WO2006131067A1

WO2006131067A1 - Method for fast handover between the base stations

Info

Publication number: WO2006131067A1
Application number: PCT/CN2006/001230
Authority: WO
Inventors: Jianjun Wu
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2005-06-06
Filing date: 2006-06-06
Publication date: 2006-12-14
Also published as: CN1794865A; CN100450285C

Abstract

A method for Fast Handover (FH) between the Base Stations (BSs) includes the following steps: sevice BS sending handover prenotice message that including the basic required information of the MSS to be handover after handover triggering; after receiving the handover prenotice message, the neighbor BS defining the handover time of MSS formally, and indicating the uplink resource of the fast handover for the MSS after up to the said time, and notifying the indicated uplink resource information of the fast handover to the MSS though the indicated message of the uplink resource; after receiving the uplink resource indicating message sent by the final object BS predefined from the said neighbor BS, and sending message to the final object BS though the uplink resource indicated by the massage, thereby executing the initial access. The object BS defines the formal handover time, and indicates Fast Ranging IE for MSS after up to the time, accordingly should indicate Fast Ranging IE within the defined time and realize the fast handover of terminals.

Description

Method for switching terminal between base stations

The present invention relates to the field of broadband wireless access technologies, and more particularly to a terminal

(MSS) A method of switching between base stations (BSs). Background of the invention

The IEEE 802.16 protocol defines the wireless metropolitan area network standard for fixed broadband wireless access (BWA), which defines different physical layer technologies for different frequency bands. The standard applies to residential, small office/home office (SOHO), teleworkers, and small business user (SME) markets.

In the IEEE 802.16 protocol, the message interaction process of the air interface when the MSS switches between BSs is described. As shown in FIG. 1, the following steps are included:

Step 101: The MSS sends a terminal handover request (MOB_MSSHO_REQ) message to the serving BS, where the message includes possible target BSs, which are assumed to be BS2 and BS3, and the time for switching.

Step 102: After receiving the MOB_MSSHO_REQ message, the serving BS communicates with the target BSs: BS2 and BS3 in the message, determines the final target BS, assumes BS3, and notifies BS3 that it is determined to be Final target BS;

Step 103: The service BS sends the determined final target BS, that is, the information of the BS3, to the MSS through a base station switching response (MOB_BSHO_RSP) message;

Step 104: After receiving the MOB_BSHO-RSP message, the MSS sends a handover indication (MOB_HOJND) message to the serving BS, and notifies the serving BS to release the air interface resource of the MSS, and the service BS releases the air interface resource after receiving the message;

Step 105: The BS3 sends an uplink resource assignment message (UL_MAP) message to the MSS. Assigning uplink search resources to the MSS;

Step 106: After receiving the UL_MAP message, the MSS sends a search request (RNG-REQ) message to the BS3 on the search resource assigned by the UL-MAP message to initiate initial access, and then the BS3 returns the RG-RSP to the MSS. The message, after which the interaction between the BS3 and the MSS completes the access process of the MSS.

The above process is a process in which a terminal provided by the IEEE802.16 protocol switches between base stations. Since in the normal case, the uplink search resource assigned by the target BS through the UL-MAP message is a common access resource area, that is, each newly accessed terminal sends an access request to the base station in the resource area, so The terminal that switches to the target base station competes with other newly accessed terminals, resulting in an extended switching time. Therefore, it is also proposed in the IEEE 802.16 protocol that, in order to speed up the handover procedure, the target BS may assign a fast access uplink resource (Fast Ranging IE) to the MSS that needs to be handed over, but the target is not stated in the IEEE 802.16 protocol. When the base station assigns the Fast Ranging IE, it cannot implement fast switching of the terminal. In addition, the flow in Figure 1 also does not show how the service BS and the target BS interact with each other in order to complete this handover, including when to specifically interact with what information. Moreover, in the prior art, only the method of initiating handover by the terminal is provided, and the triggering mode of the handover is single. Summary of the invention

In view of this, an object of the present invention is to provide a method for a terminal to perform handover between base stations, in which a target BS can assign a Fast Ranging IE at a determined time and can implement fast handover of the MSS.

To achieve the above object, the present invention provides a method for MSS to switch between BSs, the method comprising the following steps:

After the handover is triggered, the serving base station BS sends a handover pre-notification message to the neighboring BS, where the handover pre-notification message includes basic requirement information of the terminal MSS that needs to be handed over; After the neighboring BS receives the handover pre-notification message, it determines that the message corresponds to the time when the MSS is officially configured to perform the handover, and after the time is reached, the MSS is assigned the uplink resource for fast access, and the uplink resource assignment message is used. Notifying the MSS of the assigned uplink resource information of the fast access;

After the MSS receives the uplink resource assignment message sent by the final target BS in the neighboring BS, the MSS sends an initial message to the final target BS by using the uplink resource allocated by the message. In.

The switching trigger can be:

The MSS handover request message is sent by the MSS to the serving BS to trigger the handover;

Or the service BS determines to switch to the MSS of the other BS according to its own load balancing policy and control algorithm, and the MSS service status, and triggers the handover of the determined MSS;

Or, after the network controller determines that the MSS needs to be handed over to the service BS of the other BS according to the load balancing policy and the control algorithm, the network controller sends a handover request message to the determined serving BS to trigger the handover.

The time that the neighboring BS determines that the MSS is officially handed over in the step b may be: b11, the neighboring BS determines the time of the formal handover according to the MSS basic requirement information in the received handover pre-notification message, and its own radio resource scheduling policy.

