KR101080599B1 - Method for base-station scanning of mobile terminal - Google Patents

Abstract

According to the present invention, when the terminal requests scanning of a neighboring base station, when the scanning period includes a time point for performing periodic ranging of the terminal, scanning is performed after the terminal performs periodic ranging through a scanning response message. By re-requesting or scanning can be performed, there is an effect that the periodic ranging operation of the terminal is independent of the scanning operation. In addition, when the base station rejects a neighboring base station scanning request of the terminal, the scanning response message delivered to the terminal can be reduced by indicating the scanning rejection as a flag or a scanning period parameter set to 0 in the scanning response message. According to an aspect of the present invention, there is provided a method for scanning a base station of a mobile station, the method comprising: requesting a base station for scanning when a periodic ranging time point and a scanning period overlap; Receiving a response message of scanning rejection from the base station; Performing a ranging procedure with the base station when the ranging is performed; After a predetermined time elapses, a process of requesting scanning again from the base station is performed.

Broadband wireless access system, ranging, base station scanning

Description

Base station scanning method of mobile terminal {METHOD FOR BASE-STATION SCANNING OF MOBILE TERMINAL}

1 is a diagram illustrating an IEEE802.16e network structure and a handover process;

2 is a diagram illustrating a cell selection operation of IEEE802.16e.

3 is a signal flow diagram of a conventional neighbor base station scanning procedure.

4 illustrates a periodic scanning procedure according to the prior art.

5 illustrates uplink slot assignment of a serving base station for periodic ranging;

6 is a signal flow diagram of a scanning procedure according to the first embodiment of the present invention;

7 is a signal flow diagram of a scanning procedure according to a second embodiment of the present invention.

8 is a signal flow diagram of a scanning procedure according to a third embodiment of the present invention;

The present invention relates to a handover of a broadband wireless access system, and more particularly, to a neighbor base station scanning method for handover.

Unlike the existing 2nd and 3rd generation mobile communication systems, IEEE802.16e system, which is undergoing international standardization for broadband wireless access system, has a home location register (HLR), a visitor location register (VLR), a mobile switching center (MSC), It does not have a hierarchical structure such as a base station controller (BSC) or a radio network controller (RNC), but only a mobile subscriber station (MSS) as a terminal, a base station (BS) as a base station, and an authentication service authorization (ASA) as an authentication management server. Consists of. A base station and a terminal define a common physical layer (PHY) and a medium access control (MAC).

1 illustrates an IEEE802.16e network structure and a handover process, and illustrates a network structure provided by IEEE802.16e, a handover operation in a data plane and a control plane. A base station in charge of communication of a mobile terminal (MSS) is called a serving base station (Serving BS).

For the handover of a mobile station, a preprocessing process performed in a broadband wireless access system includes a network topology advertisement process of broadcasting information related to a neighboring base station in a base station and informing the mobile stations, and the neighboring base station information. There is a MSS scanning of neighbor BS process to measure the channel quality of the neighbor BSs, and association procedures for selectively matching the initial UE power value and the time difference value for synchronization with the neighbor BSs.

* Network Topology Advertisement

The service base station transmits the information related to the network configuration information to all mobile terminals in the cell through a MAC management message (MOB-NBR-ADV) by broadcasting to inform the mobile terminal in the cell of the neighbor base station information.                         

* MSS scanning of neighbor BS

The mobile station needs to scan the neighboring base station for handover. The mobile station requests the serving base station through the scanning request message (MOB_SCN-REQ) to search for the neighboring base station. A scanning response message (MOB-SCN-RSP) is transmitted to allocate a period during which the mobile station can search for a neighboring base station. In addition, the serving base station may transmit a direct scanning response message (MOB_SCN_RSP) without the request of the mobile station (Unsolicited request). At this time, the search period allocated by the service base station and the offset unit for starting the search are all allocated in units of frames.

Association Procedures

The association process (or association process) is a mobile terminal performing an initial ranging process with a neighboring base station (a mobile terminal obtaining basic information for communication from the base station) to obtain and store basic information necessary for communication with a neighboring base station in advance. After setting the communication with the target base station, which is one of the neighboring base stations, through the stored information, the mobile terminal searches for the new base station by searching for the neighboring base station. If you select, the association process is performed. The association transmits the RNG-REQ MAC message to the mobile station, and the base station transmits the RNG-RSP MAC message to the mobile station to set the uplink power offset value and the uptime timing offset value of the mobile station to appropriate values. The transmission of the RNG-REQ / RSP message by the mobile station and the base station (initial ranging operation) is the most basic operation of the IEEE802.16 system. In addition, the mobile terminal becomes a basic operation for performing a network entry process.

