UBC Theses and Dissertations
Dynamic reservation TDMA medium access control protocol for wireless ATM networks Frigon, Jean-François
To meet the anticipated demand for wireless access to the broadband Asynchronous Transfer Mode (ATM) network, the concept of wireless ATM has been proposed in 1994 . One of the main challenge in the design of a wireless ATM network resides in the conception of a Medium Access Control (MAC) protocol that will handle the different ATM services while providing an efficient utilization of the wireless channel. In this thesis, we propose a new Dynamic Reservation TDMA (DR-TDMA) MAC protocol for wireless ATM networks. DR-TDMA combines the advantage of distributed access and centralized control for transporting Constant Bit Rate (CBR), Variable Bit Rate (VBR) and Available Bit Rate (ABR) traffic efficiently over a wireless channel. The contention slots access is governed by the novel framed pseudo-Bayesian priority Aloha protocol that we introduce in this thesis. This protocol minimizes the contention delay and provides different access priorities for heterogeneous traffic. Simulation results indicate that the framed pseudo-Bayesian priority protocol offers a significant delay improvement for high priority packets with both Poisson and self-similar traffic, while low priority packets only experience a slight performance degradation. In the context of the DR-TDMA protocol, results show that the priority algorithm improves real-time traffic Quality-of-Service (QoS). The DR-TDMA resource allocation algorithm grants to terminals reserved access to the wireless ATM channel by considering their requested bandwidth and QoS. We propose scheduling algorithms for CBR, voice, VBR and ABR traffic. We also introduce a method to dynamically adjust the number of uplink control slots per frame as a function of the estimated contention traffic. Furthermore, the DR-TDMA protocol features a novel rate based allocation algorithm for VBR traffic and a cell control algorithm to determine the VBR flow conformance with the connection traffic parameters. Finally, an algorithm is proposed to integrate these algorithms to provide ubiquitous wireless ATM services. Performance, results show that the DR-TDMA MAC protocol can achieve high throughput in the range of 90 to 95% while maintaining reasonable QoS for all ATM services.
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