CN101175304B - Switching method based on relay system - Google Patents

Abstract

The present invention provides a switching method based on a relay system, which includes three steps. Firstly, a first switching node selects a switching target from the obtained candidate switching targets; secondly, the first switching node is synchronized with the downlink of the switching target; thirdly, the network reentry process is fulfilled. In the present invention, the first switchingnode can be a mobile terminal, and the switching target can be a relay station; or the first switching node can be a relay station, and the switching target can be a relay station or a base station; the technical scheme provided by the present invention realizes the switching method related to relay stations. In the present invention, the first switching node can be a mobile terminal, the switching target can be a base station, and the technical scheme provided by the present invention realizes the method by which a mobile terminal can switch base stations in the relay system.

Description

Handover Method Based on Relay System

technical field

The present invention relates to wireless communication technology, in particular to relay system-based switching technology in wireless communication technology.

Background technique

In the field of wireless communication, wireless access technology is one of the current research hotspots, especially broadband wireless access technology has received more attention because it can provide users with a high access rate. The IEEE802.16e system is a kind of broadband wireless access system, and its working group has released the final version specification of the physical layer and MAC (Media Access Control) layer of the broadband wireless access system, which includes working in 10 The requirements for fixed and mobile wireless networks with high data rate direct line-of-sight signals in the range of ~66GHz also include the requirements for fixed, portable and mobile systems operating under non-line-of-sight below 11GHz.

Both the wireless access system and the broadband wireless access system include MS (Mobile Station, mobile terminal) and BS (Base station, base station). FIG. 1 is a schematic diagram of a simple networking of a wireless access system. As shown in FIG. 1 , multiple base stations are connected to the core network together, and each base station can provide services for at least one mobile terminal. Because the mobile terminal moves from the cell covered by one base station to the cell covered by another base station or the load of the base station serving the mobile terminal is relatively large, the mobile terminal needs to change the base station serving it. We call this process handover, where , the mobile terminal is called a switching node. The base station that provides services for the mobile terminal before the handover is called the original serving base station, and the changed base station is called the target base station, which may also be called the handover target. The handover process can be initiated by the mobile terminal and the base station respectively.

Fig. 2 is a flow chart of the handover process initiated by the mobile terminal. As shown in Figure 2, it includes the following steps:

Step S201: Perform a cell reselection process, that is, the mobile terminal obtains a neighbor base station list and related information of the neighbor base stations.

Step S202: Carry out the process of initiating and judging the handover, the implementation of this process may be as follows:

The mobile terminal sends a MOB_MSHO-REQ message to the original serving base station, requesting one or more candidate target base stations;

The original serving base station replies the MOB_BSHO-RSP message to the mobile terminal, and the message may carry relevant information of one or more candidate target base stations, such as information such as the operating status of the mobile terminal under these candidate target base stations;

The mobile terminal sends a MOB_HO-IND message to the original serving base station, and the message may carry the decision of the selected target base station.

Step S203: the mobile terminal synchronizes with the downlink of the target base station;

Step S204: Perform a network re-entry process, which can be implemented in the following ways:

Perform CDMA code ranging, and the target base station allocates a contention or non-competition ranging resource for the mobile terminal;

The mobile terminal sends a RNG-REQ message to the target base station, and the message carries the identification of the mobile terminal, the identification of the original serving base station, and the identification of the ranging type;

The target base station returns a RNG-RSP message to the mobile terminal, and the RNG-RSP message may carry parameters such as service level prediction and handover process optimization;

Subsequent processing steps of the re-entry process are performed.

Step S205: The original serving base station terminates all connections and related contexts with the mobile terminal.

Fig. 3 is a flow chart of the handover process initiated by the original serving base station. The handover process initiated by the original serving base station is basically the same as the handover process initiated by the mobile terminal. The information of one or more candidate target base stations recommended by the mobile terminal. After receiving the MOB_BSHO-REQ message, the mobile terminal returns the MOB_HO-IND message to the original serving base station, and the message carries the decision of the selected target base station.

Because radio waves with high frequencies attenuate quickly with distance, the coverage of base stations operating at high frequencies is very limited. In order to solve the coverage problem of the base station, a wireless relay station can be added in the wireless access system. The relay station can communicate with the base station through the air interface and forward the data of the mobile terminal. The complexity of building a relay station is much smaller than that of building a base station. Under the same system performance requirements, such as system coverage and throughput, the time and cost of building a relay station are less than that of building a base station. Therefore, using the relay station can improve the performance of the wireless access system at a lower cost. A wireless access system using a relay station is called a relay system. FIG. 4 is a schematic diagram of a simple networking of a relay system. As shown in Fig. 4, multiple base stations are connected to the core network together, each base station can provide service for at least one mobile terminal or relay station, and each relay station can provide service for at least one mobile terminal or relay station. A relay station or base station that provides services for mobile terminals and/or relay stations is called a serving node.

In a wireless access system without a relay station, the base station is the only handover target of the mobile terminal, while in a relay system, the base station is not only the handover target of the mobile terminal, but the relay station may also be the handover target of the mobile terminal, for example, the mobile terminal When moving from the service area of the original serving relay station to the service area of another relay station inside or outside the cell, the mobile terminal also initiates a handover process at this time. In addition, the relay station can also move. When the relay station moves from the coverage area of the original serving base station to the coverage area of another base station, the relay station needs to initiate a handover process. Therefore, in the relay system, the handover node can be a mobile terminal or a relay station, and the handover target can be a relay station or a base station.

At present, there is no specific technical solution for the handover process in the relay system.

Contents of the invention

The technical problem to be solved by the embodiments of the present invention is to provide a handover method based on a relay system, so as to realize the handover method in the relay system.

In order to solve the above-mentioned technical problems, an embodiment of the present invention provides a relay system-based handover method, including: the first handover node selects a handover target from the acquired candidate handover targets, specifically including: obtaining at least one candidate handover target information, evaluate the candidate handover target, and notify the original serving node of the selected handover target; the first handover node synchronizes with the downlink of the handover target; complete the network re-entry process, specifically including: performing the CDMA code ranging process, Synchronize the uplinks of the first switching node and the switching target; the switching target allocates ranging resources for the first switching node; the first switching node sends a ranging request message to the switching target; the switching target returns the ranging to the first switching node Response message; if the handover target obtains the time when the first handover node will perform ranging in advance, it is not necessary to perform CDMA code ranging, and the handover target directly allocates non-competition ranging resources for the first handover node; wherein, the first handover node is a mobile For a terminal, the handover target is a relay station or a base station; or, the first handover node is a relay station, and the handover target is a relay station or a base station.

Compared with the prior art, the embodiment of the present invention has the following advantages:

In the embodiment of the present invention, the first handover node may be a mobile terminal, and the handover target may be a relay station, or the first handover node may be a relay station, and the handover target may be a relay station or a base station. The technical solution provided by the embodiment of the present invention realizes Handover methods involving relay stations;

In the embodiment of the present invention, the first handover node may be a mobile terminal, and the handover target may be a base station. The technical solution provided by the embodiment of the present invention realizes a method for a mobile terminal to handover a base station in a relay system.

Description of drawings

FIG. 1 is a schematic diagram of a simple networking of an existing wireless access system;

Fig. 2 is the flow chart of the handover procedure initiated by the existing mobile terminal;

FIG. 3 is a flow chart of the handover process initiated by the existing original serving base station;

FIG. 4 is a schematic diagram of a simple networking of the relay system of the present invention;

FIG. 5 is a flowchart of a first embodiment of a handover method initiated by a mobile terminal of the present invention;

FIG. 6 is a flowchart of a second embodiment of the handover method initiated by the mobile terminal of the present invention;

FIG. 7 is a flowchart of an embodiment of the handover method initiated by the original serving relay station of the present invention;

FIG. 8 is a flow chart of an embodiment of the handover method initiated by the original serving base station of the present invention;

FIG. 9 is a flow chart of the first embodiment of the handover method initiated by the relay station of the present invention;

FIG. 10 is a flow chart of the second embodiment of the handover method initiated by the relay station of the present invention.

Detailed ways

Below we will describe in detail the best implementation of the present invention with reference to the accompanying drawings. First of all, it should be pointed out that the meanings of the terms, words and claims used in the present invention should not be limited to their literal and ordinary meanings, but also include meanings and concepts that are consistent with the technology of the present invention. This is because It is up to us, as inventors, to define terms appropriately in order to best describe our inventions. Therefore, the configurations given in this specification and the accompanying drawings are only preferred implementations of the present invention, rather than enumerating all technical characteristics of the present invention. We need to recognize that there are various equivalents or modifications that could replace ours.

Firstly, the overall technical solution of the method provided by the embodiment of the present invention will be described. The relay system-based handover method in the embodiment of the present invention includes: the first handover node selects a handover target from the obtained candidate handover targets; the first handover node synchronizes the downlink of the handover target; and completes network re-entry process.

The first handover node can be a mobile terminal, the handover target can be a relay station or a base station, and the original serving node providing services for the mobile terminal can be a relay station or a base station, that is, the original serving relay station can be changed to a new one in the same cell or outside the cell The relay station or base station, the original serving base station can also be changed to a new relay station or base station in the same cell or outside the cell. The handover can be initiated by the mobile terminal, or by the original serving relay station or the original serving base station.

Now, the handover methods in the above multiple situations will be described in detail in combination with specific embodiments.

Fig. 5 is a flow chart of the first embodiment of the handover method initiated by the mobile terminal. In this embodiment, the low-capability relay station serves the mobile terminal, the base station provides service for the low-capability relay station, and the handover target of the mobile terminal is the base station, another relay station in the same cell, or another relay station in a different cell . Among them, the low-capability relay station can only transparently transmit the message, does not change the content of the MAC message, and has no ability to generate, modify or terminate the signaling involved in the handover process. The reason why the mobile terminal initiates the handover may be that the mobile terminal moves from the service area of the original serving low-capability relay station to the service area of another relay station, or moves to the coverage area of another base station. In order to obtain better service quality, the mobile terminal requests Replace the relay station or base station that serves it.

