WO2005120179A2

WO2005120179A2 - Scanning neighboring base stations in wireless access system

Info

Publication number: WO2005120179A2
Application number: PCT/KR2005/001700
Authority: WO
Inventors: Yong Ho Kim; Ki Hyoung Cho
Original assignee: LG Electronics Inc
Current assignee: LG Electronics Inc
Priority date: 2004-06-07
Filing date: 2005-06-07
Publication date: 2005-12-22
Anticipated expiration: 2006-12-07
Also published as: US20100284297A1; US8320908B2; US20070178898A1; CN1965603A; KR20050116343A; EP2464171A3; EP1759552A2; US8175595B2; JP4677444B2; US20060040662A1; KR100893861B1; US7751817B2; US7460867B2; IL179880A0; IL179880A; US8014774B2; AU2005251635A1; JP2008502204A; AU2005251635B2; US20100246433A1

Abstract

Scanning neighboring base stations in a wireless access system is provided. In one embodiment, a method of scanning neighboring base stations for assessing channel quality includes receiving from a serving base station (520) information associated with at least one neighboring base station (530, 540), and transmitting a scanning request message from a mobile subscriber station (510) to the serving base station (520), wherein the scanning request message comprises a requested scan duration and a requested scan iteration, the requested scan iteration being associated with a requested number of iterations of the scanning of the at least one neighboring base station (530, 540). The method also includes receiving a scanning response message from the serving base station (520), wherein the scanning response message comprises an allowed scan duration and an allowed scan iteration, the allowed scan iteration being associated with an allowed number of iterations of the scanning of the at least one neighboring base station (530, 540).

Description

SCANNING NEIGHBORING BASE STATIONS IN WIRELESS ACCESS

SYSTEM [DESCRIPTION] TECHNICAL FIELD

The present invention relates generally to a wireless access system, and more

particularly to scanning neighboring base stations in a wireless access system.

BACKGROUND ART

The IEEE802.16e system is part of a global standardization for broadband wireless

access systems. IEEE802.16e does not have a hierarchical structure of HLR, VLR, MSC,

BSC, RNC, etc. unlike second and third generation mobile communications systems, but

does include a mobile subscriber station (MSS), a base station (BS), and an authentication

service authorization server (ASA server). A physical (PHY) layer and a medium access

control (MAC) layer are defined between the BS and the MSS. FIG. 1 is a block diagram illustrating a related art broadband wireless access system in

which a handover operation is performed on a data plane. FIG. 2 is a block diagram

illustrating a related art broadband wireless access system in which a handover operation is

performed on a control plane.

Referring to FIG. 1 and FIG. 2, a handover in a broadband wireless access system is

performed according to IEEE802.16e, as explained below. 1. Pre-processing for Handover Pre-processing for handover includes broadcasting associated information from a base station to a neighboring base station to inform all mobile subscriber stations within a

respective cell of the associated information (Network Topology Advertisement). The pre¬

processing also includes measuring a channel quality of the neighboring base station based

on the associated information (MSS Scanning of Neighboring BS). The pre-processing

also includes matching parameters between the base station and the neighboring base

station, such as for example, an initial mobile subscriber station power, a time difference

for synchronization, and other parameters (Association Procedures). a. Network Topology Advertisement

In network topology advertisement, the base station broadcasts information associated

with network configuration to all mobile subscriber stations within a cell via a MOB_NBR-

ADV MAC message, thereby providing all mobile subscriber stations within the cell with

the information pertaining to neighboring base stations. b. MSS Scanning of Neighboring BS

In MSS scanning of neighboring BS, a mobile subscriber station (MSS) scans a

neighboring base station (BS) and requests a scanning interval for scanning the neighboring

BS from the BS via a MOB_SCN-REQ MAC message. The BS then transmits a

MOB_SCN-RSP MAC message in response to the request to assign an interval for

scanning (scanning interval) the neighboring BS. Alternatively, the BS may directly

transmit the MOB_SCN_RSP MAC message without a request from the MSS (unsolicited

response). In the case of an unsolicited response, the scanning interval and an offset unit for

scanning start are assigned on a frame unit basis. c. Association Procedures During association procedures, the MSS performs a ranging process with a BS to

normally join a cell. In the ranging process, the MSS acquires basic information for

communications from the BS. In other words, the MSS performs BS scanning to select a

new BS and then performs the association procedures. The MSS and the BS transmit a

