning a new identifier on the S1 interface for the UE and notifying the destination DeNB;

the UE-MME or the destination DeNB sending the new identifier of each UE served by the moving RN on the S1 interface assigned by the UE-MME to the RN-GW.

The switching need message in the step A further comprises information when the moving RN is taken as the UE, the information comprising an old identifier of the moving RN on the S1 interface between the source DeNB and the RN-MME;

the switching request message in the step B further comprises the new identifier of the moving RN on S1 interface assigned by the RN-MME and upstream tunnel information assigned for the moving RN by the RN-GW;

the switching response message in the step C further comprises the new identity of the moving RN on S1 interface assigned by the RN-MME, the new identity of the moving RN on S1 interface and downstream tunnel information assigned by the destination DeNB;

after the step C and before the step D further comprises: the RN-MME sending aswitching command message to the source DeNB, the message comprises the new identifier of the moving RN on S1 interface, the new identifier of the moving RN on S1 interface assigned assigned by the destination DeNB;

The step D further comprises: the RN-MME sending the downstream tunnel informationassigned for the moving RN by the destination DeNB to the RN-GW.

A method for establishing a tunnel between a DeNB of a moving RN and a gateway of the moving RN, when the moving RN switches to a new DeNB via an X2 interface, comprising:

A. a source DeNB of the RN sending a switching request message to a destination DeNB, the message comprising an identifier of each UE served by the moving RN, and upstream tunnel information assigned for the UE by a gateway of the moving RN (RN-GW);

B. the destination DeNB sending a switching response message to the source DeNB, the message comprising a new identifier of each UE served by the moving RN and downstream tunnel information assigned by the destination DeNB;

C. the destination DeNB sending the new identifier of each UE served by the moving RN on the S1 interface and the downstream tunnel information assigned by the destination DeNB to the RN-GW via a RN-MME serving the moving RN.

The method further comprises a step D after the step C: the RN-MME sending a UE context release command message to the source DeNB, the message comprising identifiers of all UEs served by the moving RN; after receiving the UE context release command message, the source DeNB releasing context information of the moving RN and context information of all UEs served by the moving RN.

After the step D, the method further comprises: establishing an S1 interface between the moving RN and the destination DeNB, maintaining the context information of all UEs served by the moving RN unchanged.

after an X2 switching is finished, the method further comprises:

for each UE served by the moving RN, the destination DeNB sending the identifier of the UE and the new identifier of the UE on the S1 interface assigned by the destination DeNB to a UE-MME serving for the UE, to update UE information stored on the UE-MME;

the UE-MME sending the identity of the UE, the new identifier of the UE on the S1 interface assigned by the destination DeNB, the new identifier of the UE on the S1 interface assigned by the UE-MME, to update information of the UE stored on the RN-GW;

the UE-MME sending the new identifier of the UE on the S1 interface assigned by the UE-MME to the destination DeNB.

the switching request message in the step A further comprises information when the moving RN is taken as the UE, the information comprising an old identifier of the moving RN on the source DeNB and upstream tunnel information assigned for the moving RN by the RN-GW;

the switching response message in the step B further comprises the old identity of the moving RN on source DeNB, the new identifier of the moving RN on destination DeNB, and downstream tunnel information assigned for the moving RN by the destination DeNB;

when sending the UE information to the RN-GW via the RN-MME by the destination DeNB, sending downstream tunnel information assigned by the destination DeNB for the moving RN to the RN-GW via the RN-MME, and sending the new identity of the moving RN on the destination DeNB to the RN-MME.

A method for establishing a tunnel between a DeNB of a moving RN and the moving RN, after the moving RN switches to a new DeNB, comprising:

A. the moving RN sending a S1 establishing request messageto the DeNB, the message comprising a new identifieron a S1 interface of each UE assigned by theDeNB when the switching is performed, current context information of each UE;

B. the DeNB sending a S1 establishing response message to the moving RN, the message comprising a new identifier on the S1 interface of each UE and upstream tunnel information assigned by the DeNB.

The S1 establishing request message in step A further comprises a station identifier of the moving RN and supported TAI information

the S1 establishing response message in step B comprises the new identifier of each UE on the S1 interface and the upstream tunnel information assigned by the destination DeNB.

A method for establishing a tunnel between a DeNB of a moving RN and a gateway of the moving RN, after the moving RN switches to a new DeNB, comprising:

A. the DeNB sending downstream tunnel information and a new identifierof a UE on the S1 interface assigned by the DeNB when the switching is performed to the gatewayof the moving RN (RN-GW) via a MME of the UE (UE-MME); the UE being each UE served by the moving RN;

B. the RN-GW sending upstream tunnel information assigned for the UE by the RN-GW to the DeNB via the UE-MME.

the step A comprises: the DeNB sending a path switching request message to the UE-MME, the UE-MME sending a changing bear request message to the RN-GW; the path switching request message and the changing bear request message comprises a new identifier of each UE on the S1 interface and downstream tunnel information assigned by the DeNB;

the step B comprises: the RN-GW sending a changing bear response message to the UE-MME, the UE-MME sending a path switching request acknowledgement message to the DeNB; the changing bear response message and the path switching request acknowledgement message comprises upstream tunnel information assigned for the UE by the RN-GW.

the changingbear request message in the step A furthercomprises a new identifierof the UE on the S1 interface assigned by the UE-MME;

The path switching request acknowledgement message further comprises a new identifier of the UE on the S1 interface assigned by the UE-MME.

when the moving RN switches to the DeNB via the S1, before the S1 switching is finished, the method further comprises:

carrying informationwhen the RN is taken as the UE in a switching need message sent by a source DeNB to a RN-MME serving the moving RN, the information comprising an old identifier of the moving RN on the S1 interface between the DeNB and the RN-MME;

carrying a new identifier of the moving RN on the S1 interface assigned by the RN-MME and upstream tunnel information assigned for the moving RN by the RN-GW in a switching request message sent by the RN-MME to the DeNB;

carrying the new identity of the moving RN on the S1 interface assigned by the RN-MME, the new identity of the moving RN on the S1 interface and downstream tunnel information assigned by the DeNB, in a switching response message sent by the DeNB to the RN-MME;

carrying a new identifier of the moving RN on the S1 interface, a new identifier of the moving RN on the S1 interface assigned by the DeNB in the switching command message sent by the RN-MME to the source DeNB;

carrying downstreamtunnel information assigned for the moving RN by the DeNB in the changing bear request message sent by the RN-MME to the RN-GW.

When the moving RN switches to the DeNB via the X2 switching, before the X2 switching is finished, the method further comprises:

carrying informationwhen the RN is taken as the UE in the switching request message sent by a source DeNB to the DeNB, the information comprising an old identifier of the moving RN on the source DeNB and upstream tunnel information assigned for the moving RN by the RN-GW;

carrying the old identity of the moving RN on the source DeNB, the new identity of the moving RN on the DeNB and upstream tunnel information assigned for the moving RN accepted by the DeNB in the switching response message sent by the DeNB to the source DeNB;

carrying downstreamtunnel information assigned for the moving RN by the DeNB in the path switching messagesent by the DeNB to the RN-MME and the changingbear request messagesent by the RN-MME to the RN-GW; carrying a new identifier of the moving RN on the DeNB in the path switching message.

As can be seen from the above technical solutions of the present invention, in the switching procedure of S1 or X2 or after the switching is finished, the tunnel between the destination DeNB of the moving RN and the gateway serving the RN is established; after the switching is finished and the S1 interface is established, the tunnel between the moving RN and the destination DeNB is established. By using the method for establishing the user plane, the user plane is established when the RN moves to the new DeNB, and the switching procedure is transparent to the UE and the data is transmitted continually.

Figure 1 is a schematic diagram illustrating the structure of a LTE supporting a RN in the prior art.

Figure 2 is a flowchart illustrating a simplified procedure of attachment of a RN in the prior art.

Figure 3 is a flowchart illustrating a work principle according to a first embodiment of the present invention.

Figure 4 is a flowchart illustrating a work principle according to a second embodiment of the present invention.

Figure 5 is a flowchart illustrating a work principle according to a third embodiment of the present invention.

Figure 6 is a flowchart illustrating a work principle according to a fourth embodiment of the present invention.

Figure 7 is a flowchart illustrating a procedure of switching to a destination DeNB by a RN via S1 according to a first embodiment of the present invention.

Figure 8 is a flowchart illustrating a procedure of switching to a destination DeNB by a RN via S1 according to a second embodiment of the present invention.