As shown in Figure 5, this embodiment comprises the following steps:

Step S501: Perform a handover target reselection process. The main purpose of this process is to enable the mobile terminal to obtain a list of neighboring relay stations or neighboring base stations and their information, which can be achieved in the following manner:

The mobile terminal obtains the list of neighbor relay stations or neighbor base stations from the neighbor broadcast message MOB_NBR-ADV. The MOB_NBR-ADV message is a broadcast message sent by the original serving low-capacity relay station or the original serving base station. The original serving relay station or the original serving base station within the service range All mobile terminals or relay stations can receive it. Among them, the mobile terminal can obtain the operator identifier, configuration update counter, block identification, total block number, number of neighbor sites, and the number of each neighbor site from the MOB_NBR-ADV message. Relevant information, the relevant information can include the physical characteristic identifier of each site, frequency allocation, site EIRP (equivalent isotropically radiated power, equivalent isotropic radiated power), BSID (base station identification), signal preamble number, handover process optimization Parameters, supportable scheduling service types, DCD (Downlink Channel Descriptor, downlink channel descriptor) configuration update count, UCD (Uplink Channel Descriptor, uplink channel descriptor) configuration update count and security information, of course, these information Some are optional. In addition, the mobile terminal can obtain the MOB_NBR-ADV message at intervals, and the list of neighbor relay stations or neighbor base stations in the MOB_NBR-ADV message may be updated;

The mobile terminal selectively scans or measures neighbor relay stations or neighbor base stations. For example, the mobile terminal can select the target of scanning or measurement from multiple lists obtained. The downlink of the base station is synchronized and the downlink signal is measured;

If the mobile terminal thinks that the obtained information is insufficient or for other reasons, it can also continue to perform ranging on the uplink of the scanned neighbor relay station or neighbor base station on the basis of scanning to obtain ranging parameters. This process is called for union.

The mobile terminal can obtain the measured result of the neighbor base station, service level prediction and distance measurement parameters that the neighbor base station can provide from the scanning or association process. Among them, in the scanning process, the mobile terminal only measures the potential target base stations, and can only obtain the measurement results of the neighbor base stations, while the joint process is based on the scanning, and performs joint ranging on the potential target base stations to obtain the ranging parameters and service level forecasts available from base stations. The measured results can include average CINR (carrier-to-interference ratio), RSSI (Received Signal Stengh Indicator, received signal strength indicator), relative delay, round-trip path delay of the anchor station, ranging parameters can include time adjustment parameters, power level adjustment , frequency adjustment, ranging status.

Through the above steps, the mobile terminal obtains the information of the neighbor relay station or the neighbor base station.

Step S502: Initiate and judge the process of handover. The main purpose of this process is to make the mobile terminal select one of the candidate target relay stations or candidate target base stations as the target relay station or target base station, which can be realized in the following manner:

The mobile terminal sends a handover request message MOB_MSHO-REQ to the original serving relay station. Since the original serving relay station is a low-capability relay station, the original serving relay station forwards the MOB_MSHO-REQ message to the original serving base station. The MOB_MSHO-REQ message indicates that the mobile terminal requests the candidate target relay station or base station;

The original serving base station returns a handover response message MOB_BSHO-RSP to the original serving relay station, and the original serving relay station forwards the MOB_BSHO-RSP message to the mobile terminal, and the MOB_BSHO-RSP message carries information of at least one candidate target relay station or base station;

The mobile terminal evaluates the candidate target relay station or base station, and sends a handover indication message MOB_HO-IND to the original serving relay station, and the original serving relay station forwards the MOB_HO-IND message to the original serving base station. The MOB_HO-IND message indicates the target relay station or base station selected by the mobile terminal. The decision of the base station, that is, it indicates which relay station or base station is selected as the target relay station or base station to be handed over.

If the handover target of the mobile terminal is the target relay station, the original serving base station will notify the base station serving the target relay station of information such as the handover target selected by the mobile terminal, and the base station providing service for the target relay station will then send a handover instruction message to the target relay station, To inform the target relay station of the allocated handover identifier (if it has been allocated in MOB_BSHO-RSP) and the start time, the format of the handover instruction message is shown in Table 1:

grammar Size (unit: bit) illustrate HO-IND message format (){ - - Management Message Type 8 message type mode 2 0b00: used for switching instructions 0b01～0b11: reserved Reserved 6 Should be set to 0. If(Mode==0b00){ If this message is for switching HO_ID-included_indicator 1 0b00: If(HO_ID-included_indicator==1){ HO_ID 8

} Action Time 2 Padding 5 is 0 TLV cncoded information 2 TLV encoded information, including authentication security information }

Table 1 Switching instruction message format

After the above process is completed, the original serving relay station stops communication with the mobile terminal.

It should be noted that the MOB_HO-IND message sent by the mobile terminal can have multiple states. If it is in the state of releasing the original serving relay station, it means that the mobile terminal will perform a handover and terminate the communication with the original serving relay station; if it is in the reject state, Then the original serving base station resends the MOB_BSHO-RSP message to re-recommend the candidate target relay station or base station; if it is in the canceled state, both the mobile terminal and the original serving base station cancel the handover operation and return to the normal working state.

It should also be noted that the candidate target relay station or base station provided by the original serving relay station or the original serving base station may be the same, partly or completely different from the neighbor relay station or neighbor base station obtained by the mobile terminal in step S501.

Step S503: The mobile terminal synchronizes with the downlink of the target relay station or base station. The main purpose of this process is to enable the mobile terminal to successfully obtain the uplink and downlink transmission parameters of the target relay station or base station. If the mobile terminal has previously Obtain the identification, operating frequency, DCD (Downlink Channel Descriptor, downlink channel descriptor) and UCD (Uplink Channel Descriptor, uplink channel descriptor) parameters of the target relay station or base station from the MOB_NBR-ADV message, which can speed up synchronization the process of.

Step S504: Complete the network re-entry process. The main purpose of this process is to enable the mobile terminal and the target relay station or base station to obtain the relevant information of the other party respectively, so as to prepare for subsequent normal information. This process includes:

Carry out the CDMA code ranging process, one purpose of this process is to synchronize the uplink between the mobile terminal and the target relay station or base station;

The target relay station or base station allocates ranging resources for the mobile terminal;

The mobile terminal sends a ranging request message RNG-REQ to the target relay station or base station. The RNG-REQ carries the identification of the mobile terminal, the identification of the original serving base station or relay station, and the identification of the ranging type. The identification of the ranging type indicates switching ranging;

The target relay station or base station returns a ranging response message RNG-RSP to the mobile terminal. The RNG-RSP message can carry the basic CID (ConnectionIdentifier, connection identifier) allocated by the target relay station or base station for the mobile terminal, the main management CID, and the target relay station or base station. Service provision capability, handover process optimization and other relevant information;

Perform the subsequent steps of the network re-entry process. If the handover target is the target base station, the subsequent steps of the network re-entry process include: re-authentication process, basic capability negotiation process, re-registration process, and service flow re-establishment process.

Wherein, in the re-authentication process, the mobile terminal sends an authentication request message to the target base station, and the authentication request message carries the identification and the digital certificate of the mobile terminal;

If the target base station determines that the mobile terminal is legal, then return an authentication response message to the mobile terminal, and the target base station distributes an authentication key to the mobile terminal in the authentication response message;

After receiving the authentication response message, the mobile terminal can further send a key request message to request a service key from the target base station;

The target base station returns a key response message to the mobile terminal, and the target base station allocates a service key to the mobile terminal in the key response message.

During the basic capability negotiation process, the mobile terminal requests the target base station for system parameters and functions it can support through a capability negotiation request, and the target base station notifies the mobile terminal of the functions agreed by the target base station through a capability negotiation response.

During the re-registration process, the mobile terminal registers its supported IP version and management mode with the target base station through the registration request message, and the target base station notifies the mobile terminal of the IP version and management mode supported by the system in the registration response message.

During the service flow re-establishment process, the mobile terminal requests the service flow and service flow type and its QoS (Quality of Service) parameters through the service flow request message establishment, and the target base station agrees or refuses to establish the service flow in the service flow establishment response message For the service flow, the mobile terminal confirms the response message in the service flow establishment confirmation message.

In each of the above processes, if the mobile terminal has been informed in the handover process optimization parameters in the RNG-RSP message that some steps can be omitted, then the corresponding steps can be omitted during the network re-entry process.

If the handover target is the target relay station, the subsequent steps of the network re-entry process may also sequentially include: a re-authentication process, a basic capability negotiation process, a re-registration process, and a service flow re-establishment process. Regardless of whether the target relay station is a high-capability relay station or a low-capability relay station, it can transparently transmit the messages exchanged between the mobile terminal and the serving base station that provides services for the target relay station. Therefore, the serving base station that provides services for the target relay station can complete the network on behalf of the target relay station Next steps in the re-entry process.

It should be noted that if the target relay station or base station obtains the time when the mobile terminal will perform ranging in advance, it is not necessary to perform CDMA code ranging, and the target relay station or base station can directly allocate non-contention ranging resources for the mobile terminal.

Step S505: The original serving relay station terminates the communication with the mobile terminal and the context, such as information in the queue, ARQ (Automatic Repeat Request, access request) state machine, counter, timer or header compression related information, etc., if The original serving relay station does not have the ability to terminate the communication and context, so the original serving base station can complete this process, and the original serving relay station only needs to transparently transmit signaling or messages.

In the embodiment shown in FIG. 5 , the original serving relay station provides services for the mobile terminal. If the original serving base station provides services for the mobile terminal, the handover steps are basically the same as those shown in FIG. 5 , as long as the The communication between the mobile terminal and the original serving relay station can be changed to the communication between the mobile terminal and the original serving base station.

In the embodiment shown in FIG. 5, if the handover target is a target relay station in the same cell as the original serving relay station, then there is no need to perform context termination, and step S505 can be omitted; if the handover target is a target relay station in a different cell from the original serving relay station target relay station, then in step S501, the list provided by the original serving relay station may be a list of neighbor base stations and/or a list of relay stations within the coverage of these neighbor base stations, and the original serving relay station may request the original serving base station to obtain these list information, the original serving station If the base station does not have the list information or the list information is insufficient and outdated, it can obtain the list information from the core network.

