Performance evaluation of candidate MAC protocols for LMCS/LMDS networks

Broadband Wireless Access (BWA) has attracted much interest these days for providing high speed data and multimedia services. It offers attractive fea tures such as ease and speed of deployment, fast realization of revenues, a nd low infrastructure cost, compared to other alternative broadband access technologies, for example, HFC and xDSL, Recently, standardization of the B WA network has been undertaken by various groups (IEEE 802.16, ETSI-BRAN Hi per-Access group, ITU 8A9B), The main objective has been to define the syst em architecture, as well as physical and media access control (MAC) layers of BWA networks. This paper focuses on Medium Access Control (MAC) alternatives that can fin d application in an LMDS/LMCS network capable of supporting multimedia traf fic. Multifrequency demand assignment TDMA-based schemes appear (at the mom ent) to be a suitable choice in this context. The selected protocol should be dynamically capable of providing multirate capabilities and quality-of-s ervice guarantees. An obvious candidate for the aforementioned purpose is t he LMDS-specific MAC proposal in the DAVIC 1.2 recommendation. For purposes of comparison, we also examine the evolving IEEE 802.14 MAC convergence pr otocol and MCNS (Multimedia Cable Network System) DOCSIS (ITU J-112) MAC St andard that are intended to support similar applications and services in an HFC (Hybrid Fiber Coax) environment. The three protocols are examined unde r noiseless and noisy channel conditions. Recent results on LMDS channel ch aracteristics are summarized and used for modeling noisy channel conditions . The candidate protocols are compared in terms of mean access delay, throu ghput, and collision multiplicity statistics, when contention of users is i nvolved. The effect of dynamic slot allocation on the performance of the ca ndidate protocols is also examined.