This paper presents a new distributed scheduling architecture for wireless ATM networks. Usually, in WATM scheduling architectures, a fixed order is defined among the different connections through their ATM service category (CBR VBR ABR UBR). We argue that although this static priority is easier to implement, this type of precedence is not necessarily a good choice for the MAC layer. The MAC layer scheduling should define an order such that it uses efficiently the resources while providing quality of service (QoS) guarantees. In this spirit, our architecture delays (without violating their QoS) the real time connections in order to improve the performance of non real time connections.

The throughput performance of a slotted, non-persistent Idle-Signal Casting Multiple Access (ICMA) protocol under the effects of various combinations of Rayleigh fading, lognormal shadowing, and spatial distribution of mobile users is studied. The opposing effects of propagation impairments on the performance of the protocol through simultaneously increasing the probability of receiver capture and attenuation of the received signal power level are demonstrated.

Markov chain models are used to derive the average stationary throughput and delay performance of Idle-Signal Casting Multiple Access (ICMA), with and without Failure Detection (/FD), protocols which are suitable for use in mobile packet radio local area networks, where propagation impairments are prevalent. The models consider the effects of pure Rayleigh fading on channel access and packet transmission. Numerical results, validated by computer simulations, are obtained that enable a quantitative study of the performance of the protocols. It is found that the performance of the ICMA/FD protocol is affected more significantly by fading on the base-to-mobile channel than is the performance of the ICMA protocol. In addition, performance improves with larger packet sizes eventhough such packets are more vulnerable to failure due to fading.