Fig. 6 is a flow chart of the second embodiment of the handover method initiated by the mobile terminal. In this embodiment, the high-capability relay station serves the mobile terminal, the base station provides services for the high-capability relay station, and the handover target of the mobile terminal is the base station, another relay station in the same cell, or another relay station in a different cell . Among them, the high-capability relay station can change the message content of the MAC, and has the ability to generate, modify or terminate the signaling involved in the handover process. The reason why the mobile terminal initiates the handover may be that the mobile terminal moves from the service area of the original serving relay station to the service area of another relay station, or moves to the coverage area of another base station. In order to obtain better service quality, the mobile terminal requests to change to The relay station or base station it serves.

As shown in Figure 6, this embodiment comprises the following steps:

Step S601: Perform the handover target reselection process. The main purpose of this process is to enable the mobile terminal to obtain the list and information of neighboring relay stations or neighboring base stations, which can be realized in the following manner:

The mobile terminal obtains the list of neighbor relay stations or neighbor base stations from the neighbor broadcast message MOB_NBR-ADV. The MOB_NBR-ADV message is a broadcast message sent by the original serving relay station or the original serving base station. All mobile terminals within the service range of the original serving relay station or the original serving base station Both the terminal or the relay station can receive it, and the mobile terminal can obtain the operator identifier, configuration update counter, block identification, total block number, number of neighbor sites, and related information of each neighbor site from the MOB_NBR-ADV message , the relevant information may include the physical characteristic identifier of each site, frequency allocation, site EIRP, BSID, signal preamble number, handover process optimization parameters, supported scheduling service types, DCD configuration update count, UCD configuration update count, and Security information, of course, some of this information is optional. In addition, the mobile terminal can obtain the MOB_NBR-ADV message at intervals, and the list of neighbor relay stations or neighbor base stations in the MOB_NBR-ADV message may be updated;

The mobile terminal selectively scans or measures neighbor relay stations or neighbor base stations. For example, the mobile terminal can select the target of scanning or measurement from multiple lists obtained. The downlink of the base station is synchronized and the downlink signal is measured;

If the mobile terminal thinks that the obtained information is insufficient or for other reasons, it can also continue to perform ranging on the uplink of the scanned neighbor relay station or neighbor base station on the basis of scanning to obtain ranging parameters. This process is called for union.

Through the above steps, the mobile terminal obtains the information of the neighbor relay station or the neighbor base station.

Step S602: Carry out handover initiation and decision process. The main purpose of this process is to enable the mobile terminal to select a target relay station or target base station from candidate target relay stations or candidate target base stations, which can be realized in the following manner:

The mobile terminal sends a handover request message MOB_MSHO-REQ to the original serving relay station, and the MOB_MSHO-REQ message indicates that the mobile terminal requests a candidate target relay station or base station;

The MOB_MSHO-REQ message sent by the mobile terminal contains the handover target list required by the mobile terminal. The original serving relay station can modify this list. If the original serving relay station has enough new relevant information about its recommended handover target, it can directly reply to MOB_BSHO -RSP; if it cannot reply directly, it needs to send a handover parameter request message to the original serving base station to request to obtain relevant information. The original serving relay station first identifies the station identified by the 8-bit neighbor station identifier in MOB_MSHO-REQ with its 48-bit complete station identifier, and then sends a switching parameter request message to request the parameters of the neighbor station that needs to request parameters from the original serving base station , these parameters can include connection resource maintenance, signal preamble index, service level prediction, network assisted handover support, authentication strategy during handover, execution time, etc. Of course, some parameters can also be requested, where the neighbor station identifier is in MOB_NBR- assigned in the ADV message. After receiving the handover parameter request message, the original serving base station inquires out the cell base stations where the recommended handover target is located, and requests these parameters from these base stations respectively. Since these base stations already know the capabilities and resource allocation of all relay stations serving, they can Reply these parameters through the core network. After receiving all reply messages from these base stations, the original serving base station can generate a handover parameter response message and send it to the original serving relay station. After the original serving relay station receives the handover parameter response message, it combines the existing neighbor station information. At the same time, if any of these neighbor stations has a base station that has allocated an 8-bit neighbor station identifier in the MOB_NBR-ADV message, it will replace it with an 8-bit identifier. 48-bit flag, generating MOB_BSHO-RSP message.

If the original serving relay station has obtained relevant information such as the latest service provision capability, handover process optimization, and post-handover authentication method indication of at least one candidate target relay station or base station, it can directly return the handover response message MOB_BSHO-RSP to the mobile terminal; otherwise, the original serving relay station The serving relay station sends a handover parameter request message to the original serving base station to request relevant information such as the latest service provision capability, handover process optimization, and post-handover authentication method indication of at least one candidate target relay station or base station, and the original serving base station returns a handover parameter response to the original serving relay station message, the handover parameter response message carries at least one candidate target relay station or base station's latest service provision capability, handover process optimization, post-handover authentication method indication and other related information, and the original serving relay station returns the handover response message MOB_BSHO-RSP to the mobile terminal, The format of the switching parameter request message and the switching parameter response message format are shown in Table 2 and Table 3 respectively;

The mobile terminal evaluates the candidate target relay station or base station, and sends a handover indication message MOB_HO-IND to the original serving relay station, and the original serving relay station forwards the MOB_HO-IND message to the original serving base station. The MOB_HO-IND message indicates the target relay station or base station selected by the mobile terminal. The decision of the base station, that is, it indicates which relay station or base station is selected as the target relay station or base station to be handed over.

grammar Size (unit: bit) illustrate

MOB_HOPARA-REQ message format () { - - Management Message Type 8 message type mode 3 0b000: Parameter request for switching 0b001～0b111: Reserved Reserved 5 Should be set to 0 If(Mode==0b000){ If this message is for switching N_Para_Req 8 Neighbor stations that require request parameters For(j=0; j<N_Para_Req; j++){ Neighbor S I D 48 The identifier of the neighbor station Para_Indicator 8 If the bit is set to 1, it means that this parameter is requested. Bit 0: Preamble index Bit 1: Service Level Prediction Bit 2: HO Process Optimization Bit 3: Network Assisted Handover Support HO support) 4th bit: Authentication policy during handover (HO_authorization_policy_support) 5th bit: Resource Retain 6th bit: Action Time 7th bit: Reserved } padding Variable Padding bits, to ensure that the length of this message is an integer multiple of 8 bits TLV encoded information 2 TLV encoded information, including authentication security information }

Table 2 Switch parameter request message format

grammar Size (unit: bit) illustrate MOB_HOPARA-RSP message format () { - - Management Message Type 8 message type

mode 3 0b000: parameter response for switching 0b001～0b111: reserved Reserved 5 Should be set to 0 If(Mode==0b000){ If this message is for switching N_Para_Req 8 Neighbor stations that require request parameters Resource Retain Flag 1 0: Release connection information 1: Keep connection information Reserved 7 Reserved bits, to be set to 0 For(j=0; j<N_Para_Req; j++){ Neighbor S I D 48 The identifier of the neighbor station Para_Indicator 8 If the bit is set to 1, it means that this parameter is requested. Bit 0: Signal preamble index Bit 1: Service level prediction Bit 2: Handover process optimization Bit 3: Network-assisted handover support Bit 4: Authentication strategy during handover Bit 5.6.7 : Reserved If Para_Indicator[bit#0]＝＝1){ Preamble index/Preamble Present 8 The signal leader of the neighbor station } lf Para_Indicator[bit#1]==1){ Service Level Prediction 8 0: No service can be provided to this MS 1: One or more authenticated services can be provided to the MS 2: For each authenticated service flow, the MAC connection can meet the requirements of the authentication QoS parameter set. 3: Unable to obtain business level forecast } If Para_Indicator[bit#2]＝＝1){ HO Process Optimization 16 Where each bit is set, it means that the steps of can be omitted during the switching process. The setting method is the same as that in 802.16e. } If Para_Indicator[bit#3]＝＝1){ Network Assisted HO support 1 0: Does not support network-assisted switching

1: Support network-assisted switching } If Para_Indicator[bit#4]＝＝1){ HO_authorization_policy_support 8 } Padding 7 Padding bits } Action time 8 Start Time padding Variable Padding bits, to ensure that the length of this message is an integer multiple of 8 bits TLV encoded information 2 TLV encoded information, including authentication security information }

Table 3 Toggle parameter response message format

If the handover target of the mobile terminal is the target relay station, the original serving base station will notify the base station serving the target relay station of information such as the handover target selected by the mobile terminal, and the base station providing service for the target relay station will then send a handover instruction message to the target relay station, The format of the handover indication message is shown in Table 1 to inform the target RS of the allocated handover identifier (if allocated in MOB_BSHO-RSP) and start time. After the above process is completed, the original serving relay station stops communication with the mobile terminal.

It should be noted that the MOB_HO-IND message sent by the mobile terminal can have multiple states. If it is in the state of releasing the original serving relay station, it means that the mobile terminal will perform a handover and terminate the communication with the original serving relay station; if it is in the reject state, Then the original serving base station resends the MOB_BSHO-RSP message to re-recommend the candidate target relay station or base station; if it is in the canceled state, both the mobile terminal and the original serving base station cancel the handover operation and return to the normal working state.

Step S603: The mobile terminal synchronizes with the downlink of the target relay station or base station. The main purpose of this process is to enable the mobile terminal to obtain the transmission parameters of the uplink and downlink of the target relay station or base station. - The identification, operating frequency, DCD (Downlink Channel Descriptor, downlink channel descriptor) and UCD (Uplink Channel Descriptor, uplink channel descriptor) parameters of the target relay station or base station are obtained in the ADV message, which can speed up the synchronization process .

Step S604: Complete the network re-entry process. The main purpose of this process is to enable the mobile terminal and the target relay station or base station to obtain the relevant information of each other and prepare for subsequent normal information. This process includes:

Carry out the CDMA code ranging process, one purpose of this process is to synchronize the uplink between the mobile terminal and the target relay station or base station;

The target relay station or base station allocates ranging resources for the mobile terminal;

The mobile terminal sends a ranging request message RNG-REQ to the target relay station or base station. The RNG-REQ carries the identification of the mobile terminal, the identification of the original serving base station or relay station, and the identification of the ranging type. The identification of the ranging type indicates switching ranging;

The target relay station or base station returns a ranging response message RNG-RSP to the mobile terminal. The RNG-RSP message can carry the basic CID (ConnectionIdentifier, connection identifier) allocated by the target relay station or base station for the mobile terminal, the main management CID, and the target relay station or base station. Service provision capability, handover process optimization and other relevant information;

Perform the subsequent steps of the network re-entry process. If the handover target is the target base station, the subsequent steps of the network re-entry process include: re-authentication process, basic capability negotiation process, re-registration process, and service flow re-establishment process.

