MXPA06014058A - Handover execution and communication resumption in wireless access system - Google Patents

Abstract

Handover execution and communication resumption in a wireless access system is provided. Performing a handover includes communicating with a serving base station through a first communication link and receiving from the serving base station, handover information associated with at least one candidate target base station. The method also includes transmitting handover indicator to the serving base station indicating a handover operation to a selected target base station and performing a ranging procedure with the selected target base station to establish a second communication link with the selected target base station while maintaining the first communication link with the serving base station. The method also includes being released from the serving base station in response to a handover complete status message from the selected target base station to the serving base station, or resuming normal communication with the serving base station if the handover fails with the selected target base station.

Description

EXECUTION OF TRANSFER AND RESUME OF COMMUNICATION IN WIRELESS ACCESS SYSTEM FIELD OF THE ART The present invention relates, in general terms, to a wireless access system, and more particularly to a transfer execution in a wireless access system. BACKGROUND OF THE TECHNIQUE The IEEE802.16e system is part of a global standardization for broadband wireless access systems. The IEEE802.16e system does not have a hierarchical structure of HLR, VLR, MSC, BSC, RNC, etc., unlike second and third generation mobile communications systems, but includes a mobile subscriber station (MSS), a base station (BS), and a server Authentication service authorization (ASA Server). A physical layer (PHY) and a medium access control layer (MAC) are defined between the base station (BS) and the mobile subscriber station (MSS). Next, a transfer process in a broadband wireless access system according to the present invention is presented. 1. Pre-processing for transfer Pre-processing for transfer includes the dissemination of associated information from a base station to a neighboring base station to report the associated information (Network Topology Advertisement) to all mobile subscriber stations within a respective cell. The pre-processing also includes the measurement of a channel quality of the neighboring base station based on the associated information (MSS scan of neighboring BS). The pre-processing also includes the matching of parameters between the base station and the neighboring base station, such as for example an initial mobile subscriber station power, a time difference for sronization, and other parameters (Association Procedures). to. Network Topology Announcement In a network topology advertisement, the base station broadcasts information associated with the network configuration to all mobile subscriber stations within a cell via a MOB_NBR-ADV MAC message, thereby providing all its mobile subscriber stations within the cell the information pertaining to neighboring base stations. b. Neighboring BS MSS Scanning In the neighboring BSS MSS scan, a mobile subscriber station (MSS) scans a neighboring base station (BS) and requests a scan interval to scan the neighboring BS from a BS through a BS message MOB SCN-REQ MAC. The BS then transmits a message MOB_SCN-RSP MAC for response to the request to assign it a range to scan (Scan interval) the neighbor BS. Alternatively, the BS can directly transmit the message MOB_SCN_RSP MAC without request of the MSS (unsolicited response). In the case of an unsolicited response, the scan interval and a lag unit for scan start are assigned in a frame unit basis, c. Association Procedures During association procedures, the MSS performs a detection process with a BS to normally enter a cell. In the detection process, the MSS acquires basic information for communications from the BS. In other words, the MSS performs a BS scan to select a new BS and then carries out the association procedures. The MSS and the BS transmit an RNG_REQ MAC message and RNG_RSP MAC message, respectively, to set values such as, for example, a power offset value, a timing offset value, and other MSS values at the appropriate values. The transmission of the RNG_REQ MAC message is known as the initial detection operation and is a basic operation that MSS can perform in a network entry procedure. When a transfer is made, a white BS accepts a new MSS and transmits elements associated with the respective cell of the new MSS to the previous serving BS and stores the information belonging to the MSS. 2. Transfer Process In a transfer process (HO), the MSS initiates a transfer with neighboring BSs based on the quality information and channel acquired in the transfer pre-processing. to. Cell Selection In a cell selection procedure, a cell is changed to allow the MSS to perform a new registration to a BS allowing the reception of a signal that has a SINR (Signal-to-interference ratio plus noise) greater than the SINR of a signal transmitted from the BS of the current cell, before a normal registration of the MSS to a cell. In such a case, since the MSS does not perform the registration procedure, the BS can not determine a movement situation of the MSS. b. Start of HO (Transfer) When initiating an HO, the transfer can be initiated by the MSS or by the BS. When the BS requests (initiates) a transfer, the BS transmits a message MOB_BSHO-REQ MAC to the MSS. On the contrary, when the MSS requests a transfer, the MSS transmits a message MOB_MSSHO-REQ MAC to the BS. If the MSS transmits a MOB MSSHO-REQ MAC message, the MSS preferably transmits the SINR of a signal received from a neighbor BS to the BS to allow transmission of the message MOB_MSSSHO-REQ MAC to a current service BS. The current service BS then selects a candidate BS as a white BS to effect the transfer. In the case in which the BS receives the message MOB MSSHO-REQ MAC from the MSS or in the case in which the BS has not yet transmitted the message MOB_BSHO-REQ MAC for transfer to the MSS, the BS may allow the transfer of the MSS after the configuration of an acknowledgment (ACK) for handling in a specific MSS from the neighboring BS. After receiving the message MOB_BSHO / MSSHO-REQ MAC, the MSS / BS transmits a message MOB_MSSHO / BSHO-RSP MAC to