Subsequently, the mobile terminal based on the channel quality information with the neighboring base station acquired in the handover preprocessing, various processes for handover (Cell Selection, Handover initiation, Handover cancellation, Termination with the serving BS, Hand Over rejection).

Cell Selection Process

Cell selection is an operation of changing a cell so that a mobile station can register a new cell to a base station that can receive an SINR of a signal superior to the signal-to-noise ratio (SINR) of a signal transmitted from a base station of a current cell before the mobile station normally registers the cell. During the cell selection process, the base station cannot know the movement of the mobile station because the mobile station has not performed the registration process. 2 shows a cell selection operation of IEEE802.16e.

* Handover Initiation Process

Handover initiation may be performed by both the base station (BS) and the mobile station (MSS). That is, when the base station BS requests a handover, the base station transmits a MOB_BSHO-REQ MAC message, and when the mobile station MSS requests a handover, the mobile station transmits a MOB_MSSHO-REQ MAC message. When the mobile station transmits the MOB_MSSHO-REQ MAC message, it transmits the SINR of the signal received from the neighboring base station to the base station, so that the list information of candidate BSs that can become a new target BS during handover is provided. Transmit to the current serving base station (Serving BS). The serving BS receives a MOB_MSSHO-REQ MAC message from the mobile station or checks an ACK for handing over a specific mobile station from a neighboring base station before transmitting the MOB_BSHO-REQ MAC message. Allow handover. A mobile terminal or serving base station that receives a MOB_BSHO-REQ MAC message (or MOB_MSSHO-REQ MAC message) sends a MOB_BSHO-RSP MAC message (or MOB_MSSHO-RSP MAC message) to perform a handover. (Target BS).

* Handover cancellation process

After the mobile station or the base station transmits a MOB_BSHO-REQ MAC message (or MOB_MSSHO-REQ MAC message) to perform a handover, the mobile station can cancel the handover. At this time, the mobile station sets a specific field of the MOB_HO-IND MAC message (HO_Type = 01) and transmits it to the base station to stop the current handover.

Termination with the serving BS

The mobile station sends a MOB_HO-IND MAC message to the serving BS to inform that the handover is completed normally and completes the handover operation. At this time, the mobile station sets a specific field of the MOB_HO-IND MAC message (HO_Type = 00) and transmits to the serving BS that the handover is normally completed. As soon as the serving BS receives the MOB_HO-IND MAC message from the mobile station, the serving BS terminates all connections related to the MAC state machine, ARQ connection, and data transmission allocated to the handovered mobile station.

* Handover rejection process

The mobile station may reject the authority handover by the serving base station. In this case, the mobile station sets a specific field of the MOB_HO-IND MAC message (HO_Type = 10) and transmits it to the serving base station. Upon receiving the Reject message from the mobile station, the serving BS reconfigures the new target BS and retransmits the MOB_BSHO RSP message to the mobile station.

3 is a signal flow diagram of a conventional neighbor base station scanning procedure.

Referring to FIG. 3, the MSS scanning of neighbor BS will be described in detail as follows.

The service base station BS1 connected to the mobile station first broadcasts information on neighboring base stations BS2 and BS3 to all mobile stations in its area. This information is transmitted by the MOB-NBR-ADV message, the format of the MOB-NBR-ADV message is shown in Table 1 below. The MOB-NBR-ADV message includes the number of neighboring base stations, an identifier of neighboring base stations, frequencies used by neighboring base stations, and channel information of neighboring base stations.

The mobile station periodically receiving the MOB-NBR-ADV message temporarily stops receiving data only when necessary, and acquires MOB-SCN-REQ from the base stations BS2 and BS3 to obtain channel quality measurement time. Send a message to the serving base station BS1. The format of the MOB-SCN-REQ message is as shown in Table 2 below.

While measuring the channel quality of the neighbor BSs BS2 and BS3, the serving BS BS1 stops and stores data transmission to the MS and transmits the data after the search time requested by the MS. The serving base station BS1 transmits the MOB-SCN-RSP message to the mobile station in response to the MOB-SCN-REQ message. The format of the MOB-SCN-RSP message is shown in Table 3 below.

The mobile station guarantees the requested search period (or scan duration), and an appointment is made between the mobile station and the serving base station BS1 that the guaranteed period starts after a predetermined start frame. If the serving base station BS1 wants to reject the scanning request of the mobile station, the serving base station BS1 sets the Scan duration field of the MOB-SCN-RSP message to 0 and delivers it to the mobile station.