Figure 9 is a flowchart illustrating a procedure of switching to a destination DeNB by a RN via X1 according to a third embodiment of the present invention.

Figure 10 is a flowchart illustrating a procedure of switching to a destination DeNB by a RN via X1 according to a fourth embodiment of the present invention.

The present invention is hereinafter further described in detail with reference to the accompanying drawings as well as embodiments so as to make the objective, technical solution and merits thereof clearer.

The present invention provides a method for establishing a user plane after a moving RN switches to a destination DeNB. The user plane includes a user plane of the RN and a user plane of anUE served by the RN. The user plane may be established in the procedure of S1 switching or X2 switching, or established after the moving RN finishes the switching.

In addition, the present invention also provides a method for establishing a tunnel for transmitting UE data between the moving RN and the DeNB of the moving RN, and the procedure may be implemented when the S1 interface is established. The methods of the present invention will be described in detail hereinafter.

The user plane includes three tunnels which are respectively located between the UE-GW and the RN-GW, between the RN-GW and the DeNB and between the DeNB and the RN. The tunnel between the UE-GW and the RN-GW does not change in the switching procedure, so as to ensure that the switchingprocedure of the RN is transparent to the UE. Figure 3 is a flowchart illustrating a method for establishing a tunnel between a DeNB and a RN-GW in a S1 switching procedure. In the method, when switching to the destination DeNB, the RN initiates an S1 switching procedure, and a switching need message carries identifier information and bear information etc. of an S1 interface of the UE, so as to establish a tunnel between the RN and the SGW/PGW of the RN (call as RN-GW hereinafter) for transmitting data of the UE. As shown in Figure 3, the procedure includes the following operations.

In block 301, a source DeNB sends a switching need message to an MME, the message includes information of a RN and information of each UE served by the RN. Specifically, the information of the UE includes an identifier of the UE and upstream tunnel information assigned by the RN GW.

In block 302, the MME sends a switching request message to the destination DeNB, the message includes the information of the RN and the information of the UE served by the RN. Specifically, the information of the UE includes the identifier of the UE and the upstream tunnel information assigned by the RN GW.

In block 303, the destination DeNB sends a switching response message to the MME, the message includes the information of the RN and the information of the UE. Specifically, the information of the UE includes an identifier of the UE on the S1 interface and downstream tunnel information assigned by the T-DeNB.

In block 304, the MME or the destination DeNB sends the information of the RN and the information of the UE to the RN-GW. The information of the UE includes a new identifier on the S1 interface and downstream tunnel information assigned by the destination DeNB for the UE.

It should be noted that,the tunnel between the DeNB and RN-GW may be established after the S1 switching. In this case, in the procedure of the S1 switching, only identifier information of the UE and context information of the UE are transmitted to the T-DeNB.

Figure 4 is a flowchart illustrating a method for establishing a tunnel between a DeNB and a RN-GW in the X2 switching procedure. In the method, when switching to a destination DeNB, the RN initiates an X2 switching procedure, and a switching request message carries identifier information and bear information etc. of an S1 interface of the UE, so as to establish a tunnel between the RN and the SGW/PGW of the RN for transmitting data of the UE. As shown in Figure 4, the procedure includes the following operations.

In block 401, a source DeNB sends a switching request message to a destination DeNB, the message includes information of a RN and information of UE served by the RN. Specifically, the information of the UE includes an identifier of the UE and upstream tunnel information assigned by the RN GW.

In block 402, the destination DeNB sends a switching response message to the source DeNB, the message includes the information of the RN and the information of the UE served by the RN. Specifically, the information of the UE includes downstream tunnel information and a new identifier of each UE served by the RN assigned by the destination DeNB.

In block 403, the destination DeNB sends a message to the MME, and the MME sends a message to the RN-GW. The message includes the information of the UE. Specifically, the information of the UE includes a new identifier of the UE on the S1 interface, and downstream tunnel information assigned by the destination DeNB.

In block 404, the RN-GW sends a message to the MME, and the MME sends a message to the destination DeNB. The message includes information of the UE. Specifically, the information of the UE includes the new identifier of the UE on the S1 interface, and upstream tunnel information assigned by a destination RN-GW.

It should be noted that, the tunnel between the DeNB and RN-GW may be established after the switching. In this case, in the procedure of the x2 switching, only the identifier information of the UE and the context information of the UE are transmitted to the T-DeNB. In addition, the context information of the UE may not be transmittedin the switching procedure, and may be transmitted to the T-DeNB in the procedure shown in Figure 6. If the context information of the UE is transmitted to the T-DeNB in the RN switching procedure, the context information of the UE is not needed to be transmitted by the RN to the T-DeNB in the procedure shown in Figure 6.

Figure 5 is a flowchart illustrating a method for establishing a tunnel between a DeNB and a RN-GW after the S1 or X2 switching procedure. In the method, when switching to the destination DeNB, the RN initiates a S1 or X2 switching procedure. After the switching is finished, a tunnel between the T-DeNB and the SGW/PGW of the RN is established for transmitting data of the UE. As shown in Figure 5, the procedure includes the following operations.

In block 501, a DeNB sends a message to an UE-MME, and the UE-MME sends a message to the RN-GW. The message includes a new identifier on the S1 interface assigned by the DeNB for the UE, downstream tunnel information assigned by the DeNB for the UE. The UE refers to the UE served by the moving RN.

In block 502, the RN-GW sends a message to the UE-MME, and the UE-MME sends a message to the DeNB. The message includes upstream tunnel information assigned by the RN-GW for the UE. The tunnel between the RN-GW and the DeNB is established.

After the processing in Figures 3 to 5, the destination DeNB assigns the new S1 interface identifier and downstream tunnel information for the UE served by the RN, and notifies the RN-GW. In addition, the destination DeNB obtains the upstream tunnel information assigned for the UE by the RN-GW previously via the source DeNB and RN-MME, and thus the tunnel for transmitting the UE data is established between the destination DeNB and RN-GW.

Figure 6 is a flowchart illustrating a method for establishing a S1 interface between a DeNB and a RN after the S1 or X2 switching procedure. In the method, when switching to the destination DeNB, the RN initiates a S1 or X2 switching procedure. After the switching is finished, a S1 interface between the DeNB and the RN is established, and tunnel information between the DeNB and the moving RN is transmitted. As shown in Figure 6, the procedure includes the following operations.

In block 601, the RN sends a S1 establishing request message to a destination DeNB, the message includes information of each UE served by the RN. The information of the UE includes current context information and a new identifier on S1 interface assigned by the DeNB for the UE when the switching is performed.

In block 602, the DeNB sends a S1 establishing response message to the RN. The message includes the information of each UE served by the RN. Specifically, the information of the UE includes an identifier of the UE on the S1 interface, context information of the UE, such as bear information.

Based on the procedure shown in Figure 6, tunnel information between the RN and the DeNB is transmitted when the S1 interface is established, to transmit UE data between the RN and the DeNB.

The first embodiment is provided.

In the first embodiment, a RN switches to a destination DeNB via a S1 interface. The S/P GW of the RN is unchanged. In the RN switching procedure, a tunnel for transmitting data is to be established for the UE between the T-DeNB and the S/PGW of the RN. When the RN switches to the destination DeNB, the MME served by the RN may also switch to the new MME. In the first embodiment, the MME served by the RN (RN-MME) is unchanged. If the RN-MME is changed, the information transmission between a source MME and a destination MME is involved. In Figure 7, the message transmitted between the source MME and the destination MME is omitted.

In block 701, the RN measures wireless environment around the RN, and sends a measurement report to a served DeNB (S-DeNB shown in the Figure). According to the measurement report, the S-DeNB decides to switch the RN to a destination DeNB with better signal quality (T-DeNB shown in the Figure).

In block 702, the S-DeNB sends a switching need message to the served MME of the RN, i.e. the RN-MME in the figure. The switching need message includes conventional information when the RN is regarded as the UE. The conventional information includes:

- An old identifier of the RN on the S1 interface between the S-DeNB and the RN-MME: eNB UE S1 AP ID, MME UE S1 AP ID；

- A switching type, which is a switching type of the moving RN;

- A destination address of the switching, which is an identifier of a destination T-DeNB of the switching, and is used by the MME for finding out the T-DeNB;

- Container of transparent transmission from the source to the destination.