inform the BS / MSS of a white BS for the transfer. c. Cancellation of HO (Transfer) On cancellation of HO, after transmission by MSS / BS of message MOB_MSSHO / BSHO-REQ MAC, the MSS can cancel the transfer. When canceling the HO (transfer), the MSS establishes a specific field (HO_Type = 01) of a message MOB_HO-IND MAC and transmits the established field to the BS. The BS receives the message and cancels a transfer in process, d. Termination with the Service BS Upon termination of the service BS, the MSS transmits the message MOB_HO-IND MAC to inform the service BS that the transfer was effected normally and then the transfer operation ends. Upon completion of the transfer operation, the MSS establishes a specific field (HO_Type = 00) of the message MOB_HO-IND MAC to transmit the information correlated with a normal transfer termination to the BS. The service BS receives the message MO_HO-IND MAC from the MSS at the end of a MAC state assigned by machine to the MSS. The service BS also terminates an ARQ (Automatic Repeat Request) connection and all connections associated with the data transmission. and. HO rejection In rejecting HO, the MSS may reject a transfer recommended by the BS. When rejecting a transfer, the MSS establishes a specific field (HO_Type = 10) of the message MOB_HO-IND MAC and transmits the message to the BS. The BS receives the reject message from the MSS, searches again for a blank BS and retransmits the message MOB_BSHO-RSP MAC to the MSS. Figure 1 is a diagram illustrating a transfer process requested by a mobile subscriber station (MSS). With reference to Figure 1, an MSS 11 performs a scanning procedure for measuring transmitted signal qualities of neighboring BSs (S110). If the MSS 11 determines that a transfer must be made based on a result of the neighboring BS scanning procedure, the MSS 11 transmits a transfer request message (MOB-MSS-HO-REQ) to a service BS 12. (Slll). The service BS 12 receives the transfer request message and transmits a pre-notification (HO-pre-notification) message that includes information in the sense that the MSS 11 has requested a transfer to a neighboring BS, as for example, the transfer white BSs (white BSs) 13 and 14 (S112, S113). The transfer pre-notification message includes an identifier (MSS identifier) of the MSS 11 requesting the transfer, connection parameters, capabilities, a required bandwidth, and quality of service information. Each of the neighboring transfer target BSs 13 and 14 receives a transfer pre-notification message and transmits a transfer pre-notification response message (HO pre-notification response) to the BS 12 in response to the message of pre-notification of transfer (S114, S115). The transfer pre-notification response message must include recognition information pertaining to the transfer pre-notification message and capacity information pertaining to the quality of service requested. The service BS 12 selects one of the neighboring transfer white BSs 13 and 14 in accordance with the response messages for the transfer pre-notification and transmits a transfer confirmation message (HO confirmation) to the selected BS BS 13 or 14 (S116). The service BS 12 then transmits a transfer response message (MOB-BSHO-RSP), which includes information pertaining to the selected transfer white BS, to the MSS 11 (S117). The MSS 11 receives the transfer response message and transmits a transfer indicator message (MOB-HO-IND) to release a connection from the MSS 11 to the service BS 12 (S118). Upon receiving the transfer indicator message from the BS 11, the service BS 12 releases its connection to the MSS 11 (S119). The MSS 11 then performs a fast detection (Quick Detection_IE), a detection request (RNG-REQ), and a detection response (RNG-RSP) with the white BS 14 (S120, S121, S122). The white BS 14 becomes the service BS 14 and the MSS 11 completes an initial network entry execution after the transfer (S123). Figure 2 is a diagram illustrating a transfer process requested by the base station (BS). With reference to Figure 2, a service BS 22 activates a procedure (activation to release MSS) to release a connection of an MSS 21 in accordance with the corresponding decision (S210). The service BS 22 then transmits a transfer pre-notification message (HO pre-notification) that includes information required for the transfer of the MSS 21 to neighboring transfer target BSs 23 and 24 (S211, S212). The transfer pre-notification message includes an identifier (MSS identifier) of the MSS 21 requesting the transfer, connection parameters, capabilities, a required bandwidth, and quality of service information. Each of the neighboring transfer target BSs 23 and 24 receives the transfer pre-notification message and transmits a transfer pre-notification response message (HO pre-notification response) to the service BS 22 in response to the transfer pre-notification message (S213, S214). The transfer pre-notification response message may include recognition information pertaining to the transfer pre-notification message and a capacity information pertaining to the required quality of service. The service BS 22 then transmits a transfer request message to the MSS 21 based on the information received through the transfer pre-notification response message (S215). The transfer request message includes information pertaining to the white BS 23 and 24 available for the transfer. The MSS 21 then performs a scanning procedure of neighboring BSs to measure the quality of signals received by the neighboring white BSs, as recognized through a transfer response message (S216). In a case in which the white BS 24 found for the transfer is found as a result of neighboring BS scanning, the MSS 21 transmits a transfer response message including white BS information for transfer to the service BS 22 (S217). The service BS 22 which then transmits a transfer confirmation message to the white BS 24 to which the MSS 21 contemplates effecting a transfer (S218). The MSS 21 then transmits a transfer indicator message (MOB-HO-IND) to release a connection from the MSS 21 to the service BS 22 (S219). Upon receiving the transfer indicator message, the service BSS 22 releases its connection to the MSS 21 (S220). The MSS 21 then executes a fast detection (Fast Detection-IE), a detection request (RNG-REQ), and a detection response (RNG-RSP) (S221, S222, S223) with the service white BS 24 