Abstract

Multiple access schemes are an important component in the development of evolving wireless LANs (WLANs), In this paper, a centralized multiple access protocol is presented for communication among a set of portables and a base station inside a cell of a WLAN. The portables compete for the uplink access to the transmission channel with minipackets in response to controlling commands issued by the base station. The real-time exchange of minipackets and controlling commands allows for the implementation of stable collision resolution algorithms to improve the delay properties of uplink data packets. The proposed protocol is further developed to allow both downlink and uplink traffic directions to time-share a common transmission channel without mutual contention.

In the analysis, the operation of the protocol is modeled by a single server queue with two classes of customers having distinct arrival and service characteristics. Stability conditions are derived together with tight upper and lower bounds on the average delays of downlink and uplink data packets. The numerical examples show protocol capacities in excess of 0.85 and 0.70 for nominal channel bit rates of 5 Mbps and 50 Mbps, respectively.

Author Keywords: Author Keywords: Wireless LANs; Wireless data communications; Bi-directional multiple access; Multiple access protocols; Collision resolution algorithms; Queues with distinct arrival streams

Article Outline

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Corresponding author. Current address: AT&T Bell Laboratories, Zadelstede 1–10, 3431 JZ , Nieuwegein, , Netherlands.

*1 This work was performed while J.L. Sobrinho was a recipient of a grant from Junta Nacional de Investigação Científica e Tecnológica, Portugal.