Survey on Delay Analysis of Multichannel Opportunistic Spectrum Access MAC Protocols

Abstract

In this paper we provide a comprehensive delay and queuing analysis for two baselines medium access
control protocols for multi-user cognitive radio networks with homogeneous users and channels and investigate the impact
of different network parameters on the system performance. In addition to an accurate Markov chain, which follows the
queue status of all users, several lower complexity queuing theory approximations are provided. Accuracy and
performance of the proposed analytical approximations are verified with extensive simulations. It is observed that using an
Aloha-type access to the control channel, a buffering MAC protocol, where in case of interruption the CR user waits for
the primary user to vacate the channel before resuming the transmission, outperforms a switching MAC protocol, where
the CR user vacates the channel in case of appearance of primary users and then compete again to gain access to a new
channel. The reason is that the delay bottleneck for both protocols is the time required to successfully access the control
channel, which occurs more frequently for the switching MAC protocol. It is thus shown that a clustering approach, where
users are divided into clusters with a separate control channel per cluster, can significantly improve the performance by
reducing the competitions over control channel.