STiCMAC: A MAC Protocol for Robust Space-Time Coding in Cooperative Wireless LANs

TL;DR

STiCMAC is a decentralized MAC protocol that enables multiple relays to transmit simultaneously using randomized distributed space-time coding, significantly enhancing throughput and robustness in mobile cooperative wireless LANs.

Contribution

This paper introduces STiCMAC, a novel MAC protocol utilizing R-DSTC for efficient multi-relay cooperation with minimal coordination in mobile wireless networks.

Findings

Network capacity is significantly improved.

Delay performance is enhanced in mobile environments.

Protocol is robust to channel variations and user mobility.

Abstract

Relay-assisted cooperative wireless communication has been shown to have significant performance gains over the legacy direct transmission scheme. Compared with single relay based cooperation schemes, utilizing multiple relays further improves the reliability and rate of transmissions. Distributed space-time coding (DSTC), as one of the schemes to utilize multiple relays, requires tight coordination between relays and does not perform well in a distributed environment with mobility. In this paper, a cooperative medium access control (MAC) layer protocol, called \emph{STiCMAC}, is designed to allow multiple relays to transmit at the same time in an IEEE 802.11 network. The transmission is based on a novel DSTC scheme called \emph{randomized distributed space-time coding} (\emph{R-DSTC}), which requires minimum coordination. Unlike conventional cooperation schemes that pick nodes with good links, \emph{STiCMAC} picks a \emph{transmission mode} that could most improve the end-to-end data rate. Any station that correctly receives from the source can act as a relay and participate in forwarding. The MAC protocol is implemented in a fully decentralized manner and is able to opportunistically recruit relays on the fly, thus making it \emph{robust} to channel variations and user mobility. Simulation results show that the network capacity and delay performance are greatly improved, especially in a mobile environment.