WO2007071112A1 - Method of maintaining transmission of packet data stream when mobile terminal moves across wireless access network - Google Patents

Abstract

A method of maintaining transmission of packet data stream when mobile terminal moves across wireless access network, in which, UE initiates handoff request across wireless access network during the process of packet data service, and obtains the BS list permitting handoff by the interaction between UE, serving BS, the serving gateway currently accessing serving network and the target gateway of target access serving network; UE selects target BS from list, and sends the handoff indication message to serving gateway through serving BS, and the serving gateway notifies the target gateway that there is terminal requiring handing over, and the serving gateway establishes packet data forward tunnel with target gateway; UE performs network access and authentication, after success, receives the data stream sent form serving gateway through serving base station, or target gateway and target BS with original IP address; UE sends handoff accomplishment message to the serving base station, and disconnects the data channel between serving base station and the UE , serving gateway, after the end of packet data service, the forward tunnel between target gateway and serving gateway is disconnected.

Description

 Method for uninterrupted packet data flow when mobile terminal moves across wireless access network

Technical field

 The present invention relates to a method of transmitting data streams as a user moves across a wireless access network service area during execution of a packet data service.

Background technique

 First, the English abbreviations used in the explanation of the present invention are explained as follows:

 WiMAX is a broadband wireless metropolitan area network technology that provides an efficient, adaptable and interoperable access method for fixed broadband wireless access systems.

As shown in Figure 1, the WiMAX system is divided into three layers: ASP, CSN, and ASP Network/Intemet. An Access Service Network (ASN) is a collection of network functional entities that provide wireless access to users. The functions of the ASN include: providing an L2 connection between the mobile terminal and the BS; the proxy forwards the AAA message to the user home network for authentication, authorization, and charging; discovering and selecting an appropriate network service provider (NSP) to access WiMA service provisioning system; provisioning for user L3 connection establishment Relay function (for example, IP address allocation); Radio resource management; Support for Intra-ASN (ASN internal mobility); Paging and location management; ASN-CSN tunneling function; Visit location registration function, etc.

 A Connected Service Network (CSN) is a collection of network functional entities that provide IP connectivity to users; an operator that provides functional entities in the CSN is called an NSP.

 The ASN includes two network elements: a base station (BS) and an access service network gateway (ASN-GW). An AS can connect to multiple CSNs, and the network operator that provides access services in the ASN is called ΝΑΡ. As the wireless access gateway, the ASN-GW establishes a connection with the BS through the L3 tunnel, receives the data packet of the user L3 tunnel sent by the BS, and forwards the user data packet to the IP packet in the format of the Ethernet IP packet. Each network node in the CSN of a standard Ethernet connection.

 As shown in FIG. 2, the mobile terminal 10 establishes a connection through the wireless air interface of WiMax and the base station network element BS 20, where the two entities are connected by a solid line, indicating air interface signaling and data between the mobile terminal 10 and the BS 20. Carrying a channel. A standard Ethernet connection is between the BS 20 and the Access Service Network Gateway ASN-GW 30. The ASN-GW 30 and the connection service network CSN are connected through the Internet network 50. The dynamic host configuration protocol server, the DHCP server 40 and the DHCP server 41, are network element devices owned by different network service providers, and are used to allocate an IP address to the mobile terminal when the mobile terminal 10 uses the packet data service, and the user can access the network by using the IP address. The resources of each node in the network authorized by the service provider, including browsing webpages, voice, video services, and the like.

 When the mobile terminal 10 moves from the radio access network coverage area provided by the network service provider NSP1 to the radio access network coverage area provided by the network service provider NSP2, the mobile terminal 10 and the ASN-GW 30, ASN-GW 31 The signaling information exchange occurs, and the mobile terminal is connected before the mobile. The ASN-GW 30 is referred to as the serving ASN-GW, and the ASN-GW 31 connected to the mobile terminal is referred to as the target ASN-GW; correspondingly, with the ASN-GW 30 The connected BS 20 is referred to as a serving BS; the BS 21 coupled to the ASN-GW 31 is referred to as a target BS.

