KR20050107254A - Method and apparatus for handover between sector in mobile orthogonal frequency division multiplexing system - Google Patents

Abstract

The present invention relates to a handover between sectors in which a subscriber station moves to a sector in the same base station according to a position movement in a wideband orthogonal frequency division multiple access communication system. The present invention relates to a handover in a wideband orthogonal frequency division multiple access communication system. A support system, comprising: a serving base station, a sector constituting the serving base station, at least one or more user terminals currently communicating with the sector, and one center frequency and sectors divided into subbands. And a system for performing handover to another sector in the same base station in performing the handover at the serving base station at the request of the subscriber station. In addition, when the subscriber station performs a handover, the subscriber station performs handover between sectors according to the set frame structure, and when the subscriber station determines that the subscriber station is a handover between sectors, It is characterized by indicating the configuration of the map for handover to the sector.

Description

Device and method for handover between sectors required by UE in broadband orthogonal frequency division multiple access scheme {METHOD AND APPARATUS FOR HANDOVER BETWEEN SECTOR IN MOBILE ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING SYSTEM}

The present invention relates to a wideband orthogonal frequency multiple access communication system. Particularly, in a wideband wireless access communication system using an orthogonal frequency division multiplexing system, when a handover is performed at a base station at the request of a terminal, the present invention relates to another sector in the same base station. The present invention relates to a handover support method capable of supporting a handover request.

Generally, in the 4th generation (4G) communication system, which is a next generation communication system, various quality of service (QoS) having a transmission rate of about 100 Mbps is referred to as "QoS". Active researches are being conducted to provide users with services. Currently, 3G (3G) communication systems generally support a transmission rate of about 384 Kbps in an outdoor channel environment having a relatively poor channel environment, and an indoor channel having a relatively good channel environment. It supports up to 2Mbps transmission speed even in the environment.

On the other hand, a wireless local area network (LAN) system and a wireless metropolitan area network (MAN) system are generally 20 Mbps to It supports a transfer rate of 50Mbps. Therefore, 4G communication system currently supports a high-speed service to be provided in the 4G communication system by developing a new communication system in the form of guaranteeing mobility and QoS in a wireless LAN system and a wireless MAN system that guarantee a relatively high transmission speed. There is a lot of research going on. However, the wireless MAN system is suitable for high-speed communication service support because of its wide coverage and high transmission speed, but does not consider mobility of a user, that is, a subscriber station (SS) at all. Because of the system, handover due to the fast movement of the subscriber station is not considered at all. Therefore, studies on devices and scenarios that support handover according to fast movement of terminals are being actively conducted. A typical example of this is an IEEE 802.16E communication system. Hereinafter, the structure of the IEEE 802.16E communication system will be described with reference to FIG. 1.

FIG. 1 is a diagram illustrating a general IEEE 802.16e communication system structure, and illustrates a cell structure of a broadband wireless access communication system using an orthogonal frequency division multiplexing system.

Referring to FIG. 1, the IEEE 802.16e communication system has a multi-cell structure, that is, a base station (BS) 110 having a cell 100 and a cell 150 and managing the cell 100. ), A base station 140 that manages the cell 150, and a plurality of subscriber stations 111, 113, 130, 151, and 153. In addition, signal transmission and reception between the base stations 110 and 140 and the subscriber stations 111, 113, 130, 151, and 153 is performed using the OFDM / OFDMA scheme. However, among the subscriber stations 111, 113, 130, 151, and 153, the subscriber station 130 is a boundary area, that is, handover, between the cell 100 and the cell 150. It exists in the area, and therefore, it is possible to support mobility for the subscriber station 130 only by supporting handover for the subscriber station 130.

The wireless MAN system is a broadband wireless access (BWA) communication system, which has a wider service area and supports higher transmission speed than the wireless LAN system. Orthogonal Frequency Division Multiplexing (OFDM) and Orthogonal Frequency Division Multiple Access (OFDM) for supporting a broadband transmission network in a physical channel of the wireless MAN system A system employing the (OFDMA: Orthogonal Frequency Division Multiplexing Access, hereinafter " OFDMA ") scheme is the IEEE 802.16a / d communication system.

That is, the IEEE 802.16a / d communication system is a broadband wireless access communication system using the OFDM / OFDMA scheme. Since the IEEE 802.16a / d communication system adopts the OFDM / OFDMA scheme to the wireless MAN system, high-speed data transmission is possible by transmitting a physical channel signal using a plurality of sub-carriers. In addition, the IEEE 802.16e communication system is a system that considers the mobility of the subscriber station in the IEEE 802.16a / d communication system. As a result, both the IEEE 802.16a / d communication system and the IEEE 802.16e communication system are broadband wireless access communication systems using the OFDM / OFDMA scheme. Hereinafter, for convenience of description, the IEEE 802.16d communication system will be described as an example. .

Next, the uplink / downlink frame structure of the IEEE 802.16d and IEEE 802.16e communication systems will be described with reference to FIG. 2.

2 is a diagram schematically illustrating a structure of an uplink / downlink frame of a broadband wireless access communication system using a general OFDM / OFDMA scheme.

Referring to FIG. 2, the downlink frame is composed of a preamble area, a broadcast control area, and a data transmission area. Through the preamble region, a synchronization signal for acquiring mutual synchronization between the base station and the subscriber station, that is, a preamble sequence, is transmitted. The broadcast control region includes a DL (DownLink) _MAP region and an UL (UpLink) _MAP region. The DL_MAP area is an area in which the DL_MAP message is transmitted, and information elements (IE) included in the DL_MAP message (hereinafter, referred to as "IE") are shown in Table 1 below.

As shown in Table 1, first, the DL_MAP message corresponds to a plurality of IEs, that is, a Management Message Type indicating a type of a transmitted message, and a modulation scheme and a demodulation scheme applied to a physical channel to obtain synchronization. PHY (PHYsical) Synchronization and Downlink Channel Descriptive (DCD) Messages Containing Downlink Burst Profiles DCD count indicating a corresponding count, a base station ID indicating a base station IDentifier, and a Number of DL_MAP Elements n indicating the number of elements existing after the base station ID. Although not shown in Table 1, the DL_MAP message includes information on ranging codes allocated to each of the rangings. Since the description of the ranging codes is described in detail below, the detailed description thereof will be omitted.

Next, the UL_MAP region is a region in which the UL_MAP message is transmitted, and IEs included in the UL_MAP message are shown in Table 2 below.

As shown in Table 2, the UL_MAP message includes a plurality of IEs, that is, a management message type indicating a type of a transmitted message, an uplink channel ID indicating an uplink channel ID used, and an uplink. A UCD count indicating a count corresponding to a configuration change of an Uplink Channel Descript (UCD) message including a burst profile, and elements present after the UCD count. Number of UL_MAP Elements n indicating the number is included. Here, the uplink channel identifier is uniquely assigned in a media access control (MAC) hereinafter referred to as "MAC" -sublayer.

In addition, the data area is a time division multiple access (TDM) / time division multiple access (TDMA) method for each subscriber station (hereinafter, referred to as "TDMA"). These areas correspond to the time slots assigned by. The base station transmits broadcast information to be broadcast to subscriber stations managed by the base station through a preset center carrier through the DL_MAP region of the downlink frame. The subscriber stations monitor all frequency bands preset in each of the subscriber stations as they are powered on, so that they have the highest size, that is, the highest pilot carrier-to-interference noise ratio (CINR). A pilot channel signal having a noise ratio (hereinafter referred to as "CINR") is detected. In addition, the base station having transmitted the pilot channel signal having the strongest pilot CINR is determined to be the base station to which the subscriber station is currently belonging, and checks the DL_MAP region and the UL_MAP region of the downlink frame transmitted by the base station to determine its uplink. And information indicating control information for controlling downlink and information indicating an actual data transmission / reception position.

Table 3 below shows the structure of the UCD message.