Syntax Size Notes MOB-NBR-ADV_Message_Format () { Management Message Type = 53 8 bits Operation ID 24 bits Unique ID assigned to the operation Configuration Change Count 8 bit Incremented each time the information for the associated neighbor BS has changed N_NEIGHBORS 8 bits for (j = 0; j <N_NEIGHBORS; j ++) { Length 8 bits Length of message information within the iteration of N_NEIGHBOR in bytes Neighbor BS-ID 24 bits The least significant 24bits of the Base Station ID parameter in the DL-MAP message of Neighbor BS. Preamble Index 8 bits The index for the PHY profile specific preamble Index is PHY specific for Sca and OFDMA. The value of preamble Index shall be ignored and a value of 'Ox00' shall be used for OFDM PHY PHY Profile ID 16 bits TBD HO Process Optimization 8 bits DCD Configuration
Change count 8 bits This represents the neighbor BS current DCD configuration change count UCD Configuration
Change count 8 bits This represents the neighbor BS current UCD configuration change count TLV Encoded
Neighbor information Variable TLV specific } }

Syntax Size Notes MOB-SCN-REQ_Message_Format () {   Management Message Type = 50 8 bits Scan Duration 8 bits Units are frames Scan type 1 bit [0] Scanning
[1] Association Reserved 3 bits If (Scan type = 0) { Interleaving interval 8 bits Units are frames Scan iteration 8 bits } Else { For (j = 0; j <N_Recommended_BS; j ++) { N_Recommended_BS can be derived from the known length of the MAC message Association Test BS ID 48 bits BS IDs of Available BS for Association } ) HMAC Tuple 21 bytes }

Syntax Size Notes MOB-SCN-RSP_Message_Format () {   Management Message Type = 50 8 bits   Scan Duration 8 bits Units are frames   Start frame 4 bits Scan type 1 bit [0] Scanning
[1] Association If (Scan type = 0) { Interleaving interval 8 bits Duration in frames Scan iteration 8 bits Report mode 2 bits 0b00: no report
0b01: periodic report
0b10: event triggered report
0b11: reserved Scan report period 8 bits Available only when the value of
Report mode is set to 0b01. Scan
report period in frames Reserved 3 bits Shall be set to zero. } Else { Reserved 7 bits For (j = 0; j <N_Recommended_BS;
j ++) { N_Recommended_BS can be derived from the known length of the MAC message Association Test BS ID 48 bits BS IDs of Available BS for Association } ) HMAC Tuple 21 bytes See 11.1.2 }

As shown in FIG. 3, the mobile terminal searches for the channel quality of the neighbor base stations BS2 and BS3 during the scan duration (N in Table 1) after the Start Frame (M in Table 1) time.

3 shows a case where scanning is performed once.

4 is a diagram illustrating a procedure for performing periodic scanning by setting Scan Iteration and Interleaving interval values in a MOB-SCN-REQ / RSP message.

The mobile station can request a plurality of periodic scannings through the scan iteration and interleaving interval of the MOB-SCN-REQ message. Receiving a plurality of periodic scanning requests, the serving base station BS1 sets the scan iteration and interleaving interval values in the MOB-SCN-RSP message and transmits them to the mobile terminal, thereby enabling the mobile terminal to perform periodic scanning. If the mobile station stops scanning during the search period and returns to the normal operation state, the mobile station sets the scan duration, interleaving interval, and scan iteration values of the MOB-SCN-REQ to 0 and delivers them to the service base station BS1. In order to stop the scanning operation of the terminal, the base station BS1 transmits the scan duration, interleaving interval, and scan iteration values of the MOB-SCN-RSP message to 0 to the terminal.

In addition, the mobile station may request an association with a specific neighboring base station through the MOB-SCN-REQ message. In this case, the mobile station may request the association from the serving base station by setting a scan duration and a start frame.

The following is a description of periodic ranging.

Ranging consists of initial ranging and periodic ranging. Initial ranging refers to a procedure in which a mobile station acquires an appropriate transmission parameter value such as a time offset or a Tx power level for uplink communication with a base station in the network registration process of the mobile station. When the initial ranging is completed, the mobile station performs periodic ranging to continuously maintain uplink communication with the base station. In the case of a broadband wireless access system, periodic ranging is performed in all physical layers, but is different in the case of a single carrier or an OFDM scheme.

The periodic ranging of the single carrier or OFDM scheme is described as follows.