for the transfer and then terminates an initial network entry execution after the transfer (S224). Figure 3 is a diagram illustrating a process by which an MSS re-enters the previous serving BS, as in the case of an interrupted call. With reference to Figure 3, an MSS 31 performs a scanning procedure for measuring the qualities of the signals transmitted from neighboring BSs (S310). If the MSS determines that a transfer must be made based on the results of the neighboring BS scanning procedure, the MSS 31 transmits a transfer request message (MOB-MSS-HO-REQ) to the service BS 32 (S311) . The service BS 32 receives the transfer request message and transmits a transfer pre-notification message (HO pre-notification) which includes information in the sense that the MSS 31 has requested the transfer to a neighboring BS, as per example, transfer to white BSs 33 and 34 (S312, S313). The pre-notification and transfer message includes an identifier (MSS identifier) of the MSS requesting the transfer, connection parameters, capabilities, a required bandwidth, and quality of service information. Each of the neighboring transfer target BSs 33 and 34 receives the transfer pre-notification message and transmits the transfer pre-notification response message (HO pre-notification response) to the service BS 32 in response to the transfer pre-notification message (S314, S315). The transfer pre-notification response message may include recognition information pertaining to the transfer pre-notification message and capacity information pertaining to the quality of service requested.

The service BS 32 selects one of the neighboring transfer white BSs 33 and 34 in accordance with the response messages from the transfer pre-notification and transmits a transfer confirmation message (HO confirmation) to the selected BSs. 33 or 34 (S316). The service BS 32 then transmits the transfer response message (MOB-BSHO-RSP) which includes information pertaining to the white BS for transfer to the MSS 31 (S317). The MSS 31 receives the transfer response message from the service BS 32 and transmits a transfer indicator message (MOB-HO-IND) to release a connection from the MSS 31 to the service BS 32 (S318) . Upon receiving the transfer indicator message, service BS 32 releases its connection to MS 31 (S319). DISCLOSURE OF THE INVENTION Accordingly, the present invention relates to an implementation of transfer and resumption of communication in a wireless access system that substantially avoids one or more of the problems caused by the limitations and disadvantages of the related art. An object of the present invention is to provide a method for efficiently resuming communications in a wireless access system when a mobile subscriber station (MSS) returns to a previous service base station (BS) in case of transfer failure. Advantages, objects, and additional features of the present invention will be presented in part in the following description and in part will be apparent to those of ordinary skill in the art in examining the presented information or may be learned from the practice of the invention. The objects and other advantages of the invention can be achieved and obtained through the structure particularly indicated in the description and in the claims as well as in the attached drawings. In order to achieve these objects and other advantages and in accordance with the purpose of the present invention, as incorporated and described in general terms herein, in one embodiment, the method for effecting a transfer operation in a wireless communication system includes communication with a service base station through a first communication link and the reception from the service base station of a transfer information associated with at least one candidate white base station, wherein the transfer information comprises the less quality of service capable of being handled by the at least one candidate white base station. The method also includes transmitting a transfer indicator to the service base station indicating a transfer operation to a selected white base station, wherein the mobile subscriber station determines whether or not a transfer is made in response to the transfer information, and perform a detection procedure with the selected white base station to establish a second communication link with the selected white base station while maintaining the first communication link with the service base station, wherein the The detection method comprises attempting to establish uplink synchronization and power adjustment between the mobile subscriber station and the selected white base station. The method also includes the release of the service base station in response to a complete transfer status message from the selected white base station to the service base station, or resuming normal communication with the service base station if the transfer fails with the selected white base station. The method can also preferably include receiving a transfer response from a service base station when transmitting the service base station a transfer confirmation to a white transfer base station, where the transfer response comprises at least a quality of service information requested for its management by the white base transfer station. The method may also preferably include a transfer initiated by the mobile subscriber station, the transmission of a transfer request to a service base station through a first communication link before receiving the transfer response from the base station of service. The method may also preferably include, in a transfer initiated by the service base station, the receipt of a transfer request from the service base station before transmitting a transfer response to the service base station. The mobile subscriber station may preferably be released from the service base station when the complete transfer status message indicates a successful transfer. The mobile subscriber station may preferably resume normal communication with the service base station when the complete transfer status message indicates a transfer failure. The step of performing the detection procedure may preferably include receiving a frame segment assignment from the white base station for fast detection, transmitting a detection request to the white base station using the segment of assigned frame, receiving a detection response from the white base station.