As shown in Table 3, the UCD message includes a plurality of IEs, that is, a management message type indicating a type of a transmitted message, an uplink channel ID indicating an uplink channel identifier used, and a configuration change count counted by a base station. Initial backoff window using initial ranging, i.e., a mini-slot size representing the size of a mini-slot of an uplink physical channel, and a starting point of the backoff using initial ranging, i.e., an initial backoff window using initial ranging. ) Ranging Backoff Start indicating the size, Ranging Backoff End indicating the end point of the backoff using the initial ranging, that is, the final backoff window size, and the starting point of the backoff for the contention data and requests. Request Backoff Start, which indicates the size of the initial backoff window, and backoff for contention data and requests. Request Backoff End, which indicates the end point of, i.e., the final backoff window size. Here, the backoff value represents a kind of waiting time value to be waited for the next ranging when the rangings to be described below fail. At this time, the base station performs the next ranging when the subscriber station fails to ranging. The backoff value, which is time information to wait, must be transmitted to the subscriber station. For example, if the values of the Ranging Backoff Start and Ranging Backoff End are determined to be "10", the subscriber station is determined by a truncated binary exponential backoff algorithm. After passing the opportunity to perform the ranging (1024 times), the next ranging must be performed.

Then, here, rangings used in the IEEE 802.16a / d communication system, that is, initial ranging, maintenance ranging, that is, periodic ranging, Bandwidth Request Ranging will be described.

First, initial ranging will be described.

The initial ranging is a ranging performed by a base station to acquire synchronization with a subscriber station. The initial ranging is performed to adjust an accurate time offset between the subscriber station and the base station and to adjust a transmit power. Ranging is performed for. That is, the subscriber station receives the DL_MAP message and the UL_MAP message / UCD message after powering on, acquires synchronization with the base station, and then adjusts the initial ranging to adjust the time offset and transmission power with the base station. Do this. Here, since the IEEE 802.16a communication system uses the OFDM / OFDMA scheme, the ranging procedure requires ranging sub-channels and ranging codes, and the base station is used for ranging purposes. In other words, the available ranging codes are allocated according to the type. This will be described in detail as follows.

The ranging code first has a predetermined length, for example, A pseudo-random noise (PN) sequence having a bit length is generated by segmenting a predetermined unit in a predetermined unit. In general, two ranging subchannels having a 53-bit length form one ranging channel, and a ranging code is formed by segmenting a PN code through a 106-bit ranging channel. The ranging codes configured as described above may be allocated to up to 48 subscriber stations (RC # 1 to RC # 48), and as a default value, at least two ranging codes per subscriber terminal are ranging for the three purposes. In other words, it applies to initial ranging, periodic ranging, and band request ranging. Thus, different ranging codes are assigned to each of the three purpose rangings, for example, N ranging codes are allocated for initial ranging (N ranging codes (N RCs) for initial ranging), and M ranging The ranging codes are allocated for periodic ranging (M RCs for maintenance ranging) and the L ranging codes are allocated to band request ranging (L RCs for BW-request ranging). The allocated ranging codes are transmitted to the subscriber stations through the DL_MAP message as described above, and the subscriber stations perform the ranging procedure using the ranging codes included in the DL_MAP message according to the purpose. .

Second, periodic ranging will be described.

The periodic ranging refers to ranging periodically performed by a subscriber station that adjusts a time offset and a transmission power with a base station through the initial ranging to adjust a channel state with the base station. The subscriber station performs the periodic ranging by using ranging codes allocated for the periodic ranging.

Third, the band request ranging will be described.

The band request ranging is a ranging in which a subscriber station having adjusted a time offset and a transmission power with a base station through the initial ranging requests a bandwidth allocation in order to perform actual communication with the base station.

Meanwhile, the DL_MAP message is periodically broadcasted to all subscriber stations at the base station, and the case in which the subscriber station can continue to receive it is referred to as synchronization with the base station. That is, the terminals receiving the DL_MAP message can receive all messages transmitted on the forward link.

As described above in Table 3, when the subscriber station fails to access, the base station transmits the UCD message including information indicating the available backoff value to the subscriber station.

On the other hand, when performing the ranging, the subscriber station transmits an RNG_REQ message to the base station, and the base station receiving the RNG_REQ message corrects the aforementioned frequency, time, and transmission power to the subscriber station. The RNG_RSP message including the information for transmission will be transmitted.

The structure of the RNG_REQ message is shown in Table 4 below.

In Table 4, the downlink channel ID means a forward channel identifier included in the ranging request message received by the subscriber station through the UCD, and the Pending Until Complete indicates the priority of the ranging response transmitted. That is, if the Pending Until Complete is "0", the previous ranging response is given priority. If the Pending Until Complete is not "0", the currently transmitted response is given priority.

In addition, the structure of the RNG_RSP message corresponding to the RNG_REQ message shown in Table 4 is shown in Table 5.

In Table 5, the uplink channel ID refers to an identifier of an uplink channel in which the base station was in the RNG_REQ message.

Meanwhile, as described above, the IEEE 802.16a communication system currently considers only a fixed state of a subscriber station, that is, a state in which the mobility of the subscriber station is not considered at all and a single cell structure. However, as described above, the IEEE 802.16e communication system is defined as a system that considers the mobility of a subscriber station in the IEEE 802.16d communication system. Thus, the IEEE 802.16e system is a subscriber in a multi-cell environment. The mobility of the terminal must be taken into account. In order to provide mobility of a subscriber station in a multi-cell environment, a change of operations of the subscriber station and a base station is required. In particular, a handover of the subscriber station considering a multi-cell structure for mobility support of the subscriber station is required. Research is active.

Meanwhile, in the broadband wireless mobile communication system as described above, the subscriber station receives preambles transmitted from a plurality of base stations. At this time, the subscriber station measures the CINRs of the received preambles. The subscriber station selects a base station having the highest CINR among the measured plurality of CINRs. That is, by selecting a base station having the best reception state among the plurality of base stations transmitting a preamble channel, the subscriber station recognizes the base station to which it belongs. Hereinafter, a base station having the best reception state in the subscriber station is called a serving base station (Serving BS).

The serving base station transmits a neighbor base station advertisement (MOB_NBR_ADV: Neighbor Advertisement, hereinafter "MOB_NBR_ADV") message to the subscriber station. Here, the MOB_NBR_ADV message structure will be described with reference to Table 6.

As shown in Table 6, the MOB_NBR_ADV message includes a plurality of IEs, that is, a management message type indicating a type of a message to be transmitted, a configuration change count indicating a number of configuration changes, an N_NEIGHBORS indicating a number of neighbor base stations, A Neighbor BS-ID indicating an identifier (ID) of the neighboring base stations, a Physical Frequency indicating a physical channel frequency of the neighboring base station, and other neighboring information indicating other information related to the neighboring base station in addition to the information. Encoded Neighbor Information). In addition, the terminal includes a hysteresis threshold indicating a reference CINR for requesting handover and MAHO report period information for periodic scan reporting.

On the other hand, the subscriber station receiving the MOB_NBR_ADV message, when the subscriber station itself wants to scan the CINRs of preamble signals transmitted from neighboring base stations, the subscriber station scans the serving base station (MOB_SCN_REQ: Scanning Interval Allocation Request, hereinafter "MOB_SCN_REQ"). Send a message). In this case, since the time point at which the subscriber station makes a scan request is not directly related to the preamble signal CINR scanning operation, a detailed description thereof will be omitted.

In addition, the MOB_SCN_REQ message structure is shown in Table 7.

As shown in Table 7, the MOB_SCN_REQ message includes a management message type indicating a plurality of IEs, i.e., a type of a message transmitted, and a scan interval indicating a scan interval for scanning CINRs of preamble signals transmitted from the neighbor base stations. Contains a Duration. The scan duration is configured in units of frames. Here, in Table 7, the Management Message Type to which the MOB_SCN_REQ message is transmitted is currently not determined (Management Message Type = undefined).

