Eliminating channel scanning phase in handoff across IEEE 802.11 wireless LANs.
ABSTRACT The current channel scanning phase in IEEE 802.11 Wireless LAN does not fit fast handoff due to the following two reasons. First, IEEE 802.11 Wireless LAN operates based on CSMA/CA. Unlike cellular system, STAs can not scan other channels while exchanging data frames with currently associated AP, because it would directly cause frame loss. To attack this problem, related works have tried to utilize Power Saving Mode (PSM) or multiple NICs. Second, beacon interval is too far apart for fast handoff (100 msec by default). Since an STA lacks knowledge about which channel its nearby APs are operating on, it should redundantly scan every single channel regardless whether any AP exists on that channel. Though shorter beacon interval or active scan enable an STA to locate its nearby BSSs more quickly, these approaches increase extra traffic to the limited bandwidth. Previous works tried to provide an STA with nearby AP information approximated by APs collaboratively.