An Intelligent Scan Mechanism for 802.11 Networks by Using Media Independent Information Server (MIIS)

Handover efficiency in wireless and mobile communication networks is an important factor in providing QoS guarantees for real time applications. The 802.11 standard requires a Mobile Node (MN) to scan all the possible channels (11 in the US) to discover available Access Points (AP´s) during a handover. In a given 802.11 cell several channels are expected to be empty. Due to a full scan the MN ends up wasting time scanning empty channels, which results in a high handover delay. This handover delay can be reduced by simple refining the scanning procedure to a limited set of channels, currently being used throughout the network or by the surrounding access points. In this paper we propose to use the Media Independent Information Server (MIIS) to inform the MN of the channel configuration information of the network or the surrounding AP´s. In our scheme the MN acquires channel configuration information from MIIS server and then uses that information to scan a limited set of channels being used by the surrounding access points or through out the network rather than scanning all possible channels resulting in reduced handover delay. We define a parameter NET_CHANNEL_CONFIG which is passed in the query by the MN to the MIIS, so that the MIIS knows which information is being requested by the MN. We also define an Information Element Container IE_CONTAINER_802.11_CHINFO which is used by MIIS to return the requested channel configuration information of the network to the MN. We call our scheme Intelligent Scan.