Analytical Modeling of Medium-Access Delay for Cooperative Wireless Networks Over Rayleigh Fading Channels

CoopMAC has been recently proposed as an efficient medium-access-control (MAC)-layer protocol for cooperative wireless networks. This protocol allows high-data-rate terminals to assist low-data-rate terminals by relaying their data. The backward compatibility of this protocol with well-known distributed local area networks (LANs), its adaptable functionality, and its capability to flatten the received signal-to-noise ratio (SNR) level over time make CoopMAC a desirable choice for cooperative communications. In spite of the prevalence and importance of this protocol, not enough attention has been paid to this protocol so far. Therefore, in this paper, we develop an analytical model to evaluate the performance of this protocol. Our proposed model is centered around a 2-D Markov chain, similar to that introduced by Bianchi for IEEE 802.11. This model empowers us to derive the probability density function (pdf) of medium-access delay in CoopMAC from which any higher statistical moments can be obtained. Using this obtained pdf, both local and global network performance metrics can be improved.