The serving base station maintains a timer called T27 for each terminal. When the timer T27 expires, the serving base station allocates an uplink slot to the mobile station to perform ranging. 5 is a diagram illustrating a service base station allocating an uplink slot for periodic ranging to a mobile station.

On the other hand, the mobile terminal maintains a timer called T4. If the mobile station does not receive an uplink slot for data transmission from the serving base station until the timer T4 expires, the mobile station determines that the uplink transmission parameter is invalid and initializes the MAC to restart initial ranging. Let's do it.

If the mobile station has allocated an uplink slot for periodic ranging, the serving base station monitors the uplink signal from the mobile station. If the ranging request message is not received from the mobile station even though a predetermined number of uplink slots have been allocated, the serving base station terminates connection management with the mobile station.

The service base station receives an uplink signal including a ranging request message from the mobile station and measures the signal quality of these uplink signals. If the measured signal quality is more than the reference value, the ranging response message indicates that the ranging is successful.

However, if the measured signal quality is below the reference value, the ranging response message indicates that the ranging should be continued along with the parameter correction value. If the signal quality of the uplink signal does not satisfy the reference value until the predetermined number of corrections is exceeded, the serving base station informs the mobile station to stop ranging through a ranging response message and manages connection with the mobile station. To exit.

Upon receiving the ranging response message, the mobile station corrects the uplink transmission parameter value and determines whether to terminate the ranging, continue, or initialize and restart the MAC.

However, in the system having the physical layer of OFDMA in the broadband wireless access system, the method of performing periodic ranging by the mobile station is different from the method described above. In an OFDMA system, a mobile terminal, not a service base station, maintains a timer controlling periodic ranging, and when the timer T4 expires, the mobile terminal delivers a ranging code to a service base station through a contention-based upslot and provides a service. The base station transmits the uplink transmission parameter correction value to the mobile station through a ranging message. Therefore, the OFDMA system does not allocate an uplink slot of a unicast to a specific terminal for periodic ranging.

Referring to the problems of the prior art as follows.

In a broadband wireless access system, a mobile station must perform ranging periodically to maintain uplink communication with a serving base station, and the serving base station must periodically allocate an uplink slot to the mobile station for this purpose. In addition, the mobile station should perform scanning or association of neighboring base stations for handover, and data transmission and reception with the serving base station is impossible while these operations are performed. Therefore, when the mobile station requests scanning or association, if the requested scanning period includes an up slot allocation time point for periodic ranging, the serving base station may reject the scanning request. However, in case of rejecting the scanning request in the related art, the scan duration value of the scanning response (MOB-SCN-RSP) message is set to 0 to inform the mobile station.

As described above, when the serving base station rejects the mobile station's scanning request by setting the scan duration of the MOB-SCN-RSP message to 0, the following two problems occur.

First, since the mobile station does not know why the scanning request is denied, the mobile station may request the scanning of the neighboring base station again by transmitting a scanning request message to the serving base station before performing periodic ranging. In this case, since the serving base station must reject the scanning request of the mobile station again through the scanning response message, it causes the unnecessary exchange of MAC messages between the mobile station and the serving base station. This unnecessary exchange of MAC messages is a factor in waste of radio resources, and degrades MAC processing efficiency.

Second, when the serving base station rejects the scanning request of the mobile station or stops the scanning of the mobile station during the interleaving interval of periodic scanning, the conventional scanning response message (MOB-SCN-RSP) is a scan duration, start frame, interleaving It has inefficiency that all 5 byte message parameter values such as interval, scan iteration, report mode, and scan period should be set to 0.

The present invention is to solve the problems described above, the object is,

Provides a method for scanning a base station of a mobile station so that the periodic ranging procedure of the mobile station can be performed regardless of the scanning operation, and the size of the scanning response message that the base station stops the periodic scanning of the mobile station or rejects the scanning request It is to provide a method for optimizing the scanning response message by reducing the.

 In order to achieve the above object, the base station scanning method of a mobile terminal according to the present invention

When a periodic ranging time point overlaps with a scanning period, requesting scanning of a base station; Receiving a response message of scanning rejection from the base station; Performing a ranging procedure with the base station when the ranging is performed; After a predetermined time elapses, a process of requesting scanning again from the base station is performed.

Preferably, the response message includes a flag indicating scanning permission or rejection or a scanning period parameter set to 0.

Preferably, the response message is characterized in that it comprises information for the predetermined time.