The complete transfer status message from the white base station to the service base station may preferably be a structure message between base stations. The transfer indicator may preferably include one of the following: (1) release of service base station, (2) transfer cancellation, and (3) transfer rejection. In another embodiment, a method for effecting a transfer operation in a wireless communication system includes receiving a transfer request from a mobile subscriber station through a first communication link, transmitting a transfer pre-notification. to a white base station, and transmitting a transfer response to the service base station receiving the transfer confirmation from the white base station. The method also includes receiving a transfer indicator from the mobile subscriber station indicating a transfer operation to the white base station and performing an adjustment procedure between the mobile subscriber station and the white base station for establishing a second communication link with the white base station while maintaining the first communication link with the service base station. The method also includes the release of the mobile subscriber station or the continuation of normal communication with the mobile subscriber station in response to a full transfer status message from the white base station to the service base station. In another embodiment, a method for performing a transfer operation in a wireless communication system comprises transmitting a transfer pre-notification to a white base station. The method also comprises transmitting a transfer response upon receiving the service base station a transfer confirmation from the white base station and transmitting a transfer request to a mobile subscriber station that is in communication with the subscriber station. service base through a first communication link. The method also comprises receiving a transfer response from the mobile subscriber station indicating a transfer operation to the white base station. The method also comprises performing an adjustment procedure between the mobile subscriber station and the white base station to establish a second communication link with the white base station while maintaining the first communication link with the base station of service. The method also comprises releasing the mobile subscriber station or continuing normal communication with the mobile subscriber station in response to a full transfer status message from the white base station to the service base station. The transfer request may preferably comprise a possible white base transfer station. The method may also preferably comprise receiving a complete transfer message from the white base station to the service base station. The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention in combination with the accompanying drawings. It will be understood that both the above general description and the following detailed description of the present invention are examples and are intended to provide a further explanation of the claimed invention. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings that are included to provide a further understanding of the invention and are incorporated into and form a part of this application illustrating embodiments of the invention and together with the description serve to explain the principles of the invention. Figure 1 is a diagram illustrating a transfer process requested by a mobile subscriber station (MSS). Figure 2 is a diagram illustrating a transfer process requested by a base station (BS). Figure 3 is a diagram illustrating a process through which an MSS re-enters a previous service BS, as in the case of an interrupted call. Figure 4 is a diagram illustrating a transfer process initiated by an MSS, in accordance with one embodiment of the present invention. Figure 5 is a diagram illustrating a transfer procedure initiated by BS, in accordance with one embodiment of the present invention. Figure 6 is a diagram illustrating a process through which MSS moon resumes communications with a previous serving BS, in the case of a transfer failure, in accordance with an embodiment of the present invention. PREFERRED MODE OF THE INVENTION Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. As far as possible, the same reference numbers will be used in all drawings to refer to the same or similar parts. Figure 4 is a diagram illustrating a transfer process initiated by a mobile subscriber station (MSS), in accordance with one embodiment of the present invention. With reference to Figure 4, an MSS 41 performs a scanning procedure for measuring qualities of signals transmitted from the neighboring base stations (BSs) (S410). If the MSS 41 determines that a transfer should be made based on the results of the neighboring BS scanning procedure, the MSS 41 can transmit a transfer request message (e.g., MOB-MSS-HO-REQ) to a BS of service 42 (S411). The service BS 42 receives the transfer request message and can transmit a transfer pre-notification message (eg, HO pre-notification) to a neighboring BS, such as white transfer BSs (white BSs) 43 and 44 (S412, S413). The transfer pre-notification message may preferably include information in the sense that the MSS 41 has requested a transfer, as well as an identifier (MSS identifier) of the MSS requesting the transfer, connection parameters, capabilities, a required bandwidth, and quality of service information. Each of the neighboring transfer target BSs 43 and 44 can receive the transfer pre-notification message and can transmit a transfer pre-notification response message (eg, HO pre-notification response) to the BS of service 42 in response to the transfer pre-notification message (S414, S415). The transfer pre-notification response message may preferably include recognition information pertaining to the transfer pre-notification message and capacity information pertaining to the quality of service that is required. The service BS 42 may select one of the neighboring transfer target BSs 43 and 44 based on the transfer pre-notification response message and may transmit transfer confirmation message (eg, HO confirmation) to the BS selected target 43 or 44 (S416). The service Bs 42 may transmit a transfer response message (e.g., MOB-BSHO-RSP), which includes information pertaining to the possible transfer white BS, to the MSS 41 (S417). The MSS 41 receives the transfer response message and can