RNG_REQ MAC message and a RNG_RSP MAC message, respectively, to set values such

as for example, a power offset value, a timing offset value, and other values of the MSS to

suitable values. Transmission of the RNG_REQ MAC message is called an initial ranging

operation and is a basic operation that the MSS may perform in a network entry procedure.

When a handover is performed, a target BS accepts a new MSS and transmits items

associated with the respective cell of the new MSS to the former serving BS and stores

information pertaining to the MSS.

2. Handover Process

In a handover (HO) process, the MSS initiates handover with the neighboring BS

based on the channel quality information acquired in the handover pre-processing. a. Cell Selection

FIG. 3 is a diagram illustrating a related art cell selection procedure in a related art

broadband wireless access system. In a cell selection procedure, a cell is changed to enable

the MSS to make a new registration to a BS, allowing for reception of a signal having an

SESfR (signal to interference noise ratio) superior to that of a signal transmitted from the BS

of the current cell, prior to a normal registration of the MSS to a cell. In such case, since the

MSS does not perform the registration procedure, the BS is unable to determine a moving

situation of the MSS. b. HO (handover) Initiation

In HO initiation, a handover may be initiated by the MSS or the BS. When the BS

requests (initiates) a handover, the BS transmits a MOB_BSHO-REQ MAC message to the

MSS. On the contrary, when the MSS requests a handover, the MSS transmits a

MOB_MSSHO-REQ MAC message to the BS.

If the MSS transmits the MOB_MSSHO-REQ MAC message, the MSS preferentially

transmits the SINR of a signal received from a neighboring BS to the BS to enable the

MOB MSSHO-REQ MAC message to be transmitted to a current serving BS. The current

serving BS then selects a candidate BS as a target BS for performing the handover. hi a case where the BS receives the MOB_MSSHO-REQ MAC message from the

MSS or in a case when the BS has not yet transmitted the MOB_BSHO-REQ MAC

message to handover the MSS, the BS may allow the handover of the MSS after

confirmation of an acknowledgement (ACK) for handing over a specific MSS from the

neighboring BS. After receiving the MOB_BSHO/MSSHO-REQ MAC message, the

MSS/BS transmits a MOB_MSSHO/BSHO-RSP MAC message to inform the BS/MSS of a

target BS for the handover. c. HO Cancellation

In HO cancellation, after the MSS/BS transmits the MOB_MSSHO/BSHO-REQ

MAC message, the MSS may cancel the handover. In canceling the HO, the MSS sets a

specific field (HO_Type=01) of a MOB HO-IND MAC message and transmits the set field

to the BS. The BS receives the message and cancels the proceeding handover. d. Termination with the Serving BS In termination with the serving BS, the MSS transmits the MOB HO-IND MAC

message to inform the serving BS that the handover is normally completed and then

completes the handover operation. In completing the handover operation, the MSS sets a

specific field (HO_Type=00) of the MOB_HO-IND MAC message to transmit the

information pertaining to the normal handover termination to the serving BS. The serving

BS receives the MOBJHO-IND MAC message from the MSS and terminates a MAC state

machine allocated to the MSS. The serving BS also terminates an ARQ (automatic repeat

request) connection and all connections associated with data transmission. e. HO Rejection h HO rejection, the MSS is capable of rejecting a handover recommended by the BS.

In rejecting a handover, the MSS sets a specific field (HO_Type=10) of the MOB_HO-IND

MAC message and transmits the message to the BS. The BS receives the rejection message

from the MSS, re-seeks for a target BS and re-transmits the MOB_BSHO-RSP MAC

message to the MSS. 3. Neighboring B S Scanning Procedure

FIG. 4 is a diagram illustrating a related art neighboring base station scanning

procedure. Referring to FIG. 4, a serving BS connected to an MSS broadcasts information

pertaining to neighboring BSs to all MSSs within a BS domain.