In order to achieve the above object, the base station scanning method of a mobile terminal according to the present invention

When a periodic ranging time point overlaps with a scanning period, requesting scanning of a base station; Receiving a response message of scanning permission from the base station; When the ranging is performed, performing a ranging procedure with the base station; When scanning is performed, a process of performing a scanning procedure for a neighboring base station is performed.

In order to achieve the above object, the base station scanning method of a mobile terminal according to the present invention

A mobile terminal of a broadband wireless access system, the method comprising: requesting a base station for scanning; And receiving a response message of scanning rejection including a flag indicating scanning permission or rejection or a scanning duration parameter set to 0 from the base station.

In order to achieve the above object, the base station Association method of the mobile terminal according to the present invention

A mobile terminal of a broadband wireless access system, the method comprising: requesting an association from a base station; And receiving, from the base station, an association rejection response message including a flag indicating association acceptance or rejection or a scanning period parameter set to 0.

In order to achieve the above object, the base station scanning method of a mobile terminal according to the present invention

When a periodic ranging time point overlaps with a scanning period, performing a base station scanning with permission of the base station; Receiving, from the base station, a scanning interruption request message including a flag indicating scanning permission or rejection or a scanning period parameter set to 0; The scanning operation is stopped and the ranging procedure with the base station is performed.

The present invention proposes the following three methods to optimize the scanning response (MOB-SCN-RSP) message of the serving base station for the scanning request of the mobile station.

First, the denial and acknowledgment of the scanning request of the mobile station is indicated by a flag of 1 bit or a scanning period parameter set to 0. When approving the scanning request of the mobile terminal, the present invention includes the scanning related parameters defined in the prior art as it is in the scanning response message. However, when rejecting the scanning request, the scanning related parameters are not included in the scanning response message. In this way, the flag indicating rejection or approval, or the scanning period parameter set to 0 can be equally applied to the association procedure of the mobile terminal.

Second, in a system supporting a single carrier or an OFDM physical layer, when the mobile terminal periodically performs a ranging ranging time (T27 time out) in a scan duration requested by the mobile station, the serving base station according to the present invention responds to the scanning response. The message informs the mobile station of the scan rejection command and the duration of the periodic ranging. After the completion of the periodic ranging, the mobile station can request the serving base station to scan again.

Third, as in the second scheme, when the scanning of the mobile terminal and the periodic ranging execution time overlap, the serving base station sets the scanning start time after performing the ranging while approving the scanning request, so that the scanning of the mobile terminal is periodically ranging. It can be adjusted to be performed later.                     

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

6 is a signal flowchart of a scanning procedure according to a first embodiment of the present invention, and [Table 4-1] and [Table 4-2] show a scanning response message accordingly. As shown in the following [Table 4-1] and [Table 4-2], the present invention places a separate flag (Scan-approved) or a scanning period parameter in the scanning response message, thereby scanning the mobile terminal to reject the scanning request. The length of the response message is greatly reduced.

Table 4-1

Syntax Size Notes MOB-SCN-RSP_Message_Format () {    Management Message Type = 50 8 bits Scan-approved 1 bit 0: Scan request denied
1: Scan request approved If (Scan-approved = 1) { Scan Duration 8 bits Units are frames Start frame 4 bits Scan type 1 bit [0] Scanning
[1] Association If (Scan type = 0) { Interleaving interval 8 bits Duration in frames Scan iteration 8 bits Report mode 2 bits 0b00: no report
0b01: periodic report
0b10: event triggered report
0b11: reserved Scan report period 8 bits Available only when the value of Report mode is set to 0b01. Scan report period in frames Reserved 2 bits Shall be set to zero. } Else { Reserved 6 bits For (j = 0; j <N_Recommended_BS;
j ++) { N_Recommended_BS can be derived from the known length of the MAC message Association Test BS ID 48 bits BS IDs of Available BS for Association } ) } Else { Reserved 7 bits Shall be set to zero. } HMAC Tuple 21 bytes See 11.1.2 }

Table 4-2

Syntax Size Notes MOB-SCN-RSP_Message_Format () {   Management Message Type = 50 8 bits     Scan Duration 8 bits Units are frames If (Scan Duration = 1) {     Start frame 4 bits Scan type 1 bit [0] Scanning
[1] Association If (Scan type = 0) { Interleaving interval 8 bits Duration in frames Scan iteration 8 bits Report mode 2 bits 0b00: no report
0b01: periodic report
0b10: event triggered report
0b11: reserved Scan report period 8 bits Available only when the value of Report mode is set to 0b01. Scan report period in frames Reserved 2 bits Shall be set to zero. } Else { Reserved 6 bits For (j = 0; j <N_Recommended_BS; j ++) { N_Recommended_BS can be derived from the known length of the MAC message Association Test BS ID 48 bits BS IDs of Available BS for Association } ) } Else { Reserved 7 bits Shall be set to zero. } HMAC Tuple 21 bytes See 11.1.2 }

Referring to Figure 6, Table 4-1 and Table 4-2, the scanning procedure according to the first embodiment of the present invention will be described.