When the mobile terminal 10 moves across the wireless access network service area during the packet data service process, the existing handover process in the WiMax system is as shown in FIG. 3, and includes the following steps -

(A) the mobile terminal 10 periodically scans adjacent BS signals; (B) when the mobile terminal 10 decides to switch, it sends a handover request message MOB_MSSHO_REQ to the serving BS 20, notifying the serving BS 20 that the mobile terminal is ready to switch;

 (C) service BS 20 transmits a handover request message HO Request notification service ASN-GW 30 The mobile terminal 10 prepares for handover;

 (D) Service ASN-GW 30 forwards the handover request message to the target ASN-GW 31 HO

Request, request target ASN-GW 31 allows the mobile terminal to switch;

 (E) The target ASN-GW 31 sends a handover response primitive HO Response to the serving ASN-GW 30, and includes a list of a plurality of target BS sets that the mobile terminal 10 is allowed to cut in;

 (F) The service ASN-GW 30 transmits a handover response message to the serving BS 20 HO Response; (G) The service BS 20 transmits a handover response message MOB_MSSHO_RSS to the mobile terminal 10 with a list of target BS sets that can be handed over;

 (H) The mobile terminal selects a suitable target BS 21 and then transmits a handover indication message MOB_HO_IN to the serving BS 20;

 (I) The service BS 20 transmits a handover indication message HO Indication to notify the service ASN-GW 30 that the mobile terminal is ready to start handover;

 (J) The mobile terminal 10 starts the network access procedure to the target BS 21;

 (K) After the mobile terminal 10 completes the network access, the target BS 21 sends a data channel establishment process to the target ASN-GW 31 to the R6 interface (ie, the channel interface between the BS base station system and the GW);

 (L) The target ASN-GW 31 sends the mobile terminal 10 data channel setup message to the service ASN-GW 30. Data Path Establishment, the notification service ASN-GW 30 establishes a data forwarding tunnel for the user;

 (M) Service The ASN-GW 30 transmits a mobile terminal data path establishment response message to the target ASN-GW 31, and starts to forward the user's data.

When the mobile terminal uses the IP address assigned by the DHCP server for packet data service, it must perform signaling interaction with the DHCP server at a fixed time interval to maintain the user's own IP address. Since the IP address of the user is dynamically provided by the local operator, the user can always use this as long as the user moves within the ASN-GW and the radio network corresponding to the operator. IP addresses. When the user enters the ASN-GW under different NSPs to perform packet data service, the user requests a new IP address from the DHCP server of the target network during the access process. The above process does not involve the application of the IP address during the handover (new The IP address is invalid for the original packet data service. If the terminal applies for a new IP address, the data stream will not be forwarded normally. If the terminal only retains the original IP address without any improvement, although the forwarded data stream can be received, since the mobile terminal has moved to the new network, the original IP address cannot be maintained, and the new IP address cannot be used. The packet data service must trigger its IP address allocation request in other processes before the packet data service can be used. This makes it difficult for the mobile terminal to successfully carry out the service after the handover.

 In addition, in the foregoing step J and step K, after the mobile terminal is accessing the target network, the target ASN-GW 31 establishes a forwarding tunnel with the serving ASN-GW 30, and then the serving ASN-GW 30 can pass the target ASN-GW. 31 and BS 21 forward the data stream to the terminal 10, but when the mobile terminal accesses the target network, it has been disconnected from the serving BS 20, and therefore, normal transmission of user data cannot be guaranteed during this period of time.

The existing 3GPP2 technology also provides a method for processing cross-region mobile handover, which needs to establish a PP of layer 3 on the packet data serving node (PDSN) through the interface on the network side and the PDSN of the target-cut network. The PDSN-PDSN interface tunnels and transmits data through the movement of the PPP link. In order to ensure that the service flow can be transmitted across the area, the service flow packet in the layer 2 tunnel needs to be transmitted on the layer 3 P-P tunnel, and a PPP link is maintained. In order to ensure the stable transmission of traffic, the P-P interface should continuously perform signaling interaction to maintain the availability of this tunnel.

If you use this method, you need to establish an interface tunnel between the two ASN-GWs to maintain the tunnel through signaling, and forward the data for the cut-in user. After the user cuts in the new network, you need to establish a PPP session. The start of forwarding the user's packet data service. This undoubtedly prolongs the time for user switching and increases the probability of packet data loss. At the same time, the availability of the signaling channel between the two ASN-GWs is increased, the overhead of the system is increased, and the signaling interaction between the user's IP address and the DHCP server cannot be solved. Summary of the invention

 The technical problem to be solved by the present invention is to propose a method for uninterrupted packet data flow when a mobile terminal moves across a radio access network.