Wherein, in the re-authentication process, the mobile terminal sends an authentication request message to the target base station, and the authentication request message carries the identification and the digital certificate of the mobile terminal;

If the target base station determines that the mobile terminal is legal, then return an authentication response message to the mobile terminal, and the target base station distributes an authentication key to the mobile terminal in the authentication response message;

After receiving the authentication response message, the mobile terminal can further send a key request message to request a service key from the target base station;

The target base station returns a key response message to the mobile terminal, and the target base station allocates a service key to the mobile terminal in the key response message.

During the basic capability negotiation process, the mobile terminal requests the target base station for system parameters and functions it can support through a capability negotiation request, and the target base station notifies the mobile terminal of the functions agreed by the target base station through a capability negotiation response.

During the re-registration process, the mobile terminal registers its supported IP version and management mode with the target base station through the registration request message, and the target base station notifies the mobile terminal of the IP version and management mode supported by the system in the registration response message.

During the re-establishment process of the service flow, the mobile terminal requests the service flow, the type of the service flow and its QoS parameters through the establishment of the service flow request message, and the target base station agrees or refuses to establish the service flow in the service flow establishment response message. The response message is confirmed in the establishment confirmation message.

In each of the above processes, if the mobile terminal has been informed in the handover process optimization parameters in the RNG-RSP message that some steps can be omitted, then the corresponding steps can be omitted during the network re-entry process.

If the handover target is the target relay station, the subsequent steps of the network re-entry process may also sequentially include: a re-authentication process, a basic capability negotiation process, a re-registration process, and a service flow re-establishment process. Regardless of whether the target relay station is a high-capability relay station or a low-capability relay station, it can transparently transmit the messages exchanged between the mobile terminal and the serving base station that provides services for the target relay station. Therefore, the serving base station that provides services for the target relay station can complete the network on behalf of the target relay station Next steps in the re-entry process.

It should be noted that if the target relay station or base station obtains the time when the mobile terminal will perform ranging in advance, it is not necessary to perform CDMA code ranging, and the target relay station or base station can directly allocate non-contention ranging resources for the mobile terminal.

Step S605: The original serving relay station terminates the communication with the mobile terminal and the context, such as information in the queue, ARQ (Automatic Repeat Request, access request) state machine, counter, timer, or header compression related information.

In the embodiment shown in FIG. 6, the original serving relay station provides services for the mobile terminal. If the original serving base station provides services for the mobile terminal, the handover steps are basically the same as those shown in FIG. 6, as long as the The communication between the mobile terminal and the original serving relay station can be changed to the communication between the mobile terminal and the original serving base station.

It should be noted that although the high-capability relay station provides services for the mobile terminal in the embodiment shown in FIG. 6 , the high-capability relay station may also have the capability of the low-capability relay station, that is, transparently transmit received messages.

In the embodiment shown in FIG. 6, if the handover target is a target relay station in the same cell as the original serving relay station, there is no need to perform context termination, and step S605 can be omitted; if the handover target is a target relay station in a different cell from the original serving relay station target relay station, then in step S601, the list provided by the original serving relay station may be a list of neighbor base stations and/or a list of relay stations within the coverage of these neighbor base stations, and the original serving relay station may request the original serving base station to obtain these list information, the original serving station If the base station does not have the list information or the list information is insufficient and outdated, it can obtain the list information from the core network.

Fig. 7 is a flow chart of an embodiment of the handover method initiated by the original serving relay station. In this embodiment, the relay station that initiates the handover is a high-capability relay station, the base station provides services for the high-capability relay station, and the handover target of the mobile terminal is the base station, another relay station in the same cell, or another relay station in a different cell. Among them, the high-capability relay station can change the message content of the MAC, and has the ability to generate, modify or terminate the signaling involved in the handover process. The reason why the original serving relay station initiates the handover may be that the mobile terminal moves from the service area of the original serving relay station to the service area of another relay station or the coverage area of another base station. In order to enable the mobile terminal to obtain better service quality, or the original serving relay station The original serving relay station can replace the mobile terminal with the relay station or base station serving it for reasons such as excessive load on itself, or the reduction of the transmission power of the original serving relay station leading to weakening of the signal of the mobile terminal.

As shown in Figure 7, this embodiment comprises the following steps:

Step S701: Perform a handover target reselection process. The main purpose of this process is to enable the mobile terminal to obtain a list of neighbor relay stations or neighbor base stations and their information, which can be achieved in the following manner:

The mobile terminal obtains the list of neighbor relay stations or neighbor base stations from the neighbor broadcast message MOB_NBR-ADV. The MOB_NBR-ADV message is a broadcast message sent by the original serving relay station or the original serving base station. All mobile terminals within the service range of the original serving relay station or the original serving base station Both the terminal or the relay station can receive it, and the mobile terminal can obtain the operator identifier, configuration update counter, block identification, total block number, number of neighbor sites, and related information of each neighbor site from the MOB_NBR-ADV message , the relevant information may include the physical characteristic identifier of each site, frequency allocation, site EIRP, BSID, signal preamble number, handover process optimization parameters, supported scheduling service types, DCD configuration update count, UCD configuration update count, and Security information, of course, some of this information is optional. In addition, the mobile terminal can obtain the MOB_NBR-ADV message at intervals, and the list of neighbor relay stations or neighbor base stations in the MOB_NBR-ADV message may be updated;

The mobile terminal selectively scans or measures neighbor relay stations or neighbor base stations. For example, the mobile terminal can select the target of scanning or measurement from multiple lists obtained. The downlink of the base station is synchronized and the downlink signal is measured;

If the mobile terminal thinks that the obtained information is insufficient or for other reasons, it can also continue to perform ranging on the uplink of the scanned neighbor relay station or neighbor base station on the basis of scanning to obtain ranging parameters. This process is called for union.

Through the above steps, the mobile terminal obtains the information of the neighbor relay station or the neighbor base station.

Step S702: Carry out handover initiation and decision process. The main purpose of this process is to enable the mobile terminal to select a target relay station or target base station from candidate target relay stations or candidate target base stations, which can be achieved in the following manner:

If the original serving relay station has obtained relevant information such as the latest service provision capability, handover process optimization, and post-handover authentication method indication of at least one candidate target relay station or base station, it can directly send the handover request message MOB_BSHO-REQ to the mobile terminal; otherwise, the original serving relay station The serving relay station sends a handover parameter request message to the original serving base station to request relevant information such as the latest service provision capability, handover process optimization, and post-handover authentication method indication of at least one candidate target relay station or base station, and the original serving base station returns a handover parameter response to the original serving relay station message, the handover parameter response message carries at least one candidate target relay station or base station's latest service provision capability, handover process optimization, post-handover authentication method indication and other related information, and the original serving relay station sends a handover request message MOB_BSHO-REQ to the mobile terminal, The MOB_BSHO-REQ message can be generated by the original serving base station or by the original serving relay station;

The mobile terminal evaluates the candidate target relay station or base station, and sends a handover indication message MOB_HO-IND to the original serving relay station, and the original serving relay station forwards the MOB_HO-IND message to the original serving base station. The MOB_HO-IND message indicates the target relay station or base station selected by the mobile terminal. The decision of the base station, that is, it indicates which relay station or base station is selected as the target relay station or base station to be handed over.

If the handover target of the mobile terminal is the target relay station, the original serving base station will notify the base station serving the target relay station of information such as the handover target selected by the mobile terminal, and the base station providing service for the target relay station will then send a handover instruction message to the target relay station, The format of the handover indication message is shown in Table 1 to inform the target RS of the allocated handover identifier (if allocated in MOB_BSHO-RSP) and start time.

After the above process is completed, the original serving relay station stops communication with the mobile terminal.

It should be noted that the MOB_HO-IND message sent by the mobile terminal can have multiple states. If it is in the state of releasing the original serving relay station, it means that the mobile terminal will perform a handover and terminate the communication with the original serving relay station; if it is in the reject state, Then the original serving base station resends the MOB_BSHO-RSP message to re-recommend the candidate target relay station or base station; if it is in the canceled state, both the mobile terminal and the original serving base station cancel the handover operation and return to the normal working state.

Step S703: The mobile terminal synchronizes with the downlink of the target relay station or base station. The main purpose of this process is to enable the mobile terminal to obtain the transmission parameters of the uplink and downlink of the target relay station or base station. The MOB_NBR-ADV message obtains the identification, operating frequency, DCD (Downlink Channel Descriptor, downlink channel descriptor) and UCD (Uplink Channel Descriptor, uplink channel descriptor) parameters of the target relay station or base station, then the synchronization can be accelerated process.

Step S704: Complete the network re-entry process. The main purpose of this process is to enable the mobile terminal and the target relay station or base station to obtain the relevant information of the other party respectively, so as to prepare for subsequent normal information. This process includes:

Carry out the CDMA code ranging process, one purpose of this process is to synchronize the uplink between the mobile terminal and the target relay station or base station;

The target relay station or base station allocates ranging resources for the mobile terminal;

The mobile terminal sends a ranging request message RNG-REQ to the target relay station or base station. The RNG-REQ carries the identification of the mobile terminal, the identification of the original serving base station or relay station, and the identification of the ranging type. The identification of the ranging type indicates switching ranging;

The target relay station or base station returns a ranging response message RNG-RSP to the mobile terminal. The RNG-RSP message can carry the basic CID (ConnectionIdentifier, connection identifier) allocated by the target relay station or base station for the mobile terminal, the main management CID, and the target relay station or base station. Service provision capability, handover process optimization and other relevant information;

Perform the subsequent steps of the network re-entry process. If the handover target is the target base station, the subsequent steps of the network re-entry process include: re-authentication process, basic capability negotiation process, re-registration process, and service flow re-establishment process.