The switching need message also includes information of an UE served by the RN, and the information is used to establish, for the UE, a tunnel for transmittingdata between a gateway of the RN (SGW and PGW) and the T-DeNB. The information of the UE includes an identifier of the UE and tunnel information (the information of the UE may include one of, parts of or all of the following information):

- A old identifier of the UE on the S1 interface between the S-DeNB and the UE-MME: eNB UE S1 AP ID, MME UE S1 AP ID；

- An identifier of the UE, e.g. a temporary identifier of the UE, S-TMSI;

- E-RAB information of the UE, e.g. an E-RAB identifier, upstream TEID and a transmission address assigned by the RN-GW, Qos information;

- Context information of the UE, e.g. an encryption capability of the UE, access-layer capability information, maximum rate on the S1 interface of the UE, RRC context, a switching limit list, location report information.

The identity of the UE may be an old identity of the UE before the RN performs the switching, or at least one of the above identifiers, which is used to identify the UE. Usually, the old identity of the UE in the messages sent subsequentlyis the same as the identity of the UE in this step. In addition, the S1 interface identifier of the UE includes an S1 interface identifier assigned by the DeNB, eNB UE S1 AP ID, and an S1 interface identifier assigned by the MME, MME UES1 AP ID; the S1 interface identifiers when the RN is taken as the UE also includes the above two types. In the switching procedure, the new identifier on the S1 interface assigned by the destination DeNB for the RN and UE is new eNB UE S1 AP ID, the new identifier on the S1 interface assigned by the RN-MME for the RN is new MME UE S1 AP ID, the new identifier on the S1 interface assigned by the MME serving for the UE (UE-MME) for the UE is new MME UE S1 AP ID.

In block 703, the RN-MME sends a switching request to the T-DeNB, the message includes conventional information when the RN is taken as the UE. If the RN-MME changes, the old MME needs to forward the message to the destination MME. The procedure of transmitting messages between the two MMEs is omitted. The conventional information when the RN is taken as the UE includes:

- A new identifier of the RN on the S1 interface between the T-DeNB and the RN-MME: new MME UE S1 AP ID. If the RN-MME is unchanged, the identifier may be reused as an identifier assigned by the MME for the UE on the old S1 interface, if the MME is changed, a new UE identifier is assigned by a new MME.

- A switching type, which is a switching type of a moving RN;

- Container of transparent transmission from the source to the destination.

- A list of E-RAB information to be established, e.g. an E-RAB identifier, a transmission layer address and upstream TEID assigned by the RN-GW, Qos information.

- The switching request message also includes information of an UE served by the RN, and the information is used to establish, for the UE, a tunnel for transmittingdata between the gateway of the RN (SGW and PGW, RN-GW in the Figure) and the T-DeNB. The information of the UE includes an identifier of the UE and tunnel information:

- A old identifier ofthe UE on the S1 interface between the S-DeNB and the UE-MME: MME UE S1 AP ID; eNB UE S1 AP ID (one of the identifiers may be included)；

- An identifier of the UE, e.g. a temporary identifier of the UE, S-TMSI;

- A list of E-RAB information of the UE, e.g. an E-RAB identifier, upstream TEID and a transmission address assigned by the RN-GW, Qos information.

Based on the above blocks, the T-DeNB can receive the upstream tunnel information assigned by the RN-GW before the moving RN performs the switching.

In block 704, the T-DeNB sends a switching response message to the RN-MME, the message includes the conventional information when the RN is taken as the UE. The conventional information includes:

- A new identifier of the RN on the S1 interface between the T-DeNB and the RN-MME: new MME UE S1 AP ID, new eNB UE S1 AP ID;

- Container of transparent transmission from the source to the destination;

A list of E-RAB information established successfully, which includes E-RAB information, e.g. an E-RAB identifier, a transmission layer address and downstream TEID assigned by the T-DeNB.

The switching response message also includes information of an UE served by the RN, and the information is used to establish, for the UE, a tunnel for transmitting data between the gateway of the RN (SGW and PGW) and the T-DeNB. The information of the UE includes a new identifier of the UE on the S1 interface and tunnel information (the information of the UE may include one of, parts of or all of the following information):

- A new identifier of the UE in the S1 interface between the T-DeNB and the UE-MME: new eNB UE S1 AP ID;

- A old identifier of the UE on the S1 interface between the S-DeNB and the UE-MME: MME UE S1 AP ID, eNB UE S1 AP ID；

- An identifier of the UE, e.g. a temporary identifier of the UE, S-TMSI (only one of the MME UE S1 AP ID, eNB UE S1 AP ID and the identifier of the UE may be included, to identify the UE by the RN-MME);

A list of E-RAB information of the UE including information of the E-RAB, e.g. an E-RAB identifier, downstream TEID and a transmission address assigned by the T-DeNB.

Based on the block, the RN-MME can receive the downstream tunnel information and the new S1 interface identifier assigned by the T-DeNB for the UE.

In block 705, the RN-MME sends a switching commandmessage to the S-DeNB. The message includes the conventional information when the RN is taken as the UE. The conventional information includes:

- Container of transparent transmission from the source to the destination;

- A switching type, which is a switching type of a moving RN.

In block 706, the S-DeNB sends a RRC message switching command to the RN, to make the RN switch to a destination cell on the destination DeNB. The message is the same as the conventional RRC message and is not described herein.

In block 707, the RN synchronizes with the destination cell, and sendsan upstream RRC message switching finish message to the destination DeNB. The message is the same as the conventional RRC message and is not described herein.

In block 708, the destination DeNB sends a path switching message to the RN-MME. The message includes conventional information when the RN is regarded as the UE. The conventional information includes:

- A new identifier of the RN on the S1 interface between the T-DeNB and the RN-MME: MME UE S1 AP ID, eNB UE S1 AP ID;

- An identifier of the destination cell;

- Destination TAI;

In block 709, the RN-MME sends a changing bear request message to the gateway of the RN (SGW and PGW).

- The message includes conventional information when the RN is regarded as the UE. The conventional information includes:

- A list of E-RAB information of the RN, which includes E-RAB information, e.g. an E-RAB identifier, a transmission layer address and downstream TEID assigned by the T-DeNB.

The changing bear request message also includes information of an UE served by the RN. The information of the UE includes (one of, parts of or all of the following information):

- A old identifier of the UE on the S1 interface between the S-DeNB and the UE-MME: MME UE S1 AP ID; eNB UE S1 AP ID；

- A new identifier of the UE on the S1 interface between the T-DeNB and the UE-MME: MME UE S1 AP ID, eNB UE S1 AP ID;

- An identifier of the UE, e.g. a temporary identifier of the UE, S-TMSI;

E-RAB information of the UE, e.g. an E-RAB identifier, a transmission layer address and downstream TEID assigned by the T-DeNB.

Based on the block, the RN-MME can send the RN-GW the downstream tunnel information assigned by the T-DeNB for the UE which is received in the block 704.

Or, the block 709 may be replaced by the following steps:

The first step: the RN-MME sends a changing bear request message to the gateway of the RN (SGW and PGW). The message includes conventional information when the RN is regarded as the UE. The conventional information includes:

- A list of E-RAB information of the RN, which includes E-RAB information, e.g. an E-RAB identifier, downstream TEID assigned by the T-DeNB and a transmission layer address.

The second step: the T-DeNB sends a path update message to RN-GW. The message includes information of the UE served by the RN. The information of the UE includes (one of, parts of or all of the following information):

- A new identifier of the UE on the S1 interface between the T-DeNB and the UE-MME: new eNB UE S1 AP ID;

- An identifier of the UE, e.g. a temporary identifier of the UE, S-TMSI;

- E-RAB information of the UE, e.g. an E-RAB identifier, a transmission layer address and downstream TEID assigned by the T-DeNB.

In block 710, the gateway of RN (SGW and PGW) sends a changing bear response message to the RN-MME. The message includes information of RN and information of the UE served by the RN:

- A list of E-RAB information of the RN including information of the E-RAB, e.g. an E-RAB identifier, upstream TEID assigned by the RN-GW, and a transmission address.

- A old identifier of the UE in the S1 interface between the S-DeNB and the UE-MME: MME UE S1 AP ID; eNB UE S1 AP ID；

- An identifier of the UE, e.g. a temporary identifier of the UE, S-TMSI;

- E-RAB information of the UE, e.g. an E-RAB identifier, upstream TEID assigned by the RN-GW, and a transmission layer address.

Similar with block 709, if the block 709 is implemented by using two messages, the block 710 may be implemented by two response messages.

The first response message: the gateway of RN (SGW and PGW) sends a changing bear response message to the RN-MME. The message includes information of RN.