 In order to solve the above technical problem, the present invention provides a method for uninterrupted packet data flow when a mobile terminal moves across a radio access network, including the following steps -

(a) the mobile terminal initiates a handover request across the radio access network in the packet data service process, and the interaction between the mobile terminal, the serving base station, the serving gateway of the current access service network, and the target gateway of the target access service network, Obtain a list of base stations that are allowed to be handed in;

 (b) the mobile terminal selects a target base station from the list, and sends a handover indication message to the serving gateway via the serving base station, where the serving gateway notifies the target gateway that the terminal has to cut in and establishes a packet data forwarding tunnel between the target gateways;

 (c) the mobile terminal performs network access, and after the access is completed, performs authentication, and after the authentication is passed, simultaneously receives data sent by the serving gateway through the serving base station by using the original IP address, and the serving gateway Decoding the data flow forwarded by the target gateway and the target base station;

 (d) the mobile terminal sends a handover complete message to the serving base station, and the data channel between the serving base station and the mobile terminal and the serving gateway is removed, and after the packet data service ends, the target is removed. Packet data forwarding tunnel between the gateway and the serving gateway.

Further, the foregoing method may further have the following feature: in the handover process, the target gateway also applies a protocol server to the local dynamic host configuration protocol server to apply for a new IP address for the mobile terminal, and maintains the lease of the IP address. And, after the step (d) of the packet data service ends, when the mobile terminal enters the dormant and idle modes, the target gateway actively initiates an update process of the IP address, and allocates the pre-reserved IP address to the mobile terminal.

 Further, the foregoing method may further have the following feature: after the packet data forwarding tunnel between the target gateway and the service gateway is established, starting to apply for a new IP address to the local dynamic host configuration protocol server for the mobile terminal. The process of the address.

Further, the foregoing method may further have the following features: in the step (a), when the target gateway sends a handover response message to the serving gateway, the label with the packet data forwarding tunnel The process of establishing the tunnel is started. In the step (b), after receiving the handover indication message, the serving gateway sends a handover confirmation message to the target gateway, confirming that the tunnel has been established, and then the service gateway is At the same time as the packet data stream is sent to the serving base station, the packet data stream is started to be forwarded to the target gateway.

 Further, the foregoing method may further have the following features: in the step (b), after the target gateway establishes a packet data forwarding tunnel between the serving gateways, the target base station is further notified that the terminal has a terminal to cut in, and the target base station is in the target base station. Establishing a data channel with the target gateway.

 Further, the foregoing method may further have the following features: in the step (a), the target gateway obtains a user authentication request from the received handover request message sent by the serving base station by using the serving gateway. Information, in step (d), after the terminal accesses, the authentication of the terminal and the user data stream is directly performed by the target base station and the target gateway.

 Further, the foregoing method may further have the following features: The process of establishing a data channel between the target base station and the target gateway may further be divided into the following steps:

 The target gateway forwards a handover confirmation message to the target base station, and notifies the base station that a mobile terminal is about to cut in;

 The target base station initiates a setup request message of the mobile terminal R6 interface to the target gateway; the target gateway sends an R6 interface response message to the target base station, and the data channel establishment between the two is completed. '

Further, the above method may further have the following features: The step (d) further includes the following steps:

 (dl) the mobile terminal sends a handover complete message to the serving base station, the serving base station tears down the connection with the mobile terminal, and simultaneously sends a user tunnel teardown message to the serving gateway;

(d2) after receiving the message, the serving gateway removes the data channel between the serving base station and returns an answer message, and stops sending the packet data stream of the user to the serving base station;

(d3) the target gateway continues to send the received user packet data stream to the target base station, and then sent by the target base to the mobile terminal; (d4) after the packet service ends, the target gateway forwards the tunnel teardown message by sending the user data, and notifies the service gateway to tear down the forwarding tunnel of the mobile terminal;

 (d5) The serving gateway sends a user data forwarding tunnel teardown response message to the target gateway to completely clear all information of the mobile terminal that has switched.