Wherein, in the re-authentication process, the mobile terminal sends an authentication request message to the target base station, and the authentication request message carries the identification and the digital certificate of the mobile terminal;

If the target base station determines that the mobile terminal is legal, then return an authentication response message to the mobile terminal, and the target base station distributes an authentication key to the mobile terminal in the authentication response message;

After receiving the authentication response message, the mobile terminal can further send a key request message to request a service key from the target base station;

The target base station returns a key response message to the mobile terminal, and the target base station allocates a service key to the mobile terminal in the key response message.

During the basic capability negotiation process, the mobile terminal requests the target base station for system parameters and functions it can support through a capability negotiation request, and the target base station notifies the mobile terminal of the functions agreed by the target base station through a capability negotiation response.

During the re-registration process, the mobile terminal registers its supported IP version and management mode with the target base station through the registration request message, and the target base station notifies the mobile terminal of the IP version and management mode supported by the system in the registration response message.

During the re-establishment process of the service flow, the mobile terminal requests the service flow, the type of the service flow and its QoS parameters through the establishment of the service flow request message, and the target base station agrees or refuses to establish the service flow in the service flow establishment response message. The response message is confirmed in the establishment confirmation message.

In each of the above processes, if the mobile terminal has been informed in the handover process optimization parameters in the RNG-RSP message that some steps can be omitted, then the corresponding steps can be omitted during the network re-entry process.

If the handover target is the target relay station, the subsequent steps of the network re-entry process may also sequentially include: a re-authentication process, a basic capability negotiation process, a re-registration process, and a service flow re-establishment process. Regardless of whether the target relay station is a high-capability relay station or a low-capability relay station, it can transparently transmit the messages exchanged between the mobile terminal and the serving base station that provides services for the target relay station. Therefore, the serving base station that provides services for the target relay station can complete the network on behalf of the target relay station Next steps in the re-entry process.

It should be noted that if the target relay station or base station obtains the time when the mobile terminal will perform ranging in advance, it is not necessary to perform CDMA code ranging, and the target relay station or base station can directly allocate non-contention ranging resources for the mobile terminal.

Step S705: The original serving relay station terminates the communication with the mobile terminal and the context, such as information in the queue, ARQ (Automatic Repeat Request, access request) state machine, counter, timer or information related to header compression, etc.

It should be noted that although the high-capability relay station provides services for the mobile terminal in the embodiment shown in FIG. Initiate a handover, then it can first send a request message to the original serving base station, after the original serving base station generates a MOB_BSHO-REQ message, send it to the original serving relay station, and the original serving relay station sends the MOB_BSHO-REQ message to the mobile terminal.

In the embodiment shown in FIG. 7, if the handover target is a target relay station in the same cell as the original serving relay station, then there is no need to perform context termination, and step S705 can be omitted; if the handover target is a target relay station in a different cell from the original serving relay station target relay station, then in step S701, the list provided by the original serving relay station may be a list of neighbor base stations and/or a list of relay stations within the coverage of these neighbor base stations, and the original serving relay station may request the original serving base station to obtain these list information, the original serving station If the base station does not have the list information or the list information is insufficient and outdated, it can obtain the list information from the core network.

Fig. 8 is a flowchart of an embodiment of a handover method initiated by the original serving base station. In this embodiment, the low-capability relay station serves the mobile terminal, the base station provides service for the low-capability relay station, and the handover target of the mobile terminal is the base station, another relay station in the same cell, or another relay station in a different cell . Among them, the low-capability relay station can only transparently transmit the message, does not change the content of the MAC message, and has no ability to generate, modify or terminate the signaling involved in the handover process. The reason why the original serving base station initiates the handover may be that the mobile terminal moves from the service area of the original serving low-capability relay station to the service area of another relay station or the coverage area of another base station. In order to enable the mobile terminal to obtain better service quality, or the original If the load of the serving base station itself is too large, or the signal of the mobile terminal is weakened due to the reduction of the transmission power of the original serving base station, the original serving base station can replace the mobile terminal with a relay station or base station serving it.

As shown in Figure 8, this embodiment comprises the following steps:

Step S801: Perform a handover target reselection process. The main purpose of this process is to enable the mobile terminal to obtain a list of neighboring relay stations or neighboring base stations and their information, which can be implemented in the following manner:

The mobile terminal obtains the list of neighbor relay stations or neighbor base stations from the neighbor broadcast message MOB_NBR-ADV. The MOB_NBR-ADV message is a broadcast message sent by the original serving relay station or the original serving base station. All mobile terminals within the service range of the original serving relay station or the original serving base station Both the terminal or the relay station can receive it, and the mobile terminal can obtain the operator identifier, configuration update counter, block identification, total block number, number of neighbor sites, and related information of each neighbor site from the MOB_NBR-ADV message , the relevant information may include the physical characteristic identifier of each site, frequency allocation, site EIRP, BSID, signal preamble number, handover process optimization parameters, supported scheduling service types, DCD configuration update count, UCD configuration update count, and Security information, of course, some of this information is optional. In addition, the mobile terminal can obtain the MOB_NBR-ADV message at intervals, and the list of neighbor relay stations or neighbor base stations in the MOB_NBR-ADV message may be updated;

The mobile terminal selectively scans or measures neighbor relay stations or neighbor base stations. For example, the mobile terminal can select the target of scanning or measurement from multiple lists obtained. The downlink of the base station is synchronized and the downlink signal is measured;

If the mobile terminal thinks that the obtained information is insufficient or for other reasons, it can also continue to perform ranging on the uplink of the scanned neighbor relay station or neighbor base station on the basis of scanning to obtain ranging parameters. This process is called for union.

Through the above steps, the mobile terminal obtains the information of the neighbor relay station or the neighbor base station.

Step S802: Carry out handover initiation and decision process. The main purpose of this process is to enable the mobile terminal to select a target relay station or target base station from candidate target relay stations or candidate target base stations, which can be achieved in the following manner:

The original serving base station sends a handover request message MOB_BSHO-REQ to the original serving relay station, and the original serving relay station forwards the MOB_BSHO-REQ message to the mobile terminal, and the MOB_BSHO-REQ message carries information of at least one candidate target relay station or base station;

The mobile terminal evaluates the candidate target relay station or base station, and sends a handover indication message MOB_HO-IND to the original serving relay station, and the original serving relay station forwards the MOB_HO-IND message to the original serving base station. The MOB_HO-IND message indicates the target relay station or base station selected by the mobile terminal. The decision of the base station, that is, it indicates which relay station or base station is selected as the target relay station or base station to be handed over.

If the handover target of the mobile terminal is the target relay station, the original serving base station will notify the base station serving the target relay station of information such as the handover target selected by the mobile terminal, and the base station providing service for the target relay station will then send a handover instruction message to the target relay station, The format of the handover indication message is shown in Table 1 to inform the target RS of the allocated handover identifier (if allocated in MOB_BSHO-RSP) and start time.

After the above process is completed, the original serving base station stops communication with the mobile terminal.

It should be noted that the MOB_HO-IND message sent by the mobile terminal can have multiple states. If it is in the state of releasing the original serving relay station, it means that the mobile terminal will perform handover and terminate the communication with the original serving base station; if it is in the reject state, Then the original serving base station resends the MOB_BSHO-RSP message to re-recommend the candidate target relay station or base station; if it is in the canceled state, both the mobile terminal and the original serving base station cancel the handover operation and return to the normal working state.

It should also be noted that the candidate target relay station or base station provided by the original serving base station may be the same, partly or completely different from the neighbor relay station or neighbor base station obtained by the mobile terminal in step S801.

Step S803: The mobile terminal synchronizes with the downlink of the target relay station or base station. The main purpose of this process is to enable the mobile terminal to obtain the transmission parameters of the uplink and downlink of the target relay station or base station. - The identification, operating frequency, DCD (Downlink Channel Descriptor, downlink channel descriptor) and UCD (Uplink Channel Descriptor, uplink channel descriptor) parameters of the target relay station or base station are obtained in the ADV message, which can speed up the synchronization process .

Step S804: Complete the network re-entry process. The main purpose of this process is to enable the mobile terminal and the target relay station or base station to obtain the relevant information of the other party respectively, so as to prepare for subsequent normal information. This process includes:

Carry out the CDMA code ranging process, one purpose of this process is to synchronize the uplink between the mobile terminal and the target relay station or base station;

The target relay station or base station allocates ranging resources for the mobile terminal;

The mobile terminal sends a ranging request message RNG-REQ to the target relay station or base station. The RNG-REQ carries the identification of the mobile terminal, the identification of the original serving base station or relay station, and the identification of the ranging type. The identification of the ranging type indicates switching ranging;

The target relay station or base station returns a ranging response message RNG-RSP to the mobile terminal. The RNG-RSP message can carry the basic CID (ConnectionIdentifier, connection identifier) allocated by the target relay station or base station for the mobile terminal, the main management CID, and the target relay station or base station. Service provision capability, handover process optimization and other related information;

Perform the subsequent steps of the network re-entry process. If the handover target is the target base station, the subsequent steps of the network re-entry process include: re-authentication process, basic capability negotiation process, re-registration process, and service flow re-establishment process.

Wherein, in the re-authentication process, the mobile terminal sends an authentication request message to the target base station, and the authentication request message carries the identification and the digital certificate of the mobile terminal;

If the target base station determines that the mobile terminal is legal, then return an authentication response message to the mobile terminal, and the target base station distributes an authentication key to the mobile terminal in the authentication response message;

After receiving the authentication response message, the mobile terminal can further send a key request message to request a service key from the target base station;

The target base station returns a key response message to the mobile terminal, and the target base station allocates a service key to the mobile terminal in the key response message.

During the basic capability negotiation process, the mobile terminal requests the target base station for system parameters and functions it can support through a capability negotiation request, and the target base station notifies the mobile terminal of the functions agreed by the target base station through a capability negotiation response.

During the re-registration process, the mobile terminal registers its supported IP version and management mode with the target base station through the registration request message, and the target base station notifies the mobile terminal of the IP version and management mode supported by the system in the registration response message.

During the re-establishment process of the service flow, the mobile terminal requests the service flow, the type of the service flow and its QoS parameters through the establishment of the service flow request message, and the target base station agrees or refuses to establish the service flow in the service flow establishment response message. The response message is confirmed in the establishment confirmation message.