Subsequently, the serving base station receiving the MOB_SCN_REQ message from the subscriber station transmits a MOB_SCN_RSP message including information to be scanned by the mobile subscriber station to the mobile subscriber station. Here, the structure of the MOB_SCN_RSP message will be described with reference to Table 8.

As shown in Table 8, the MOB_SCN_RSP message includes a Management Message Type indicating a plurality of IEs, that is, a type of a transmitted message, and a connection identifier (CID: connection ID, hereinafter " CID ") of the mobile subscriber station that transmitted the MOB_SCN_REQ message. CID ", and a scan period. In Table 8, the Management Message Type to which the MOB_SCN_RSP message is to be transmitted is currently undetermined (Management Message Type = undefined), and the scan interval indicates a period during which the mobile subscriber station performs the pilot CINR scanning.

The mobile subscriber station receiving the MOB_SCN_RSP message including the scanning information scans the pilot CINRs for neighbor base stations recognized through the MOB_NBR_ADV message corresponding to the scanning information parameters.

 As such, in order to support handover in the IEEE 802.16e system, the subscriber station must measure the CINRs of neighbor BSs and the preamble signal transmitted from the base station to which the subscriber station belongs, that is, the serving base station. If the CINR of the preamble signal transmitted from the base station is smaller than the CINRs of the preamble signals transmitted from the neighbor base stations, the subscriber station requests a handover to the active base station. Here, the content of "measuring the CINR of the preamble signal" will be referred to as "scan or scan the CINR of the preamble signal". Here, it should be noted that the concept of scanning or scanning is the same concept but mixed for convenience of description.

3 is a diagram illustrating the concept of a sector applied in the general 802.16d specification. 3 illustrates a sector structure of a broadband wireless access communication system using a general OFDM / OFDMA scheme.

Referring to FIG. 3, one base station is composed of three sectors, and each sector has sectorized antenna beam shaping. Sectors belonging to the same base station all use the same center frequency, and each sector is divided into three subchannel sets to divide bandwidth. However, it is not clearly stated in the specification whether the concept of this subchannel is divided only into the data area or divided into the whole band.

Then, the handover request process of the mobile subscriber station in the IEEE 802.16e system as described above will be described with reference to FIG.

FIG. 4 is a signal flow diagram schematically illustrating a handover request process by a mobile subscriber station in a broadband wireless access communication system using a general OFDM / OFDMA scheme. In particular, FIG. 4 is a mobile subscriber station request by a mobile subscriber station in an IEEE 802.16e system. Signal flow diagram schematically illustrating a handover process of a terminal.

Referring to FIG. 4, the serving base station 440 first transmits a MOB_NBR_ADV message to the mobile subscriber station 400 (step 411). The mobile subscriber station 400 receiving the MOB_NBR_ADV message transmits a MOB_SCN_REQ message to the base station 440 when the mobile subscriber station 400 itself wants to scan CINRs of pilot signals received from neighboring base stations (413). step). Here, since the time point at which the mobile subscriber station 400 makes a scan request is not directly related to the pilot CINR scanning operation, a detailed description thereof will be omitted. Meanwhile, the serving base station 440 receiving the MOB_SCN_REQ message transmits a MOB_SCN_RSP message including information to be scanned by the mobile subscriber station 400 to the mobile subscriber station 400 (step 415). Upon receiving the MOB_SCN_RSP message including the scanning information, the mobile subscriber station 400 receives pilot signals corresponding to the parameters included in the MOB_SCN_RSP message, that is, the scan interval, for the neighbor BSs recognized through the MOB_NBR_ADV message. CINR scanning is performed (step 417).

Subsequently, after the scanning of the CINRs of the pilot signals received from the neighbor base stations, the mobile subscriber station 400 determines that the serving base station to which the mobile subscriber station 400 belongs to itself should be changed (step 419). That is, when the mobile subscriber station 400 determines that the current serving base station should be changed to a new base station different from the base station 440, the mobile subscriber station 400 requests the mobile base station 440 for a mobile subscriber station handover request. (MOB_MSSHO_REQ: Mobile Subscriber Station HandOver Request, hereinafter referred to as "MOB_MSSHO_REQ") The message is transmitted (step 421). Here, the MOB_MSSHO_REQ message structure is shown in Table 9.

As shown in Table 9, the MSS_MSSHO_REQ message includes a plurality of IEs, that is, a Management Message Type indicating a type of a transmitted message and N_Recommended indicating a result of scanning by a mobile subscriber station. Here, N_Recommended indicates identifiers of neighbor base stations, CINR of pilot signals for each of the neighbor base stations, and a service level expected to be provided to the subscriber station by the neighbor base stations, as shown in Table 9 above. It also includes an Estimated HO start parameter that indicates when the handover will occur.

When the serving base station 440 receives the MOB_MSSHO_REQ message transmitted by the mobile subscriber station 400, the target base station list information is determined from the N_Recommeded information of the MOB_MSSHO_REQ message in step 423. The serving base station 440 transmits a HO_notification message to neighboring base stations belonging to a list of possible target base stations (steps 425 and 427). Here, neighbor base stations belonging to the target base station list, which are possible for convenience of description, are set as target base station 1 460 and target base station 2 480. The structure of the HO_notification message transmitted to the target base stations by the serving base station 440 is shown in Table 10 below.

As shown in Table 10, the HO_notification message includes a plurality of IEs, that is, an identifier (MSS ID) of a subscriber station to be handed over to target base station 1 460 or target base station 2 480, and starts handover. It is expected to have information such as the expected time, the bandwidth required by the subscriber station 400 to the neighboring base station to be a new serving base station, and the service level to be provided by the subscriber station 400. The bandwidth and service level required by the subscriber station 400 are the same as the expected service level information recorded in the MOB_MSSHO_REQ message of Table 11.

Meanwhile, when the target base station 1 460 and the target base station 2 480 receive the HO_notification message transmitted by the serving base station 440, the target base station 1 460 and the target base station 2 480 transmit the HO_notification_response message to the serving base station 440 in response. (Steps 429 and 431). Here, the structure of the HO_notification_response message is shown in Table 11.

As shown in Table 11, the HO_notification_response message includes an identifier (MSS ID) of the subscriber station 400 to handover to a plurality of IEs, that is, target base stations 460 and 480, and target base stations 460,. A response (ACK / NACK) to whether the 480 can accept the handover request of the subscriber station 400 and each target when the subscriber station 400 moves to each target base station 460 or 480. It has bandwidth and service level information that the base stations 460 and 480 can provide.

When the serving base station 440 receives the HO_notification_response message from the target base station 1 460 and the target base station 2 480 as in step 429 or 431, the serving base station 440 determines that the subscriber station 400 receives the HO_notification_response message. When the mobile station moves, the target base stations 460 and 480 are selected to provide the bandwidth and service level required by the subscriber station. For example, in step 429, the target base station 1 460 transmits information indicating that the subscriber station 400 can provide a low level of service in a HO_notification_response message, and the target base station 2 480 in step 431. ) Transmits the information indicating that the same level of service can be provided to the subscriber station 400 in the HO_notification_response message. Accordingly, in step 433, the serving base station 440 selects target base station 2 480 that can provide the same service level, and transmits a HO_notification_confirm message in response to the HO_notification_response message of the selected target base station 2 480. do. Here, the structure of the HO_notification_confirm message transmitted to the selected target base stations 460 and 480 will be described with reference to Table 12.

As shown in Table 12, the HO_notification_confirm message includes an identifier (MSS ID) of the subscriber station 400 to handover to a plurality of IEs, that is, selected target base stations 460 and 480, and the selected target base station. It displays the bandwidth and service level information that can be provided from the target base station (460, 480) when the subscriber station 400 is moved to the (s) 460, 480.

