Handoff Latency Minimization by Relative Distance Method

A mobile station (MS) undergoes handoff when it travels out of the coverage area of its current access point (AP) and tries to associate with another AP. In this paper we propose a method using GPS (Global Positioning System) to minimize the number of APs to be scanned by the MS during each handoff procedure. The entire geographical area is considered as a two dimensional plane divided into hexagonal coverage areas. Average Distance (d) is defined as the distance travelled by the MS in a time interval td (where td is defined as the total time delay in scanning, authentication etc. for a new AP). A new hexagonal area of side ‘b’ is created within the pre-existing hexagonal cell of side ‘a‘ by excluding the area covered by the MS in time td (as defined by ‘d’). A new variable‘s’ is defined which keeps track of the MS within the cell and when s>b handoff occurs. To minimize the number of APs to be scanned, cell sectoring approach is adopted in which every hexagonal cell is divided into 6 equal segments of 60 0 each. This will result in a reduction of number of APs to be scanned and the handoff latency will also be reduced to a great extent.