The service base station BS1 connected to the mobile station first broadcasts information on neighboring base stations BS2 and BS3 to all mobile stations in its area. (S10) This information is transmitted in a MOB-NBR-ADV message. do.

The mobile station periodically receiving the MOB-NBR-ADV message sends a scanning request (MOB-SCN-REQ) message to the serving base station BS1 to request scanning of the neighboring base station. (S20) May request periodic scanning according to the scanning iteration and the interleaving interval of the scanning request message.

The serving base station BS1 transmits the MOB-SCN-RSP message to the mobile station in response to the MOB-SCN-REQ message. (S30) In this case, the serving base station BS1 transmits the MOB-SCN-RSP message. This tells the mobile station whether to accept or reject the scanning. In case of rejecting the scanning request, the service base station BS1 sets the scan-approved field to 0 and omits the remaining scan parameters (Scan duration, Start frame, Interleaving interval, Scan iteration, etc.) (Table 4-1). ]) Set the scan duration to 0 and omit the remaining parameters (Start frame, Interleaving interval, Scan iteration, etc.) (for [Table 4-2]) to deliver the scanning response message to the mobile terminal.

On the other hand, when approving the scanning request, the service base station BS1 sets the Scan-approved field to 1 and sets the remaining Scan parameters (Scan duration, Start frame, Interleaving interval, Scan iteration, etc.) (see Table 4). -1]) Set the scan duration to a non-zero value and set the remaining parameters (Start frame, Interleaving interval, Scan iteration, etc) (for [Table 4-2]) to deliver the scanning response message to the terminal. do. The mobile station, which has been approved for scanning, synchronizes with the neighboring base stations BS2 and BS3 when the scanning start time comes and measures the signal quality.

The mobile station which performs scanning periodically synchronizes with the serving base station BS1 and maintains communication with the serving base station BS1 during the interleaving interval at the end of the scan duration (S50). Downlink synchronization with neighboring base stations BS2 and BS3 is measured and signal quality is measured (S60).

Then, when the periodic scanning of the mobile station is to be terminated, the service base station BS1 sets the Scan-approved field of the scanning response message to 0 or sets the scan duration to 0 for the interleaving interval, and delivers it to the mobile station. The received mobile terminal ends the periodic scanning and returns to the normal operation state to communicate with the serving base station BS1 (S70).

7 is a signal flow diagram of a scanning procedure according to a second embodiment of the present invention, and Table 5 below shows a scanning response message. The scanning response message of Table 5 includes not only a separate flag or a scanning duration parameter (Scan-approved) set to 0, but also information (REQ-duration) on the execution duration of periodic ranging.

The mobile station according to the second embodiment of the present invention performs the scanning request again after a period of time (REQ-duration) determined by the serving base station.

Syntax Size Notes MOB-SCN-RSP_Message_Format () { Management Message Type = 50 8 bits Scan-approved 1 bit 0: Scan request denied
1: Scan request approved If (Scan-approved = 1) { Scan Duration 8 bits Units are frames Start frame 4 bits Scan type 1 bit [0] Scanning
[1] Association If (Scan type = 0) { Interleaving interval 8 bits Duration in frames Scan iteration 8 bits Report mode 2 bits 0b00: no report
0b01: periodic report
0b10: event triggered report
0b11: reserved Scan report period 8 bits Available only when the value of Report mode is set to 0b01. Scan report period in frames Reserved 2 bits Shall be set to zero. } Else { Reserved 6 bits For (j = 0; j <N_Recommended_BS;
j ++) { N_Recommended_BS can be derived from the known length of the MAC message Association Test BS ID 48 bits BS IDs of Available BS for Association } ) } Else { Reserved 7 bits Shall be set to zero. TLV encoded value 24 bits This TLV parameter is REQ-duration, which is time duration until Scan Request may be retried (in frames) in case of Scan request denied. This value may be included only in SCa, OFDM PHY. } HMAC Tuple 21 bytes See 11.1.2 }

Table 6 below shows examples of TLV values that may be included in a scanning response (MOB-SCN-RSP) message.