The step b11 may further include:

Μ 2. The formal handover time information determined by the neighbor BS and the response information of the MSS basic requirement information are returned to the service BS by using the handover pre-notification response information;

Μ3, after receiving the handover pre-notification response message returned by the neighboring BS, the serving BS sends the information of the neighboring BS and the information in the corresponding handover pre-notification response message to the MSS;

After receiving the information sent by the serving BS, the M4, the MSS determines the final target BS according to the information; In the step c, the final target BS determined in the neighboring BS is the final target BS determined in the step M4.

The time that the neighboring BS determines that the MSS is officially performing the handover in the step b may include: b21. After the neighboring BS receives the handover pre-notification message according to the received handover pre-notification message, the neighboring BS passes the response information of the MSS basic requirement information by using the handover pre-notification response information. Return to the service BS;

B22, the service BS receives the handover pre-notification response message returned by the neighboring BS, determines the time when the MSS is officially switched, and sends the time to the neighboring BS through the handover notification message;

B23. The time that the neighboring BS sends the serving BS is determined as the time when the handover is formally performed. As can be seen from the above solution, in the present invention, the target BS determines the time for the formal handover, and after the time arrives, assigns the Fast Ranging IE to the MSS, so that the target BS can assign the Fast Ranging IE to the MSS at the determined time. In the present invention, the time for the formal handover is determined by the MSS or the serving BS, and the determined time for the formal handover is sent to the target BS, so that the target BS determines the time for the formal handover to be guaranteed. The normal operation of the MSS when it is within the scope of serving the BS;

In the present invention, the time when the MSS is officially switched by the target BS according to its own policy is determined, and the normal operation of the MSS after switching to the target BS is ensured;

In the present invention, after receiving the handover pre-notification message, the target BS allocates an HO-ID whose occupied resource is smaller than the MAC address for the MSS that initiates the handover, and sends the HO-ID to the serving BS by switching the pre-notification response message. Then, the serving BS resends the HO_ID to the MSS, so that the MSS can use the HO-ID during the process of accessing the target BS, thereby saving the Fast Ranging IE resource;

In the present invention, after receiving the handover information finally confirmed by the MSS, the serving BS sends a message to the final confirmed target BS to notify it of the official handover time, thereby avoiding the BS initially selecting it, and finally the MSS has no choice. The BS sends the above message, Thereby reducing the message flow and saving resources;

In addition, the present invention also provides different solutions, and a solution in the case where there is no interface between the BSs, and the message cannot be directly transmitted, which increases the scope of application of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS ₍

1 is a message exchange flow diagram of an air interface when an MSS switches between BSs in the IEEE802.16 protocol;

Figure 2 is a general flow chart of the present invention;

Figure 3 is a flow chart of the first embodiment of the present invention;

Figure 4 is a flow chart of a second embodiment of the present invention;

Figure 5 is a flow chart of a third embodiment of the present invention;

Figure 6 is a partial flow chart of an eighth embodiment of the present invention. Mode for carrying out the invention

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described in detail with reference to the accompanying drawings.

The main idea of the present invention is that, after the handover trigger, the serving BS sends a handover pre-notification message including the MSS basic requirement information that needs to be handed over to the neighboring BS. After receiving the handover pre-notification message, the neighboring BS determines that the message corresponds to the MSS. The time of the handover, and after the time is reached, the MSS is assigned the uplink resource of the fast access, and the uplink resource information of the fast access is notified to the MSS by using the uplink resource assignment message; the MSS receives the After the uplink resource assignment message sent by the final target BS is determined, a message is sent to the final target BS for initial access on the uplink resource that is assigned in the message. The overall process of the present invention is shown in Figure 2, and the specific steps are as follows:

Step 201: After the handover triggering, the serving BS sends a handover pre-notification message including the MSS basic requirement information that needs to be handed over to the neighboring BS.

Step 202: After receiving the handover pre-notification message, the neighboring BS determines the time when the MSS is officially switched, and after the time is reached, assigns the fast access uplink resource to the MSS, and passes the UL-MAP message. Notifying the MSS of the assigned uplink resource information of the fast access;

Step 203: After receiving the uplink resource assignment message sent by the final target BS, the MSS sends a message to the final target BS for initial access on the uplink resource that is allocated in the message.

In the above step 201, the handover trigger may be triggered by the terminal, may be triggered by the base station, or may be triggered by the network controller.

In addition, in the present invention, the target BS may also allocate a handover identifier (HO_ID) occupying less resources for the MSS that performs handover to save the amount of resources required for interaction between the MSS and the target BS during the access procedure.

The invention will now be described in detail by way of specific examples.

In the first embodiment of the method of the present invention, the handover is initiated by the MSS, and the process is as shown in FIG. 3, and the specific steps are as follows:

Step 301: The MSS periodically receives a neighbor broadcast message (NBR_ADV) sent by the serving BS, where the NBR_ADV message includes a frequency point of each BS adjacent to the serving BS and Preamble Index information, and according to the NBR-ADV The frequency points of the neighboring BSs and the Preamble Index information are scanned and measured on the neighboring BSs in advance by the scanning interval determined by the negotiation with the serving BS to obtain the signal quality of the neighboring BSs. The signal quality here can be signal to noise ratio information.

In this step, the MSS can also perform an initial search with the neighboring BS and synchronize. 2006/001230 To speed up the process of accessing the search when the terminal is handed over to a neighboring base station. The initial search and synchronization process here is the same as the prior art and will not be elaborated.