After the target base stations 460 and 480 are selected in step 433, the serving base station 440 will call the mobile subscriber station 400 a handover response (MOB_HO_RSP) for the MOB_MSSHO_REQ (MOB_HO_RSP). In step 435, the message is transmitted. Here, the MOB_HO_RSP message structure is shown in Table 13.

As shown in Table 13, the MOB_HO_RSP message includes a plurality of IEs, that is, a Management Message Type indicating a type of a transmitted message, a time expected to start a handover procedure, and target base stations selected by the serving base station 440. N_Recommended indicating the result for (460, 480). Here, N_Recommended includes identifiers of the selected target base stations 460 and 480 as shown in Table 13, and a service level expected to be provided to the subscriber station 400 by each of the target base stations 460 and 480. Is indicated.

After receiving the MOB_HO_RSP message, the mobile subscriber station 400 selects a target base station to be moved by the N_Recommended information provided by the MOB_HO_RSP message transmitted by the serving base station 440. After selecting the target base station, the mobile subscriber station 400 transmits a MOB_HO_IND message, which is a response to the MOB_HO_RSP message, to the serving base station 440 (step 437). Here, the MOB_HO_IND message structure is shown in Table 14.

As shown in Table 14, the MOB_HO_IND message includes a plurality of IEs, that is, a management message type indicating a type of a transmitted message, an identifier of a target base station selected by the subscriber station 400, and a serving base station for handover to the serving base station. In addition to disconnecting, the HO-IND type can be canceled or rejected.

After receiving the MOB_HO_IND message, the serving base station 440 knows that the mobile subscriber station 400 will move to the target base station indicated in the MOB_HO_IND message and releases the link with the mobile subscriber station 400 (step 439). ).

As described above, the mobile subscriber station 400 releases the link with the serving base station 440 in step 439 and starts a handover procedure to the selected target base station.

Subsequently, when the subscriber station 400 receives the DL-MAP / UL-MAP from the target base station, which becomes the new serving base station in step 441, the subscriber station 400 receives fast ranging information (Fast ranging IE) as shown in Table 15 and accesses without contention. The interval is allocated. In this case, as in steps 443 and 445 through the allocated ranging region, an uplink ranging procedure is performed with a new target base station transmitting an RNG-REQ and receiving an RNG-RSP. After the lamination procedure is completed, the terminal 400 performs data transmission and reception with a new serving base station in step 447.

Table 15 below shows the fast ranging information.

Table 15 shows UIUC indicating UE's MAC address and modulation / demodulation scheme to be used in uplink as OFDM information, OFDM symbol offset, Subchannel offset, OFDM symbol number, and subchannel number indicating a ranging region. Contains information.

As described above, the handover procedure proposed in the conventional broadband orthogonal frequency division multiple access communication system has only a handover procedure between different base stations, which makes it difficult to support handover in a sectorized cell. .

That is, the handover procedure proposed by the conventional 802.16e in the multi-cell structure to support mobility of the subscriber station defines a scenario, procedure, and message for handover between base stations. However, as 802.16d sees a base station as a combination of sectors, efficient scenarios, procedures, and messages are needed to support handover between sectors within the same serving base station.

Accordingly, there is a need for a system and method capable of supporting handover between sectors in consideration of a handover procedure between base stations in a conventional broadband orthogonal frequency division multiple access communication system.

Accordingly, the present invention has been made to solve the above-mentioned problems of the prior art, an object of the present invention is to ensure the mobility of the user terminal included in the wireless broadband wireless communication system and at the same time to perform a smooth data communication and In providing a method.

Another object of the present invention is to provide an apparatus and a method for performing handover between sectors in a broadband wireless communication system to ensure mobility of a subscriber station.

It is still another object of the present invention to provide a frame structure for supporting inter-sector handover in a broadband wireless communication system for ensuring inter-sector mobility of a subscriber station.

In addition, another object of the present invention is to receive a handover request message including handover related information from a subscriber station by a handover request of a subscriber station, and to perform another communication in the same cell to be handed over by a serving base station performing data communication. To provide a device and method for determining and delivering to the user terminal.

The present invention for achieving the above object is a handover between sectors in the mobile terminal in a broadband orthogonal frequency division multiple access system having a serving base station and a sector constituting the serving base station and at least one subscriber station that performs current communication. In this method, a frame structure supporting inter-sector handover is proposed, and the base station determines a handover between sectors of the terminal and instructs the configuration of a map for handover to another sector in its base station. And a base station and a sector identifier.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings. In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

In the present invention, a sector operating system in a wideband orthogonal frequency division multiplexing access (OFDMA) system uses one center frequency and sectors are divided into subbands. Consider handover between sectors as appropriate for the current system.

Accordingly, in the present invention, when the same serving base station uses the same center frequency and sectors are divided into subbands, sectors in the base station are divided by antenna beam shaping and channel modulation and demodulation is performed in the same base station. Since the location and distance of the same are the same, there is no need for a quick ranging procedure performed when the handover to the new base station is completed. In the case of sectors that divide the band, if the base station controls the sub-frequency resource allocation, the message exchange of the network-side that has to be performed in the process of handover to the new base station is unnecessary, and the procedure of authentication and registration can be omitted.

On the other hand, the frame structure of IEEE 802.16d and IEEE 802.16e does not currently have a frame structure for supporting a sector. That is, it is designed to receive data allocation in any area irrespective of sectors within a single cell. In order to support sectors in this structure, two frame structures may be considered depending on a method of operating a downlink information control region. One is classified into a case in which all sectors each have an information control area and the other in a case in which an information control area is provided in units of base stations.

In this case, when all of the sectors each have an information control region, a different sub-frequency region is used so that the other sectors and neighboring base stations are not interfered with. In addition, when the information control region is used for each base station unit and the sub-frequency is divided between sectors, there is a conciseness that only the base station changes the position of the allocated time slot when handover occurs between sectors.

Hereinafter, a preferred embodiment of the present invention will be described with reference to the accompanying drawings, FIGS. 5 to 12.

First, a frame structure supporting handover between sectors according to the present invention will be described with reference to FIGS. 5 and 6.

5 and 6 are diagrams illustrating a frame structure for supporting handover between different sectors according to the present invention, and FIG. 5 is a view illustrating several maps for supporting handover between sectors in a broadband wireless access communication system using an OFDMA scheme. 6 is a diagram illustrating a frame structure in the case where there exists, and FIG. 6 is a diagram illustrating a frame structure of a subset concept for supporting handover between sectors in a broadband wireless access communication system using the OFDMA scheme.

Referring to FIG. 5, in FIG. 5, three sectors constituting the base station use three sub-frequency regions other than the preamble in the downlink. Each sector is divided into DL-MAP / UL-. The uplink shows a frame structure in which the MAP and the uplink divide the preamble, the data area, and the ranging area by the number of sectors so that terminals corresponding to each sector can access only the data area and the information control area of the corresponding sector. Here, in the downlink, a terminal corresponding to each sector receives and demodulates a sector DL-MAP from each sector, and accesses its data area to receive data. The UL-MAP received from the sector is received to detect the uplink data area, and then data transmission is performed.

Referring to FIG. 6, FIG. 6 shows that the data area is divided into a subset of sectors. The sector corresponding to the information control area such as the preamble and the DL-MAP / UL-MAP is shared by all sectors. Only three times, the mobile station of each sector represents a frame structure in which a time slot for data transmission and reception can be allocated only within a subset allocated to each sector. Here, the uplink includes a preamble, a data region, and a ranging region corresponding to each sector as in FIG. 5.

Meanwhile, for handover between sectors as described above, an identifier (ID) for distinguishing sectors is required. Identifiers for handover between the sectors are shown in Table 16 below.

As shown in Table 16, a part of a base station identifier (BS-ID: Base Station IDentifier, hereinafter referred to as "BS-ID") consisting of 48 bits in the current IEEE 802.16e system is defined and configured as shown in Table 16 above. This can be used to distinguish between sectors and base stations.

