An Overview Of Cross-Layer Based Design Of Media Access Control (Mac) For Cdma Ad-Hoc Networks

Decentralized ad-hoc networks are plagued with the problem of low network capacity at high traffic load or high node density. Recent proposals on CDMA ad-hoc networks propose to alleviate this problem and in addition, provide benefits of Spread Spectrum (SS) communication. These proposals follow a cross-layer based approach to Media Access Control (MAC) layer design, and exploit the link-layer properties in conjunction with dynamic power control to enhance system capacity. These protocols provide a promising solution to increase throughput in a single hop neighborhood as compared to widely accepted CSMA/CA based protocols like 802.11. A cross-layer design framework which uses spread spectrum/CDMA and power control techniques in physical layer as well as in link layer provides a more optimized approach to increase network capacity. Multiple simultaneous transmissions in such protocols are supported on the basis of interference level considerations in the network. In this review article, we discuss some proposals on issues of power control and CDMA based MAC in ad-hoc networks with a greater focus on interference measurement problems in a distributed scenario. We provide a qualitative comparison of the approaches and investigate opportunities for future research.