Step 302: After the MSS determines that the handover needs to be triggered, the MSS sends a terminal handover request (MOB_MSSHO_REQ) message to the serving BS to trigger the handover, and the MOB_MSSHO-REQ message includes the signal quality obtained by the MSS through scanning. The neighboring BS and the estimated start of the handover, the neighboring BS with better signal quality is the possible target BS selected by the MSS, and the method for the MSS to estimate the start of handover is: MSS The signal quality of the serving BS obtained according to the scan Information, such as signal-to-noise ratio, is compared to the minimum signal-to-noise ratio threshold required for MSS demodulation data to determine the time at which this minimum threshold may be reached, and a margin is left on the basis of this time to estimate Switch the official start time.

In this step, the MSS may trigger the handover by comparing the quality of the service BS and the neighbor BS signal, that is, when the MSS determines that the signal quality of the serving BS is lower than the signal quality of a neighboring BS, the MSB sends the MOB to the serving BS. The MSSHO-REQ message may also trigger the handover by detecting the error rate of the currently received signal, that is, when detecting that the error rate of the current signal reaches a threshold determined in advance by simulation or other manner, the packet is sent to the serving BS. MOB - MSSHO - REQ message.

Step 303: After receiving the MOB_MSSHO_REQ message sent by the MSS, the serving BS sends a handover pre-notification message (HO_Pre-Notification-Request) to each neighboring BS included in the message, and notifies the neighboring BS of the The MSS in the message may initiate a switch to it. The basic requirement information of the MSS that initiates the handover is included in the HO-Pre-Notification-Request message, and specifically includes the following parameters: the MSS identifier to be switched, the connection and service flow parameters, the capability, and the required bandwidth and QoS. The MSS identifier is the MAC address of the MSS; the connection and service flow parameters refer to the service connections currently owned by the MSS and the parameters describing the service flow characteristics of the connections; Having QoS, such as delay or loss, is the bandwidth required for the service that the terminal currently has. Packet rate, delay jitter, etc.

Step 304: The neighboring BS that receives the HO_Pre-Notification-Request message determines whether to allow the MSS to switch over, and if allowed, according to the parameters included in the message and its current load situation, through its own radio resource management policy. The MSS is switched over, whether the bandwidth and QoS allocated to the MSS support authentication authentication, and if authentication authentication, specific supported authentication method information, etc. are supported, and the determined responses to the MSS basic requirement information are determined. The information is returned to the monthly service BS to which the HO_Pre-Notification-Request message is sent by switching the Pre-Notification-Response (RSP) message.

Step 305: The serving BS receives the HO-Pre-Notification-RSS message sent by the neighboring BS within a preset time, and after the preset time arrives, according to the information carried in the messages, and the foregoing MOB_MSSHO - the signal quality of each neighboring BS carried in the REQ message, selecting the target BS capable of providing the best service for the MSS, and then the serving BS performing step 306 and then performing step 307, or performing step 307 and then performing step 306, or simultaneously Step 306 and step 307 are performed.

In this step, the switching target BS selected by the serving BS may be one or more than one. If the selected handover target BS is one, the target BS is the final handover target BS.

Step 306: The serving BS sends the information in the selected target BS and the corresponding HO_Pre_Notification_RSP message to the corresponding MSS through a base station handover response (MOB_BSHO_RSP) message.

Step 307: The serving BS sends a handover notification (HO_Notification) message to the selected target BS, where the message includes the MSS officially to the handover target. The time of the BS handover, so that the handover target BS can assign the fast accessing uplink resource (Fast Ranging IE) to the MSS at a determined time. The foregoing switching time may be a relative time, that is, a time difference between the time when the MSS officially switches to the target BS and the time when the serving BS sends the HO—Notification message to the target BS, and the time difference may be in units of frames.

After the serving BS selects the handover target BS in step 305, it needs to send a HO-Notification message to the selected handover target BS to notify it to assign the Fast Ranging IE to the MSS, and on the other hand, to send the MOB_BSHO-RSP to the MSS. The message is notified to the selected target BS, so the above steps 306 and 307 may be performed by the serving BS at the same time, or the step 306 may be performed first, or the step 307 may be performed first.

Step 308: After receiving the HO_Notification message sent by the serving BS, the handover target BS waits for the formal handover time to arrive in the message, and assigns the Fast Ranging IE to the MSS after the time is reached. Here, the target BS is a resource area allocated by the MSS for the MSS, and the MSS can ensure that the MSS can quickly exchange information with the target BS without delaying the switching time.

Step 309: After receiving the MOB_BSHO-RSP message, the MSS determines the handover result information according to the handover target BS information in the message, and sends the determined result information to the service by using a handover indication (MOB_HO_IND) message. BS. Here, if the target BS is included in the MOB_BSHO-RSP message sent by the serving BS, determining the handover result information includes selecting a target BS that can best satisfy the MSS service quality requirement, and whether to continue the handover, etc.; The MOB-BSHO-RSP message sent by the BS includes only one target BS, and determining the handover result information refers to determining whether to continue the handover.

Step 310: After receiving the MOB_HO-IND message, the monthly service BS determines the cancellation. Whether the information contained in the information is to continue switching, if it is to continue the handover, step 311 is performed; otherwise, step 312 is performed.

Step 311: The serving BS starts a preset timer that reserves resources for the MSS, and automatically releases the resources allocated for the MSS after the timer expires, and then performs step 313.

In this step, after determining that the handover is continued, the serving BS may further determine whether the target BS selected by the original serving BS is one. If yes, only the startup timer is executed and the resource is automatically released after the timeout; otherwise, the serving BS In addition to the step of executing the start timer and automatically releasing the resource after the timeout, it is also possible to determine the target BS that the service BS has selected, but the MSS has not selected, and send a cancel switch (HO_Withdraw) message to the determined BSs to notify the BSs. There is no need to establish a Fast Ranging IE for the MSS. After receiving the message, these BSs no longer establish a Fast Ranging IE for the MSS, and will not send a UL-MAP message to the MSS.