Compared with the prior art, the present invention solves the problem that the packet data service flow is continuous when users cross different wireless access networks. It also overcomes the cumbersome process of establishing a data path using PPP in the CDMA2000 solution in 3GPP2, and speeds up the switching process of the user's packet data service flow. BRIEF abstract

 1 is a schematic diagram of network association of a packet domain in a WiMax system in the prior art;

 2 is a schematic structural diagram of an access network in a WiMax system in the prior art;

 3 is a schematic diagram of a user handover process across an ASN-GW in the prior art;

 4 is a schematic diagram of a process of a user handover preparation phase across an ASN-GW in an embodiment of the present invention; FIG. 5 is a schematic diagram of a process of a user handover intermediate phase across an ASN-GW in an embodiment of the present invention; Schematic diagram of the process of ending the phase of user switching across the ASN-GW.

BEST MODE FOR CARRYING OUT THE INVENTION

 In the present application, the primitive refers to an operation of performing a signaling message, or an operation of not performing a signaling message, and there is no operation in which only part of the signaling information is performed. The present invention uses the existing operating primitives and corresponding carrying information in the WiMax system, and also defines the primitives of the handover process of the present invention. These primitives are used for signaling message interaction in the embodiment, and the present invention proposes The set of primitives supporting the handover (HO) procedure can be used between the BS and the ASN-GW, or between the two BSs and between the two ASN-GWs, and the proposed information can satisfy the mobile terminal cross Handover requirements between ASN-GWs.

Most of the primitives involved in the handover process of this embodiment are listed in the following table, but some well-known primitives in the art, such as DHCP Request, R6 Requests MOB-MSSHO-REQ, MOB MSSHO RSP, etc., are omitted. (1) Primitives for switching mobile terminals

 Table 1

(2) The HO control primitive is divided into the following two stages:

 1) HO preparation phase: At the time when the mobile terminal or the ASN-GW decides to initiate the HO, until the mobile terminal indicates that it is ready to leave the service BS by the handover indication primitive MOB HO IND, this phase is defined as the HO preparation phase, HO The preliminary stage primitives are shown in Table 2 below:

 Table 2

 IS 5 Direction of implementation Message content

 Now switch request primitive service BS→target service BS identifier: BS ID,

 Have HO Request ASN-GW

 The target BS list of the candidate cut-in area: Technology Candidate Target BS ID list, Operation Mobile terminal identification information: MSS-ID, Lifting the attribute information of the mobile terminal:

 Out the MSS QoS Profile ID,

 Connection session information of the mobile terminal:

 Session Info Report,

 Support for HO parameter optimization information:

 Info—Support— HO—Optimization Switching Response Primitive Target ASN-GW→Service Service BS Identification Information-

HO Response BS, Serving BS ID,

 Recommended to be cut into the target BS list:

Recommended Target BS ID list, ID of the mobile terminal: MSS—ID 2) Implementation phase of HO: From the mobile terminal, the MOB_HO_ID message indicates that the service BS has been prepared to leave, until it successfully completes the network reentry to the target BS. This phase is defined as the implementation phase of the HO, the HO implementation phase. The primitives are shown in Table 3 below.

下面结合图 4、 图 5和图 6和对本发明具体实施例所介绍的移动终端在 进行分组数据业务过程中， 跨 ASN-GW (即跨移动接入网）时数据流不中断 的实现方法做一详细说明， 但不作为对本发明的限定。

In the following, in conjunction with FIG. 4, FIG. 5 and FIG. 6 and the mobile terminal introduced in the specific embodiment of the present invention, in the process of performing packet data service, the data flow is not interrupted when the ASN-GW (ie, across the mobile access network) is implemented. The detailed description is not intended to limit the invention.

