WO2007051379A1

WO2007051379A1 - A method for service handover in wireless cellular communication system

Info

Publication number: WO2007051379A1
Application number: PCT/CN2006/001401
Authority: WO
Inventors: Yujie Zhang
Original assignee: Zte Corporation
Priority date: 2005-11-05
Filing date: 2006-06-20
Publication date: 2007-05-10
Also published as: CN100502587C; CN1960561A

Abstract

A method for service handover in wireless cellular communication system, when a wireless communication terminal device determines to handover after initiating handover request, anchor data path function has determines whether to start ARQ mechanism or sequence number feedback mechanism according to different services, and buffers MAC SDU data packet, sends MAC SDU data packet to terminal through the current serving data path function before handover, the terminal sends feedback information to anchor data path function through target data path function when handover accessing, the anchor data path function send MAC SDU data packet to the terminal through target data path function according to the feedback information, then handover accomplished. The present invention enables service data can still maintain enough integrity during handover process, processing logic for the ARQ mechanism or sequence number feedback mechanism is simple, and reduce the complexity for buffer processing system data and save the buffer space because it only performs buffer in anchor data path function.

Description

Service switching method in wireless peak-and-cell communication system

The present invention relates to a handover method in a wireless cellular communication system, and more particularly to a method for protecting data integrity during handover in a non-real time service. Background technique

Different types of services require different link quality transmissions to wireless communication terminals. The main measurement parameters are data integrity, delay, and jitter. The impact of switching on these parameters should be minimized. More precisely, the data integrity during the handover process is guaranteed. That is, the packet loss rate, retransmission, and out-of-order should not be increased due to handover. Data tunnel setup delays and jitter should be kept to a minimum. For example, the MS (mobile station) assisted handover mechanism proposed in 802.16e is an air mechanism for ensuring data integrity.

For example, in the WiMAX Forum Network Working Group, a data integrity solution for HO is proposed to ensure data integrity during the handover process. However, a disadvantage of this scheme is that the ARQ (automatic repeat request) mechanism and the SN (sequence number) feedback mechanism are implemented in the non-master data tunneling functional entity, thereby making the state of the ARQ and It is extremely difficult and cumbersome for the SN to transmit status information to be shared among multiple non-master data tunneling functional entities.

Therefore, an improved method of implementing the ARQ mechanism and the SN feedback mechanism in the main control data tunnel function body is needed to better meet the requirements. Summary of the invention

It is an object of the present invention to provide a service switching method for use in the field of wireless cellular communications to reduce the amount of message interaction used between the service data tunneling function and the target data tunneling function to maintain data synchronization.

The invention provides a service switching party for guaranteeing data integrity in a wireless cellular communication system The method includes a master data tunnel function, a service data tunnel function, a target data tunnel function, and a plurality of terminals, and the method includes the following steps:

A. After determining the handover after receiving the handover request initiated by the terminal, the main control data tunnel function body has determined whether to start the ARQ mechanism or the serial number feedback mechanism according to different services, and cache the MAC SDU data packet;

B. Before the main control data tunnel function is switched, the MAC data SDU data packet is sent to the terminal through the service data tunnel function body currently communicating with the terminal;

C. When switching access, the terminal sends feedback information to the main control data tunnel function body through the target data tunnel function body according to the received MAC SDU data packet;

D. The master data tunnel function body sends or retransmits the MAC SDU data packet to the terminal in the manner of forwarding the target data tunnel function according to the feedback information, and the handover is completed. A significant advantage of the present invention is that the processing logic for the ARQ mechanism and the SN feedback mechanism is simple and natural, avoiding a large amount of message interaction between the service data tunnel function and the target data tunnel function for maintaining data synchronization, including ARQ. The state and the SN send status information interaction. In addition, the implementation data is only cached in the main control data tunnel function body, which avoids the second level cache on the service data tunnel function body and the target data tunnel function body, reduces the complexity of the system data cache processing, and saves the cache. space. BRIEF abstract

1 is a distribution diagram of each data tunnel function body according to the method of the present invention; FIG. 2 is a detailed structural diagram of a data tunnel involved in the method according to the present invention;

3 is a flow chart of implementing an ARQ mechanism in the method according to the present invention;

4 is a flow chart showing the implementation of the SN feedback mechanism in the method of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