transmit a transfer indicator message (e.g., MOB-HO-IND) to release a connection from the MSS 41 to the service BS 42 (S418). An example configuration of the transfer indicator message is shown in Table 1. [Table 1] Syntax Size Notes MOB HO IND Message Format (). { Message Type 8 bits of Operation = 56 reserved 6 bits Reserved; must be set to zero HO_IND_type 2 bits 00: Release of service BS 01: cancellation of HO 10: rejection of HO 11: Resume Communication Target BS ID 48 Applicable only when HO-IND_type Bits is set to 00 or 01 HAMC Tupie 21 bytes} The transfer indicator message (MOB_HO_IND) may include information to notify the previous service BS 42 that it resumes communication with the MSS 41 if the transfer of the MSS 41 to the transfer white BS fails. Before releasing the connection of the MSS 41 to the service BS 42, the MSS 41 may preferably perform a fast detection (e.g., Quick Detection_IE), a detection request (e.g., RNG REQ), and a detection response (e.g., RNG-RSP) with the target BS selected for the transfer (S419, S420, S421). In the embodiment, the white BS 44 is selected for the transfer. The detection request may preferably require an uplink synchronization between the MSS 41 and the white BS 44. The fast detection may preferably comprise a frame segment assignment by the white base station 44 to allow the MSS 41 to use the assigned frame segment for quick detection. In one modality, yes. the transfer is successful, the transfer white BS 44 can transmit a transfer result to the service BS 42 through a complete transfer message (eg, HO-Complete). The previous serving BS 42 may preferably recognize the successful completion of the transfer through the complete transfer message and may release the connection of the serving BS 42 with the MSS 41 (S423). The execution of the initial network entry can then end (S424). An example configuration of the complete transfer message is shown in Table 2. [Table 2] Field. Size Notes Global 152-bit Header Unique Identifier 48 48-bit unique identifier of MSS bits used by MSS in initial network entry 8-bit Reason # 0: Successful Transfer # 1: Transfer Failure due to xxx # 2: Transfer Failure by yyy # 3 ~ 7: Reserved Security Field TBD Medium to authenticate this message The complete transfer message may preferably be a structure message between base stations for the purpose of providing notification of a transfer status to the MSS 41 from a new service BS to the previous service BS 42. Using the full transfer message, the above service MSS 42 can determine whether the MSS 41 has completed the transfer to the transfer white BS 44. In a case where there is a transfer fault, the reason for the transfer failure (failure reason) can preferably set to be supplied to the previous serving BS 42. The failure reason may be, for example, an interrupted call which causes the MSS 41 to fail in its access to the transfer white BS 44. In the case where the transfer process ends, the previous service BS 42 may maintain resources and information associated with the MSS 41 for a predetermined period of time (when there is no instruction of the new service BS 44). Figure 5 is a diagram illustrating a transfer procedure initiated by a BS, in accordance with one embodiment of the present invention. With reference to Figure 5, a service BS 52 activates a procedure (e.g., activation to release MSS) to release a connection of an MSS 51 in accordance with a corresponding determination (S510). The service BS 52 may transmit a transfer pre-notification message (eg, HO pre-notification) which includes information required for the transfer of the MSS 51 to neighboring transfer target BSs 53 and 54 (S511, S512) . The transfer pre-notification message may include an identifier (MSS identifier) of the MSS requesting the transfer, connection parameters, capacities, a required bandwidth, as well as quality of service information. Each of the neighboring transfer target BSs 53 and 54 can receive a transfer pre-notification message and can transmit a transfer pre-notification response message (eg, HO pre-notification response) to the service BS 52 in response to the transfer pre-notification message (S513, S514). The transfer pre-notification response message may preferably include recognition information pertaining to the transfer pre-notification message and capacity information pertaining to the quality of service requested. The service BS 52 may preferably transmit a transfer response message to the MSS 51 based on the information received through the transfer pre-notification response message (S515). The transfer response message may preferably include information pertaining to the white BSs 53 and 54 available for the transfer. The MSS 51 may preferably perform a neighboring BS scanning procedure to measure the quality of the signals received in the neighboring white BSs, recognized through the transfer response message (S516). In another embodiment, in a case in which the neighboring BS scanning procedure is the neighboring BS 54 for the transfer, the MSS 51 can transmit a transfer response message including white BS information for the transfer to the BS of service 52 (S517). The service BS 52 may also transmit a transfer confirmation message to the BS • target 54 with which the MSS 51 determines to effect the transfer (S518). The MSS 51 can transmit a transfer indicator message (e.g., MOB-HO-IND) to release a connection from the MSS 51 to the service BS 52 (S519). The transfer indicator message may preferably be configured as shown in Table 1. Before releasing the connection from the MSS 51 to the service BS 52, the MSS 51 may preferably execute a fast detection (e.g., Quick Detection_IE) , a detection request (e.g., RNG-REQ), and a detection response (e.g., RNG-RSP) with the service white BS 54 for the transfer (S520, S521, S522). In another embodiment, if the transfer is successful, the transfer white BS 54 can transmit a transfer result to the service BS 52 through a complete transfer message (HO-complete). The complete transfer message may preferably be configured as shown in Table 2. The above serving BS 52 may preferably recognize the successful completion of the transfer through the complete transfer message and may release its connection to the MSS 51 (S524) . The execution of an initial network entry can then be carried out (S525). Figure 6 is a diagram illustrating a process by which an MSS resumes communications with a