Hereinafter, a handover process between sectors requested by the subscriber station in the frame structure as shown in FIG. 5 will be described with reference to FIG. 7.

FIG. 7 is a diagram illustrating a handover process between sectors in response to a subscriber station request in a frame structure considering FIG. 5 in a broadband wireless access communication system using the OFDMA scheme according to the present invention. Hereinafter, the handover process of FIG. 7 will be described with reference to the frame structure of FIG. 5.

Referring to FIG. 7, the subscriber station 701 belongs to serving base station 1 703 and sector 1. The subscriber station 701 receives the information on the neighboring sector and the neighboring base station from the serving base station 1 703 through a neighbor base station advertisement (NBR_ADV: NBR_ADV) message (705). In step 707, DL-MAP / UL-MAP belonging to sector 1 of the serving base station 1 703 is received. In this case, it should be noted that the order of steps 705 and 707 may be changed. Here, the control information area may be received only by the subscriber station belonging to sector 1 of the serving base station 1 703.

Meanwhile, the subscriber station 707 receiving the DL-MAP / UL-MAP from the serving base station 1 703 performs data transmission with the base station (709). At this time, the subscriber station 701 detects that the subscriber station itself has entered the handover region or serves a serving base station rather than a reference carrier-to-interference noise ratio (CINR). If the CINR drops, the serving base station 1 703 requests scanning through a Scan Interval Allocation Request (SCAN_REQ) message (hereinafter referred to as " SCAN_REQ "). Then, the serving base station 1 703 informs the subscriber station 701 of the scanning method through a scan response (SCAN_RSP: SCAN_RSP) message with respect to the SCAN_REQ message (713). ).

At this time, the subscriber station 701 measures the CINR of the preambles of neighboring sectors and receives a subscriber station handover request (MSSHO_REQ) when a preamble CINR larger than sector 1 of the serving base station 1 703 performing current data transmission / reception is received. A handover request is made to the serving base station 1 703 through a Mobile Subscriber Station HandOver Request (hereinafter referred to as "MSSHO_REQ") message (715).

If the sector having the largest preamble CINR in the MSSHO-REQ message that is the message for requesting the handover is another sector in the same serving base station as in sector 2 of serving base station 1 703 as in step 715, the process 717 is performed. In addition, the serving base station processes the handover process between sectors.

Subsequently, if the handover requested by the pressurizer terminal 701 is a handover between sectors, the serving base station 1 703 determines the resource status of its sectors and the required bandwidth and service of the terminal without exchanging a message from the network. Compare the quality. Subsequently, the serving base station 1 703 performs a base station handover response (BSHO_RSP: BSHO_RSP) message after performing the comparison, as described in step 719. Send a handover response message to the. At this time, since there is no message exchange at the network end, neighboring sectors included in the message may be limited to sectors belonging to the base station.

Meanwhile, the subscriber station 701 transmits a HO_IND message in step 721 in response to the BSHO_RSP message. In this case, since the serving base station transmits and receives data only by changing the sub-frequency as in the case of handover between sectors, the handover type does not fit the serving base station to terminate the connection of the terminal after the end of the handover. Therefore, a new type indicating handover between sectors needs to be added. In order to add this type, an existing spare bit is inserted as shown in Table 19 below. In this case, as shown in Table 19, a spare 2 bits can be allocated as a handover type to distinguish handover between sectors and handover of a base station. Here, the HO_IND message structure is shown in Table 17 below.

As shown in Table 17, the HO_IND message includes a plurality of IEs, that is, a Management Message Type indicating a type of a message to be transmitted, an identifier of a target base station selected by a subscriber station, and its own connection to a serving base station for handover. In addition to the release, the HO-IND type can be canceled or rejected. In addition, HO_type for informing the handover between sectors is newly defined and inserted in the existing spare bit as shown in Table 17 to add the type. As shown in Table 17, two bits can be allocated as a handover type to distinguish handover between sectors and handover of a base station.

Meanwhile, when the serving base station 703 receives the handover type between sectors through the HO_IND message from the subscriber station 701 as shown in step 721, resource allocation for supporting mobility of the subscriber station 701 to sector 2 is performed. The DL-MAP / UL-MAP in the sector 2 region is modified (723). Thereafter, the subscriber station 701 receives the DL-MAP / UL-MAP corresponding to the sector 2 region (725), detects the position allocated to the uplink / downlink for data transmission and reception, and then performs data transmission. (727).

As in the above procedure, the present invention may omit a quick rajin procedure or a procedure for registration and authentication, which is necessary for an existing handover.

Hereinafter, a handover process between sectors requested by the subscriber station in the frame structure as shown in FIG. 6 will be described with reference to FIG. 8.

8 is a diagram illustrating a handover process between sectors in response to a subscriber station request in a frame structure considering FIG. 6 in a broadband wireless access communication system using the OFDMA scheme according to the present invention. Hereinafter, the handover process of FIG. 8 will be described with reference to the frame structure of FIG. 6.

Referring to FIG. 8, the subscriber station 801 belongs to serving base station 1 and sector 1. At this time, the subscriber station 801 receives information on the neighboring sector and the neighboring base station from the serving base station 1 803 through an NBR-ADV message (805), and the DL-MAP of the serving base station 1 803 Receive / UL-MAP as step 807. In this case, the order of steps 805 and 807 may be reversed. In addition, this control information area is bandwidth and information commonly used in all sectors of the serving base station 1 803. Therefore, regardless of the sector, all of the subscriber station belonging to the same serving base station receive the same information.

Meanwhile, in step 807, the subscriber station 801 receiving the DL-MAP / UL-MAP performs data transmission with a base station (809). At this time, the bandwidth area for transmitting and receiving the data is different for each sector. Subsequently, the subscriber station 801 detects that the UE has entered the handover area or if the CINR of the serving base station is lower than the reference CINR, requests the serving base station 1 803 to scan through the SCAN-REQ message (811). Then, the serving base station 1 803 receiving the notification informs the subscriber station 801 of a scanning method through a SCAN-RSP message (813).

In this case, the subscriber station 801 measures the CINR of the preambles of neighboring sectors and receives a serving base station 1 (MSSHO-REQ) message when the preamble CINR larger than the sector 1 of the serving base station 1 performing the current data transmission / reception is received. 803 requests a handover (815). If the sector having the largest preamble CINR in the MSSHO-REQ message that is the message for requesting the handover is another sector in the same serving base station as in sector 2 of serving base station 1 as in step 815, the serving base station is an intersectoral hand as in step 817. It is handled by over process.

Next, when the handover requested by the subscriber station 801 is determined to be a handover between sectors, the serving base station 1 803 determines the resource status of its sectors, the required bandwidth, and the quality of service of the terminals without exchanging messages from the network. Compare. Subsequently, when the comparison is completed, a handover response message is transmitted to the subscriber station 801 through a BSHO-RSP message as shown in step 819. At this time, since there is no network exchange of messages, neighboring sectors included in the message may be limited to sectors belonging to the base station.

In response to the BSHO_RSP message, the subscriber station 801 transmits a HO_IND message to the serving base station 1 803 in step 821 in step 821. In this case, since the serving base station transmits and receives data only by changing the sub-frequency as in the case of handover between sectors, the handover type does not fit the serving base station to terminate the connection of the terminal after the end of the handover. Therefore, a new type for handover between sectors needs to be added. In order to add this type, the existing spare bit is inserted as shown in Table 19 above.

Subsequently, when the serving base station receives the terminal as a handover type through the HO_IND from the terminal as shown in step 821, the UE requests to change the resource allocation into the data allocation area of sector 2 to allocate the resource for mobility support to sector 2. Modify the DL-MAP / UL-MAP to do this (823). Next, after detecting the handover between sectors, the subscriber station 801 does not receive DL-MAP / UL-MAP corresponding to another center frequency or another area, but in the same manner as the general mode, the DL-MAP of the serving base station. Receiving the / UL-MAP (825) detects the location assigned to the uplink / downlink for data transmission and reception and performs the data transmission (827).

