The implementation and performance evaluation of handoff in a CORBA-based WATM signalling system

Abstract

In this paper, the design, prototyping and performance evaluation of a CORBA--based handoff signalling system isdiscussed. The wireless terminal communicates with the base stations using UNJ 4.0 signalling augmented by handoffcontrol messages.·The base stations then call on the services provided by a Handoff Manager CORBA entity that perfonnsthe handoffs using an incremental re-establishment scheme with the crossover switch being dynamically selectedusing Dijkstra's shortest path algorithm. The Handoff Manager makes use of a generic control of the switches using SNMP \Vhereby WATM mobility management can be rea1ized with comn1ercially available ATM switches. The signaling system provides a flexible platfonn to evaluate different handoff algorithms. The experimental results showthat effective ATM handoffs can be achieved with a latency of~ 92 ms, transition delay of= 18.5 ms, and a low cellloss depending on the traffic characteristics. It was found that fewer packets were lost when using AAL 5 as compared to AAL 3/4.