previous serving BS, in the event of a transfer failure, in accordance with an embodiment of the present invention. The transfer failure may be due, for example, to a call interruption or to another cause of failure. With reference to Figure 6, an MSS 61 performs a scanning procedure to measure the qualities of signals transmitted from neighboring BSs (S10). If the MSS 61 determines that a transfer must be made based on the results of the neighboring BS scanning procedure, the MSS 61 may preferably transmit a transfer request message (e.g., MOB-MSS-HO-REQ) to a BS of service 62 (S611). Service BS 62 receives the transfer request message and can transmit a transfer pre-notification message (for example), pre-notification of HO) including information that the MSS 61 has requested a transfer to a neighboring BS such as transfer white BSs 63 and 64 (S612, S613). The transfer pre-notification message may also include an identifier (MSS identifier) of the MSS requesting the transfer, connection parameters, capabilities, a required bandwidth, and quality of service information. Each of the neighboring transfer target BSs 63 and 64 can receive the transfer pre-notification message and can transmit a transfer pre-notification response message (eg, HO pre-notification response) to the service BS 62 in response to the pre-notification or transfer message (S614, S615). The transfer pre-notification response message may preferably include recognition information pertaining to the transfer pre-notification message and capacity information pertaining to the required quality of service. Service BS 62 may preferably select one of the neighboring transfer target BSs 63 and 64 based on the transfer pre-notification response message and may transmit a transfer confirmation message (eg, HO confirmation) to the BS selected target 63 or 64 (S616). The service BS 62 may also transmit a transfer response message (e.g., MOB-HO-RSP), which includes information pertaining to a transfer white BS to the MSS 61 (S617). The MSS 61 receives the transfer response message and can transmit a transfer indicator message (e.g., MOB-HO-IND) to release a connection from the MSS 61 to the service BS 62 (S618).

In another embodiment, when the MSS 61 attempts to connect to the white BS 64, a transfer failure occurs, such as a call interruption (S619). The MSS 61 can preferentially recognize the transfer failure and can notify the transfer white BS 64. The MSS 61 can also cancel the transfer of the previous service BS r 62 and can transmit the message to resume communications with the service BS above 62. Since the connection between the service BS 62 and the MSS 61 has not yet been released, the MSS 61 can maintain the connection with the service BS 62 without executing a procedure to re-enter the service BS 62. Thus, even when the transfer attempt fails, the MSS 61 can maintain the connection with the service BS 62 without executing a procedure to re-enter the service BS 62. To resume communications with the previous service BS 62, the message of the The transfer shown in Table 1 can be preferably used. In one embodiment, a method for effecting a transfer operation in a wireless communication system includes communication with the service base station through a first communication link and reception from the information service base station transfer associated with at least one candidate target link station, wherein the transfer information comprises at least quality of service that can be handled by the at least one candidate base station. The method also includes the transmission of a transfer indicator to the service base station indicating a transfer operation to a selected white base station where the mobile subscriber station determines whether a transfer is made in response to the information of the subscriber. transfer, and perform a detection procedure with the selected white base station to establish a second communication link with the selected white base station while maintaining the first communication link with the service base station, wherein the detection comprises trying to establish an uplink synchronization and power adjustment between the mobile subscriber station and the selected white base station. The method also includes the release of the service base station in response to a complete transfer status message of the selected white base station to the service base station, or the resumption of normal communication with the base station of service if the transfer fails with the selected white base station. The method may also preferably include receiving a transfer response from a service base station when transmitting the service base station a transfer confirmation to a white base transfer station where the transfer response comprises at least service quality information requested to be handled by the white base transfer station. The method may also preferably include, in a transfer initiated by mobile subscriber station, the transmission of a transfer request to a service base station through a first communication link prior to receiving the transfer response from the subscriber station. service base. The method may also preferably include, in a transfer initiated by the service base station, the receipt of a transfer request from the service base station before transmitting a transfer response to the service base station. The mobile subscriber station may preferably be released from the service base station when the complete transfer status message indicates a successful transfer. The mobile subscriber station may preferably resume normal communication with the service base station when the full transfer status message indicates a transfer failure. The step of performing the detection method may preferably include receiving a frame segment assignment of the white base station for fast detection, transmitting a detection request to the white base station using the assigned frame segment, and receiving a detection response from the white base station. The complete transfer status message from the white base station to the service base station may preferably be an inter-base station structure message. The transfer indicator may preferably include one of the following: (1) service base station release, (2) transfer cancellation, and (3) transfer rejection. In another embodiment, a method for performing the transfer operation in a wireless communication system includes the receipt