The second response message: the gateway of RN (SGW and PGW) sends a path update response message to the T-DeNB. The message includes information of the UE served by the RN:

- An identifier of the UE, e.g. a temporary identifier of the UE, S-TMSI;

- E-RAB information of the UE, e.g. an E-RAB identifier, a transmission layer address and upstream TEID assigned by the RN-GW.

Thus, the information of upstream and downstream tunnels between the T-DeNB and RN-GW is transmitted, and the tunnel may be established.

In block 711, the RN-MME sends a UE context release command message to the S-DeNB, so as to release context information which is stored in the S-DeNB and relates to the RN and the UE of the RN. The message includes the old identifierof the UE on the S1 interface eNB S1 AP ID and MME S1 AP ID, or only includes MME S1 APID. The message also includes a release reason. The difference between the message and the message defined currently includes that: the message can include context information of multiple UEs, via including identifiers on the S1 interface of one group of UEs in the message.

In block 712, the S-DeNB sends a UE context release finish message to the RN-MME.

In block 713, a S1 interface is to be established between the RN and T-DeNB. After the switching, the T-DeNB becomes the new DeNB of the RN, which is still called as the T-DeNB for concise description. The RN sends a S1 establishing request message to the T-DeNB. The message includes a station identifier of the RN, TAI supported by the RN. The message also includes information of UE of the RN. The information of the UE includes:

- information of the GUMMEI served by the UE;

- An old identifier of the UE on the S1 interface between the S-DeNB and the RN: eNB UE S1 AP ID；

- An old identifier of the UE on the S1 interface between the S-DeNB and the UE-MME: MME UE S1 AP ID;

- Other information, e.g. history information of the UE, activation information.

The information of the UE served by the RN may be sent to the T-DeNB via a single message after the S1 is established.

In block 714, the T-DeNB sends a S1 establishing response message. The message includes information should be sent to the RN by the T-DeNB as the MME:

- A served GUMMEI information list, the GUMMEI information includes a PLMN identifier, a MME group identifier and a MME code.

- An indication indicating MME supporting RN.

- Capability information of the MME.

The S1 establishing response message also includes information related to the UE served by the RN, which includes:

- A new identifier of the UE on the S1 interface between the T-DeNB and the RN: new eNB UE S1 AP ID, new MME UE S1 AP ID;

- A list of E-RAB information of the UE including information of the E-RAB, e.g. an E-RAB identifier, a transmission layer address and upstream TEID assigned by the T-DeNB.

Similar with block 614, the information of the UE served by the RN may be sent to the T-DeNB via a single message after the S1 is established.

Thus, the S1 interface is established, and in the establishing procedure, the tunnel information between the RN and T-DeNB is transmitted. Or the tunnel information between the RN and T-DeNB may be transmitted after the S1 interface is established.

Afterwards, the UE identifier on the UE-MME and RN-GW is updated.

In block 715, T-DeNB finds out the served MME of the UE, and sends a message to update the UE information stored in the served MME. The message includes:

- An old identifier of the UE on the S1 interface between the S-DeNB and the MME: MME UE S1 AP ID, eNB UE S1 AP ID；

- A new identifier of the UE in the S1 interface between the T-DeNB and the MME: new eNB UE S1 AP ID;

In block 716, the served MME of the UE sends a message to the T-DeNB to update the UE identifier. The message may include information of a group of UEs, and the information of one UE includes:

- A new identifier of the UE on the S1 interface between the T-DeNB and the MME: new eNB UE S1 AP ID, new MME UE S1 AP ID;

- Encryption information.

In the block 717, the UE identifier stored in the RN-GW is updated, which may be implemented by the following methods:

The first method, the T-DeNB sends an information update message to the RN-GW, the message includes:

- A new identifier of the UE on the S1 interface between the T-DeNB and the MME: new MME UE S1 AP ID, new eNB UE S1 AP ID;

The second method, the UE-MME sends an information update message to the RN-GW, the message includes:

- A new identifier of the UE on the S1 interface between the T-DeNB and the MME: new eNB UE S1 AP ID.

In the above procedure, the message may includes the old identifieron the S1 interface of the UE (MME UE S1 AP ID, eNB UE S1 AP ID) and/or the unique identifier of the UE (e.g. the temporary identifier of the UE), which are called as the identifier of the UE and are used to identify the corresponding UE. Specifically, one of or any combination of the above identifiers may be included in the message, but generally, the UE identifier transmittedbetween the entities should be identical.

The second embodiment is provided.

In the second embodiment, a RN switches to a destination DeNB via a S1 interface. The S/P GW of the RN is unchanged. In the RN switching procedure, a tunnel for transmitting data is to be established for the UE between the T-DeNB and the S/PGW of the RN, and a tunnel for transmitting data is to be established between the RN and the T-DeNB. When the RN switches to the destination DeNB, the MME served by the RN may also switch to the new MME. In the second embodiment, the MME served by the RN is unchanged. If the RN-MME is changed, the information transmission between a source MME and a destination MME is involved. In Figure 8, the message transmitted between the source MME and the destination MME is omitted.

In block 801, the RN measures wireless environment around the RN, and sends a measurement report to a served DeNB (the S-DeNB shown in the Figure). According to the measurement report, the DeNB decides to switch the RN to a destination DeNB with better signal quality (T-DeNB shown in the Figure).

In block 802, the S-DeNB sends a switching need message to the served MME of the RN, i.e. the RN-MME in the figure. The switching need message includes conventional information when the RN is regarded as the UE. The conventional information includes:

- An old identifier on the S1 interface of the RN between the S-DeNB and the RN-MME: eNB UE S1 AP ID, MME UE S1 AP ID；

- A switching type, which is a switching type of the moving RN;

- A destination address of the switching, which is an identifier of a destination T-DeNB of the switching, and is used by the MME to find out the T-DeNB;

- Container of transparent transmission from the source to the destination.

The switching need message also includes information of an UE served by the RN, and the information of the UE served by the RN needs to be switched to the destination DeNB in the switching procedure, and may include information of the multiple UEs. The information of each UE includes (the information of the UE may include one of, parts of or all of the following information):

- An identifier on the S1 interface of the UE between the S-DeNB and the UE-MME: eNB UE S1 AP ID, MME UE S1 AP ID；

- Context information of the UE, e.g. an encryption capability of the UE, access-layer capability information, maximum rate of the UE on the S1 interface, E-RAB information to be established, RRC context, a switching limit list, location report information.

In block 803, the RN-MME sends a switching request to the T-DeNB, the message includes conventional information when the RN is taken as the UE. If the RN-MME changes, the old MME needs to forward the message to the destination MME. The procedure of transmitting messages between the two MMEs is omitted. The conventional information when the RN is taken as the UE includes:

- A new identifier of the RN on the S1 interface between the T-DeNB and the RN-MME: new MME UE S1 AP ID. If the RN-MME is unchanged, the identifier may be reused as an identifier assigned by the MME for the UE in the old S1 interface, if the MME is changed, a new UE identifier is assigned by the new MME.

- A switching type, which is a switching type of the moving RN;

- Container of transparent transmission from the source to the destination.

The switching request message also includes information of an UE served by the RN, and the information of the UE served by the RN needs to be switched to the destination DeNB in the switching procedure, and may include information of the multiple UEs. The information of each UE includes (the information of the UE may include one of, parts of or all of the following information):

- An identifier on the S1 interface of the UE between the S-DeNB and the UE-MME: eNB UE S1 AP ID; MME UE S1 AP ID；

- Other information, such as, history information of the UE, activation information.

In block 804, the T-DeNB sends a switching response message to the RN-MME, and the message includes the conventional information when the RN is taken as the UE. The conventional information includes:

- Container of transparent transmission from the source to the destination;

In block 805, the RN-MME sends a switching command message to the S-DeNB. The message includes the conventional information when the RN is taken as the UE. The conventional information includes:

- Container of transparent transmission from the source to the destination;

- A switching type, which is a switching type of the moving RN.

In block 806, the S-DeNB sends a RRC message switching command message to the RN, to make the RN switch to a destination cell on the destination DeNB. Themessage is the same as the conventional RRC message and is not described herein.

In block 807, the RN synchronizes with the destination cell, and sends an upstream RRC message switching finish message to the destination DeNB. The message is the same as the conventional RRC message and is not described herein.

In block 808, the destination DeNB sends a path switching message to the RN-MME. The message includes conventional information when the RN is regarded as the UE. The conventional information includes:

- An identifier of the destination cell;

- Destination TAI;

In block 809, the RN-MME sends a changing bear request message to the gateway of the RN (SGW and PGW). The message includes conventional information when the RN is regarded as the UE. The conventional information includes:

- A list of E-RAB information of the RN, which includes E-RAB information, e.g. an E-RAB identifier, downstream TEID assigned by the T-DeNB, and a transmission layer address.