8 differs from FIG. 7 in that the common control information area is used, and there is no need to move the area for reading DL-MAP / UL-MAP in case of handover between sectors.

As described above, in the above-described process, a quick ranging procedure or registration and authentication procedure required for the existing handover may be omitted.

Hereinafter, an operation process of a subscriber station that handles handover between sectors in the above process will be described with reference to FIG. 9.

FIG. 9 is a diagram illustrating an operation process of a terminal for processing handover between sectors in a frame structure considering FIG. 5 of the broadband wireless access communication system using the OFDMA scheme according to the present invention. That is, FIG. 9 illustrates a process of a subscriber station in handover between sectors in the process of FIG. 7.

Referring to FIG. 9, the subscriber station receives an NBR-ADV message capable of collecting information of neighbor sectors, that is, collects information of neighbor sectors as shown in step 901. Subsequently, the subscriber station receives the uplink / downlink information (DL-MAP / U-MAP) corresponding to the sector 1 region of the serving base station 1 in step 903 and transmits and receives data (705). Thereafter, when the subscriber station reaches a time point for requesting scanning, a message requesting scanning (SCAN_REQ) is transmitted in step 907 to request CINR measurement of an adjacent sector. Then, in step 909, a response to the scanning method (SCAN_RSP) is received from the serving base station. That is, the CINR measurement method of the neighboring sectors is allocated, and then the CINRs of the preambles of the neighboring sectors are measured in step 911.

At this time, if the measured CINR of the neighboring sector is smaller than that of the serving sector, that is, the CINR of the serving sector is larger, the subscriber station returns to the initial process 901 and receives the NBR_ADV message again. On the other hand, if the measured CINR of the neighboring sector is larger than the CINR of the serving sector (913), the subscriber station transmits an MSSHO-REQ message to request a handover (915). Subsequently, a response to the handover (BSHO_RSP) message is received from the base station (917), and it is checked whether the target sector of the response message, that is, the BSHO-RSP is another sector of the same base station (919).

In this case, if the target sector is not another sector of the same base station, a quick ranging procedure is performed to the target sector of another base station (921). If the target sector is another sector of the same base station, the type of HO_IND is used. A HO_IND message is transmitted by specifying a handover between sectors (923), and a DL-MAP / UL-MAP of sector 2 is received (925). Subsequently, the subscriber station detects the location of its uplink / downlink allocation burst in the received DL-MAP / UL-MAP and performs data transmission / reception in sector 2 (927).

Hereinafter, an operation process of a base station that handles handover between sectors in the above process will be described with reference to FIG. 10.

FIG. 10 is a diagram illustrating an operation process of a base station for processing handover between sectors in the frame structure considering FIG. 5 of the broadband wireless access communication system using the OFDMA scheme according to the present invention. That is, FIG. 10 illustrates a process performed by the base station during handover between sectors in the process of FIG. 7.

Referring to FIG. 10, sector 1 of serving base station 1 transmits an NBR-ADV message including sector information for subscriber stations belonging to its sector as step 1001. Then, the subscriber station receives the uplink / downlink information (DL-MAP / UL-MAP) corresponding to sector 1 of the base station 1 and detects the location of its data transmission burst as in step 1003. Subsequently, when the base station1 receives the scanning measurement request (SCAN_REQ) message from the subscriber station in step 1007, the base station 1 transmits a response message for a method of measuring the preamble CINR of the neighboring sector through the SCAN-RSP (1009). Then, when receiving the MSSHO-REQ message requesting a handover from the subscriber station (1011), the serving base station determines whether the preamble CINR information of neighbor sectors reported by the subscriber station is greater than the preamble CINR of the serving sector. (1013).

At this time, if the preamble CINR of another sector in the same serving base station is higher than the preamble CINR of the serving sector, it is recognized as a request for handover between sectors and the available capacity of the adjacent sectors is checked, and then the BSHO-RSP is performed as in step 1017. Send the message. If the largest preamble CINR is a sector of an adjacent base station instead of another sector of the same serving base station, a handover process between the existing base stations is performed as in step 1015. Subsequently, after receiving the HO_IND message from the subscriber station, the serving base station checks 1021 whether the handover type is set to "01" indicating handover between sectors. Subsequently, if the check result is a handover type between sectors, the uplink / downlink burst for the subscriber station is allocated to the DL-MAP / UL-MAP of the control region corresponding to sector 2 of the base station 1 as in step 1023. DL-MAP / UL-MAP in sector 2 area of base station 1 is transmitted to the subscriber station. If the handover type is not "01", the process returns to step 1015 to follow a procedure performed according to the handover type in handover between base stations. Thereafter, if there is a bandwidth request and uplink data from the subscriber station, data transmission and reception are performed (1027).

Hereinafter, an operation of a subscriber station during handover between sectors according to the process of FIG. 8 will be described with reference to FIG. 11.

11 is a diagram illustrating an operation process of a terminal for processing handover between sectors in the frame structure considering FIG. 6 of the broadband wireless access communication system using the OFDMA scheme according to the present invention. That is, FIG. 11 illustrates a process performed by the subscriber station during handover between sectors in the process of FIG. 8.

Referring to FIG. 11, the subscriber station receives an NBR-ADV message capable of collecting information on neighboring sectors as in step 1101, and corresponds to uplink / downlink information corresponding to the common control information region of the serving base station 1 (DL-MAP). / U-MAP) and receives (1103) and performs data transmission and reception (1105). After that, when the subscriber station reaches a time point for requesting scanning, a message for requesting scanning (SCAN_REQ) is transmitted as in step 1107. Subsequently, a CINR measurement method of neighboring sectors is allocated from the serving base station through a response to the scanning method (SCAN_RSP) as in step 1109, and the CINR of the preambles of neighboring sectors is measured in step 1111.

At this time, if the measured CINR of the neighboring sector is larger than the serving sector's CINR (1113), the subscriber station sends a MSSHO-REQ message to request a handover (1115), if the serving sector has a larger CINR. The process returns to step 1101 to receive the NBR-ADV message again. Subsequently, the subscriber station receives a response message for handover from the base station (1117), and then checks whether the target sector of the response message, that is, the BSHO-RSP is another sector of the same base station (1119).

At this time, if the target sector is not another sector of the same base station, a fast ranging procedure to a target sector of another base station is performed (1121). If the target sector is another sector of the same base station, the sector is a type of HO_IND. The HO_IND message is transmitted by specifying a handover (1123), and then, unlike handover between base stations, the UE receives a DL-MAP / UL-MAP transmitted by its serving base station as in a general data transmission / reception process (1125). Thereafter, the DL-MAP / UL-MAP detects the position of its uplink / downlink allocation burst and performs data transmission and reception (1127).

Hereinafter, an operation of a subscriber station during handover between sectors according to the process of FIG. 8 will be described with reference to FIG. 12.

12 is a diagram illustrating an operation process of a base station for processing handover between sectors in the frame structure considering FIG. 6 of the broadband wireless access communication system using the OFDMA scheme according to the present invention. That is, FIG. 12 illustrates a process performed by the base station during handover between sectors in the process of FIG. 8.

Referring to FIG. 12, the serving base station 1 transmits an NBR-ADV message including information of sectors for terminals belonging to its sector as in step 1201. Then, the subscriber station receives the uplink / downlink information (DL-MAP / UL-MAP) of the common control area of the base station 1 and detects the location of its own data transmission burst as in step 1203. Then, when receiving the scanning measurement request (SCAN_REQ) message from the subscriber station as shown in step 1207, the base station transmits a response message for the method of measuring the preamble CINR of the neighboring sector through the SCAN-RSP message (1209) ). Subsequently, upon receiving the MSSHO-REQ message requesting handover from the subscriber station (1211), the serving base station determines whether the preamble CINR information of the neighbor sectors reported by the subscriber station is greater than the preamble CINR of the serving sector (1213). .