In each of the above processes, if the mobile terminal has been informed in the handover process optimization parameters in the RNG-RSP message that some steps can be omitted, then the corresponding steps can be omitted during the network re-entry process.

If the handover target is the target relay station, the subsequent steps of the network re-entry process may also sequentially include: a re-authentication process, a basic capability negotiation process, a re-registration process, and a service flow re-establishment process. Regardless of whether the target relay station is a high-capability relay station or a low-capability relay station, it can transparently transmit the messages exchanged between the mobile terminal and the serving base station that provides services for the target relay station. Therefore, the serving base station that provides services for the target relay station can complete the network on behalf of the target relay station Next steps in the re-entry process.

It should be noted that if the target relay station or base station obtains the time when the mobile terminal will perform ranging in advance, it is not necessary to perform CDMA code ranging, and the target relay station or base station can directly allocate non-contention ranging resources for the mobile terminal.

Step S805: The original serving base station terminates the communication with the mobile terminal and the context, such as information in the queue, ARQ (Automatic Repeat Request, access request) state machine, counter, timer or information related to header compression, etc.

In the embodiment shown in FIG. 8, the original serving relay station provides services for the mobile terminal. If the original serving base station provides services for the mobile terminal, the handover steps are basically the same as those shown in FIG. 8, as long as the The communication between the mobile terminal and the original serving relay station can be changed to the communication between the mobile terminal and the original serving base station.

In the embodiment shown in FIG. 8, if the handover target is a target relay station in the same cell as the original serving relay station, then there is no need to perform context termination, and step S805 can be omitted; if the handover target is a target relay station in a different cell from the original serving relay station For the target relay station, in step S801, the list provided by the original serving base station may be a list of neighbor base stations and/or a list of relay stations within the coverage of these neighbor base stations.

It should be noted that, in the embodiment shown in FIG. 8 , the original serving relay station may be a high-capacity relay station, and it may also transparently transmit the received message related to the handover process.

The first handover node can also be a relay station, the handover target can be a relay station or a base station, and the original serving node providing services for the relay station can be a relay station or a base station, that is, the original serving relay station providing services for the relay station can be changed to a new service node in the same cell The relay station or base station, the original serving base station can also be changed to a new relay station or base station in the same cell. The handover may be initiated by the relay station, or may be initiated by the original serving relay station or the original serving base station.

It should be noted that if the original serving relay station or the original serving base station serving the first switching node is changed to a new relay station or base station, the second switching node receiving the service provided by the first switching node may choose to work with the first switching node Switch, you can also choose a different switching target, and you can also choose not to switch. Wherein, after switching together is selected, the first switching node after switching still provides services for the second switching node; after selecting a different switching target, it is a new relay station or base station that provides services for the second switching node; after choosing not to switch, It is the original serving relay station or the original serving base station that provides the service for the first switching node to provide the service for the second switching node.

Now, the handover methods in the above multiple situations will be described in detail in combination with specific embodiments.

Fig. 9 is a flow chart of the first embodiment of the handover method initiated by the relay station. In this embodiment, the base station provides services for the relay station, and the handover target of the relay station is the base station, another relay station in the same cell, or another relay station in a different cell. The reason why the relay station initiates the handover can be that the relay station moves from the coverage area of the original serving base station to the coverage area of another base station, or moves to the service area of another relay station. In order to obtain better service quality, the relay station requests to replace the service station relay station or base station.

As shown in Figure 9, this embodiment comprises the following steps:

Step S901: Perform a handover target reselection process. The main purpose of this process is to enable the relay station to obtain the list of neighbor relay stations or neighbor base stations and their information, which can be implemented in the following manner:

The relay station obtains the list of neighbor relay stations or neighbor base stations from the neighbor broadcast message MOB_NBR-ADV. The MOB_NBR-ADV message is a broadcast message sent by the original serving base station. All relay stations or mobile terminals within the service range of the original serving base station can receive it. , the relay station can obtain the operator identifier, configuration update counter, block identification, total block number, number of neighbor sites, and related information of each neighbor site from the MOB_NBR-ADV message. The related information can include the physical Feature identifier, frequency allocation, site EIRP, BSID, signal preamble number, handover process optimization parameters, supported scheduling service types, DCD configuration update count, UCD configuration update count, and security information. Of course, some of these information are optional Optional, in addition, the relay station can obtain MOB_NBR-ADV messages at intervals, and the list of neighbor relay stations or neighbor base stations in the MOB_NBR-ADV message may be updated;

The relay station selectively scans or measures neighbor relay stations or neighbor base stations. For example, the relay station can select the target to scan or measure from multiple lists obtained. During the scan or measurement process, the relay station will scan or measure the downlink The link is synchronized and the downlink signal is measured;

If the relay station thinks that the obtained information is insufficient or for other reasons, the relay station can also continue to measure the uplink of the scanned neighbor relay station or neighbor base station on the basis of scanning to obtain ranging parameters. This process is called joint .

Through the above steps, the relay station obtains information of neighboring relay stations or neighboring base stations.

Step S902: Initiate and judge the handover process. The main purpose of this process is to enable the relay station to select a target relay station or target base station from candidate target relay stations or candidate target base stations, which can be implemented in the following manner:

The relay station sends a handover request message MOB_RSHO-REQ to the original serving base station, and the MOB_RSHO-REQ message indicates that the relay station requests a candidate target relay station or base station;

The original serving base station returns the handover response message MOB_BSHO-RSPMOB_BSHO-RSP to the relay station, carrying information of at least one candidate target relay station or base station;

The relay station evaluates the candidate target relay station or base station, and sends a handover instruction message MOB_HO-IND to the original serving base station. The MOB_HO-IND message indicates the decision of the target relay station or base station selected by the relay station, that is, which relay station or base station is selected as the one to be handed over. target relay station or base station.

If the handover target of the relay station is the target relay station, the original serving base station shall notify the base station serving the target relay station of the information such as the handover target selected by the relay station, and the base station providing service for the target relay station shall send a handover instruction message to the target relay station to notify Table 1 shows the handover identifier assigned by the target relay station (if it has been assigned in MOB_BSHO-RSP) and start time, and the format of the handover indication message.

After the above process is completed, the original serving base station stops communication with the relay station.

It should be noted that the MOB_HO-IND message sent by the relay station can have multiple states. If it is in the state of releasing the original serving relay station, it means that the relay station will perform handover and terminate the communication with the original serving base station; The serving base station resends the MOB_BSHO-RSP message to re-recommend the candidate target relay station or base station; if it is in the canceled state, both the relay station and the original serving base station will cancel the handover operation and return to the normal working state.

It should also be noted that the candidate target relay station or base station provided by the original serving base station may be the same, partly or completely different from the neighbor relay station or neighbor base station obtained by the relay station in step S901.

Step S903: The relay station synchronizes with the downlink of the target relay station or base station. The main purpose of this process is to enable the relay station to obtain the uplink and downlink transmission parameters of the target relay station or base station. The identification, operating frequency, DCD (Downlink Channel Descriptor, downlink channel descriptor) and UCD (Uplink Channel Descriptor, uplink channel descriptor) parameters of the target relay station or base station are obtained in the message, which can speed up the synchronization process.

Step S904: Complete the network re-entry process. The main purpose of this process is to enable the relay station and the target relay station or base station to obtain the relevant information of each other to prepare for subsequent normal information. This process includes:

Carry out the CDMA code ranging process, one purpose of this process is to synchronize the uplink between the relay station and the target relay station or base station;

The target relay station or base station allocates ranging resources for the relay station;

The relay station sends a ranging request message RNG-REQ to the target relay station or base station. The RNG-REQ carries the identifier of the relay station, the identifier of the original serving base station or relay station, and the identifier of the ranging type. The identifier of the ranging type indicates switching ranging;

The target relay station or base station returns a ranging response message RNG-RSP to the relay station. The RNG-RSP message can carry the basic CID (Connection Identifier, connection identifier) allocated by the target relay station or base station for the relay station, the main management CID, and the service provision of the target relay station or base station. Capability, handover process optimization and other relevant information;

Perform the subsequent steps of the network re-entry process. If the handover target is the target base station, the subsequent steps of the network re-entry process include: re-authentication process, basic capability negotiation process, re-registration process, and service flow re-establishment process.

Wherein, in the re-authentication process, the relay station sends an authentication request message to the target base station, and the authentication request message carries the identifier and the digital certificate of the relay station;

If the target base station determines that the relay station is legal, it returns an authentication response message to the relay station, and the target base station assigns an authentication key to the relay station in the authentication response message;

After receiving the authentication response message, the relay station can further send a key request message to request a service key from the target base station;

The target base station returns a key response message to the relay station, and the target base station allocates a service key to the relay station in the key response message.

During the basic capability negotiation process, the relay station requests the target base station for system parameters and functions it can support through a capability negotiation request, and the target base station notifies the relay station of the functions agreed by the target base station through a capability negotiation response.

During the re-registration process, the relay station registers its supported IP version and management mode with the target base station through the registration request message, and the target base station notifies the relay station of the IP version and management mode supported by the system in the registration response message.

During the service flow re-establishment process, the relay station requests the service flow and the service flow type and its QoS parameters through the service flow request message establishment, the target base station agrees or refuses to establish the service flow in the service flow establishment response message, and the relay station confirms the service flow establishment The response message is acknowledged in the message.

In each of the above processes, if the relay station has been informed in the handover process optimization parameters in the RNG-RSP message that some steps can be omitted, then the corresponding steps can be omitted during the network re-entry process.

If the handover target is the target relay station, the subsequent steps of the network re-entry process may also sequentially include: a re-authentication process, a basic capability negotiation process, a re-registration process, and a service flow re-establishment process. Regardless of whether the target relay station is a high-capability relay station or a low-capability relay station, it can transparently transmit the messages exchanged between the relay station and the serving base station that provides services for the target relay station. Go to the next steps in the process.

It should be noted that if the target relay station or base station obtains the time when the relay station will perform ranging in advance, it is not necessary to perform CDMA code ranging, and the target relay station or base station can directly allocate non-competition ranging resources for the relay station.