The information pertaining to the neighboring BSs is delivered via a MOB-NBR-ADV

message. A configuration of the MOB-NBR-ADV message is shown in Table 1. [Table 1]

Referring to Table 1, the MOB-NBR-ADV message includes a neighboring BS

number, a neighboring BS identifier, a neighboring BS frequency, neighboring BS channel

information, and other information. After the MSS receives the MOB-NBR-ADV message, the MSS temporarily stops

receiving data transmitted from the serving BS and transmits a MOB-SCN-REQ message

for acquiring a time for channel quality measurement from the neighboring BS to the BS.

A configuration of the MOB-SCN-REQ message is shown in Table 2.

[Table 2]

While the MSS measures channel qualities of the neighboring BSs, the serving BS

stops transmitting data to the MSS is then able to transmit data after receiving a scanning

duration request from the MSS. The serving BS transmits a MOB-SCN-RSP message to the

MSS in response to the MOB-SCN-REQ message. A configuration of the MOB-SCN-REQ

message is shown in Table 3.

[Table 3]

As shown in the MOB-SCN-REQ message, the BS secures the scanning duration

requested by the MSS, and the MSS starts the BS scanning after standing by for a start

frame time.

The related art neighboring BS scanning method has several problems and

disadvantages. In order to provide a seamless service from the BS, a moving MSS may

request the handover. Alternatively, the BS may request the handover in order to balance its

load. If the BS requests the handover, the MSS performs scanning on neighboring BSs to

decide whether to perform the handover. If the handover is needed, the neighboring BSs

must be continuously scanned. However, in order to obtain channel quality information in

the related art method, the MSS must transmit the scanning request message and receive the

corresponding scanning response message each time. Hence, the MSS continually occupies

limited radio resources and unnecessarily consumes power for message transmission and

reception.

DISCLOSURE OF THE INVENTION

Accordingly, the present invention is directed to scanning neighboring base stations in

a wireless access system that substantially obviates one or more problems of the related art.

An object of the present invention is to provide a neighboring BS scanning method in which an mobile subscriber station (MSS) efficiently measures a quality of a physical

channel required for a handover and transmits a corresponding result to a base station (BS). Additional advantages, objects, and features of the invention will be set forth in part in

the description which follows and in part will become apparent to those having ordinary

skill in the art upon examination of the following or may be learned from practice of the

invention. The objectives and other advantages of the invention may be realized and

attained by the structure particularly pointed out in the written description and claims

hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with the purpose of

the invention, as embodied and broadly described herein, in one embodiment, a method of

scanning neighboring base stations for assessing channel quality in a wireless

communication system includes receiving from a serving base station information

associated with at least one neighboring base station, and transmitting a scanning request

message from a mobile subscriber station to the serving base station, wherein the scanning

request message comprises a requested scan duration and a requested scan iteration, the

requested scan iteration being associated with a requested number of iterations of the

scanning of the at least one neighboring base station. The method also includes receiving a

scanning response message from the serving base station, wherein the scanning response

message comprises an allowed scan duration and an allowed scan iteration, the allowed

scan iteration being associated with an allowed number of iterations of the scanning of the

at least one neighboring base station.

The scanning request message ma preferably further comprise a requested interleaving interval associated with a requested time period between each scan. The

scanning response message may preferably further comprise an allowed interleaving

interval associated with an allowed time period between each scan.

During each of the allowed interleaving interval the serving base station and the

mobile subscriber station may preferably be in a normal operation mode. If the mobile

subscriber station transmits any data to the serving base station during the allowed scan

duration then the scanning of the at least one neighboring base station may preferably be

terminated.

The requested scan duration may preferably be associated with a requested time period

in which the mobile subscriber station initiates and terminates the scanning of the at least

one neighboring base station. The allowed scan duration may preferably be associated with

an allowed time period in which the mobile subscriber station initiates and terminates the

scanning of the at least one neighboring base station.