At this time, if the preamble CINR of another sector in the same serving base station is higher than the preamble CINR of the serving sector, it is recognized as a request for handover between sectors and the available capacity of the adjacent sectors is checked. Then, the BSHO-RSP message is performed as in step 1217. Send. If the largest preamble CINR is a sector of an adjacent base station instead of another sector of the same serving base station, the handover process between the existing base stations is performed as in step 1215.

After receiving the HO-IND message from the subscriber station, the serving base station checks 1221 whether the handover type is set to " 01 " for handover between sectors.

In this case, in case of a handover type between sectors, as shown in step 1223, the burst position is changed to a data area corresponding to sector 2 of the base station 1, and the DL-MAP / UL-MAP of the common control area is modified. The DL-MAP / UL-MAP is transmitted to the subscriber station through the common control area. If the handover type is not 01, the process returns to step 1215 to perform a procedure according to the handover type in the handover between base stations. If there is a bandwidth request and uplink data from the terminal, data transmission and reception is performed (1227). .

As described above, although the present invention has been described by way of limited embodiments and drawings, the present invention is not limited thereto and is intended by those skilled in the art to which the present invention pertains. Of course, various modifications and variations are possible within the scope of the claims to be described.

As described above, according to the apparatus and method for inter-sector handover required by the terminal in the broadband orthogonal frequency division multiple access scheme of the present invention, an 802.16e system is defined by defining a frame structure, a scenario, and a message capable of supporting the inter-sector handover. In addition to the handover between the base station can support the handover between the sectors, through this has the advantage that can support the mobility of the terminal between the sectors.

1 is a diagram illustrating a cell structure of a broadband wireless access communication system using a general orthogonal frequency division multiplexing / orthogonal frequency division multiple access scheme;

FIG. 2 is a diagram schematically illustrating a structure of an uplink / downlink frame of a broadband wireless access communication system using a general orthogonal frequency division multiple access scheme; FIG.

3 is a diagram illustrating a sector structure of a broadband wireless access communication system using a general orthogonal frequency division multiplexing / orthogonal frequency division multiple access scheme;

4 is a diagram illustrating a handover processing scenario required by a terminal of a broadband wireless access communication system using a general orthogonal frequency division multiple access scheme;

5 is a diagram illustrating an embodiment of a frame structure for supporting handover between sectors in a broadband wireless access communication system using an orthogonal frequency division multiple access scheme according to the present invention;

6 is a diagram illustrating an embodiment of a frame structure for supporting handover between sectors in a broadband wireless access communication system using an orthogonal frequency division multiple access scheme according to the present invention;

FIG. 7 is a diagram illustrating handover between sectors in a frame structure considering FIG. 5 in a broadband wireless access communication system using an orthogonal frequency division multiple access scheme according to the present invention;

8 is a diagram illustrating handover between sectors in a frame structure considering FIG. 6 in a broadband wireless access communication system using an orthogonal frequency division multiple access scheme according to the present invention;

9 is a flowchart illustrating an operation of a terminal for processing handover between sectors in a frame structure considering FIG. 5 in a broadband wireless access communication system using an orthogonal frequency division multiple access scheme according to the present invention;

FIG. 10 is a flowchart illustrating an operation of a base station for processing handover between sectors in a frame structure considering FIG. 5 in a broadband wireless access communication system using an orthogonal frequency division multiple access scheme according to the present invention;

FIG. 11 is a diagram illustrating an operation process of a terminal for processing handover between sectors in a frame structure considering FIG. 6 in a broadband wireless access communication system using an orthogonal frequency division multiple access scheme according to the present invention;

12 is a diagram illustrating an operation process of a base station for processing handover between sectors in a frame structure considering FIG. 6 in a broadband wireless access communication system using an orthogonal frequency division multiple access scheme according to the present invention.

Claims (22)