Step S905: The original serving base station terminates the communication with the mobile terminal and the context, such as information in the queue, ARQ (Automatic Repeat Request, access request) state machine, counter, timer or information related to header compression, etc.

In the embodiment shown in FIG. 9, the original serving base station provides services for the relay station that initiates the handover. If a serving relay station provides services for the relay station that initiates the handover, the steps of the handover are basically the same as those shown in FIG. Same, as long as the communication between the relay station and the original serving base station is changed to the serving relay station forwarding the messages sent and received between the relay station and the original serving base station.

In the embodiment shown in FIG. 9, if the handover target is the target relay station served by the original serving base station, then there is no need to perform context termination, and step S905 can be omitted; if the handover target is the target relay station in a different cell, then in step S901, The list provided by the original serving base station may be a list of neighbor base stations and/or a list of relay stations within the coverage of these neighbor base stations. If the original serving base station does not have these list information or the list information is insufficient and outdated, it can obtain these from the core network list information.

In the embodiment shown in FIG. 9, when the relay station changes the serving base station, the mobile terminal served by the relay station does not know that the serving base station has changed, so the relay station needs to send a message to the target base station after completing the context termination step. The mobile terminal parameter update request message, the target base station can return the mobile terminal parameter update response message to the relay station, the parameter update response message can carry the parameter update information of all mobile terminals served by the relay station, and the relay station receives the parameter update response message. The mobile terminal sends a RNG-RSP message.

After the target base station receives the mobile terminal parameter update request message, it can also directly generate an RNG-RSP message. The RNG-RSP message can carry the parameter update information of all mobile terminals served by the relay station. All mobile terminals forward the RNG-RSP message. The format of the mobile terminal parameter update request message and the mobile terminal parameter update response message format are shown in Table 4 and Table 5 respectively.

grammar Size (unit: bit) illustrate MS_Para-REQ message format (){ - - Management Message Type 8 message type BSID 48 BSID of the base station of the original cell

N_MS 8 The number of MS request parameters For(j=0; j<N_MS; j++){ MS MAC 48 MS MAC address } Padding 6 is 0 TLV encoded information 2 TLV encoded information, including authentication security information }

Table 4 Mobile terminal parameter update request message format

grammar Size (unit: bit) illustrate MS_Para-REQ message format (){ - - Management Message Type 8 message type BSID 48 BSID of the base station of the original cell N_MS 8 The number of MS request parameters For(j=0; j<N_MS; j++){ If this message is for switching MS MAC 48 MS MAC address Basic CID 16 Basic Connection Identifier Primary management CID 16 main management connection identifier HO process optimization 16 Optimization of switching process } Padding 6 is 0 TLV encoded information 2 TLV encoded information, including authentication security information }

Table 5 Mobile terminal parameter update response message format

In addition, after the relay station completes the handover and before sending a mobile terminal parameter update request message to the target base station, it can also determine whether the mobile terminal that originally received the service provided by the relay station is still receiving the service provided by the relay station. The relay station can adopt such a judgment method, that is, if the relay station can periodically receive the ranging request from the mobile terminal, it means that the mobile terminal is still accepting the service provided by the relay station; otherwise, it means that the mobile terminal has not accepted the service provided by the relay station. The relay station can also adopt such a judgment method, that is, the relay station requests the mobile terminal that originally received the service to perform a periodic ranging request. If the mobile terminal can send a ranging request to the relay station, it means that the mobile terminal is still receiving the service provided by the relay station. Otherwise, it means that the mobile terminal has not accepted the service provided by the relay station. If the relay station determines that the mobile terminal originally served by the relay station is still receiving the service provided by the relay station, it sends a mobile terminal parameter update request message to the target base station; otherwise, it does not need to send a mobile terminal parameter update request message to the target base station.

In the embodiment shown in FIG. 9, the handover is initiated by the relay station. In practical applications, the base station can also initiate the handover. The difference between the handover process and the process shown in FIG. 9 is that in step S902, the original serving base station first Send a handover request message MOB_BSHO-REQ to the relay station, the MOB_RSHO-REQ message carries information of at least one candidate target relay station or base station, the relay station evaluates the candidate target relay station or base station, and sends a handover instruction message MOB_HO-IND to the original serving base station, The MOB_HO-IND message indicates the decision of the target relay station or base station selected by the relay station, that is, which relay station or base station is selected as the target relay station or base station to be handed over.

During the handover process initiated by the relay station, the mobile terminal served by the relay station can also initiate the handover. In this case, the relay station can send the MOB_HO-IND message to the base station after receiving the MOB_HO-IND message sent by the mobile terminal and stopping communication with the mobile terminal. IND news. The handover method in this case will be described below in conjunction with an embodiment.

Fig. 10 is a flow chart of the second embodiment of the handover method initiated by the relay station. In this embodiment, the relay station provides services for the mobile terminal, and the base station provides services for the relay station. The handover target of the mobile terminal is the base station, another relay station in the same cell, or another relay station in a different cell. The handover of the relay station The target is a base station, another relay station within the same cell, or another relay station in a different cell. The reason why the mobile terminal initiates the handover may be that the mobile terminal moves from the service area of the original serving relay station to the service area of another relay station, or moves to the coverage area of another base station. In order to obtain better service quality, the mobile terminal requests to change to The relay station or base station it serves. The reason why the relay station initiates the handover can be that the relay station moves from the coverage area of the original serving base station to the coverage area of another base station, or moves to the service area of another relay station. In order to obtain better service quality, the relay station requests to replace the service station relay station or base station.

As shown in Figure 10, this embodiment comprises the following steps:

Step S1001: Perform a handover target reselection process. The main purpose of this process is to enable the relay station to obtain the list and information of neighboring relay stations or neighboring base stations, which can be realized in the following manner:

The relay station obtains the list of neighbor relay stations or neighbor base stations from the neighbor broadcast message MOB_NBR-ADV. The MOB_NBR-ADV message is a broadcast message sent by the original serving base station. All relay stations or mobile terminals within the service range of the original serving base station can receive it. , the relay station can obtain the operator identifier, configuration update counter, block identification, total block number, number of neighbor sites, and related information of each neighbor site from the MOB_NBR-ADV message. The related information can include the physical Feature identifier, frequency allocation, site EIRP, BSID, signal preamble number, handover process optimization parameters, supported scheduling service types, DCD configuration update count, UCD configuration update count, and security information. Of course, some of these information are optional Optional, in addition, the relay station can obtain MOB_NBR-ADV messages at intervals, and the list of neighbor relay stations or neighbor base stations in the MOB_NBR-ADV message may be updated;

The relay station selectively scans or measures neighbor relay stations or neighbor base stations. For example, the relay station can select the target to scan or measure from multiple lists obtained. During the scan or measurement process, the relay station will scan or measure the downlink The link is synchronized and the downlink signal is measured;

If the relay station thinks that the obtained information is insufficient or for other reasons, based on the scanning, the mobile terminal can continue to perform ranging on the uplink of the scanned neighbor relay station or neighbor base station to obtain ranging parameters. This process is called joint.

Through the above steps, the relay station obtains information of neighboring relay stations or neighboring base stations.

Step S1002: Initiate and judge the handover process. The main purpose of this process is to enable the relay station to select a target relay station or target base station from candidate target relay stations or candidate target base stations, which can be implemented in the following manner:

The relay station sends a handover request message MOB_RSHO-REQ to the original serving base station, and the MOB_RSHO-REQ message indicates that the relay station requests a candidate target relay station or base station;

The original serving base station returns the handover response message MOB_BSHO-RSPMOB_BSHO-RSP to the relay station, carrying information of at least one candidate target relay station or base station;

The relay station evaluates the candidate target relay station or base station, and sends a handover instruction message MOB_HO-IND to the original serving base station. The MOB_HO-IND message indicates the decision of the target relay station or base station selected by the relay station, that is, which relay station or base station is selected as the one to be handed over. target relay station or base station.

If the handover target of the relay station is the target relay station, the original serving base station shall notify the base station serving the target relay station of the information such as the handover target selected by the relay station, and the base station providing service for the target relay station shall send a handover instruction message to the target relay station to notify Table 1 shows the handover identifier assigned by the target relay station (if it has been assigned in MOB_BSHO-RSP) and start time, and the format of the handover indication message.

After the above process is completed, the original serving base station stops communication with the relay station.

It should be noted that the MOB_HO-IND message sent by the relay station can have multiple states. If it is in the state of releasing the original serving relay station, it means that the relay station will perform handover and terminate the communication with the original serving base station; The serving base station resends the MOB_BSHO-RSP message to re-recommend the candidate target relay station or base station; if it is in the canceled state, both the relay station and the original serving base station will cancel the handover operation and return to the normal working state.

Please refer to FIG. 10 again. If the relay station receives the MOB_MSHO-REQ message sent by the mobile terminal before sending the handover instruction message MOB_HO-IND to the original serving base station, the relay station will stop its own subsequent handover process and give priority to the request of the mobile terminal. After the communication with the mobile terminal is stopped, the subsequent handover process is performed. The relay station can use such a method to stop the subsequent handover process, that is, the relay station can send a MOB_HO-IND message to the base station, and the status of the MOB_HO-IND message is rejected. After receiving the rejected MOB_HO-IND message, the base station will re-recommend Candidate target base stations or relay stations are repeated in this way to ensure that the relay station can continue to maintain communication with the base station before the mobile terminal stops communicating with the relay station. The relay station can also cancel the handover process in the MOB_HO-IND message, and if the subsequent process can be performed, the relay station can request the base station to continue the handover process.

It should also be noted that the candidate target relay station or base station provided by the original serving base station may be the same, partly or completely different from the neighbor relay station or neighbor base station obtained by the relay station in step S1001.

Step S1003: The relay station synchronizes with the downlink of the target relay station or base station. The main purpose of this process is to enable the relay station to obtain the uplink and downlink transmission parameters of the target relay station or base station. The identification, operating frequency, DCD (Downlink Channel Descriptor, downlink channel descriptor) and UCD (Uplink Channel Descriptor, uplink channel descriptor) parameters of the target relay station or base station are obtained in the message, which can speed up the synchronization process.