The scanning response message from the serving base station may further comprise a

scan report mode, wherein the scan report mode is associated with a reporting frequency of

the mobile subscriber station to the serving base station. The scan report mode may

preferably comprise at least one of (1) no report, (2) periodic report, and (3) event triggered

report. The mobile subscriber station may preferably transmit a scan report to the serving

base station in response to the scan report mode. The allowed scan duration and the allowed scan iteration may preferably be

determined by the serving base station in response to the requested scan duration and the

requested scan iteration and a network load. In another embodiment, a method of scanning neighboring base stations for assessing

channel quality in a wireless communication system, includes receiving from a serving base

station information associated with at least one neighboring base station, and receiving a

message comprises a scan duration and a scan iteration, the scan iteration being associated

with a number of iterations of the scanning of the at least one neighboring base station.

In yet another embodiment, a method of scanning neighboring base stations for

assessing channel quality in a wireless communication system includes transmitting to a

mobile subscriber station information associated with at least one neighboring base station,

and transmitting a scanning response message from a serving base station, wherein the

scanning response message comprises an allowed scan duration and an allowed scan

iteration, the allowed scan iteration being associated with an allowed number of iterations

of the scanning of the at least one neighboring base station. The method may preferably

also include receiving a scanning request message from a mobile subscriber station to the

serving base station before transmitting the scanning response message, wherein the

scanning request message comprises a requested scan duration and a requested scan

iteration, the requested scan iteration being associated with a requested number of iterations

of the scanning of the at least one neighboring base station.

It is to be understood that both the foregoing general description and the following

detailed description of the present invention are exemplary and explanatory and are

intended to provide further explanation of the invention as claimed.

The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present

invention when taken in conjunction with the accompanying drawings. It is to be

understood that both the foregoing general description and the following detailed

description of the present invention are exemplary and explanatory and are intended to

provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of

the invention and are incorporated in and constitute a part of this application, illustrate

embodiments of the invention and together with the description serve to explain the

principles of the invention.

FIG. 1 is a block diagram illustrating a broadband wireless access system in which a

handover operation is performed on a data plane.

FIG. 2 is a block diagram illustrating a broadband wireless access system in which a

handover operation is performed on a control plane.

FIG. 3 is a diagram illustrating a cell selection procedure in a broadband wireless

access system.

FIG. 4 is a diagram illustrating a neighboring base station scanning procedure. FIG. 5 is a diagram illustrating a neighboring base station scanning procedure,

according to one embodiment of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

Reference will now be made in detail to the preferred embodiments of the present

invention, examples of which are illustrated in the accompanying drawings. Wherever

possible, the same reference numbers will be used throughout the drawings to refer to the

same or like parts.

In one embodiment, a request to perform a scan for channel quality measurement

(scanning request message) of neighboring base stations is sent to a serving base station

(BS). A mobile subscriber station (MSS) transmits a cycle and an iteration count for

performance of the scan (scanning) to the serving BS to enable periodic scanning. In

periodic scanning of the neighboring BSs, the cycle for performing the scanning may

correspond to a time between scan execution intervals. The time between scan execution

intervals may be, for example, a general interleaving interval for transmitting data between

the MSS and the serving BS. The cycle for performing the scanning is called a normal

operation interval (interleaving interval). During the normal operation interval, the MSS

and the serving BS may communicate traffic data. Information pertaining to channel quality

(channel quality information) measured by the MSS may include a signal to interference

noise ratio (SINR) from a neighboring BS, a bit error rate, a quality of service identifier,

and other information.

An exemplary configuration of a scanning request message (scan request message) is

shown in Table 4. [Table 4]

Referring to Table 4, the MSS transmits information for periodic scan execution to the

serving BS using a scanning request message. The scanning request message may include

information pertaining to a length of a scanning duration (scan duration), a time to start the

scanning (start frame), a count of iterated scanning (scan iteration), and a general function

execution interval (interleaving interval). In response to receipt of the scanning request

message, the serving BS transmits a scanning response message to the MSS.