A handover support system in a broadband orthogonal frequency division multiple access communication system, A serving base station, a sector constituting the serving base station, at least one or more user terminals currently communicating within the sector, and a system using one center frequency and dividing a band into subbands between sectors; , In the system, the handover from the serving base station to perform the handover to another sector in the same base station at the request of the subscriber station. The method of claim 1, When the subscriber station performs handover, the subscriber station performs handover between sectors according to the set frame structure. The base station, when it is determined that the subscriber station is a handover between sectors, instructs the configuration of a map for handover to another sector in its base station. The method of claim 2, The frame, And the data allocation is performed in all areas irrespective of sectors within a single cell. The method of claim 2, And wherein the frame comprises a frame structure in which all sectors each have an information control area. The method of claim 4, wherein The frame structure is characterized in that for the handover occurs using a different frequency domain. The method of claim 2, The frame includes a frame structure that uses an information control region in units of base stations and uses a sub-frequency between sectors. The method of claim 6, The frame structure may be performed by changing a location of an allocated time slot at a base station when a handover occurs between sectors. The method of claim 2, And the base station configures an identifier of the base station as a base station and a sector identifier, respectively. A handover support method in a wideband orthogonal frequency division multiple access communication system comprising a serving base station, a sector constituting the serving base station, and at least one subscriber station currently communicating within the sector, Requesting an intersectoral handover from the subscriber station; And determining, by the serving base station receiving the request from the subscriber station, an intersectoral handover support frame through the intersectoral handover support frame to allow the subscriber station to perform a handover to another sector in the same base station. Characterized in that the method. The method of claim 9, The frame, A frame including at least one map for supporting handover between sectors; And a subset of frames for handover support between sectors. The method of claim 10, The frame in which the at least one map exists, A frame when three sectors constituting the base station are downlink and a frame when three sectors constituting the base station are uplink, In the case of the downlink, the frame is divided into three sub-frequency regions other than the preamble, and the divided frequency regions are divided into sectors having uplink / downlink information (DL_MAP / UL_MAP), respectively. In the case of the uplink, the frame is divided into a preamble, a data area, and a ranging area by the number of sectors so that subscriber stations corresponding to each sector can access only the data area and the information control area of the corresponding sector. Said method. The method of claim 11,  In the downlink, a subscriber station corresponding to each sector receives and demodulates a sector DL-MAP from each sector, accesses its data area, and receives data. In the uplink, the method characterized in that the UL-MAP received from the sector to which the subscriber station belongs, detects the uplink data area and performs data transmission. The method of claim 10, The subset frame, The data area is divided into subsets by the number of sectors, the parts corresponding to the preamble and the information control area of the DL-MAP / UL-MAP are allocated to all sectors for common use, and the data allocation area is divided into three parts to add subscribers of each sector. The method of claim 1, wherein the terminal can be allocated a time slot for data transmission and reception only within a subset allocated in each sector. The method of claim 9, The base station is characterized in that it comprises an identifier for identifying the sector for inter-sector handover. In a frame structure in which at least one map exists, the method for supporting intersector handover according to a request of a subscriber station, When the subscriber station belongs to a serving base station and a first sector, the subscriber station receives a neighbor base station advertisement (NBR_ADV) message and up / down information belonging to the first sector of the serving base station from the serving base station, and then the data. Performing the transfer; After the data transmission, if the subscriber station itself detects entering the handover area or if the serving base station CINR is lower than the reference carrier-to-interference noise ratio (CINR) to request scanning through the scan request (SCAN_REQ) message to the serving base station Steps, After the scanning request, if a scanning method is allocated through a scan response (SCAN_RSP) message from the serving base station, the subscriber station measures the CINR of the preamble of neighboring sectors; Requesting a handover to the serving base station through a subscriber station handover request (MSSHO_REQ) message when a preamble CINR larger than a first sector of the serving base station performing data transmission and reception is received as a result of the CINR measurement; Receiving the handover request, if the requested handover is determined to be a handover between sectors, comparing the resources of its sectors with the required bandwidth and quality of service of the terminal; A handover response to the subscriber station through a base station handover response (BSHO_RSP) message after the comparison is performed, and the subscriber station transmits a HO_IND message in response to the handover response message; When the serving base station receives the inter-sector handover type through the HO_IND message, modifying the subscriber station to the DL-MAP / UL-MAP in the sector 2 region for resource allocation for mobility support to sector 2; And receiving the DL-MAP / UL-MAP corresponding to the sector 2 region, detecting the position allocated to the uplink / downlink for data transmission / reception, and then performing data transmission. The method. The method of claim 15, The HO_IND message is a method for allocating handover between sectors and handover between base stations by allocating a spare 2 bits as a handover type. The method of claim 15, The HO_IND message is, And a handover type for informing a handover between sectors is defined and inserted into an existing spare bit to add the type. In a frame structure in which at least one map exists, the method for supporting intersector handover according to a request of a subscriber station, The subscriber station receives information on the neighboring sector and the neighboring base station from the serving base station through an NBR-ADV message, and receives the DL-MAP / UL-MAP of the serving base station; The subscriber station receiving the DL-MAP / UL-MAP performs data transmission with a base station; When the subscriber station detects that the UE has entered a handover area or when the serving base station has a CINR lower than the reference CINR, requesting the serving base station to scan through a SCAN-REQ message; Informing the subscriber station of a scanning method through a SCAN-RSP message at the serving base station receiving the scanning request; The subscriber station receiving the scanning method measures a CINR of preambles of neighboring sectors and hands over to a serving base station through an MSSHO-REQ message when a preamble CINR larger than sector 1 of a serving base station currently performing data transmission and reception is received. Requesting, When the handover requested by the subscriber station is determined to be handover between sectors, the serving base station comparing the resources of its sectors with the required bandwidth and quality of service of the terminal; Transmitting a handover response message to the subscriber station through a BSHO-RSP message when the comparison is completed; The subscriber station transmitting a HO_IND message to a serving base station in response to the BSHO_RSP message; When the serving base station receives an inter-sector handover type from the terminal through HO_IND, the terminal may request a resource allocation change in the data allocation area of sector 2 for resource allocation for mobility support to sector 2; Modifying the UL-MAP, After detecting the handover between sectors, the subscriber station receives the DL-MAP / UL-MAP of the serving base station in the same manner as the normal mode, detects the position allocated to the uplink / downlink for data transmission and reception, and then performs data transmission. Said method comprising the steps of: A method for processing in a subscriber station during intersector handover in a frame in which at least one map is present, The subscriber station receives an NBR-ADV message capable of collecting information of neighboring sectors and DL-MAP / U-MAP corresponding to the first sector of the serving base station, and then performs data transmission and reception; Transmitting a message requesting scanning (SCAN_REQ) when the subscriber station reaches a time point for requesting scanning, requesting CINR measurement of an adjacent sector; Measuring a CINR of a preamble of adjacent sectors when a response (SCAN_RSP) message to a scanning method is received from the serving base station; Returning to the initial stage when the measured CINR of the neighboring sector is smaller than the CINR of the serving sector, and requesting handover by transmitting an MSSHO-REQ message when the measured CINR of the neighboring sector is larger than the CINR of the serving sector; , Receiving a response to a handover (BSHO_RSP) message from the base station, checking whether a target sector of the BSHO-RSP is another sector of the same base station; If the target sector is not another sector of the same base station, a fast ranging procedure is performed to a target sector of another base station. If the target sector is another sector of the same base station, HO_IND is specified by specifying handover between sectors in the HO_IND type. Sending a message, After the transmission, if the DL-MAP / UL-MAP of the sector 2 is received, the DL-MAP / UL-MAP detects the position of its uplink / downlink allocation burst and then transmits and receives data in the sector 2. Said method comprising the steps of: A processing method in a base station during intersector handover in a frame in which at least one map is present, Sector 1 of the serving base station transmits an NBR-ADV message including sector information for the subscriber stations belonging to its sector and a DL-MAP / UL-MAP corresponding to sector 1 of the base station; Receiving a scanning measurement request (SCAN_REQ) message from the subscriber station, transmitting a response message for a method of measuring a preamble CINR of a neighboring sector through a SCAN-RSP; Receiving the MSSHO-REQ message requesting handover from the subscriber station, the serving base station checking whether the preamble CINR information of neighbor sectors reported by the subscriber station is greater than the preamble CINR of the serving sector; If the preamble CINR of another sector in the same serving base station is higher than the preamble CINR of the serving sector, it is recognized as a request for handover between sectors, the available capacity of the neighboring sectors is checked, and then a BSHO-RSP message is transmitted. If the preamble CINR is a sector of an adjacent base station rather than another sector of the same serving base station, performing a handover procedure between the existing base stations; Receiving, by the serving base station, a HO_IND message from the subscriber station and checking whether the handover type is set to "01" indicating handover between sectors; If the check result indicates that the sector is a handover type, the uplink / downlink burst for the subscriber station is allocated to the DL-MAP / UL-MAP in the control region corresponding to sector 2 of the base station, and the DL-MAP / UL in the sector 2 region of the base station. Sending a MAP to the subscriber station; If the handover type is not "01", performing the handover between base stations according to the handover type, and performing data transmission and reception when there is a bandwidth request and uplink data from the subscriber station. The method. A method of operating a subscriber station for processing intersectoral handover in a subset frame structure, The subscriber station receives an NBR-ADV message capable of collecting information of neighboring sectors, receives a DL-MAP / U-MAP corresponding to the common control information area of the serving base station, and then performs data transmission and reception; When the subscriber station reaches a time point for requesting scanning, a message for requesting scanning (SCAN_REQ) is transmitted, and if a CINR measurement method for a neighboring sector is allocated from the serving base station through a response to the scanning method (SCAN_RSP), the neighboring sector Measuring the CINR of the preamble of the terminal, If the measured CINR of the neighboring sector is larger than that of the serving sector, the subscriber station sends an MSSHO-REQ message to request a handover, and if the serving sector has a larger CINR, receiving the NBR-ADV message again. , Receiving, by the subscriber station, a response message for handover from the base station, and then checking whether the target sector of the response message BSHO-RSP is another sector of the same base station; If the target sector is not another sector of the same base station, a fast ranging procedure is performed to a target sector of another base station. If the target sector is another sector of the same base station, HO_IND is specified by specifying handover between sectors in the HO_IND type. Sending a message, After the transmission, it receives DL-MAP / UL-MAP transmitted by its serving base station, detects the position of its uplink / downlink assignment burst in the received DL-MAP / UL-MAP, and then transmits and receives data. Said method comprising the step of performing. In the operating method of the base station for processing the inter-sector handover in the subset frame structure, The serving base station transmits an NBR-ADV message including information of sectors and DL-MAP / UL-MAP of a common control area of the base station for terminals belonging to its sector; The base station transmits a response message through a SCAN-RSP message when receiving a scanning measurement request (SCAN_REQ) message from the subscriber station, and receives the MSSHO-REQ message requesting a handover from the subscriber station. Checking whether the reported preamble CINR information of the neighboring sectors is larger than the preamble CINR of the serving sector; If the preamble CINR of another sector in the same serving base station is higher than the preamble CINR of the serving sector, it is recognized as a request for handover between sectors, the available capacity of the neighboring sectors is checked, and then a BSHO-RSP message is transmitted. If the preamble CINR is a sector of an adjacent base station rather than another sector of the same serving base station, performing a handover procedure between the existing base stations; Receiving, by the serving base station, a HO-IND message from the subscriber station and checking whether the handover type is set to "01" indicating handover between sectors; In case of the handover type between the sectors, the location of the burst is changed to the data area corresponding to sector 2 of the base station, the DL-MAP / UL-MAP of the common control area is modified, and then the DL-MAP / UL-MAP is changed through the common control area of the base station. And transmitting to the subscriber station, and if the handover type is not 01, performing a procedure according to the handover type in the handover between base stations.