Step S1004: Complete the network re-entry process. The main purpose of this process is to enable the relay station and the target relay station or base station to obtain the relevant information of each other, and prepare for subsequent normal information. This process includes:

Carry out the CDMA code ranging process, one purpose of this process is to synchronize the uplink between the relay station and the target relay station or base station;

The target relay station or base station allocates ranging resources for the relay station;

The relay station sends a ranging request message RNG-REQ to the target relay station or base station. The RNG-REQ carries the identifier of the relay station, the identifier of the original serving base station or relay station, and the identifier of the ranging type. The identifier of the ranging type indicates switching ranging;

The target relay station or base station returns a ranging response message RNG-RSP to the relay station. The RNG-RSP message can carry the basic CID (Connection Identifier, connection identifier) allocated by the target relay station or base station for the relay station, the main management CID, and the service provision of the target relay station or base station. Capability, handover process optimization and other relevant information;

Perform the subsequent steps of the network re-entry process. If the handover target is the target base station, the subsequent steps of the network re-entry process include: re-authentication process, basic capability negotiation process, re-registration process, and service flow re-establishment process.

Wherein, in the re-authentication process, the relay station sends an authentication request message to the target base station, and the authentication request message carries the identifier and the digital certificate of the relay station;

If the target base station determines that the relay station is legal, it returns an authentication response message to the relay station, and the target base station assigns an authentication key to the relay station in the authentication response message;

After receiving the authentication response message, the relay station can further send a key request message to request a service key from the target base station;

The target base station returns a key response message to the relay station, and the target base station allocates a service key to the relay station in the key response message.

During the basic capability negotiation process, the relay station requests the target base station for system parameters and functions it can support through a capability negotiation request, and the target base station notifies the relay station of the functions agreed by the target base station through a capability negotiation response.

During the re-registration process, the relay station registers its supported IP version and management mode with the target base station through the registration request message, and the target base station notifies the relay station of the IP version and management mode supported by the system in the registration response message.

During the service flow re-establishment process, the relay station requests the service flow and the service flow type and its QoS parameters through the service flow request message establishment, the target base station agrees or refuses to establish the service flow in the service flow establishment response message, and the relay station confirms the service flow establishment The response message is acknowledged in the message.

In each of the above processes, if the relay station has been informed in the handover process optimization parameters in the RNG-RSP message that some steps can be omitted, then the corresponding steps can be omitted during the network re-entry process.

If the handover target is the target relay station, the subsequent steps of the network re-entry process may also sequentially include: a re-authentication process, a basic capability negotiation process, a re-registration process, and a service flow re-establishment process. Regardless of whether the target relay station is a high-capability relay station or a low-capability relay station, it can transparently transmit the messages exchanged between the relay station and the serving base station that provides services for the target relay station. Go to the next steps in the process.

It should be noted that if the target relay station or base station obtains the time when the relay station will perform ranging in advance, it is not necessary to perform CDMA code ranging, and the target relay station or base station can directly allocate non-competition ranging resources for the relay station.

Step S1005: The original serving base station terminates the communication with the mobile terminal and the context, such as information in the queue, ARQ (Automatic Repeat Request, access request) state machine, counter, timer or information related to header compression, etc.

In the embodiment shown in FIG. 10, the original serving base station is the one that provides services for the relay station. If it is a serving relay station that provides services for the mobile terminal, the steps of handover are basically the same as those shown in FIG. 10, as long as the relay station The communication with the original serving base station is changed to the serving relay station forwarding the messages sent and received between the relay station and the original serving base station.

In the embodiment shown in FIG. 10 , if the handover target is the target relay station served by the original serving base station, there is no need to perform context termination, and step S1005 can be omitted; if the handover target is the target relay station in a different cell, then in step S1001, The list provided by the original serving base station may be a list of neighbor base stations and/or a list of relay stations within the coverage of these neighbor base stations. If the original serving base station does not have these list information or the list information is insufficient and outdated, it can obtain these from the core network list information.

In the embodiment shown in Figure 10, the handover is initiated by the relay station and the mobile terminal. In practical applications, the handover can be initiated by the original serving base station or the original serving relay station, and the original serving base station or the original serving relay station can be initiated simultaneously or sequentially. Handover for relay stations and mobile terminals.

The above-mentioned several embodiments are only some typical implementation manners for implementing the method of the present invention. It should be noted that the present invention also has multiple embodiments for implementing the switching method. For example, handover may be initiated by a handover node, by a service node that provides services for the handover node, by a service node that provides services for the service node, and so on, and may even be initiated by a handover target. When the handover is initiated by the handover target, the handover target can send a handover request message through the serving node that provides services for the handover node. In addition, whether it is the serving node serving the handover node or the handover target, if the latest relevant information is not obtained or the relevant information is insufficient, they can request corresponding information from the serving base station or core network providing services for the mobile terminal.

The above is only a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications should also be It is regarded as the protection scope of the present invention.

Claims (18)

1. A switching method based on a relay system, characterized in that it comprises: Selecting a handover target from the acquired candidate handover targets by the first handover node specifically includes: obtaining information of at least one candidate handover target, evaluating the candidate handover target, and notifying the original service node of the selected handover target; The first handover node is synchronized with the downlink of the handover target; Complete the network re-entry process, specifically including: performing a CDMA code ranging process to synchronize the uplinks of the first handover node and the handover target; the handover target allocates ranging resources for the first handover node; the first handover node sends the handover target Send a ranging request message; the handover target returns a ranging response message to the first handover node; if the handover target obtains the time when the first handover node will perform ranging in advance, it is not necessary to perform CDMA code ranging, and the handover target is directly the first handover Nodes allocate non-competitive ranging resources; Wherein, the first handover node is a mobile terminal, and the handover target is a relay station or a base station; or, the first handover node is a relay station, and the handover target is a relay station or a base station. 2. The relay system-based handover method according to claim 1, wherein the process of the first handover node selecting a handover target from the obtained candidate handover targets is specifically implemented by the following steps: The first switching node sends a switching request message to the original serving node, and the switching request message requests the original serving node to provide information of at least one candidate switching target; The original serving node returns a handover response message to the first handover node, and the handover response message carries information of at least one candidate handover target; The first handover node evaluates the candidate handover target, and sends a handover indication message to the original serving node, and the handover indication message carries the determination of the selected handover target. 3. The relay system-based handover method according to claim 1, wherein the process of the first handover node selecting a handover target from the obtained candidate handover targets is specifically implemented by the following steps: The original serving node sends a handover request message to the first handover node, and the handover request message carries information of at least one candidate handover target; The first handover node evaluates the candidate handover target, and sends a handover indication message to the original serving node, and the handover indication message carries the determination of the selected handover target. 4. The relay system-based handover method according to claim 2 or 3, wherein if the handover target is a target relay station, further comprising: The original serving base station providing service for the first handover node communicates with the serving base station providing service for the handover target; The serving base station serving the handover target sends a handover indication message to the target relay station. 5. The relay system-based handover method according to claim 1, wherein if the first handover node serves the second handover node before handover, and before the first handover node completes the step of selecting a handover target , the second switching node is selecting a switching target, the first switching node waits until the second switching node completes the step of selecting a switching target, and then completes the step of selecting a switching target. 6. The relay system-based handover method according to claim 5, wherein: if the first handover node receives the handover request message sent by the second handover node before sending out the handover instruction message, the first handover node sends The serving node providing service for the first switching node before the handover sends a handover instruction message in a reject state or a cancel state. 7. The relay system-based handover method according to claim 5, wherein if the first handover node receives the handover indication message sent by the second node, the first handover node terminates the communication with the second node communication. 8. The relay system-based handover method according to claim 5, wherein if the first handover node receives the handover indication message sent by the second node, it will provide services to the first handover node before the handover The service node sends a handover request message. 9. The relay system-based handover method according to claim 5, characterized in that: after the second handover node completes the step of selecting a handover target, it further comprises: The second handover node synchronizes with the downlink of the selected handover target; Complete the network re-entry process. 10. The relay system-based handover method according to claim 1, wherein if the first handover node provides services for the second handover node before the handover, after completing the network re-entry process, further comprising: The first switching node sends a second switching node parameter update request message to the switching target; The handover target returns a second handover node parameter update response message or a ranging response message to the first handover node; The first switching node sends or forwards the ranging response message to the second switching node. 11. The relay system-based handover method according to claim 1, wherein if the first handover node provides services for the second handover node before the handover, after completing the network re-entry process, further comprising: The first switching node judges whether the second switching node is still receiving the service provided by the first switching node; If the first switching node determines that the second switching node is still accepting the service provided by the first switching node, sending a second switching node parameter update request message to the switching target; The handover target returns a second handover node parameter update response message or a ranging response message to the first handover node; The first switching node sends or forwards the ranging response message to the second switching node. 12. The switching method based on the relay system according to claim 11, wherein the method for the first switching node to judge whether the second switching node is still receiving the service provided by the first switching node is: the first switching node judges Whether the ranging request message sent by the second switching node is received at intervals, and if yes, it is determined that the second switching node is still accepting the service provided by the first switching node. 13. The relay system-based handover method according to claim 11, wherein the method for the first handover node to judge whether the second handover node is still accepting the service provided by the first handover node is as follows: The first switching node requests the second switching node to periodically send ranging request messages; If the first switching node periodically receives the ranging request message sent by the second switching node, it determines that the second switching node is still accepting the service provided by the first switching node. 14. The relay system-based handover method according to any one of claims 10-13, characterized in that: after each second handover node receives the ranging response message, it further includes: the second handover node and the handover target Subsequent steps in the network re-entry process. 15. The relay system-based handover method according to claim 1, characterized in that before the first handover node obtains the candidate handover target, it further comprises: performing a handover target reselection process. 16. The handover method based on the relay system as claimed in claim 15, characterized in that the reselection process of the handover target is realized by the following steps: The first switching node acquires a neighbor node list from a neighbor broadcast message; Scan or measure neighbor nodes to obtain the information of the scanned or measured neighbor nodes. 17. The relay system-based handover method according to claim 16, wherein performing a handover target reselection process further comprises: The first switching node requests specific information of neighbor nodes from the original serving node; The original serving node returns the requested specific information to the first switching node. 18. The relay system-based handover method according to claim 1, further comprising: the original serving node terminates all connections and contexts with the first handover node.

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