An exemplary configuration of the scanning response message is shown in Table 5.

[Table 5]

Referring to Table 5, the serving BS transmits the scanning response message to the

MSS in response to receipt of the scanning request message. The scanning response

message may include information pertaining to a length of a scanning duration (scan

duration), a time to start the scanning (start frame), a count of iterated scanning (scan

iteration), and a general function execution interval (interleaving interval).

The MSS periodically measures the channel quality of the neighboring BSs based on

the information included in the scanning response message transmitted from the serving BS.

In another embodiment, the information pertaining to the length of a scanning duration

(scan duration), the time to start the scanning (start frame), the count of iterated scanning

(scan iteration), and the general function execution interval (interleaving interval) are

transmitted by the BS to the MSS in response to the request from the MSS. Alternatively,

the information pertaining to the length of a scanning duration (scan duration), the time to

start the scanning (start frame), the count of iterated scanning (scan iteration), and the

general function execution interval (interleaving interval) may be transmitted by the serving

BS to the MSS without a request from the MSS (unsolicited response).

FIG. 5 is a diagram illustrating a neighboring base station scanning procedure,

according to one embodiment of the present invention. Referring to FIG. 5, in one

embodiment, a 1st BS (serving BS) 520 may preferably store the data rather than transmit the data to an MSS 510 during a scanning duration (scan duration), such as the scan

durations related to the 1^st, 2ⁿ ,^• and 3^r iteration intervals 555, 565, and 575, respectively, in

which the MSS 510 is measuring channel quality of neighboring BSs (target BSs), i.e. the

2^nd BS 530 and the 3^rd BS 540. The serving BS 520 may then transmit the stored data

during an interval in which the MSS 510 is not scanning the neighboring BSs 530 and 540,

i.e., during a general function execution interval (interleaving interval).

In another embodiment, if a data transmission time is prolonged such that the data

transmission is not completed by a new scanning start time (start frame) of the MSS 510,

the serving BS 520 may ignore the scanning start time and continue transmitting the data.

Alternatively, the data transmission may be stopped to allow for the new scanning start

time. In such case where the data transmission is stopped, the data transmission may be

restarted after the scanning duration of the MSS 510 ends.

In yet another embodiment, if the serving BS 520 ignores the scanning start time of the

MSS 510 and continues transmitting the data, the MSS 510 may stop performing scanning

in response to a determination by the MSS 510 that the scanning duration, the general

function execution interval (interleaving interval), and the scanning iteration count assigned

by the serving BS 520 via the scanning response message are no longer valid. Also, in such

case where the serving BS 520 ignores the scanning start time of the MSS 510 and

continues transmitting the data, data and scanning procedures received from the serving BS

520 which relate to an iteration count that has not been executed may then be executed.

Alternatively, the MSS 510 may continue scanning during the data transmission from the

serving BS 520, thereby enabling the MSS 510 to perform scanning during the entire scanning duration (scan duration x scan iteration) initially assigned by the serving BS 520.

In still another embodiment, the serving BS 520 may use a result of neighboring

(target) BS channel quality measurement acquired from scanning by the MSS 510 to

determine whether to command execution of the handover to the MSS 510. In this case, the

serving BS 520 may request the neighboring BS channel quality measurement from the

MSS 510 to determine whether it is necessary to perform the handover. The serving BS 520

may also command execution of the handover to the MSS 510 to adjust the network load of

the serving BS 520.

In yet another embodiment, the channel quality measurement request from the serving

BS 520 to the MSS 510 may be initiated based on necessity of the serving BS 520. In this

case, the MSS 510 transmits the result of neighboring BS channel quality measurement

(channel quality measurement result) to the requesting (serving) BS 520. For example, the

MSS 510 may preferably send parameters including requested scan iteration, interleaving

interval, and scan duration to the serving base station 520. The serving BS 520 may use

these received parameters in combination with the scheduling and data buffer capabilities

of the serving BS 520. Alternatively, the serving BS 520 may change the parameters. The

transmission of the channel quality measurement result may be executed by periodically

reporting the channel quality measurement result regardless of the time point or cycle of the

measurement. Alternatively, the channel quality measurement result may be reported each

time the MSS 510 measures the channel qualities. The measurement reporting method of

the MSS 510 may be selected by the serving BS 520 or the MSS 510.