Name Type Length Value REQ-duration TBD 1 Byte Number of frames until Scan Request may be retried

Referring to Figure 7 and Table 5, the scanning procedure according to the second embodiment of the present invention will be described.

The service base station BS1 connected to the mobile station first broadcasts information on neighboring base stations BS2 and BS3 to all mobile stations in its area. (S110) This information is transmitted in a MOB-NBR-ADV message. do.

The mobile station periodically receiving the MOB-NBR-ADV message sends a scanning request (MOB-SCN-REQ) message to the serving base station BS1 to request scanning of the neighboring base station.

The serving base station BS1 transmits the MOB-SCN-RSP message to the mobile station in response to the MOB-SCN-REQ message (S130). In this case, the serving base station BS1 transmits the MOB-SCN-RSP message. This tells the mobile station whether to accept or reject the scanning. When the periodic ranging time of the mobile station is included in the scan duration requested by the mobile station, the scan-approved field of the scanning response message is set to 0, and the REQ-duration value is set so that the mobile station can perform periodic ranging. It is set and delivered to the mobile terminal.

After receiving the scanning response message having the REQ-duration value, the mobile station requests scanning again after the REQ-duration, and after the REQ-duration passes, the mobile station determines whether to request the scanning again.

When it is time to perform periodic ranging, the mobile station receiving the scanning response message transmits the ranging request message to the serving base station BS1 using an uplink slot allocated from the serving base station BS1 (S140).                     

The service base station BS1 receiving the ranging request message from the mobile station transmits the uplink transmission parameter correction value of the mobile station to the mobile station through the ranging response message so that the mobile station can maintain the uplink communication. )

Thereafter, after the REQ-duration, the mobile station re-requests scanning of the neighboring base station by transferring the scanning request message to the serving base station BS1 (S160). The serving base station BS1 scan-approved the scanning response message. The field is set to 1, the scan parameter value is set, and transmitted to the mobile terminal, thereby approving scanning (S170).

The mobile station, which has been approved for scanning, synchronizes with the neighboring base stations BS2 and BS3 when the scanning start time is reached, and measures signal quality. (S180) If the mobile station requests periodic scanning, If the periodic ranging time of the mobile station is included during the scan duration, the serving base station BS1 sets the Scan-approved field of the scanning response message to 0 during the interleaving interval and transmits it to the mobile station to terminate the periodic scanning at any time. In addition, periodic ranging may be performed using an uplink slot allocated by the serving base station BS1.

8 is a signal flow diagram of a scanning procedure according to a third embodiment of the present invention, and Table 7 below shows a scanning response message. The scanning response message of Table 7 includes a separate flag or a scanning period parameter (Scan-approved) set to 0, and has a start frame value configured to perform scanning of the mobile terminal after periodic ranging.                     

Syntax Size Notes MOB-SCN-RSP_Message_Format () { Management Message Type = 50 8 bits Scan-approved 1 bit 0: Scan request denied
1: Scan request approved If (Scan-approved = 1) { Scan Duration 8 bits Units are frames Start frame 8 bits Scan type 1 bit [0] Scanning
[1] Association If (Scan type = 0) { Interleaving interval 8 bits Duration in frames Scan iteration 8 bits Report mode 2 bits 0b00: no report
0b01: periodic report
0b10: event triggered report
0b11: reserved Scan report period 8 bits Available only when the value of Report mode is set to 0b01. Scan report period in frames Reserved 4 bits Shall be set to zero. } Else { Reserved 6 bits For (j = 0; j <N_Recommended_BS;
j ++) { N_Recommended_BS can be derived from the known length of the MAC message Association Test BS ID 48 bits BS IDs of Available BS for Association } ) } Else { Reserved 7 bits Shall be set to zero. } HMAC Tuple 21 bytes See 11.1.2 }

In the third embodiment of the present invention, since the scanning start time is controlled by the start frame, the size of the start frame field should be modified to be equal to or larger than the scan duration. In addition, by setting the scan-approved in the scanning response message to 0, the serving base station may reject the scanning request of the mobile station or stop the periodic scanning in which the mobile station is performing.                     

Referring to FIG. 8 and Table 7, the scanning procedure according to the third embodiment of the present invention will be described.

The service base station BS1 connected to the mobile station first broadcasts information on neighboring base stations BS2 and BS3 to all mobile stations in its area. (S210) This information is transmitted in a MOB-NBR-ADV message. do.

The mobile station periodically receiving the MOB-NBR-ADV message sends a scanning request (MOB-SCN-REQ) message to the serving base station BS1 to request scanning of the neighboring base station.

