An access protocol for supporting multiple classes of service in a local wireless environment

This paper presents a time split token-based contention resolution (TS-TBCR) protocol for providing multiple classes of traffic access to a shared wireless media. Since the protocol requires immediate response from the base station, it is best suited for short-range wireless applications. The key feature of the protocol is that it allows multiplexing of various services with high throughput even under heavy traffic loads. The protocol provides near perfect scheduling of information transfer by reserving a small part of the bandwidth for contention resolution. This resolves contention in an a priori manner, thus preventing collisions and leading to high channel bandwidth utilization. This protocol allows the system to support a high load while keeping packet loss probability within acceptable limits. Using a token-based mechanism, the protocol implements an access scheme, as well as a service (scheduling) discipline. The protocol is analytically modeled and extensive simulations performed to evaluate its performance. Results indicate that for multimedia traffic transport, the protocol can dynamically, and without any centralized control, realize any service discipline from first-in first-out (FIFO: complete fairness) to head-of-line (HOL: complete biasing), merely based on the relative service requirements of the traffic classes. This brings in fairness since no service class is excessively penalized