 In normal operation, the mobile terminal 10 periodically scans neighboring BSs for collecting quality information of signals, which are then forwarded by the BS to the ASN-GW 30, when the mobile terminal 10 is ready to move from the ASW-GW 30 to the ASW-GW 31. When switching, perform the following steps;

 Step A: The mobile terminal 10 sends a handover request message MOB_MSSHO_REQ to the serving BS 20, and prepares to cut into the target BS 21;

Step B: After receiving the handover request message MOB_MSSHO_REQ sent by the mobile terminal 10, the serving BS 20 sends a handover request message HO Request to the service ASN-GW 30, Notifying the service ASN-GW 30 to prepare a list of target BSs that can be recommended;

 The handover request message HO Request carries the following information: the identifier of the serving BS, Serving BS_ID, the list of target BSs of the candidate to be cut-in area (empty), the Candidate Target BS ID list, the mobile terminal identification information MSSjD, and the attribute information MSS of the mobile terminal. QoS Profile ID, connection session information of the mobile terminal Session Info Report, information supporting HO parameter optimization Info_Support- HO- Optimization;

 Step C: The service ASN-GW 30 forwards the handover request message HO Request through the R4 interface, and communicates with the multiple candidate target ASN-GWs, requesting the handover judgment of the mobile terminal;

 The handover request message HO Request carries the following information: Service BS ID Serving BS ID, mobile terminal identifier MSS_ID, information supporting HO parameter optimization Info_Support_HO__Optimization, connection session information of the mobile terminal Session Info Report, and the like. The target GW can obtain session information, attribute information, and connection information of the user through the handover request message.

 Step D: When the target ASN-GW 31 allows the mobile terminal to switch, the handover response message HO Response is sent to the serving ASN-GW 30. In addition to the recommended target BS list, the embodiment also has a packet data forwarding tunnel identifier, which is started. a tunnel establishment process between the target ASN-GW 31 and the serving ASN-GW 30;

 Step E: The serving ASN-GW 30 forwards the handover response message HO Response to the serving BS 20; Step F: The serving BS 20 sends a handover response message MOB_MSSHO_RSP to the mobile terminal 10, and notifies the mobile terminal 10 of the selectable target BS. ;

 Step G: The mobile terminal selects one target BS 21 from the set of available target BSs, and sends a handover indication message MOB_HOJND to the serving BS 20 to start the handover HO process.

 Step H: The serving BS 20 sends a handover indication message HO Indication to the service ASN-GW 30, notifies the service ASN-GW 30 that the mobile terminal is ready to start handover, and the handover indication message HO Indication carries the identification information of the target BS 21 Target BS ID;

Step 1: After receiving the handover indication message HO Indication, the serving ASN-GW sends a handover confirmation message HO Confirmation to the target ASN-GW 31, notifying the target BS 21 that the tunnel has been established, and a mobile terminal is about to cut in. ASN-GW 30 will net The packet data stream of the mobile terminal 10 received by the network side is transmitted to both the serving BS 20 and the target ASN-GW 31;

 The difference between the foregoing process and the prior art is that a forwarding tunnel is first created between the serving ASN-GW and the target ASN-GW, so that the serving ASN-GW forwards the data stream to the target ASN-GW and the serving BS in both directions. Since the handover process is an intermediate process, the mobile terminal selects the reception according to the quality of the wireless signal, and the mobile terminal does not necessarily ensure that the mobile terminal receives the original signal when switching across the access network. Therefore, in this embodiment, two-way forwarding is adopted during handover, and data forwarding is performed on two channels, and data is not lost due to the selection time of the wireless channel (even if a small amount of data is lost, it can be retransmitted by the target GW) Further ensure the continuity of the business data flow.

 The above completes the operation of the handover preparation phase, followed by the operation of the intermediate phase:

Step J: The target ASN-GW 31 forwards the handover confirmation message HO Confirmation to the target BS 21, and notifies the target BS 21 that a mobile terminal is about to cut in;

 Step K: The target BS 21 initiates a setup request message for the R6 interface of the mobile terminal to the target ASN-GW 31. R6 Request;

 Step L: The target ASN-GW 31 sends an R6 interface response message R6 Reply to the target BS 21. Step M: The target ASN-GW 31 sends an IP address request message DHCP Request to the local DHCP server 41 as a DHCP Client, requesting the mobile terminal 10 New IP address;

 Step N: The DHCP Server 41 sends a response message DHCP Reply response carrying the newly assigned IP address to the target ASN-GW 31, which brings the assigned user IP address to it, and the target ASN-GW 31 maintains the IP as the DHCP Client. The lease period of the address, the DHCP IP address maintenance process will continue until the mobile terminal 10 that initiates the handover actively disconnects the packet service data flow during the handover process, or when the service is interrupted and disconnected by the network side;

 The above process starts the R6 tunnel and then starts to apply for the DHCP process of the IP address. Therefore, the process of applying for DHCP has a strict trigger condition, but it is not necessary.