In block 810, the gateway of RN (SGW and PGW) sends a changing bear response message to the RN-MME. The message includes conventional information when the RN is regarded as the UE. The conventional information includes:

- A list of E-RAB information of the RN, including information of the E-RAB, e.g. an E-RAB identifier, upstream TEID assigned by the RN SGW, a transmission address.

In block 811, the RN-MME sends a UE context release command to the S-DeNB, so as to release context information which relates to the RN and is stored in the S-DeNB. The message includes the identifierof the RN and a release reason. In block 812, the S-DeNB sends a UE context release finish message to the RN-MME.

Afterthe block 812, the switching procedure when the RN is regarded as the UE is finished. In the above blocks, tunnel information for transmittingthe RN data and radio bear information of the Un interface between the RN and the DeNB are created between the T-DeNB and the RN-GW. But the tunnel information for transmitting the UE user data is not created, and the tunnel information of the UE is transmitted after the switching is finished.

In block 813, a S1 interface is to be established between the RN and T-DeNB. After the switching, the T-DeNB becomes the new DeNB of the RN, which is still called as the T-DeNB for concise description. The RN sends a S1 establishing request messageto the T-DeNB. The message includes a station identifier of the RN, TAI supported by the RN. The message also includes information of UE served by the RN. The information of the UE includes (one of, parts of or all of the following information):A old identifierof the UE on the S1 interface between the S-DeNB and the RN: MME UE S1 AP ID, eNB UE S1 AP ID；

- A new identifier of the UE on the S1 interface between the T-DeNB and the RN: new eNB UE S1 AP ID;GUMMEI information served by the UE;

- An old identifier of the UE on the S1 interface between the S-DeNB and the UE-MME: MME UE S1 AP ID, eNB UE S1 AP ID;

- Identifier of the UE, such as S-TMSI;

The information of the UE above the RN may be sent to the T-DeNB via a single message after the S1 is established.

In block 814, T-DeNB sends a S1 establishing response message. The message includes information should be sent to the RN by the T-DeNB as the MME:

- An indication indicating the MME supporting the RN.

- Capability information of the MME.

The S1 establishing response message also includes information related to the UE served by the RN which includes:

- A new identifier of the RN on the S1 interface between the T-DeNB and the RN: new eNB UE S1 AP ID, new MME UE S1 AP ID;

- A list of E-RAB information of the UE, which includes E-RAB information, e.g. the identifier of the E-RAB, a transmission layer address and upstream TEID assigned by the T-DeNB.

Thus, the S1 interface is established, and in the establishing procedure, the tunnel information between the RN and T-DeNB is transmitted. Similarly, the information of the UE may be transmitted to the RN via a single response message after the S1 interface is established.

It should be noted that, the

blocks

813 and 814 may be taken as a single processing and used with other methods, and are not limited to be combined with the blocks in the embodiment.

In block 815: T-DeNB finds out the served MME of the UE, and sends a path switching request message to update the UE information stored in the served MME. The message includes:

- An old identifier of the UE on the S1 interface between the S-DeNB and the MME: eNB UE S1 AP ID, MME UE S1 AP ID；

- A new identifier of the UE on the S1 interface between the T-DeNB and the MME: new eNB UE S1 AP ID;

- A list of E-RAB information of the UE, which includes E-RAB information, e.g. an E-RAB identifier, downstream TEID assigned by the T-DeNB, and a transmission layer address;

- The address of the RN GW.

In block 816, the UE-MME sends a changing bear request message or establishing bear request message to the gateway of the RN. The message may include information of a group of UEs, and the information of one UE includes:

- The identifier of the UE, e.g. the S-TIMSI of the UE;

- The identifier of the UE on the S1 interface between the S-DeNB and UE-MME: new eNB S1 AP ID, MME S1 AP ID;

- A list of E-RAB information to be established, which includes E-RAB information, e.g. an E-RAB identifier, downstream TEID assigned by the T-DeNB, and a transmission layer address.

In block 817, the gateway of the RN sends a changing bear response message to the UE-MME. The message includes information of a group of UEs, and the information of one UE includes:

- The identifier of the UE, e.g. the S-TIMSI of the UE;

- The identifier of the UE on the S1 interface between the S-DeNB and UE-MME: eNB S1 AP ID, MME S1 AP ID;

- A new identifier of the UE on the S1 interface between the T-DeNB and the MME: new eNB UE S1 AP ID, new MME S1 AP ID;

- A list of E-RAB information to be established, which includes E-RAB information, e.g. an E-RAB identifier, upstream TEID assigned by the RN-GW, and a transmission layer address.

In block 818, the UE-MME sends a response message to the T-DeNB. The message includes:

- encryptation information;

A list of E-RAB information of the UE, which includes E-RAB information, e.g. an E-RAB identifier, upstream TEID assigned by the RN GW, and a transmission layer address.

In the blocks 815-818, the tunnel information of the UE between the T-DeNB and RN-GW is transmitted, and thus the tunnel between the T-DeNB and RN-GW is established for transmitting UE information.

Similar with the first embodiment, in the above procedure, the message may includes the old identifier on the S1 interface of the UE (MME UE S1 AP ID, eNB UE S1 AP ID) and/or the unique identifier of the UE (e.g. the temporary identifier of the UE), which are all called as the identifier of the UE and are used to identify the corresponding UE. Specifically, one of or any combination of the above identifiers may be included in the message, but generally, the UE identifier transmitted between the entities should be identical.

The third embodiment is provided.

Figure 9 is a flowchart illustrating a procedure of switching to a destination DeNB by a RN via X2 according to a third embodiment of the present invention. The S/P GW of the RN is unchanged. In the RN switching procedure, a tunnel for transmittingdata is to be established for the UE between the T-DeNB and the S/PGW of the RN.

In block 901, the RN measures wireless environment around the RN, and sends a measurement report to a served DeNB (the S-DeNB shown in the Figure). According to the measurement report, the DeNB decides to switch the RN to a destination DeNB with better signal quality (T-DeNB shown in the Figure), the X2 interface is already established between the S-DeNB and T-DeNB, and the S-DeNB initiates an X2 switching. In block 902, the S-DeNB sends a switching request message to the T-DeNB. The switching request message includes conventional information when the RN is regarded as the UE. The conventional information includes:

- An old identifier of the RN on the S-DeNB: old eNB UE X2 AP ID；

- A switching reason, which is a switching reason of the moving RN;

- A destination address of the switching, which is an identifier of the switching destination cell;

- The identity GUMMEI of the MME;

- RRC context;

- E-RAB information to be established, e.g. an E-RAB identifier, a transmission layer address and upstream TEID assigned by the RN-GW, Qos information.

The switching request message also includes information of an UE served by the RN. The information of the UE may be transmitted by a single switching request message. The message includes information of one or multiple UEs which is used to establish a tunnel for transmittingdata for the UE between the gateway of the RN (SGW and PGW) and the T-DeNB. The information of the UE includes an identifier of the UE and tunnel information (the information of the UE may include one of, parts of or all of the following information):

- An old identifier of the UE on the S1 interface between the S-DeNB and the UE-MME: eNB UE S1 AP ID, MME UE S1 AP ID；

- An old identifier of the UE on the S-DeNB: old eNB UE X2 AP ID；

- The identity GUMMEI of the MME of the UE;

- E-RAB information of the UE, e.g. an E-RAB identifier, a transmission layer address and upstream TEID assigned by the RN-GW, Qos information.

Context information of the UE, e.g. an encryption capability of the UE, access-layer capability information, maximum rate on the S1 interface of the UE, RRC context, a switching limit list, location report information;

The identifier of the UE is the old identifier of the UE before the RN switches. In the embodiment, the old identifier of the UE may be the old identifier on the S1 interface eNB UE S1 AP ID, MME UE S1 AP ID, old identifier of the UE on the S-DeNB old eNB UE X2 AP ID. Specifically, one of or any combination of the above identifiers may be included in the message, in general, the UE old identifier in the messages sent subsequently is identical with the UE identifier of the block. In block 903, the T-DeNB sends a switching response message to the S-DeNB, the message includes conventional information when the RN is taken as the UE, and theconventional information includes:

- A new identifier of the RN on the T-DeNB: new eNB UE X2 AP ID；

- An old identifier of the RN on the S-DeNB: old eNB UE X2 AP ID；

- Accepted E-RAB information, including an E-RAB identifier, an IP address of the T-DeNB and an identifier of the tunnel, which are used to receive data sent by the RN-GW;

- Container of transparent transmission from the source to the destination.

