Wireless ATM (W-ATM) is now being actively considered as a potential solution to the future wireless multimedia communications. Basically, W-ATM, as an extension of broadband wired ATM to the wireless medium, is desirable to provide ATM services in wireless environments. On the other hand, in W-ATM networks, the limited radio resources and error prone characteristics make it extremely difficult to meet diverse QoS (Quality of Service) requirements for different services. As a consequence, additional MAC (Medium Access Control) and DLC (Data Link Control) sub-layers are added as essential elements of W-ATM. In particular, MAC protocol which is responsible for radio resource allocation plays a very important role in accomplishing QoS guarantee and a high channel utilization in W-ATM netwo...[ Read more ]

Wireless ATM (W-ATM) is now being actively considered as a potential solution to the future wireless multimedia communications. Basically, W-ATM, as an extension of broadband wired ATM to the wireless medium, is desirable to provide ATM services in wireless environments. On the other hand, in W-ATM networks, the limited radio resources and error prone characteristics make it extremely difficult to meet diverse QoS (Quality of Service) requirements for different services. As a consequence, additional MAC (Medium Access Control) and DLC (Data Link Control) sub-layers are added as essential elements of W-ATM. In particular, MAC protocol which is responsible for radio resource allocation plays a very important role in accomplishing QoS guarantee and a high channel utilization in W-ATM networks.

This thesis contributes to the design of MAC protocol, specifically the scheduling schemes for MAC protocol, in two-folds. Firstly, we propose a W-ATM MAC protocol which is based on a hierarchical fair-queueing scheduling with adaptive weights. The weight adaptation mechanism has been shown to be potentially useful in a centralized TDMA/TDD access architecture, yielding a low cell transfer delay and a high channel utilization while maintaining fairness among multiple users.

Secondly, we propose an adaptive fair-queueing scheduling scheme coupled with a type-II hybrid ARQ (Automatic Repeat reQuest) which takes the error prone characteristics of practical radio channels into account. Unlike previous works where the error recovery and scheduling schemes were often separately dealt with in DLC and MAC sub-layers, we combine both schemes together in order to come up with a fair and efficient resource allocation algorithm. Specifically, we employ a two-state Markov model to model the wireless channel. Both the error control scheme and the scheduling algorithm are designed to adapt to the varying channel conditions. It has been shown with extensive simulations that the proposed schemes can satisfy the delay and reliability requirements of multimedia services with substantially improved channel utilization compared with other existing schemes.