of a transfer request from a mobile subscriber station through a first communication link, the transmission of a transfer pre-notification. to a white base station, and the transmission of a transfer response upon receiving the service base station a transfer confirmation from the white base station. The method also includes receiving a transfer indicator from the mobile subscriber station indicating a transfer operation to the white base station and performing an adjustment procedure between the mobile subscriber station and the white base station to establish a second communication link with the white base station while maintaining the first communication link with the service base station. The method also includes the release of the mobile subscriber station or the continuation of normal communication with the mobile subscriber station in response to a complete transfer status message from the white base station to the service base station. In another embodiment, a method for performing a transfer operation in a wireless communication system comprises transmitting a transfer pre-notification to a white base station. The method also comprises transmitting a transfer response upon receiving the service base station a transfer confirmation from the white base station and transmitting a transfer request to a mobile subscriber station that is in communication with the base station of service through a first communication link. The method also comprises receiving a transfer response from the mobile subscriber station indicating a transfer operation to the white base station. The method also comprises performing an adjustment procedure between the mobile subscriber station and the white base station to establish a second communication link with the white base station while maintaining the first communication link with the base station of service. The method also comprises releasing the mobile subscriber station or continuing normal communication with the mobile subscriber station in response to a full transfer status message from the white base station to the service base station. The transfer request may preferably comprise a possible white base transfer station. The method may also preferably comprise receiving the complete transfer message from the white base station to the service base station. Accordingly, the present invention can efficiently execute a transfer and / or resume communications in the wireless access system when a mobile subscriber station (MSS) returns to the previous service base station (BS), in case of failed transfer. It will be apparent to the person skilled in the art that various modifications and variations may be made to the present invention without departing from the spirit or scope of said invention. Thus, it is contemplated that the present invention encompasses modifications and variations of this invention provided they are within the scope of the appended claims and their equivalents.

INDUSTRIAL EXPLOITATION The present invention can be applied to a broadband wireless access system.

Claims (25)

1. CLAIMS A method for performing a transfer operation in a wireless communication system, the method comprising: communicating with a service base station through a first communication link; receiving from the serving base station a transfer information associated with at least one candidate white base station, wherein the transfer information comprises at least one quality of service capable of being handled by the at least one candidate white base station; transmitting a transfer indicator to the service base station indicating a transfer operation to a selected white base station, wherein the mobile subscriber station determines whether or not to effect the transfer in response to the transfer information; performing a detection procedure with the selected white base station to establish a second communication link with the selected white base station while maintaining the first communication link with the service base station, wherein the detection method comprises the attempt to establish an uplink synchronization and power adjustment between the mobile subscriber station and the selected white base station; and releasing the service base station in response to a complete transfer status message from the selected white base station to the service base station, or resume normal communication with the service base station without the transfer fails with the selected white base station.
2. The method according to claim 1, further comprising: receiving a transfer response from a service base station by transmitting the service base station a transfer confirmation to a white transfer base station, wherein the response transfer comprises at least information and quality of service that is required for its management by the white base transfer station.
3. The method according to claim 1, further comprising: in a transfer initiated by mobile subscriber station, transmitting a transfer request to a service base station through the first communication link before receiving the transfer response from the service base station.
4. The method according to claim 1, further comprising: in a transfer initiated by service base station, receiving a transfer request from the service base station before transmitting a transfer response to the base station of service.
5. The method according to claim 1, wherein the mobile subscriber station is released from the service base station when the full transfer status message indicates a successful transfer.
6. The method according to claim 1, wherein the mobile subscriber station resumes a normal communication with the service base station when the complete transfer status message indicates transfer failure.
7. The method according to claim 1, wherein the step of performing the detection method comprises: receiving a frame segment assignment of the white base station for rapid detection; transmit a request and detection to the white base station using the assigned frame segment; and receive a detection response from the white base station.
8. The method according to claim 1, wherein the complete transfer status message from the white base station to the service base station is a structure message between base stations.
9. The method according to claim 1, wherein the transfer indicator comprises one of the following: (1) service base station release, (2) 'transfer cancellation, and (3) transfer rejection.