The switching response message also includes information of the UE served by the RN. The information of the UE includes:

- A new identifier of the UE on the T-DeNB: new eNB UE X2 AP ID；

- An old identifier of the UE on the S-DeNB: old eNB UE X2 AP ID；

Accepted E-RAB information, including an E-RAB identifier, an IP address of the T-DeNB and an identifier of the tunnel, which are used to receive data sent by the RN-GW,

By using the above blocks, the T-DeNB receives and accepts upstream tunnel information assigned for the UE by the RN-GW before the RN switches, and the T-DeNB also assigns a tunnel for receiving downstream data for the user data.

In block 904, the S-DeNB sends a RRC message switch commandmessage to the RN, so as to make the RN switch to the destination cell on the destination DeNB. The message is the same as the conventional RRC message and is not described herein.

In block 905, the RN synchronizes with the destination cell, and sends an upstream RRC message switching finish message to the destination DeNB. The message is the same as the conventional RRC message and is not described herein.

In block 906, the destination DeNB sends a path switching request message to the RN-MME. The message includes conventional information when the RN is regarded as the UE. The conventional information includes:

- A new identifier of the RN on the S1 interface between the T-DeNB and the RN-MME: new MME UE S1 AP ID;

- An old identifier of the RN on the S1 interface between the S-DeNB and the RN-MME: MME UE S1 AP ID;

- Switched E-RAB information, e.g. the identifier of the E-RAB, a transmission layer address and downstream TEID assigned by the T-DeNB.

- An identifier of the destination cell;

- Destination TAI;

The path switching request message may also includes information of the UE served by the RN, and includes information of one or multiple UEs, each of the information of the UE includes:

Switched E-RAB information, e.g. the identifier of the E-RAB, a transmission layer address and downstream TEID assigned by the T-DeNB and.

After this block, RN-MME receives downstream tunnel information assigned for the UE by the T-DeNB.

In block 907, the RN-MME sends a changing bear request message to the gateway of the RN (SGW and PGW). The message includes conventional information when the RN is regarded as the UE. The conventional information includes:

- The identifier of the RN, which may be a temporary identifier of the RN assigned by the RN-MME, e.g. P-TMSI;

A list of E-RAB information of the RN, which includes E-RAB information, e.g. an E-RAB identifier, downstream TEID assigned by the T-DeNB, a transmission layer address.

The message also includes information of an UE served by the RN, The information of the UE includes:

- An old identifier of the UE on the S1 interface between the S-DeNB and the UE-MME: MME UE S1 AP ID; eNB UE S1 AP ID；

- An identifier of the UE, e.g. a temporary identifier of the UE, P-TMSI;

Switched E-RAB information, e.g. an E-RAB identifier, a transmission layer address and downstream TEID assigned by the T-DeNB.

Based on this block, the RN-MME can send the downstream tunnel information assigned by the T-DeNB for the UE which is received in the block 906 to the RN-GW.

In block 908, the gateway of RN (SGW and PGW) sends a changing bear response message to the RN-MME. The message includes conventional information when the RN is taken as the UE. The conventional information includes:

- An identifier of the RN, e.g. a temporary identifier of the RN assigned by the RN-MME, e.g. P-TMSI;A new identifier of the RN on the S1 interface between the T-DeNB and the RN-MME: new eNB UE S1 AP ID；

- A list of E-RAB information of the RN including information of the E-RAB, e.g. an E-RAB identifier, downstream TEID assigned by the T-DeNB and a transmission address.

- An old identifier of the UE on the S1 interface between the S-DeNB and the UE-MME: MME UE S1 AP ID, eNB UE S1 AP ID；

- An identifier of the UE, e.g. a temporary identifier of the UE, e.g. S-TMSI;

A list of E-RAB information of the UE including information of the E-RAB, e.g. an E-RAB identifier, upstream TEID assigned by the RN GW and a transmission address.

Thus, the transmission of the information of upstream and downstream tunnels between the T-DeNB and RN-GW is finished, and the tunnel may be established.

In block 909, the RN-MME sends a path switch acknowledgement to the T-DeNB. The message includes information of the RN and an identifier of the UE, bear information. The conventional information when the RN is taken as the UE includes:

- A new identifier of the RN on the S1 interface between the T-DeNB and the RN-MME: new eNB UE S1 AP ID, new MME UE S1 AP ID；

- A list of E-RAB information of the RN including information of the E-RAB, e.g. an E-RAB identifier, downstream TEID assigned by the T-DeNB, and a transmission address.

The information of the UE includes:

- An identifier of the UE, e.g. a temporary identifier of the UE, e.g. S-TMSI;

- A list of E-RAB information of the UE including information of the E-RAB, e.g. an E-RAB identifier, upstream TEID assigned by the RN GW, and a transmission address .

In block 910, the RN-MME sends a UE context release command to the S-DeNB, so as to release context information which relates to the RN and is stored in the S-DeNB. The message includes the identifierof the UE and a release reason, or includes the identifier of the RN, after receiving the identifier; the S-DeNB cancels the information of the RN and information of the UE severed by the RN. In block 911, the S-DeNB sends a UE context release finish message to the RN-MME.

In block 912, a S1 interface is to be established between the RN and T-DeNB. After the switching, the T-DeNB becomes the new DeNB of the RN, which is still called as the T-DeNB for concise description. The RN sends a S1 establishing request message to the T-DeNB. The message includes a station identifier of the RN, TAI supported by the RN. The message also includes information of UE served by the RN. The information of the UE includes (one of or parts of or all of):

- An old identifier on the S1 interface of the UE between the S-DeNB and the RN: eNB UE S1 AP ID；

- information of the GUMMEI served by the UE;

- An old identifier of the UE on the S1 interface between the S-DeNB and the UE-MME: new MME UE S1 AP ID, new eNB UE S1 AP ID;

- Context information of the UE, e.g. an encryption capability of the UE, access-layer capability information, maximum rate on the S1 interface of the UE, E-RAB information to be established, RRC context, a switching limit list, location report information.

In block 913, the T-DeNB sends a S1 establishing response message. The message includes information should be sent to the RN by the T-DeNB as the MME:

- An indication indicating MME supporting RN.

- Capability information of the MME.

- A new identifier of the UE on the S1 interface between the T-DeNB and the RN: eNB UE S1 AP ID, MME UE S1 AP ID;

A list of E-RAB information of the UE, including the E-RAB information, e.g. an E-RAB identifier, a transmission layer address and upstream TEID assigned by the T-DeNB.

Thus, the S1 interface is established, and in the establishing procedure, the tunnel information between the RN and T-DeNB is transmitted. Afterwards, the UE identifier on the UE-MME and RN-GW are to be updated.

In block 914, T-DeNB finds out the served MME of the UE, and sends a message to update the UE information stored in the served MME. The message includes:

- An old identifier of the UE on the S1 interface between the S-DeNB and the MME: eNB UE S1 AP ID, MME UE S1 AP ID；A new identifier of the UE on the S1 interface between the T-DeNB and the MME: new eNB UE S1 AP ID;

In block 915, the UE-MME sends a changing bear request message to the gateway of the RN. The message includes:

- The identifier of the UE, e.g. the temporary identifier of the UE S-TMSI;

- An old identifier of the UE on the S1 interface between the S-DeNB and the UE-MME: eNB UE S1 AP ID, MME UE S1 AP ID；A new identifier of the UE on the S1 interface between the T-DeNB and the MME: new eNB UE S1 AP ID, new MME UE S1 AP ID.

In block 916, the gateway of RN sends a changing bear response message to the UE-MME. The message includes:

- The identifier of the UE, e.g. the temporary identifier of the UE P-TMSI;

In block 917, the UE-MME sends a response message to the T-DeNB. The message includes:

- Encryption information;

- A list of E-RAB information of the UE, including the E-RAB information, e.g. an E-RAB identifier, upstream TEID assigned by the RN GW, and a transmission layer address.

Similar with the first embodiment, in the above procedure, the message may include the old identifier on the S1 interface of the UE (MME UE S1 AP ID, eNB UE S1 AP ID), the old identifier of the UE on the S-DeNB (old eNB UE X2 AP ID) and/or the unique identifier of the UE (e.g. the temporary identifier of the UE), which are all called as the identifier of the UE and are used to identify the corresponding UE. Specifically, one of or any combination of the above identifiers may be included in the message, but generally, the UE identifier transmitted between the entities should be identical.