An exemplary configuration of a scanning response message including the information pertaining to the selection is shown in Table 6.

[Table 6]

The MSS may preferably report the channel quality measurement result according to

an identifier of the scanning response message received from the serving BS at each

measurement. Alternatively, the MSS may preferably report the channel quality

measurement result according to an identifier of the scanning response message received

from the serving BS periodically. In the case of reporting the channel quality measurement

result periodically, a separate measurement result report period may be set. Alternatively,

the MSS may not report the channel quality measurement result.

In one embodiment, the MSS is not required to send a confirm message in response to

receiving the scanning response message from the serving BS. For example, if the MSS

performs an action different from that commanded by the serving BS, the serving BS may

determine that the scanning response message is incorrect and send another scanning

response message.

When a message requesting a new scanning and report is received from the target BS

while the target BS is in the process of reporting a scanning result to the serving BS, the

MSS may ignore all current scanning and report procedures and may perform a scanning

and report procedure according to the new request message.

Periodically repeated scan duration and interleaving intervals that enable data

transmission and or reception may be interrupted by a request from the serving BS. When

the serving BS requests such an interruption, the serving BS may fill a specific entry (scan

duration, interleaving interval, scan iteration) in the scanning response message shown in Table 5 with a specific value, e.g., 0, for notification purposes. Furthermore, repeated scan

duration and interleaving intervals that enable data transmission and/or reception may also

be interrupted by a request from the MSS. When the MSS requests such an interruption, the

MSS may fill a specific entry (scan duration, interleaving interval, scan iteration) in the

scanning request message shown in Table 4 with a specific value, e.g., 0, for notification

purposes.

In one embodiment, a method of scanning neighboring base stations for assessing

channel quality in a wireless communication system includes receiving from a serving base

station information associated with at least one neighboring base station, and transmitting a

scanning request message from a mobile subscriber station to the serving base station,

wherein the scanning request message comprises a requested scan duration and a requested

scan iteration, the requested scan iteration being associated with a requested number of

iterations of the scanning of the at least one neighboring base station. The method also

includes receiving a scanning response message from the serving base station, wherein the

of the scanning of the at least one neighboring base station.

The scanning request message may preferably further comprise a requested

interleaving interval associated with a requested time period between each scan. The

interval associated with an allowed time period between each scan.

During each of the allowed interleaving interval the serving base station and the mobile subscriber station may preferably be in a normal operation mode. If the mobile

terminated. The requested scan duration may preferably be associated with a requested time period

scanning of the at least one neighboring base station. The scanning response message from the serving base station may further comprise a

base station in response to the scan report mode.

The allowed scan duration and the allowed scan iteration may preferably be

requested scan iteration and a network load.

In another embodiment, a method of scanning neighboring base stations for assessing

scanning response message from the serving base station, wherein the scanning response message comprises a scan duration and a scan iteration, the scan iteration being associated

In yet another embodiment, a method of scanning neighboring base stations for

of the scanning of the at least one neighboring base station. Accordingly, the MSS performs scanning of neighboring BSs in a wireless access

system without repeatedly transmitting or receiving the scanning request or response

messages.

It will be apparent to those skilled in the art that various modifications and variations

can be made in the present invention without departing from the spirit or scope of the

inventions. Thus, it is intended that the present invention covers the modifications and

variations of this invention provided they come within the scope of the appended claims

and their equivalents. INDERSTRIAL APPLICABILITY

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

Claims

[CLAIMS]

1. A method of scanning neighboring base stations for assessing channel quality in a

wireless communication system, the method comprising: receiving from a serving base station information associated with at least one

neighboring base station; transmitting a scanning request message from a mobile subscriber station to the

serving base station, wherein the scanning request message comprises a requested scan

duration and a requested scan iteration, the requested scan iteration being associated with a

requested number of iterations of the scanning of the at least one neighboring base station;

and receiving a scanning response message from the serving base station, wherein the

of the scanning of the at least one neighboring base station

2. The method of claim 1, wherein the scanning request message further comprises a

requested interleaving interval associated with a requested time period between each scan.