Step 312: The serving BS sends a HO_Withdraw message to the target BS selected in step 305, and notifies the BS that the Fast Ranging IE is not allocated to the MSS, and the BS that receives the HO_Withdraw message no longer allocates the Fast Ranging IE to the MSS. A UL-MAP message will be sent to the MSS.

Step 313: After the handover time arrives, the target BS notifies the MSS of the Fast Ranging IE information assigned by the MSS in the UL-MAP message.

Step 314: After receiving the UL_MAP message, the MSS interacts with the target BS on the Fast Ranging IE that the target BS assigns to the MSS, performs an initial access process, and after completing the access, the target BS moves to the original serving BS. A handover confirmation (HO_Confirm) message is sent to notify the original serving BS that the MSS that initiated the handover has accessed the target BS.

Step 315: After receiving the HO_Confirm message, the original serving BS determines whether the timer started in step 311 times out. If the timeout expires, the process ends directly; otherwise, the process is terminated. In step 316, the resources allocated for the MSS are directly released.

The above is a description of the flow of the first embodiment of the present invention, and the embodiment will be further described below in a specific case.

It is assumed that the serving BS is BS1. In the above step 302, the possible target BS selected by the MSS includes BS2 and BS3, and after the determined switching time is 7 frames, in step 303, BS1 sends HO_Pre- Notification to BS2 and BS3 respectively. — Request message. It is further assumed that, in step 305, BS1 selects the handover target as BS3 according to the HO_Pre-Notification-RSS message returned by BS2 and BS3, respectively, and the MOB_MSSHO-REQ message sent by the MSS has passed at this moment. At the time of 4 frames, in step 307, BS1 transmits only the HO_Notification message to the BS, and the relative time of the initiated handover included in the message is 3 frames calculated by subtracting 4 from 7. After receiving the HO_Notification message, BS3 assigns the Fast Ranging IE to the MSS that initiates the handover in the third frame, and sends the Fast Ranging IE information to the MSS through the UL-MAP message. After receiving the UL_MAP message, the MSS receives the UL_MAP message. And sending, according to the Fast Ranging IE information in the message, the RNG_REQ message to the BS3 on the corresponding Fast Ranging IE to enter the initial access.

In step 301 of the flow of the embodiment, the MSS scans the neighboring BSs to obtain the signal quality information of the neighboring BSs before initiating the handover, and then in the step 302, the MSS initiates the handover, and the terminal handover request message directly includes these. Pre-acquired neighbor BS signal quality information. However, in this embodiment, the MSS may scan the signal quality of the neighboring BS after the handover is initiated. Specifically, in the foregoing step 301, the MSS only receives the NBR-ADV message sent by the serving BS, but does not execute. The process of performing the scanning with the serving BS, and in step 302, before sending the terminal switching request message to the serving BS, the MSS first sends a scan request message to the serving BS, and the serving BS sends the scan request message to the MSS after receiving the scan request message. Scan the response message, after which the MSS is at the root Scanning the adjacent BS according to the scanning interval sent in the scan request message and the information in the NBR_ADV message received in step 301 to obtain the signal quality information of the neighboring BS, and then performing the terminal switching request to the serving BS. The step triggers the switch.

In the second embodiment of the present invention, the MSS still periodically receives the NBR_ADV message sent by the serving BS, according to the frequency of the neighboring BS in the NBR_ADV and the pilot (Preamble Index M is determined in advance by negotiation with the serving BS) The scanning interval is scanned for each neighboring BS to obtain the signal quality of these neighboring BSs. However, in this embodiment, unlike the first embodiment, the MSS period passes the signal quality of these neighboring BSs through the scanning measurement report. (MOB—SCAN—Report) The message is reported to the service BS.

On the basis of the foregoing MSS reporting the quality of the adjacent BS signal to the serving BS, the process of this embodiment is shown in FIG. 4, and the specific steps are as follows:

Step 401: The serving BS receives the MOB_SCAN_Report message reported by the MSS, and determines whether the MSS needs to switch to another BS according to its own load balancing policy and control algorithm, and the service status of each MSS connected to the serving BS. If yes, the switch is triggered, that is, step 402 is performed; otherwise, this step is returned.

In this step, when the resource BS is relatively tight, or the load is heavy, the MSS or a certain MSS needs to be switched. If there is only one MSS, this process only refers to the process in which the serving BS interacts with the MSS; if there are several MSSs, the serving BS and each MSS perform this process to interact. The service BS determines whether the handover is required or not based on whether the currently allocated air interface resource or the current load exceeds a preset threshold. The load here mainly refers to the processor resources of the BS itself, such as queue resources, CPU load rate, and port traffic of the BS back-end network. The MSs that need to be switched by the BS are based on the idleness information of the MSS service in the UE, or the priority information of the service flow of the MSS, or the user subscription level information of the MSS, and select the most idle service according to the preset threshold. , or business The stream has the lowest priority, or the MSS with the lowest user subscription level.

Step 402: The serving BS sends a HO_Pre-Notification-Request message to the neighboring BS included in the message according to the MOB_SCAN_Report message reported by the MSS.

