A Dynamic Token-Polling Based Multiple Access Control Guaranteeing VBR Video QoS in Wireless ATM Networks

This paper proposes a dynamic token polling scheduling algorithm (DTSA) based MAC scheme for wireless ATM networks. Token model of every connection is constructed in the base station for slot allocation. In order to deal with dynamic nature and stringent QoS requirement of rt VBR such as compressed video, emergency message is defined to inform the base station of the source's rate variation and buffer status. After receiving emergency message, the scheduler in base station computes out the number of slots required by the source and puts tokens into emergency token buffer, which has higher nonpreemptive priority over those of other rt VBR. By including emergency token buffer into scheduling scheme, more flexible and timely slot allocation scheme is developed. Through simulation results, we find that the scheme proposed can achieve better performance of delay and loss for rt VBR video. Also, we discuss the parameters that affect the performance.