Autonomous Migration with Admission Control for Mobiles Affected by Access Network Failures

When wireless network access points (APs) fail, every mobile user that is connected through the failed resources performs an unanticipated hard handover, resulting in disrupted connections. The APs the users migrate to, if already heavily loaded, may restrict the number of incoming users using call admission control (CAC) algorithms. Rejected users will experience loss of connectivity for longer periods of time as they are forced to try to connect to other available APs. This paper quantifies the effect of limited capacity in target APs when multiple displaced users attempt to connect to them. We derive expressions for handover success probability and the mean number of displaced users that are successfully admitted on their first attempt. This leads to a simple, decentralized probabilistic scheme that displaced users can use to minimize crowding effects at target APs. We also obtain a performance bound by developing an optimal reassignment scheme using linear programming, and we compare both schemes to an algorithm that chooses an AP based on received signal strength (RSS).