An adaptive reservation scheme for VBR voice traffic in wireless ATM networks

A reservation scheme, named dynamic hybrid partitioning, is proposed for th e Medium Access Control (MAC) protocol of wireless ATM (WATM) networks oper ating in Time Division Duplex (TDD) mode. The goal is to improve the perfor mance of the real-time Variable Bit Rate (VBR) voice traffic in networks wi th mixed voice/data traffic. In most proposed MAC protocols for WATM networ ks, the reservation phase treats all traffic equally, whether delay-sensiti ve or not. Hence, delay-sensitive VER traffic sources have to compete for r eservation each time they wake up from idle mode. This causes large and var iable channel access delays, and increases the delay and delay variation (j itter) experienced by ATM cells of VER traffic. In the proposed scheme, the reservation phase of the MAC protocol is dynamically divided into a conten tion-free partition for delay-sensitive idle VER traffic, and a contention partition for other traffic. Adaptive algorithms dynamically adjust the par tition sizes to minimize the channel bandwidth overhead. Simulation results show that the delay performance of delay-sensitive VER traffic is improved while minimizing the overhead.