The fourth embodiment is provided.

Figure 10 is a flowchart illustrating a procedure of switching to a destination DeNB by a RN via X2. The S/P GW of the RN is unchanged. In the RN switching procedure, a tunnel for transmitting data is to be established for the UE between the T-DeNB and the S/PGW of the RN.

In block 1001, the RN measures wireless environment around the RN, and sends a measurement report to a served DeNB (the S-DeNB shown in the Figure). According to the measurement report, the DeNB decides to switch the RN to a destination DeNB with better signal quality (T-DeNB shown in the Figure), the X2 interface is already established between the S-DeNB and T-DeNB, and the S-DeNB initiates a X2 switching. In block 1002, the S-DeNB sends a switching request message to the T-DeNB. The switching request message includes conventional information when the RN is regarded as the UE. The conventional information includes:

- An old identifier of the RN on the S-DeNB: old eNB UE X2 AP ID；

- A switching reason;

- A destination address of the switching, which is an identifier of a switching destination cell;

- The identity GUMMEI of the MME;

- RRC context;

The switching request message also includes information of an UE served by the RN. Some of the information of the UE served by the RN needs to be switched to the destination DeNB in the switching procedure. The message may include information of multiple UEs and the information of each UE includes:

- An identifier of the UE on the S1 interface between the S-DeNB and the UE-MME: eNB UE S1 AP ID, MME UE S1 AP ID;

- Context information of the UE, e.g. an encryption capability of the UE, access-layer capability information, maximum rate on the S1 interface of the UE, E-RAB information to be established, RRC context, a switching limit list, location report information;

In block 1003, the T-DeNB sends a switching message to the S-DeNB, the message includes conventional information when the RN is taken as the UE, and the conventional information includes:

- A new identifier of the RN on the T-DeNB: new eNB UE X2 AP ID；

- A old identifier of the RN on the S-DeNB: old eNB UE X2 AP ID；

- Accepted E-RAB information, including an E-RAB identifier;

- Container of transparent transmission from the source to the destination.

By using the above blocks, tunnel information of the RN is transmitted between the T-DeNB and the RN-GW, but the tunnel information of the UE is not transmitted, which will be transmitted after the switching.

In block 1004, the S-DeNB sends a RRC message switch commandto the RN, so as to make the RN switch to the destination cell on the destination DeNB. The message is the same as the conventional RRC message and is not described herein.

In block 1005, the RN synchronizes with the destination cell, and sends an upstream RRC message switching finish message to the destination DeNB. The message is the same as the conventional RRC message and is not described herein.

In block 1006, the destination DeNB sends a path switching message to the RN-MME. The message includes conventional information when the RN is regarded as the UE. The conventional information includes:

- A new identifier of the RN on the S1 interface between the T-DeNB and the RN-MME: new eNB UE S1 AP ID;

- A new identifier of the RN on the S1 interface between the S-DeNB and the RN-MME: new MME UE S1 AP ID;

- Switched E-RAB information, e.g. the identifier of the E-RAB, a transmission layer address and the downstream TEID assigned by the T-DeNB.

- An identifier of the destination cell;

- Destination TAI

In block 1007, the RN-MME sends a changing bear request message to the gateway of the RN (SGW and PGW). The message includes conventional information when the RN is regarded as the UE. The conventional information includes:

- A list of E-RAB information of the RN, which includes E-RAB information, e.g. an E-RAB identifier, downstream TEID assigned by the T-DeNB, a transmission layer address.

In block 1008, the gateway of RN (SGW and PGW) sends a changing bear response message to the RN-MME.

In block 1009, the RN-MME sends a UE context release command message to the S-DeNB, so as to release context information which relates to the RN and is stored in the S-DeNB. The message includes the identifier of the UE and a release reason.

In block 1010, the S-DeNB sends a UE context release finish message to the RN-MME.

In block 1011, an S1 interface is to be established between the RN and T-DeNB. After the switching, the T-DeNB becomes the new DeNB of the RN, which is still called as the T-DeNB for concise description. The RN sends a S1 establishing request message to the T-DeNB. The message includes a station identifier of the RN, TAI supported by the RN. The message also includes information of UE above of the RN. The information of the UE includes:

- information of the GUMMEI served by the UE;

In block 1012, the T-DeNB sends a S1 establishing response message. The message includes information should be sent to the RN by the T-DeNB as the MME:

- An indication indicating MME supporting RN.

- Capability information of the MME.

Thus, the S1 interface is established, and in the establishing procedure, the tunnel information between the RN and T-DeNB is transmitted.

In block 1013, the T-DeNB finds out the served MME of the UE, and sends a message to update the UE information stored in the served MME. The message includes:

- An old identifier on the S1 interface of the UE between the S-DeNB and the MME: eNB UE S1 AP ID, MME UE S1 AP ID (or only MME UE S1 AP ID is included )；A new identifier of the RN in the S1 interface between the T-DeNB and the MME: new eNB UE S1 AP ID;

- A list of E-RAB information of the UE, including the E-RAB information, e.g. an E-RAB identifier, a downstream TEID assigned by the T-DeNB, and a transmission layer address.

In block 1014, the UE-MME sends a changing bear request message to the gateway of the RN. The message includes (one of or parts of or all of):

- The identifier of the UE, e.g. the temporary identifier of the UE S-TMSI;

- A list of E-RAB information of the UE, including the E-RAB information, e.g. anE-RAB identifier, downstream TEID assigned by the T-DeNB, a transmission layer address.

In block 1015, the gateway of RN sends a changing bear response message to the UE-MME. The message includes:

- The identifier of the UE, e.g. the temporary identifier of the UE P-TMSI;

- A list of E-RAB information of the UE, including the E-RAB information, e.g. an E-RAB identifier, upstream TEID assigned by the RN-GW, a transmission layer address.

In block 1016, the UE-MME sends a response message to the T-DeNB. The message includes:

- Encryption information;

A list of E-RAB information of the UE, including the E-RAB information, e.g. an E-RAB identifier, upstream TEID assigned by the RN GW, and a transmission layer address.

According to the blocks 1013-1016, the tunnel information between the RN-GW and T-DeNB is transmitted. Thus, the tunnel between the T-DeNB and RN-GW is established for transmitting data of UE.

Similar with the third embodiment, in the above procedure, the message may include the old identifier on the S1 interface of the UE (MME UE S1 AP ID, eNB UE S1 AP ID), the old identifier of the UE on the S-DeNB (old eNB UE X2 AP ID) and/or the unique identifier of the UE (e.g. the temporary identifier of the UE), which are all called as the identifier of the UE and are used to identify the corresponding UE. Specifically, one of or any combination of the above identifiers may be included in the message, but generally, the UE identifier transmitted between the entities should be identical.

By using the method of the present invention, the tunnel between the T-DeNB and RN-GW is established for transmitting information of UE in the switching procedure of the moving RN or after the switching is finished; in addition, the tunnel information between the RN and the T-DeNB is transmitted atthe same time when the S1 is established. In the above procedure, the bear information between the RN and the UE is always unchanged. Therefore, even if the RN moves or switches, the switching procedure is transparent for the UE, and thus the data is transmitted continually

The foregoing is only preferred embodiments of the present invention. It should be noted that those skilled in the art may make improvement and modification within the principle of the present invention, and the improvement and modification should be covered in the protection scope of the invention.