Figure 1 shows the distribution of the various data tunneling functionalities in the access service network system. Master The data tunnel function (Anchor Data Path Function) is the same as the non-master data tunnel function body (that is, the next level function of the master data tunnel function body, which is called the service data tunnel function body or the target data tunnel function body in the present invention. Between, establish a data tunnel, used to carry L2 (layer 2) packets. The relevant handover control message transmitted by the data tunnel is finally sent to the main control data tunnel function body, and the main control data tunnel function body ensures the continuous retransmission of the data after the handover. The non-master data tunneling function should parse the control information of the master data tunnel function body to assist in the protection of data integrity during the handover process.

The layer 2 session and layer 2 data processing, including the ARQ mechanism, are transmitted between the master data tunnel function and the core network, and the layer 2 packet buffer is implemented. After the IP layer data packet arrives at the master data tunnel function body, a layer 2 data packet can be generated and compressed into a tunnel packet to be transmitted to the service data tunnel function body or the target data tunnel function body. A tunnel packet is a packet encapsulated by a layer 2 packet using a certain protocol, such as CUDP (compress User Datagram Protocol) or UDP (User Datagram Protocol) protocol. The Serving Data Path Function in Figure 1 is associated with the physical layer of the MS with the 802.16 standard, maintains the air interface with the MS, and is responsible for transmitting all MAC layer messages to the MS. The target data path function in FIG. 1 is that the MS moves to another cell and satisfies the target under the handover condition. When the handover ends, the target data tunnel function becomes the MS new service data tunnel function. In Figure 1, the master does not actually communicate with the MS, but indirectly controls the communication through the service data tunnel function or the target data tunnel function, so it is indicated by a dotted line.

FIG. 2 shows a detailed structure of the data tunnel. In the present invention, the master data tunnel function body 201 is implemented in the base station control system BSC, and the non-master data tunnel function body 202 is placed in the base station transceiver system BTS. The implementation may be a service data tunnel function or a target data tunnel function. Of course, there are other implementations in the prior art. For example, if there is no master data tunnel function body, the IP layer data packet is directly sent by the data tunnel to the service data tunnel function body or the target data tunnel function body, the service data tunnel function body and the target data tunnel. The functional entities are each implemented in a complete base station system BS. For the downlink data packet, that is, the data packet transmitted by the AGW to the master data tunnel function body through the 102, the basic process of the conversion is that the master data tunnel function classifies the application layer IP packet (L3 data packet) into each service stream. After processing by the compression header, a MAC SDU (service data unit) is generated, and additional control information, such as SDU SN, is added thereto, and then compressed into a tunnel packet by using the cUDP protocol or the UDP protocol, and transmitted to the non-transit by 101. The main control data tunnel function body is decompressed by the non-master tunnel function body, and the control information is removed, and then a MAC PDU (protocol data unit) is formed and transmitted. The upper layer IP packet accessed by the master data tunnel function can be transmitted from the AGW (access gateway).

For uplink packets, the service data tunnel function first receives the MAC PDU and removes additional information such as MAC header, CRC (cyclic redundancy check). It is then compressed into a tunnel packet using cUDP or UDP protocol and transmitted to the master data tunnel function. After the main control data tunnel function is decompressed into a MAC SDU, it is restored to an IP data packet by header compression processing, and finally sent to the core network.

In the system, different mechanisms are used for different services to ensure data integrity during the handover process. The ARQ mechanism and the SN feedback mechanism can operate independently. For non-real-time services, the ARQ mechanism is used to ensure that the ARQ mechanism is enabled and the SN feedback mechanism is enabled. For real-time services, retransmission mechanisms cannot be used because the most important real-time requirements cannot be guaranteed, so data integrity is difficult to guarantee.