3. The method of claim 1, wherein the scanning response message further comprises

an allowed interleaving interval associated with an allowed time period between each scan.

4. The method of claim 3, wherein during each of the allowed interleaving interval the

serving base station and the mobile subscriber station are in a normal operation mode.

5. The method of claim 1, wherein if the mobile subscriber station transmits any data

to the serving base station during the allowed scan duration then the scanning of the at least

one neighboring base station is terminated.

6. The method of claim 1, wherein the requested scan duration is associated with a

requested time period in which the mobile subscriber station initiates and terminates the

scanning of the at least one neighboring base station.

7. The method of claim 1, wherein the allowed scan duration is associated with an

allowed time period in which the mobile subscriber station initiates and terminates the

scanning of the at least one neighboring base station.

8. The method of claim 1, wherein the scanning response message from the serving

base station further comprises a scan report mode, wherein the scan report mode is associated with a reporting frequency of the mobile subscriber station to the serving base

station.

9. The method of claim 8, wherein the scan report mode comprises one of (1) no

report, (2) periodic report, and (3) event triggered report.

10. The method of claim 8, wherein the mobile subscriber station transmits a

scan report to the serving base station in response to the scan report mode.

11. The method of claim 1 , wherein the allowed scan duration and the allowed

scan iteration are determined by the serving base station in response to the requested scan

duration and the requested scan iteration and a network load.

12. A method of scanning neighboring base stations for assessing channel

quality in a wireless communication system, the method comprising: receiving from a serving base station information associated with at least one

neighboring base station; and receiving a scanning response message from the serving base station, wherein the

scanning response message comprises a scan duration and a scan iteration, the scan

iteration being associated with a number of iterations of the scanning of the at least one neighboring base station

13. The method of claim 12, wherein the scanning response message further

comprises an interleaving interval associated with a time period between each scan.

14. The method of claim 13, wherein during each of the interleaving interval the

serving base station is in a normal operation mode.

15. The method of claim 12, wherein the scan duration is associated with a time

period in which the serving base station initiates and terminates the scanning of the at least

one neighboring base station.

16. The method of claim 12, wherein the scanning response message from the

serving base station further comprises a scan report mode, wherein the scan report mode is

associated with a reporting frequency.

17. The method of claim 16, wherein the scan report mode comprises one of ( 1 )

no report, (2) periodic report, and (3) event triggered report.

18. A method of scanning neighboring base stations for assessing channel quality in a wireless communication system, the method comprising: transmitting to a mobile subscriber station information associated with at least one

neighboring base station; and transmitting a scanning response message from a serving base station, wherein the

of the scanning of the at least one neighboring base station

19. The method of claim 18, further comprising receiving a scanning request message from a mobile subscriber station to the serving

base station before transmitting the scanning response message, wherein the scanning

scanning of the at least one neighboring base station.

20. The method of claim 19, wherein the scanning request message further

comprises a requested interleaving interval associated with a time period between each scan.

21. The method of claim 19, wherein the scanning response message further

comprises an allowed interleaving interval associated with a time period between each scan.

22. The method of claim 21 , wherein during each of the allowed interleaving

interval the serving base station and the mobile subscriber station are in a normal operation

mode.

23. The method of claim 19, wherein if the mobile subscriber station transmits

any data to the serving base station during the allowed scan duration then the scanning of

the at least one neighboring base station is terminated.

24. The method of claim 18, wherein the requested scan duration is associated

with a time period in which the mobile subscriber station initiates and terminates the

scanning of the at least one neighboring base station.

25. The method of claim 18, wherein the allowed scan duration is associated

scanning of the at least one neighboring base station.

26. The method of claim 18, wherein the scanning response message from the

associated with a reporting frequency of the mobile subscriber station to the serving base station.