Step 0: The mobile terminal 10 and the target BS start network access. After the access, the target BS 21 and the target ASN-GW 31 complete the authentication and authorization process, and then the original IP address can be used to receive the service ASN- The GW 30 receives the data stream from the service BS while receiving the slave service. The data stream forwarded by the ASN-GW 30 via the target ASN-GW 31 and the target BS 21; since the target ASN-GW 31 has obtained the session information, the attribute information, and the connection information of the user in the previous step, the present embodiment is The authentication and authorization process can be done directly by the target BS 21 and the target ASN-GW 31. During the access process, there is a key authentication of the target BS and the terminal. Through the user attribute information and the session authentication information, the target BS can perform authentication on the terminal. Similarly, the GW can perform authentication of the user data stream access by performing an authentication algorithm according to the information.

 It should be noted that the network access procedure initiated by the mobile terminal 10 and the target BS 21 is not performed after the data channel establishment between the target BS and the target ASN-GW, but is sent to the serving BS. After HO Indication, you can start. The above is just for the convenience of description.

 It can be seen from the flow of the above two phases that after receiving the handover indication message, the serving ASN-GW of the embodiment establishes a channel with the target ASN-GW and starts forwarding, and does not need to wait for the terminal and the target ASN- After the radio link establishment of the BS is completed, the target BS actively establishes an R6 interface channel to the target ASN-GW, which can speed up the process of the terminal accessing the network, and between the service ASN-GW and the target ASN-GW before the access process is completed. A forwarding tunnel has been established. After the authentication, the mobile terminal can directly receive the packet data stream forwarded by the serving ASN-GW through the target ASN-GW and the target BS by using the original IP address, thereby avoiding access to the service ASN-GW and then When the forwarding tunnel is established between the target ASN-GW, the service flow is interrupted.

 So far, the mobile terminal 10 completes the access procedure to the new ASN-GW 31 and enters the handover end phase.

Step P: The mobile terminal 10 transmits a handover complete message MOB_HO_FIN to the serving BS 20; Step Q: The serving BS 20 tears down the connection with the mobile terminal 10, while the serving BS 20 sends a user tunnel teardown message R6 Revoke to the serving ASN-GW. 30. The notification service ASN-GW 30 deletes the session information of the user.

Step R: The service ASN-GW 30 tears down the R6 interface data channel of the user, stops sending the user packet data stream to the serving BS 20, and sends a user tunnel teardown response message R6 Revoke Response to the serving BS 20, the service ASN-GW 30 only forwards the handover user 10 packet service data stream to the target ASN-GW 31 through the R4 interface;

 Step S: The target ASN-GW 31 sends the received user packet data stream to the target BS 21, and the target BS 21 transmits the data information to the mobile terminal 10 (the process is after the data channel between the target ASN-GW and the terminal is established). It has been going on);

 Step T: When the mobile terminal 10 enters the dormant and idle mode, the target ASN-GW 31 actively initiates a DHCP update process of the IP address to the mobile terminal 10 as the DHCP server, and assigns the pre-reserved IP address to the mobile terminal 10;

 It can be seen that, in this embodiment, when the mobile terminal accesses the network, the target ASN-GW proxy applies for an IP address, and then in step T, the target ASN-GW initiates an IP address update to the terminal. After the end of the user packet data stream, there is no IP address and no space can be used for the service. At this point, the user enters the new access network, and the original service flow is stopped. Then the original IP address cannot be used, and the next event that can trigger the IP address application can be used to perform the normal service.

 Step U: The target ASN-GW 31 tears down the message by sending a user data forwarding tunnel. R4

Tunnel Revoke, notification service ASN-GW 30, tearing down the forwarding tunnel of the mobile terminal 10, with the identifier of the mobile terminal 10 in the message;

 Step V: The service ASN-GW 30 sends a user data forwarding tunnel teardown response message to the target ASN-GW 31 to completely clear all the information of the mobile terminal 10 that has switched, and the message also carries the identifier of the mobile terminal 10.