Figure 3 shows a flow chart of the ARQ mechanism in the method of the present invention. 301 is a service system, 302 is a target system, and 303 is a master control system. Each system includes a physical/MAC function body, a data tunnel function body, and a switching function body, wherein the data tunnel function bodies in 301, 302, and 303 are a service data tunnel function body, a target data tunnel function body, and a master data tunnel, respectively. Functional body. The MAC SDU is generated by the master data tunnel function and transmitted to the service data tunnel function by the data tunnel. The service data tunnel function reassembles the MAC SDU composed of the ARQ block into a MAC PDU and sends it to the MS. After the MS receives the ARQ Block, is it sent? The function receives the feedback information of an ARQ block to the service data tunnel function body, and the service data tunnel function forwards the information to the master data tunnel function body, and the master data tunnel function body determines whether the ARQ block needs to be retransmitted. Send the next new ARQ Block. Such an ARQ Block transmission process, regardless of whether or not a handover occurs, is performed in accordance with such a transmission principle. The effect of the handover on the switch is that the ARQ feedback message sent by the MS is sent to the service data tunnel function body, and is forwarded by the service data tunnel function body to the master data tunnel function body; after switching the access target, the MS The sent ARQ feedback message is sent to the target data tunnel function body, and is forwarded by the target data tunnel function body to the master data tunnel function body. For the master data tunnel function, whether or not the handover occurs does not affect its ARQ mechanism, thereby completing the handover of the service system to the target system and ensuring data integrity.

When the service of the ARQ feedback mechanism is switched, the method includes the following steps:

Step a: The terminal initiates a handover request, and when the system decides to enter the handover, the main control data tunnel function has started the ARQ feedback mechanism according to the service type, and caches the MAC SDU data packet in the main control data tunnel function body;

Step b: The master data tunnel function body sends a .MAC SDU data packet composed of an ARQ Block to the service data tunnel function currently communicating with the terminal;

Step c: The service data tunnel function sends the received ARQ Block to the terminal through the air interface;

Step d: The terminal sends a receiving confirmation message to the service data tunnel function body for each received ARQ block, and the service data tunnel function body is further forwarded to the main control data tunnel function body. If the receiving confirmation message is that the terminal does not receive the ARQ, Block, the master data tunnel function weight transfer;

Step e: When the access is switched, the terminal sends the acknowledgement information of the ARQ block received from the service data tunnel function to the target data tunnel function, and the target data tunnel function body forwards the function to the master data tunnel function body;

Step f: The main control data tunnel function body determines whether to retransmit the feedback signal according to the receiving confirmation information. ARQ Block indicated by the information: If the feedback information is that the terminal does not receive the ARQ Block, the master data tunnel function body transmits the weight to the target data tunnel function. FIG. 4 shows the flow of the SN feedback mechanism in the method of the present invention. 401 is the same as the service system in FIG. 3, 302 is the target system in FIG. 3, and 303 is the main control system in FIG. The MAC SDU is generated by the main control data tunnel function and transmitted to the service data tunnel function body through the data tunnel. The service data tunnel function group packet is formed into a MAC PDU and then transmitted to the MS. On the air interface processing, the MS can have acknowledgement feedback for each MAC SDU, or no. When the handover starts to access the target side, the MS feeds back the SN sequence number of the last MAC SDU received by the original service data tunnel function to the target data tunnel function, and the target data tunnel function forwards it to the master data tunnel. The function body, the master data tunnel function determines the first MAC SDU to be transmitted after the handover.

When the service of the SN feedback mechanism is switched, the method includes the following steps:

Step a: When the terminal initiates the handover request, the system determines to switch, and the main control data tunnel function body starts the SN feedback mechanism according to the service type, and caches the MAC SDU data packet in the main control data tunnel function body;

Step b: The master data tunnel function body sends a MAC SDU data packet to the service data tunnel function currently communicating with the terminal;

Step c: The service data tunnel function sends the received MAC SDU data packet to the terminal through the air interface, and sends the MAC SDU data packet carrying the SN sequence number to the terminal according to the period negotiated by the terminal and the master data tunnel function body;

Step d: After receiving the MAC SDU packet carrying the SN sequence number, the terminal automatically updates its saved SN sequence number. When receiving the MAC SDU packet that does not carry the SN sequence number, the terminal automatically adds one of the SN sequence numbers saved by itself. ;

Step e: The terminal feeds back the SN sequence number of the last MAC SDU packet received by the service data tunnel function from the target data tunnel function body, and then the target data tunnel function The body forwards the received SN sequence number to the master data tunnel function body;

Step f: The master data tunnel function body confirms that the terminal has successfully received the last MAC SDU sent by the service data tunnel function body according to the received SN sequence number, and the master data tunnel function body is next to the SN sequence number. The MAC SDU data packet corresponding to the sequence number starts to send the subsequent MAC SDU data packet to the target data tunnel function body;

Step g: The target data tunnel function sends the received MAC SDU data packet to the terminal.

