Performance evaluation of crossover switch discovery algorithms for wireless ATM LANs

In a connection-oriented wireless LAN, the mobility of mobile hosts results in the establishment and disconnection of new and old virtual circuits. The resulting increase in signalling traffic along with the need to support multimedia stream handovers demand a fast, continuous and bandwidth-efficient handover protocol. We adopt a handover scheme based on partial re-establishments, where a new partial path converges to an existing path. Connection rerouting (CR) operations are then performed at the convergence/crossover switch (CX). To achieve localised handovers, a wireless cell clustering scheme is proposed. The clustering of base stations to cluster switches (CLSs) provides fast intra-cluster handovers since the CR operations are performed at the CLS. To support fast inter-cluster handovers, four CX discovery schemes (loose select, prior path, distributed hunt and backward tracking) are introduced. Simulation results obtained from a trace-driven mobile network simulator on four different network topologies (random, star, tree and hierarchical redundancy) reveal that both prior path and distributed hunt discoveries outperform the others by providing the fastest convergence with shorter resulting paths and higher circuit reuse efficiency.