Step 403: The neighboring BS that receives the HO-Pre-Notification-Request message sent by the serving BS returns a HO-Pre-Notification-RSP to the serving BS. Step 404: The serving BS receives the neighbor in a preset time. The HO-Pre-Notification-RSS message returned by the BS, and after reaching the preset time, according to the information carried in the message, and the signal quality information of the neighboring BS carried in the MOB_SCAN_Report message, select the MSS The switching target BS. Afterwards, the serving BS sends the selected handover target BS to the MSS through the MOB_BSHO-RSP message on the one hand, and sends a handover notification message including the handover time to the selected handover target BS through the HO_Notification message, on the one hand, and the subsequent The switching process, and the specific implementation of the foregoing steps 402 and 403 are the same as those in the first embodiment, and are not described in detail in this embodiment.

Different from the first embodiment, the above-mentioned handover time included in the handover notification message is determined by the serving BS according to its own handover triggering factor. For example, the handover trigger is because the queue resource in the BS reaches the set handover trigger threshold, and the BS can determine that the handover needs to be formally performed according to the maximum value of the queue that guarantees its normal operation and the maximum speed of the queue growth. time.

The above is a description of the second embodiment of the present invention. In the second embodiment, the serving BS selects the neighboring BS that transmits the HO_Pre-Notification-Request message according to the neighbor BS information reported by the MSS. In the third embodiment of the present invention, the MSS does not report the signal quality information of the neighboring BS to the serving BS, or the serving BS does not receive the signal quality information of the neighboring BS reported by the MSS, or in the serving BS, the MSS Reported neighbor BS letter If the quality information has expired, that is, if the serving BS has deleted or discarded the information, the serving BS may also initiate a handover. The third embodiment will be described in detail below.

In addition, in this embodiment, the serving BS may also actively request the MSS to scan the neighboring BS, and report the signal quality information obtained by the scanning to the serving BS, specifically: the serving BS determines that the MSS needs to be switched to After the other BSs, the scanning response message is sent to the neighboring BS, and the scanning response message is sent to the terminal that needs to be switched. After receiving the scanning response information, the terminal according to the scanning response information and the serving BS The information in the sent NBR_ADV message is scanned by the neighboring BSs, and after the signal quality information of the neighboring BSs is obtained by scanning, the signal quality information of the neighboring BSs is reported to the serving BS; The BS still selects the handover target BS according to the response information carried in the HO_Pre-Notification_RSP returned by the neighbor BS and the signal shield information of the neighbor BS reported by the terminal.

In the third embodiment of the present invention, the method for the serving BS to initiate the handover is the same as that in the second embodiment. As shown in FIG. 5, most of the steps in the flow are also the same as those in FIG. 4 in the second embodiment. Only the steps that are different are explained.

In step 501, the serving BS determines, according to its own load balancing policy and control algorithm, and the service status of each MSS connected to the serving BS, whether the MSS needs to be switched to another BS, and if yes, step 502 is performed; otherwise, Perform this step. Subsequent steps 502 and 503 are the same as steps 402 and 403 in FIG. 4, and in step 504, unlike step 404 in FIG. 4, the serving BS is only based on HO_Pre- Notification returned by the neighboring BS. The information carried in the RSP selects the handover target BS of the MSS.

In the above first embodiment, the handover is initiated by the MSS, and in the second and third embodiments, the handover is initiated by the serving BS. In the present invention, the handover may also be initiated by the network controller (ASN GW), and the following describes the case where the ASN GW initiates the handover by using the fourth embodiment. Detailed description.

In the fourth embodiment of the present invention, the ASN GW determines whether the MSS in a certain BS needs to be handed over to another BS according to the load balancing policy and the control algorithm of the BS set in the UE, and if so, selects the MSS to be switched in the BS. And sending a handover request message to the selected MSS accessing the MSS that needs to be switched, and including the MSS information to be switched and the time of the formal handover in the request message; otherwise, returning to the execution of this step.

Here, the ASN GW specifically determines whether the handover is required or not based on whether the current resource or load of each BS controlled by the BS exceeds a preset threshold. The method of determining the formal handover time may also be the same as the time when the MSS determined by the serving BS in the second embodiment is officially switched, that is, determined by the ASN GW according to the load balancing policy and the control algorithm of the BS set therein. In addition, the manner of selecting the MSS that needs to be switched is also the same as the manner in which the serving BS selects the MSS that needs to be handed over in the second embodiment, that is, according to the MSS service idle situation information in the BS, or the priority information of the MSS service flow, Or the user subscription level information of the MSS, and select the MSS with the most idle service, or the service flow priority, or the lowest user subscription level according to the preset threshold.

After receiving the handover request information sent by the ASN GW, the monthly service BS determines the basic requirement information required for the MSS to perform handover according to the MSS information in the message and the information of the MSS stored in the message, and the information is obtained. The HO_Pre-Notification-Request message is sent to the neighboring BS. The BS that receives the handover request information is the service BS of the MSS that needs to perform handover. Thereafter, the flow of switching may be the same as any of the above three embodiments, and will not be described in detail herein.

In the fourth embodiment, before the serving BS sends the HO_Pre-Notification_Request message to the neighboring BS, whether the neighboring BS of the MSS reported by the MSS may be present in the serving BS. The signal quality information is judged. If there is signal quality information of the neighboring BS reported by the MSS in the serving BS, only the HOJPre_Notification_Request message is sent to the neighboring BS, and when the target BS is selected from the neighboring BSs, according to the HOJPre - Notification - The information in the RSP is integrated with the signal quality information of the neighboring BS reported by the MSS; otherwise, if there is no signal shield information of the neighboring BS reported by the MSS, the serving BS may receive the handover request sent by the ASN GW. After the information, the scan response message is sent to the MSS, and the MSS is notified to scan the neighboring BSs to obtain the signal quality of the neighboring BSs, and report the signal quality to the serving BS. The MSS receives the scan response message. After the scan is performed and the signal quality information of the neighboring BS obtained by the scan is reported to the serving BS, the serving BS still reports the information according to the HO_Pre-Notification-RSP and the MSS when selecting the target BS from the neighboring BSs. The signal quality information of the adjacent BSs is comprehensively performed.