Industrial applicability

 The method of the invention can be applied to a mobile communication network such as WiMax, and solves the problem that the packet data service flow is continuous when the user uses the dynamic IP, and the data flow is continuous across different wireless access networks, and overcomes the use of the PPP to establish a data path in the CDMA2000 solution in the 3GPP2. The cumbersome process accelerates the switching process of the user's packet data service flow.

Claims

Claim A method for uninterrupted packet data flow when a mobile terminal moves across a wireless access network, comprising the following steps  (a) the mobile terminal initiates a handover request across the radio access network in the packet data service process, and the interaction between the mobile terminal, the serving base station, the serving gateway of the current access service network, and the target gateway of the target access service network, Obtain a list of base stations that are allowed to be handed in;  (b) the mobile terminal selects a target base station from the list, and sends a handover indication message to the serving gateway via the serving base station, where the serving gateway notifies the target gateway that the terminal has to cut in and establishes a packet data forwarding tunnel between the target gateways;  (c) The mobile terminal performs network access, and performs authentication after the access is completed. After the authentication is passed, the data sent from the serving gateway through the serving base station is simultaneously received by the original IP address, and the serving gateway is a data stream forwarded by the target gateway and the target base station;  (d) the mobile terminal sends a handover complete message to the serving base station, and the data channel between the serving base station and the mobile terminal and the serving gateway is removed, and after the packet data service ends, the target is removed. Packet data forwarding tunnel between the gateway and the serving gateway.  2. The method according to claim 1, wherein the target gateway further requests a new IP address for the mobile terminal to the local dynamic host configuration protocol server as a proxy during the handover process, and maintains the The lease period of the IP address, until the mobile terminal enters the dormant and idle modes after the step (d) packet data service ends, the target gateway initiates an IP address update process, and the pre-reserved IP address is Assigned to the mobile terminal.  The method according to claim 2, wherein the target gateway is configured to start a local dynamic host configuration protocol server as the mobile terminal after establishing a packet data forwarding tunnel with the serving gateway. The process of applying for a new IP address. The method according to claim 1, wherein in the step (a), when the target gateway sends a handover response message to the serving gateway, the identifier of the packet data forwarding tunnel is started, and the In the step of establishing a tunnel, in the step (b), after receiving the handover indication message, the serving gateway sends a handover confirmation message to the target gateway, confirming that the tunnel has been established, and then the service gateway is in the packet data flow. At the same time as being sent to the serving base station, The standard gateway forwards the packet data stream.  The method according to claim 1, wherein in the step (b), after the target gateway establishes a packet data forwarding tunnel between the serving gateways, the target base station is further notified that the terminal has to be cut in, and A data channel is established between the target base station and the target gateway.  The method according to claim 1, wherein in the step (a), the target gateway obtains a user from a received handover request message sent by the serving base station via the serving gateway. For the information required for authentication, in step (d), after the terminal accesses, the authentication of the terminal and the user data stream is directly performed by the target base station and the target gateway.  The method according to claim 5, wherein the process of establishing a data channel between the target base station and the target gateway is further divided into the following steps:  The target gateway forwards a handover confirmation message to the target base station, and notifies the base station that a mobile terminal is about to cut in;  The target base station initiates a setup request message of the mobile terminal R6 interface to the target gateway; the target gateway sends an R6 interface response message to the target base station, and the data channel establishment between the two is completed.  8. The method of claim 1 wherein said step (d) further comprises the step of:  (dl) the mobile terminal sends a handover complete message to the serving base station, the serving base station tears down the connection with the mobile terminal, and simultaneously sends a user tunnel teardown message to the serving gateway; (d2) the service gateway receives After the message, the data channel between the serving base station is removed and a response message is returned, and the packet data stream of the user is stopped from being sent to the serving base station;  (d3) the target gateway continues to send the received user packet data stream to the target base station, and then the target base station sends the mobile terminal to the mobile terminal;  (d4) after the packet service ends, the target gateway forwards the tunnel teardown message by sending the user data, and notifies the service gateway to tear down the forwarding tunnel of the mobile terminal;  (d5) The serving gateway sends a user data forwarding tunnel teardown response message to the target gateway to completely clear all information of the mobile terminal that has switched.