An experimental study on Layer 2 roaming for 802.11 based WLANs

In this paper, we argue that the roaming functionalities implemented at the data link layer (Layer 2) have certain drawbacks causing delay in the handoff process for mobile hosts in a wireless local area network. Through real experiments, we show how the triggering of the roam process is delayed which affects data transmission. Even though the network interface cards and drivers were from different manufactures, the decision process related to the hand-offs had significant similarities ¿ the use of a crude timer and an un-sophisticated approach for detecting error conditions. Identifying the mechanisms that cause a mobile host to roam, we suggest a pro-active algorithm that eases the effects of waiting too long to roam. By monitoring the current received signal strength, we were able to initiate the probing process early enough which in turn helped the roaming process.