In addition, since in the above four embodiments, the serving BSs all send the HO_Notification message to the selected target BS before receiving the MOB_HO_IND message sent by the MSS, the target BS is assigned the Fast Ranging IE for the MSS in advance. On the one hand, if the target BS selected by the serving BS at this time is not selected by the MSS as the final target BS, the serving BS needs to send a HO_Withdraw message to the BSs to notify it that the Fast Ranging IE is not assigned to the MSS; The service BS also needs to send a HO_Withdraw message to the target BS that has sent the HOJSk) tification message to notify it not to assign the Fast to the MSS because the information contained in the MOB_HO_IND message reported by the MSS is no longer to be switched. Ranging IE. In order to save the foregoing HO-Notification message and the HO-Withdraw message, and in order to further save the network resource, the serving BS may send the HO__Notification message after receiving the MOB_HO_IND message sent by the MSS, and the following is adopted by the fifth embodiment. Detailed instructions are given.

In the fifth embodiment of the present invention, after the serving BS selects the handover target BS, only The step of transmitting a message including the selected handover target BS information to the MSS is performed, and the specific implementation of the step and the flow before the step may be the same as any of the above four embodiments. Then, after receiving the message including the selected handover target BS information sent by the serving BS, the MSS returns a MOB_HO_IND message to the serving BS, if the information included in the message is to continue the handover. After receiving the MOB_HO_IND message returned by the MSS, the serving BS determines whether the message is to continue the handover, and if yes, sends a HO-Notification message to the handover target BS in the message to notify the MSS of the official handover time; If not, the switching process is ended directly.

Generally, when the MSS interacts with the target BS for initial access, the MAC address of the MSS is used as the identifier of the MSS. The resource occupied by the MAC address is 48 bytes, and the occupied resources are relatively large. For the target base station, the number of MSSs that are switched to it is not too large, and it is not necessary to use the MAC address that occupies a large resource as the identifier of the MSS. Therefore, in the sixth embodiment of the present invention, after receiving the HO_Pre_Notification_Request message, the target BS allocates a handover identifier (HO_ID) that occupies less resources for the MSS that initiates the handover. In general, it is sufficient to allocate an 8-byte resource for the HO-ID. Of course, in special cases, the number of bytes allocated for the HO-ID can be more, such as 10 bytes, or 12 bytes. After the target BS will assign the HO_ID to the switched MSS, the HO_ID assigned to the MSS is notified to the serving BS by the HO_Pre-Notification__RSP message, and the serving BS sends the HO_ID to the MOB_BSHO-RSP message to Corresponding MSS, the MSS uses the HO-ID instead of the MAC address in the process of initial interaction with the target BS, thereby reducing the amount of resources required for the interaction between the MSS and the target BS, so that the target BS is the handover. The size of the Fast Ranging IE allocated by the MSS can also be reduced.

In the above embodiments, the time for the formal handover is determined by the device that initiates the handover, such as the terminal, the BS, or the ASN GW, but in the present invention, the formal implementation is performed. The time of the handover can also be determined by the target BS, which will be described in detail below through the seventh embodiment. The handover procedure of the seventh embodiment of the present invention may be based on the above six embodiments, and the difference from the above six embodiments is that, when the handover is initiated, whether it is the terminal, the serving BS or the ASN GW, and the formal handover is not determined. Time, but after receiving the HOJPre_Notification_Request message sent by the serving BS, the target BS determines the time when the MSS can be officially switched according to the basic requirement information of the MSS in the message and its own radio resource scheduling policy, and the time is The HO_Pre-Notification-RSP message is sent to the serving BS, and the target BS assigns the Fast Ranging IE to the MSS when the time of the formal handover determined by itself, and sends a UL_MAP message including the Fast Ranging IE information to the MSS. After receiving the HO_Pre_Notification_RSP message sent by the target BS, the serving BS resends the time of the formal handover included in the message to the MSS that performs the handover. After receiving the time of the formal handover sent by the serving BS, the MSS may select the target BS according to the signal quality of each target BS, the target BS selected and delivered by the serving BS, and the basic requirement information of the target MSs to the MSS when selecting the final target BS. The response information and the time at which the target BS transmits the official handover by the serving BS are integrated. In addition, the serving BS does not need to include the time of the formal handover in the HO_Notification message sent to the neighboring BS.

Each of the above embodiments is based on the case where an interface is provided between BSs, and communication can be directly performed through the interface. In the present invention, there is also provided a solution in the case where there is no interface between the BSs, that is, when the messages cannot be directly transmitted between the BSs, and the difference between the solution and the above embodiments is that, in the above embodiment The message exchanged between the BSs needs to be performed through the ASN GW between the two BSs. The following is an example in which the MSS initiates the handover. Other specific processes such as the BS initiates the handover, the ASN GW initiates the handover, and adopts the HO ID and the like, and refer to the foregoing implementations. The example and the eighth embodiment can be implemented.

As shown in FIG. 6, after the MSS sends the MOB_MSSHO_REQ message to the serving BS in step 601, the serving BS transmits the neighbor BS information and the MSS reported by the MSS through the handover request (HO_REQ) message in step 602. The request information is notified to the ASN GW. After receiving the HO_REQ message, the ASN GW determines whether the neighbor BS in the message is the BS controlled by the ASN GW. If yes, step 604 is performed; otherwise, step 606 is performed.