10. A method for effecting a transfer operation in a wireless communication system, the method comprises: Receiving a transfer request from a mobile subscriber station through a first communication link; transmit a transfer pre-notification to the white base station; transmitting a transfer response upon receiving the service base station a transfer confirmation from the white base station; receiving a transfer indicator from the mobile subscriber station indicating a transfer operation to the white base station; make; performing an adjustment procedure between the mobile subscriber station and the white base station to establish a second communication link with the white base station while maintaining the first communication link with the service base station; and releasing the mobile subscriber station or continuing normal communication with the mobile subscriber station in response to a complete transfer status message from the white base station to the service base station. .
11. The method according to claim 10, wherein the mobile subscriber station is released from the service base station when the full transfer status message indicates a successful transfer. .
12. The method according to claim 10, wherein the mobile subscriber station resumes a normal communication with the service base station when the full transfer status message indicates a transfer failure. .
13. A method for effecting a transfer operation in a wireless communication system, the method comprises: transmitting a transfer pre-notification to a white base station; transmitting a transfer response upon receiving the service base station a transfer confirmation from the white base station; transmitting a transfer request to a mobile subscriber station that is in communication with the service base station through a first communication link; receiving a transfer response from the mobile subscriber station indicating a transfer operation to the white base station; performing an adjustment procedure between the mobile subscriber station and the white base station to establish a second communication link with the white base station while maintaining the first communication link with the service base station; and releasing the mobile subscriber station or following normal communication with the mobile subscriber station in response to a complete transfer status message from the mobile subscriber station in response to a complete transfer status message from the white base station to the service base station.
14. The method according to claim 13, wherein the transfer request comprises a possible white base transfer station.
15. The method according to claim 13, further comprising: receiving a complete transfer message from the white base station to the service base station.
16. 16. A mobile subscriber station in a wireless communication system, the mobile subscriber station comprises: means for communicating with a service base station through a first communication link; means for receiving from the serving base station a transfer information associated with at least one candidate white base station, wherein the transfer information comprises at least quality of service capable of being handled by the at least one white base station candidate; means for transmitting a transfer indicator to the service base station indicating a transfer operation to a selected white base station, wherein the mobile subscriber station determines whether or not the transfer in response to the transfer information is effected; means for performing a detection procedure with the selected white base station to establish a second communication link with the selected white base station while it is being used. maintains the first communication link with the service base station, wherein the detection method comprises attempting to establish an uplink synchronization and power adjustment between the mobile subscriber station and the selected white base station; and half to be released from the service base station in response to a complete transfer status message from the selected white base station to the service base station, or resume normal communication with the base station of service if the transfer fails with the selected white base station. . The mobile subscriber station according to claim 16, further comprising: means for receiving a transfer response from a service base station by transmitting the service base station a transfer confirmation to a white base transfer station , wherein the transfer response comprises at least requested quality of service information to be handled by the white transfer base station. . The mobile subscriber station according to claim 16 further comprising: in a transfer initiated by mobile subscriber station, means for transmitting a transfer request to a service base station through a first communication link before receiving the transfer response of the service base station. . The mobile subscriber station according to claim 16, wherein the means for performing the detection method comprises: means for receiving a frame segment assignment from the white base station for fast detection; means for transmitting a detection request to the white base station using the assigned frame segment; and means for receiving a detection response from the white base station. . A network for performing a transfer operation with a mobile subscriber station in a wireless communication system, the network comprising: means for receiving a transfer request from a mobile subscriber station through a first communication link; means for transmitting a transfer pre-notification to a white base station; means for transmitting a transfer response upon receiving the service base station a transfer confirmation from the white base station; means for receiving a transfer indicator from the mobile subscriber station indicating a transfer operation to the white base station; means for effecting an adjustment procedure between the mobile subscriber station and the white base station to establish a second communication link with the white base station while maintaining the first communication link with the service base station; means for releasing the mobile subscriber station or continuing normal communication with the mobile subscriber station in response to a complete transfer status message from the white base station to the service base station. . The network according to claim 20, wherein the mobile subscriber station is released from the service base station when the full transfer status message indicates a successful transfer. . The network according to claim 20, wherein the mobile subscriber station resumes normal communication from the service base station when the full transfer status message indicates a transfer failure. . A network for performing a transfer operation with a mobile subscriber station in a wireless communication system, the network comprising: means for transmitting a transfer pre-notification to a white base station; means for transmitting a transfer response upon receiving the service base station a transfer confirmation of the white base station; means for transmitting a transfer request to a mobile subscriber station that is in communication with the service base station through a first communication link; means for receiving a transfer response from the mobile subscriber station indicating a transfer operation to the white base station; means for performing an adjustment procedure between the mobile subscriber station and the white base station to establish a second communication link with the white base station while maintaining the first communication link with the service base station; and means for releasing the mobile subscriber station or for continuing normal communication with the mobile subscriber station in response to a complete transfer status message from the white base station to the service base station. The network according to claim 23, wherein the transfer request comprises a possible white base transfer station. The network according to claim 23, further comprising: means for receiving a complete transfer message from the white base station to the service base station.