27. The method of claim 26, wherein the scan report mode comprises one of (1)

no report, (2) periodic report, and (3) event triggered report

28. The method of claim 26, wherein the mobile subscriber station transmits a

scan report to the serving base station in response to the scan report mode.

29. The method of claim 18, wherein the allowed scan duration and the allowed

duration and the requested scan iteration and a network load.

30. A mobile subscriber station configured to scan neighboring base stations for

assessing channel quality in a wireless communication system, the mobile subscriber

station comprising: means for receiving from a serving base station information associated with at least

one neighboring base station; means for transmitting a scanning request message from the mobile subscriber station

to a serving base station, wherein the scanning request message comprises a requested scan

duration and a requested scan iteration, the requested scan iteration being associated with a requested number of iterations of the scanning of the at least one neighboring base station;

and means for receiving a scanning response message from the serving base station,

wherein the scanning response message comprises an allowed scan duration and an allowed

scan iteration, the allowed scan iteration being associated with an allowed number of

iterations of the scanning of the at least one neighboring base station

31. The mobile subscriber station of claim 30, wherein the scanning request

message further comprises a requested interleaving interval associated with a requested

time period between each scan.

32. The mobile subscriber station of claim 30, wherein the scanning response

message further comprises an allowed interleaving interval associated with a requested time

period between each scan.

33. The mobile subscriber station of claim 30, wherein the requested scan

duration is associated with an allowed time period in which the mobile subscriber station

initiates and terminates the scanning of the at least one neighboring base station.

34. The mobile subscriber station of claim 30, wherein the allowed scan duration is associated with an allowed time period in which the mobile subscriber station

35. The mobile subscriber station of claim 30, wherem the scanning response

message from the serving base station further comprises a scan report mode, wherein the

scan report mode is associated with a reporting frequency of the mobile subscriber station

to the serving base station.

36. The mobile subscriber station of claim 35, wherein the scan report mode

comprises one of (1) no report, (2) periodic report, and (3) event triggered report.

37. A mobile subscriber station configured to scan neighboring base stations for

one neighboring base station; and means for receiving a scanning response message from the serving base station,

wherein the scanning response message comprises a scan duration and a scan iteration, the

scan iteration being associated with a number of iterations of the scanning of the at least

one neighboring base station .

38. The mobile subscriber station of claim 37, wherein the scanning response message further comprises an interleaving interval associated with a time period between each scan.

39. The mobile subscriber station of claim 37, wherein the scan duration is associated with a time period in which the mobile subscriber station initiates and terminates the scanning of the at least one neighboring base station.

0 40. The mobile subscriber station of claim 37, wherein the scanning response message from the serving base station further comprises a scan report mode, wherein the scan report mode is associated with a reporting frequency of the mobile subscriber station to the serving base station.

5 41. The mobile subscriber station of claim 40, wherein the scan report mode comprises one of (1) no report, (2) periodic report, and (3) event triggered report.

42. A base station configured to scan neighboring base stations for assessing channel quality in a wireless communication system, the base station comprising:

o means for transmitting to a mobile subscriber station information associated with at least one neighboring base station; and means for transmitting a scanning response message from a serving base station,

iterations of the scanning of the at least one neighboring base station

The base station of claim 42, further comprising means for receiving a scanning request message from a mobile subscriber station to

the serving base station before transmitting the scanning response message, wherein the

of the scanning of the at least one neighboring base station.

44. The base station of claim 43, wherein the scanning request message further

45. The base station of claim 43, wherein the scanning response message further

46. The base station of claim 42, wherein the requested scan duration is associated with a time period in which the mobile subscriber station initiates and terminates

the scanning of the at least one neighboring base station.

47. The base station of claim 42, wherein the allowed scan duration is associated

scanning of the at least one neighboring base station.

48. The base station of claim 42, wherein the scanning response message from

the serving base station further comprises a scan report mode, wherein the scan report mode

is associated with a reporting frequency of the mobile subscriber station to the serving base

station.

49. The base station of claim 48, wherein the scan report mode comprises one of

(1) no report, (2) periodic report, and (3) event triggered report.