Here, if there are multiple neighboring BSs, the ASN GW determines whether each neighboring BS is within its own control range, and performs step 604 for each neighboring BS in its own control range; Step 606 is performed by neighboring BSs within their own control range.

In step 604, the ASN GW sends a HO-Pre-Notification-Request message including the basic requirement information of the MSS that initiates the handover to the neighboring BS controlled by itself, and then in step 605, the neighboring BS receives the HO-Pre-Notification of the ASN GW. — After the Request message, the HO_Pre-Notification-RSP message is returned to the ASN GW. The specific content contained in these messages is the same as in the previous embodiment.

In step 606, the ASN GW sends a handover pre-notification (HO_Pre-Notification) message to the neighboring ASN GW to which the neighboring BS belongs according to the information of the neighboring BS, and the content included in the message is removed from the HO-Pre- In addition to the content in the Notification_Request message, the information of the neighboring BS is further included. After receiving the HO_Pre-Notification message, the neighboring ASN GW sends the HO to the corresponding BS according to the neighbor BS information in the message. - Pre-Notification-Request message; Then, in step 608, the neighboring BS returns a HO-Pre-Notification-RSP message to the neighboring ASN GW to which the neighboring BS belongs after receiving the HO-Pre-Notification-Request message; In step 609, after the neighboring ASN GW receives the HO_Pre-Notification-RSP message, Return HO-Pre-Notification-RSP message to the original ASN GW.

In step 610, the ASN GW receives the HO-Pre-Notification-RSP message within a preset time after receiving the HO-REQ message, and after receiving the preset time, the received HO-Pre- The information in the Notification-Request message is notified to the serving BS by the HO-RSP message. In step 611, the serving BS selects the neighboring BS as the handover target BS recommended to the MSS according to the above information carried in the HO-RSS, and then passes the MOB_BSHO_RSP. The message is sent to the MSS.

Thereafter, in the subsequent process, the interaction between the MSS and the serving BS and the interaction between the target BS and the MSS are the same as in the first embodiment, and the interaction process between the BSs is different from that in the first embodiment, and the specific reference is made. The foregoing steps 602 to 611 are implemented, and only the specific message in the step 602 to the step 611 is changed to the message corresponding to the interaction between the BSs in the subsequent process of the first embodiment, which is not described in detail herein.

The above description is only the preferred embodiment of the present invention, and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., which are included in the present invention, should be included in the present invention. Within the scope of protection.

Claims

Claim

A method for a terminal to switch between base stations, characterized in that the method comprises the following steps:

After the handover is triggered, the serving base station BS sends a handover pre-notification message to the neighboring BS, where the handover pre-notification message includes basic requirement information of the terminal MSS that needs to be handed over;

After the neighboring BS receives the handover pre-notification message, it determines that the message corresponds to the time when the MSS is officially configured to perform the handover, and after the time is reached, the MSS is assigned the uplink resource for fast access, and the uplink resource assignment message is used. Notifying the MSS of the assigned uplink resource information of the fast access;

The method according to claim 1, wherein the handover triggering is: sending, by the MSS, an MSS handover request message to the serving BS to trigger the handover;

Or, after the network controller ASN GW determines that the MSS needs to be handed over to the service BS of the other BS according to the load balancing policy and the control algorithm, sending a handover request message to the determined serving BS triggers the handover.

The method according to claim 1, wherein the MSS basic requirement information included in the handover pre-notification message in step a includes: an MSS identifier, a connection and service flow parameter, a capability parameter, and a required Bandwidth and QoS.

4. The method according to claim 1, wherein said adjacent in step b The BS determines the time for the MSS to officially switch:

Bll. The neighboring BS determines the time of the formal handover according to the MSS basic requirement information in the received handover pre-notification message and its own radio resource scheduling policy.

The method according to claim 4, wherein the step b11 further comprises:

Bl2, the formal switching time information determined by the neighbor BS and the response information of the MSS basic requirement information are returned to the service BS by switching the pre-notification response information;

Bl3, after receiving the handover pre-notification response message returned by the neighboring BS, the serving BS sends the information of the neighboring BS and the information in the corresponding handover pre-notification response message to the MSS;

After receiving the information delivered by the serving BS, the M4 and the MSS determine the final target BS according to the information;

In the step c, the final target BS determined from the neighboring BSs is the final target BS determined in the step bl4.

The method according to claim 1, wherein the time when the neighboring BS determines that the MSS is officially switched in the step b includes:

B21, after the neighboring BS receives the handover pre-notification message, the response information of the MSS basic requirement information is returned to the service BS by using the handover pre-notification response information;

B23. The time that the neighboring BS sends the serving BS is determined as the time when the handover is formally performed.

The method according to claim 6, wherein in the step b22, the step of the service BS determining that the MSS is officially performing the handover is:

The MSS determines the time when the handover is officially performed according to the signal quality information of the serving BS, and reports the time to the serving BS; when the serving BS receives the official handover of the MSS report After the interval, the time is determined as the time when the MSS is officially switched;

Or the service BS determines the time when the MSS is officially switched according to its own load balancing policy and control algorithm;

Or the ASN GW determines, according to the BS load balancing policy and the control algorithm, the time when the MSS is officially switched in the BS, and then sends the time to the serving BS. The service receives the time when the BS sends the formal handover to the ASN GW. After that, the time is determined as the time when the MSS is officially switched.

The method according to claim 6, wherein after the step b22, the method further comprises:

The MSS sends a handover indication message including the predetermined final target BS information to the serving BS, and after receiving the handover indication message, the serving BS determines, according to the final target BS information in the handover indication message, that the handover notification message is previously sent and is not the final destination. The neighboring BS of the BS then sends a cancel handover message to the determined neighboring BS, informing it to cancel the uplink resource for which the MSS is scheduled to access the fast access.

