An efficient AP channel scanning scheme for real-time streaming over WLAN

As the demand for mobile broadcasting and streaming services such as mobile IPTV increases, providing QoS-supported handover for the real-time multimedia in IEEE 802.11 WLAN is becoming an important issue of research. In WLAN handover, majority of the delay is caused by channel scan which occurs during target AP search. In this paper we suggest a channel scanning scheduling method that can provide QoS support for the real-time service over WLAN as well as reduced handover latency. In the proposed scheme, the MS sets the channel scan time(CST) according to the QoS requirement of the ongoing data transmission and performs channel scanning alternately with data transmission. A combined passive/active scan mechanism is used to schedule the channel scans with minimum total channel scan time. Simulation results show that the proposed scheme improves the performance over the existing schemes in terms of channel scanning and handover latency.