The serving base station BS1 transmits the MOB-SCN-RSP message to the mobile station in response to the MOB-SCN-REQ message (S230). In this case, the serving base station BS1 transmits the MOB-SCN-RSP message. This tells the mobile station whether to accept or reject the scanning. When the periodic ranging timing of the mobile station is included in the scan duration requested by the mobile terminal, the service base station BS1 sets the start frame of the scanning response message after the ranging time and scan-approved the scanning response message. Set field to 1 and send it to mobile station. In this case, however, the size of the start frame field must be greater than or equal to the scan duration field because the start frame must be able to indicate whether a periodic ranging time is included during the scan duration.

When it is time to perform the periodic ranging, the mobile station receiving the scanning response message transmits the ranging request message to the serving base station BS1 using an uplink slot allocated from the serving base station BS1 (S240).                     

The service base station BS1 receiving the ranging request message from the mobile station transmits the uplink transmission parameter correction value of the mobile station to the mobile station through the ranging response message so that the mobile station can maintain the uplink communication (S250). After that, when the start frame is reached, the mobile station synchronizes downlink with a neighboring base station and measures signal quality.

If the mobile station requests periodic scanning, if the periodic ranging time of the mobile station is included during the second and subsequent scan durations, the serving base station BS1 sets the scan-approved field of the scanning response message to 0 during the interleaving interval. By setting and transmitting to the mobile station, periodic scanning can be terminated at any time, and periodic ranging can be performed using the uplink slot allocated by the serving base station BS1.

Although the present invention has been described with reference to the embodiments illustrated in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

As described above, the present invention, when the service base station rejects the scanning request of the mobile station, instead of setting all the scan parameters of the Scanning response message to 0, a flag of 1 bit that can indicate the scanning approval and rejection or By using the scanning period parameter set to 0, it is possible to reduce the size of the scanning response message and save radio resources.

In addition, when the mobile station requests base station scanning, when the scanning period includes a time point for performing periodic ranging of the mobile station, the mobile station performs periodic ranging through a scanning response message. By requesting Scanning again or allowing Scanning to be performed, the periodic ranging operation of the mobile terminal can be prevented regardless of the Scanning operation.

Claims (14)

In the case where the periodic ranging timing overlaps with the scanning period, Requesting the base station for scanning; Receiving a response message of scanning rejection from the base station; Performing a ranging procedure with the base station when the ranging is performed; And after the predetermined time has elapsed, requesting the base station for scanning again. The method of claim 1, wherein the response message And a flag indicating a scanning permission or a rejection. The method of claim 1, wherein the response message And a scanning period parameter set to 0 indicating scanning permission and rejection. The method of claim 1, wherein the response message The base station scanning method of a mobile terminal, characterized in that it comprises information about the predetermined time. In the case where the periodic ranging timing overlaps with the scanning period, Requesting the base station for scanning; Receiving a response message of scanning permission from the base station; Performing a ranging procedure with the base station when the ranging is performed; When the scanning is performed, the base station scanning method of a mobile terminal, characterized in that consisting of a process for performing a scanning procedure for a neighboring base station. The method of claim 5, wherein the response message And a flag indicating a scanning permission or a rejection. The method of claim 5, wherein the response message And a scanning period parameter set to 0 indicating scanning permission or rejection. The method of claim 5, wherein the response message The base station scanning method of a mobile terminal, characterized in that it comprises information on the scanning time. The method of claim 5, wherein the scanning point is A base station scanning method of a mobile terminal, characterized in that set after the ranging time. In the mobile terminal of the broadband wireless access system, Requesting the base station for scanning; Receiving a flag indicating scanning permission or rejection from the base station, or receiving a response message of a scanning rejection including a scanning period parameter set to 0. The method of claim 10, wherein the response message And a scanning period parameter set to 0 indicating scanning permission or rejection. In the mobile terminal of the broadband wireless access system, Requesting association from the base station; And receiving, from the base station, a response message of association rejection including a flag indicating association permission and rejection. The method of claim 12, wherein the response message And a scanning period parameter set to 0 indicating scanning permission or rejection. In the case where the periodic ranging timing overlaps with the scanning period, Performing base station scanning with permission of the base station; Receiving a flag indicating scanning permission or rejection from the base station or a scanning interruption request message including a scanning period parameter set to 0; A method for scanning a base station of a mobile terminal, the method comprising: stopping a scanning operation that is being performed and performing a ranging procedure with the base station.

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