Claims

A method for establishing a tunnel between a Donor NodeB (DeNB) of a moving Relay Node (RN) and a gateway of the moving RN, when the moving RN switches to a new DeNB via an S1 interface, comprising:

A. a source DeNB of the moving RN sending a switching need message to an Mobile Management Entity serving the moving RN (RN-MME), the message comprising an identifier of each UE served by the moving RN, and upstream tunnel information assigned for the UE by a gateway of the moving RN (RN-GW);

B. the RN-MME sending a switching request message to the destination DeNB of the moving RN, the message comprising the identifier of each UE served by the moving RN, and the upstream tunnel information assigned for the UE by the RN-GW;

C. the destination DeNB sending a switching response message to the RN-MME, the message comprising a new identifier on the S1 interface of each UE served by the moving RN and downstream tunnel information assigned by the destination DeNB;

D. the RN-MME or the destination DeNB sending the new identifier on the S1 interface of each UE served by the moving RN and the downstream tunnel information assignedby the destination DeNB to the RN-GW.
The method of claim 1, wherein the step D comprises: the RN-MME sending a changing bear establishing request message to the RN-GW, the message comprising the new identifier on the S1 interface of each UE served by the moving RN and the downstream tunnel information assigned by the destination DeNB to the RN-GW;

Or,

the destination DeNB sending a path updating message to the RN-GW, the message comprising the new identifier on the S1 interface of each UE served by the moving RN and the downstream tunnel information assigned by the destination DeNB to the RN-GW.
Themethod of claim 1, further comprising a step E after the step D: the RN-MME sending a UE context release command message to the source DeNB, the message comprising identifiers of all UEs served by the moving RN; after receiving the UE context release command message, the source DeNB releasing context information of the moving RN and context information of all UEs served by the moving RN.
Themethod of claim 3, after the step E, further comprising: establishing an S1 interface between the moving RN and the destination DeNB, maintaining the context information of all UEs served by the moving RN unchanged.
The method of claim 1, after an S1 switching is finished, further comprising:

for each UE served by the moving RN, the destination DeNB sending the identifier of the UE and the new identifier of the UE on the S1 interface assigned by the destination DeNB to a UE-MME serving the UE, to update UE information on the UE-MME; the UE-MME assigning a new identifier on the S1 interface for the UE and notifying the destination DeNB;

the UE-MME or the destination DeNB sending the new identifier of each UE served by the moving RN on the S1 interface assigned by the UE-MME to the RN-GW.
Themethod of any one of claims 1 to 5, wherein the switching need message in the step A further comprises information when the moving RN is taken as the UE, the information comprising an old identifier of the moving RN on the S1 interface between the source DeNB and the RN-MME;

the switching request message in the step B further comprises the new identifier of the moving RN on S1 interface assigned by the RN-MME and upstream tunnel information assigned for the moving RN by the RN-GW;

the switching response message in the step C further comprises the new identity of the moving RN on S1 interface assigned by the RN-MME, the new identity of the moving RN on S1 interface and downstream tunnel informationassigned by the destination DeNB;

after the step C and before the step D further comprises: the RN-MME sending a switching command message to the source DeNB, the message comprises the new identifier of the moving RN on S1 interface, the newidentifier of the moving RN on S1 interface assigned assigned by the destination DeNB;

The step D further comprises: the RN-MME sending the downstream tunnel informationassigned for the moving RN by the destination DeNB to the RN-GW.
A method for establishing a tunnel between a DeNB of a moving RN and a gateway of the moving RN, when the moving RN switches to a new DeNB via an X2 interface, comprising:

A. a source DeNB of the RN sending a switching request message to a destination DeNB, the message comprising an identifier of each UE served by the moving RN, and upstream tunnel information assigned for the UE by a gateway of the moving RN (RN-GW);

B. the destination DeNB sending a switching response message to the source DeNB, the message comprising a new identifier of each UE served by the moving RN and downstream tunnel information assigned by the destination DeNB;

C. the destination DeNB sending the new identifier of each UE served by the moving RN on the S1 interface and the downstream tunnel information assigned by the destination DeNB to the RN-GW via a RN-MME serving the moving RN.
The method of claim 7, further comprising a step D after the step C: the RN-MME sending a UE context release command message to the source DeNB, the message comprising identifiers of all UEs served by the moving RN; after receiving the UE context release command message, the source DeNB releasing context information of the moving RN and context information of all UEs served by the moving RN.
The method of claim 8, after the step D, further comprising: establishing an S1 interface between the moving RN and the destination DeNB, maintaining the context information of all UEs served by the moving RN unchanged.
The method of claim 1, wherein after an X2 switching is finished, further comprising:

for each UE served by the moving RN, the destination DeNB sending the identifier of the UE and the new identifier of the UE on the S1 interface assigned by the destination DeNB to a UE-MME serving for the UE, to update UE information stored on the UE-MME;

the UE-MME sending the identity of the UE, the new identifier of the UE on the S1 interface assigned by the destination DeNB, the new identifier of the UE on the S1 interface assigned by the UE-MME, to update information of the UE stored on the RN-GW;

the UE-MME sending the new identifier of the UE on the S1 interface assigned by the UE-MME to the destination DeNB.
Themethod of any one of claims 7 to 10, wherein the switching request message in the step A further comprises information when the moving RN is taken as the UE, the information comprising an old identifier of the moving RN on the source DeNB and upstream tunnel information assigned for the moving RN by the RN-GW;

the switching response message in the step B further comprises the old identity of the moving RN on source DeNB, the new identifier of the moving RN on destination DeNB, and downstream tunnel information assigned for the moving RN by the destination DeNB;

when sending the UE information to the RN-GW via the RN-MME by the destination DeNB, sending downstream tunnel information assigned by the destination DeNB for the moving RN to the RN-GW via the RN-MME, and sending the new identity of the moving RN on the destination DeNB to the RN-MME.
A method for establishing a tunnel between a DeNB of a moving RN and the moving RN, after the moving RN switches to a new DeNB, comprising:

A. the moving RN sending a S1 establishing request messageto the DeNB, the message comprising a new identifier on a S1interface of each UE assigned by the DeNB when the switching is performed, current context information of each UE;

B. the DeNB sending a S1 establishing response message to the moving RN, the message comprising a new identifier on the S1 interface of each UE and upstream tunnel information assigned by the DeNB.
Themethod of claim 12, wherein the S1 establishing request message in step A further comprises a station identifier of the moving RN and supported TAI information

the S1 establishing response message in step B comprises the new identifier of each UE on the S1 interface and the upstream tunnel information assigned by the destination DeNB.
A method for establishing a tunnel between a DeNB of a moving RN and a gateway of the moving RN, after the moving RN switches to a new DeNB, comprising:

A. the DeNB sending downstream tunnel information and a new identifierof a UE on the S1 interface assigned by the DeNB when the switching is performed to the gateway of the moving RN (RN-GW) via a MME of the UE (UE-MME); the UE being each UE served by the moving RN;

B. the RN-GW sending upstream tunnel information assigned for the UE by the RN-GW to the DeNB via the UE-MME.
Themethod of claim 14, wherein the step A comprises: the DeNB sending a path switching request message to the UE-MME, the UE-MME sending a changing bear request message to the RN-GW; the path switching request message and the changing bear request message comprises a new identifier of each UE on the S1 interface and downstream tunnel information assigned by the DeNB;

the step B comprises: the RN-GW sending a changing bear response message to the UE-MME, the UE-MME sending a path switching request acknowledgement message to the DeNB; the changing bear response message and the path switching request acknowledgement message comprises upstream tunnel information assigned for the UE by theRN-GW.
Themethod of claim 15, wherein the changingbear request message in the step A furthercomprises a new identifier of the UE on the S1 interface assigned by the UE-MME;

The path switching request acknowledgement message further comprises a new identifier of the UE on the S1 interface assigned by the UE-MME.
Themethod of claims 14, 15 or 16, when the moving RN switches to the DeNB via the S1, before the S1 switching is finished, further comprising:

carrying informationwhen the RN is taken as the UE in a switching need message sent by a source DeNB to a RN-MME serving the moving RN, the information comprising an old identifier of the moving RN on the S1 interface between the DeNB and the RN-MME;

carrying a new identifier of the moving RN on the S1 interface assigned by the RN-MME and upstream tunnel information assigned for the moving RN by the RN-GW in a switching request message sent by the RN-MME to the DeNB;

carrying the new identity of the moving RN on the S1 interface assigned by the RN-MME, the new identity of the moving RN on the S1 interface and downstream tunnel information assigned by the DeNB, in a switching response message sent by the DeNB to the RN-MME;

carrying a new identifier of the moving RN on the S1 interface, a new identifier of the moving RN on the S1 interface assigned by the DeNB in the switching command message sent by the RN-MME to the source DeNB;

carrying downstream tunnel information assigned for the moving RN by the DeNB in the changing bear request message sent by the RN-MME to the RN-GW.
Themethod of claims 14, 15 or 16, when the moving RN switches to the DeNB via the X2 switching, before the X2 switching is finished, further comprising:

carrying informationwhen the RN is taken as the UE in the switching request message sent by a source DeNB to the DeNB, the information comprising an old identifier of the moving RN on the source DeNB and upstream tunnel information assigned for the moving RN by the RN-GW;

carrying the old identity of the moving RN on the source DeNB, the new identity of the moving RN on the DeNB and upstream tunnel information assigned for the moving RN accepted by the DeNB in the switching response message sent by the DeNB to the source DeNB;

carrying downstreamtunnel information assigned for the moving RN by the DeNB in the path switching message sent by the DeNB to the RN-MME and the changing bear request message sent by the RN-MME to the RN-GW; carrying a new identifier of the moving RN on the DeNB in the path switching message.