In summary, the present invention aims to propose a reasonable broadband wireless access network handover method, so that the service data can still ensure sufficient integrity during the handover process. Industrial applicability

The present invention proposes a service switching method in a wireless cellular communication system that enables service data to maintain sufficiently good integrity during handover. The processing logic of the ARQ mechanism and the SN feedback mechanism is simple and natural, and avoids a large number of message interactions between the service data tunnel function body and the target data tunnel function body for maintaining data synchronization, including ARQ status and SN transmission. The interaction of status information. In addition, the data is only cached in the main control data tunnel function, which avoids the second level cache on the service data tunnel function and the target data tunnel function, which reduces the complexity of the system data cache processing and saves the cache space.

Claims

Claim

A service switching method for ensuring data integrity in a wireless cellular communication system, wherein the system includes a main control data tunnel function body, a service data tunnel function body, a target data tunnel function body, and a plurality of terminals, and is characterized in that The following steps:

C: When switching access, the terminal sends feedback information to the main control data tunnel function body through the target data tunnel function body according to the received MAC SDU data packet;

D. The master data tunnel function body sends or retransmits the MAC SDU data packet to the terminal in the manner of forwarding the target data tunnel function according to the feedback information, and the handover is completed.

The method according to claim 1, wherein in the step A, the master data tunnel function generates a MAC SDU data packet and caches the data, wherein, for the service adopting the ARQ mechanism, The MAC SDU data packet is decomposed into a certain size ARQ Block in the main control data tunnel function body.

The method according to claim 1 or 2, wherein the feedback information sent by the terminal in the step C is - for the ARQ mechanism, the feedback information refers to the receiving confirmation information of the ARQ block; Mechanism, the feedback information refers to the MAC SDU packet sequence number.

The method according to claim 1, wherein when the service request is initiated by the service with the serial number feedback mechanism enabled,

The step B includes the following steps: Step B1, when the service data tunnel function sends the MAC SDU data packet received from the master data tunnel function to the terminal through the air interface, according to the terminal and the master data tunnel The function of the functional entity negotiation sends the MAC SDU data packet carrying the serial number to the terminal. Step B2: After receiving the MAC SDU data packet carrying the serial number, the terminal automatically updates the serial number saved by itself, and receives the serial number that does not carry the serial number. When the MAC SDU packet is used, the serial number saved by itself is automatically incremented by one;

The step C includes:

The terminal feeds back the sequence number of the last MAC SDU packet received by the service data tunnel function from the target data tunnel function body, and then the target data tunnel function forwards the received sequence number to the master data tunnel function body;

The step D includes:

The master data tunnel function body confirms that the terminal has successfully received the last MAC SDU sent by the service data tunnel function body according to the received sequence number, and the master data tunnel function body corresponds to the MAC address corresponding to the next sequence number of the sequence number. The SDU data packet begins to send subsequent MAC SDU data packets to the target data tunnel function body, and the target data tunnel function body forwards the MAC SDU data packet to the terminal.

The method according to claim 1, wherein when the service request is initiated by the ARQ feedback mechanism,

The step B includes the following steps:

Step Bl, the main control data tunnel function body sends an ARQ Block to the service data tunnel function body currently communicating with the terminal;

Step B2: The service data tunnel function sends the received ARQ block to the terminal through the air interface.

Step B3: The terminal sends feedback information to the service data tunnel function body to each received ARQ block, and the service data tunnel function body forwards the function to the master data tunnel function body. If the feedback information is that the terminal does not receive the ARQ block, Then, the master data tunnel function is weight-transmitted; the step C includes:

After receiving the ARQ block received by the service data tunnel function, the terminal sends the ARQ Block receiving confirmation information to the target data tunnel function, and is forwarded by the target data tunnel function. Give the master data tunnel function body;

The step D includes:

The master data tunnel function determines whether to retransmit the ARQ Block indicated by the acknowledgement information according to the feedback information: If the feedback information is that the terminal does not receive the ARQ Block, the master data tunnel function body transmits the weight to the target data tunnel function.