The method according to claim 6, wherein, in the step b22, before the sending of the formal handover time to the neighboring BS, the method further includes:

After receiving the handover pre-notification response message returned by the neighboring BS, the serving BS receives the post-reported phase according to the information in the received handover pre-notification response message or according to the information in the received handover pre-notification response message and the MSS scan. The signal quality information of the neighboring BS is determined from the neighboring BSs in the return handover pre-notification response message as the final target BS, and the information in the handover pre-notification response message returned by the BS and the BS is sent to the MSS;

After receiving the information sent by the serving BS, the MSS determines whether to continue the handover according to the information and the signal quality information obtained by the neighboring BS scan, and sends the determined result information of whether to continue the handover to the service through the handover indication message. BS;

After receiving the handover indication message, the serving BS determines whether the message continues to enter the indication. Line switching, such as:

Transmitting a notification message to the neighboring BS; otherwise, directly ending the process;

In the step b22, the time is sent to the neighbor BS by using a handover notification message: the time is sent to the final target BS determined by the service BS by using a handover notification message.

The method according to claim 6, wherein, in the step b22, before the sending the formal handover time to the neighbor BS, the method further includes:

The serving BS directly sends the information in the neighbor BS information that returns the handover pre-notification response information and the information in the corresponding handover pre-notification response message to the MSS, or selects more than one neighboring BS from the neighboring BSs that return the pre-notification response message. And sending the selected neighbor BS information and the information in the corresponding handover pre-notification response message to the MSS;

After the MSS sends the information, the MSS determines whether to continue the handover according to the information, and if yes, determines the final target BS according to the information and the neighbor BS signal quality information acquired by the self-scan, and determines the result. Sending to the serving BS by using a handover indication message;

After receiving the handover indication message, the serving BS determines whether the information in the message is to continue to be switched, and if yes, performing the step of transmitting the time when the handover is officially performed to the neighboring BS by using a handover notification message; Otherwise, the process ends directly;

And sending the time to the neighboring BS by using a handover notification message to: send the time to the final target BS determined by the MSS by using a handover notification message.

The method according to claim 9 or 10, wherein the MSS scan acquires signal quality information of the neighboring BS as:

The MSS scans the adjacent BSs according to the information in the neighboring cell broadcast message delivered by the serving BS and the scanning interval obtained by the negotiation with the serving BS to obtain the signal quality information of the neighboring BS.

Or in step a, before the serving BS sends a handover pre-notification message to the neighboring BS, The MSS sends a scan response message. After receiving the scan response message, the MSS scans the neighbor BS to obtain the signal quality information of the neighbor BS according to the information and the information in the neighbor broadcast message sent by the serving BS. .

The method according to claim 6, wherein, in the step b22, after receiving the handover pre-notification response message returned by the neighboring BS, the serving BS further includes: the serving BS receives the handover returned by the neighboring BS. After the pre-notification response message, the information of the neighboring BS and the information in the corresponding handover pre-notification response message are sent to the MSS; after receiving the information sent by the serving BS, the MSS determines the final target BS according to the information;

In the step c, the final target BS determined in the adjacent BS is the final target BS determined by the MSS.

The method according to claim 5 or 12, wherein the sending the information of the neighboring BS and the information in the corresponding handover pre-notification response message to the MSS further includes:

The service selects according to the information in the handover pre-notification response message returned by the neighboring BS, or according to the information in the handover pre-notification response message returned by the neighboring BS and the signal quality information of the neighboring BS reported after the MSS scan is recorded therein. Possible as a neighboring BS of the handover target BS;

The information of the neighboring BS and the information in the corresponding handover pre-notification response message are sent to the MSS: the serving BS sends the selected neighboring BS information and the information in the corresponding handover pre-notification response message to the MSS;

Then the MSS determines that the final target BS includes:

The MSS determines whether the number of neighboring BSs in the information sent by the serving BS is one, and if yes, determines the neighboring BS as the final target BS; otherwise, the MSS selects from the neighboring BS according to the information delivered by the serving BS. One identified as the final target BS;

Then, the final target BS determined in the neighboring BS in step c is: the MSS Determine the final target BS.

The method according to any one of claims 1 to 10, or 12, wherein, in the step b, after receiving the handover pre-notification message sent by the serving BS, the neighboring BS further includes:

The neighboring BS allocates a handover identifier to the MSS in the handover pre-notification message, and sends the handover identifier to the service BS by using a handover pre-notification response message;

The step c further includes:

After receiving the handover pre-notification response message, the serving BS sends the handover identifier assigned by the neighboring BS to the MSS to the MSS;

In the step c, when the MSS sends a message to the final target BS for initial access, the handover identifier is used as the identity.

The method according to claim 14, wherein the uplink resource assignment message in step b uses the handover identifier as the MSS identifier.

The method according to any one of claims 1 to 10, or 12, wherein, when the messages cannot be directly transmitted between the BSs, the step of performing message interaction between the BSs is: the sender BS first The message is sent to the ASN GW to which the sender belongs. After receiving the message sent by the sender BS, the sender's ASN GW determines whether the receiver BS is a BS within its own control range. If yes, the message sent by the sender BS is directly sent. Forwarding to the receiver BS; otherwise, the sender ASN GW forwards the message sent by the sender BS to the receiver ASN GW to which the receiver BS belongs, and the receiver ASN GW receives the message sent by the sender ASN GW, and then sends the message. Forward to the receiving BS.