Method and apparatus for channel scanning in a wireless communication system

Patent metadata

Field	Value
Publication number	US-9088911-B2
Application number	US-201113078794-A
Country	US
Kind code	B2
Filing date	Apr 1, 2011
Priority date	Apr 2, 2010
Publication date	Jul 21, 2015
Grant date	Jul 21, 2015

Abstract

A method and apparatus perform channel scanning in a wireless communication system. A signal intensity of an Access Point (AP) is compared with a scanning threshold, when the AP signal intensity not less than the scanning threshold, a channel scanning schedule list is generated in consideration of a scan time based on a passive channel scan scheme and a scan time based on an active channel scan scheme. The channel scanning is performed every channel scanning time, according to the channel scanning schedule list.

First claim

What is claimed is:

1. A method in a wireless mobile station (MS) for channel scanning in a wireless communication system, the method comprising:
comparing a signal intensity of a serving Access Point (AP) with a scanning threshold;
when the serving AP signal intensity is less than the scanning threshold, generating a channel scanning schedule list using a scan time based on a passive channel scan scheme and a scan time based on an active channel scan scheme; and
performing the channel scanning every channel scanning time, according to the channel scanning schedule list.

2. The method of claim 1 , further comprising:
after performing the channel scanning, monitoring the serving AP signal intensity; and
determining whether to perform a handover based on the comparison between the monitored AP signal intensity and a handover threshold.

3. The method of claim 1 , wherein generating the channel scanning schedule list comprises:
determining a scan time (t_pas) for each AP in each channel based on the passive channel scan scheme;
sorting, in ascending order, the t_pas and mapping each t_pas to a corresponding AP and at least one of a corresponding channel, a beacon reception time, and a corresponding AP address;
comparing, for each AP on the channel scanning schedule list by the sorted order, the t_pas with a maximum wait time (MaxChannelTime) by channel of a Mobile Station (MS) based on the active channel scan scheme, and determining a scan scheme for the corresponding channel;
comparing a total channel scan time (total_scantime) based on the determined scan scheme for each AP with a maximum scan time (t_pasmax) based on the passive channel scan scheme; and
if the total_scantime is greater than the t_pasmax, updating the channel scanning schedule list.

4. The method of claim 3 , wherein the t_pas for each AP is determined according to the equation below:
t — pas=T wait — bcon −T sw , if T wait — boon >T sw
T wait — bcon +τ p −T sw , if T wait — bcon <T sw

wherein:
T wait — bcon denotes a time until receiving a beacon from each AP at next channel scanning time point (T next ),
T sw denotes a channel switching time,
τ p denotes a beacon signal period, and
T wait — bcon is defined by the equation below:

T
wait_bcon

=

(

T
prevbcon

+

τ
p

·

⌈

T
next

τ
p

⌉

-

T
next

)

⁢
mod
⁢

⁢

τ
p

wherein T prevbcon denotes beacon reception time point at a previous handover.

5. The method of claim 3 , wherein, when a Channel Scanning Time (CST) is less than the total_scantime, a scanning duration is divided into individual Scanning Units (SUs) that can be performed within the CST.

6. The method of claim 5 , wherein the number of SUs is determined every CST according to the equation below:

N
maxscan

=

Max
⁡

(
n
)

⁢

s
.
t
.

⁢

∑

i
=
k

n

⁢

T_SU
i

≤

C
⁢

⁢
S
⁢

⁢

T
⁡

(

1
≤
k
≤

N
AP

,

k
≤
n
≤

N
AP

)

wherein Max(n) is a maximum integer that satisfies

∑

i
=
k

n

⁢

T_SU
i

≤

C
⁢

⁢
S
⁢

⁢
T

,

 and T_SU is a time duration for determining each SU.

7. The method of claim 3 , wherein updating the channel scanning schedule list comprises:
determining whether a time gap between a first t_pas and a second t_pas in the channel scanning schedule list is greater than the MaxChannelTime; and
when the time gap is greater than the MaxChannelTime, changing a channel scan scheme of the corresponding channel of an AP that corresponds to the t_pasmax to the active cha

Assignees

• Lee Hyun-Chul
• Jeon Jin-Woo
• Han Young-Seop
• Kim Young-Jip
• Youn Hee-Yong
• Kim Kyung-Tae
• Samsung Electronics Co Ltd
• Univ Sungkyunkwan Found

Inventors

• Lee Hyun-Chul
• Jeon Jin-Woo
• Han Young-Seop
• Kim Young-Jip
• Youn Hee-Yong
• Kim Kyung-Tae

Classifications

• H04W24/10 Primary

  Scheduling measurement reports {; Arrangements for measurement reports} · CPC title

• H04W84/12

  WLAN [Wireless Local Area Networks] · CPC title

• H04W36/30

  by measured or perceived connection quality data · CPC title

• H04W36/0083

  Determination of parameters used for hand-off, e.g. generation or modification of neighbour cell lists · CPC title

• H04W36/302

  due to low signal strength · CPC title