Stochastic medium access for cognitive radio ad hoc networks

TitleStochastic medium access for cognitive radio ad hoc networks
Publication TypeJournal Article
Year of Publication2011
AuthorsWang, X., A. Wong, and P-H. Ho
JournalIEEE Journal on Selected Areas in Communications
Pagination770 - 783
Keywordsad hoc network, ad hoc networks, clear to send, cognitive radio, dedicated control channel, Markov chain model, Markov process, medium access control design, Monte Carlo scheme, request to send, stochastic medium access

In ad hoc cognitive radio (CR) networks, medium access control (MAC) design has been raised as a major challenge due to its highly dynamic nature and strong user diversity, particularly in situations where a dedicated control channel is not reserved among the distributed CR nodes. In this paper, we propose a novel Stochastic Medium Access (SMA) scheme that takes interference constraints into account to improve spectrum sharing efficiency. Specifically, the proposed SMA scheme is developed to serve in a CR network without dedicated control channels, such that the probability of successful channel accesses can be maximized. The formulated optimization problem is then solved by using a dynamic Markov-Chain Monte-Carlo scheme. Moreover, the paper introduces a suite of mechanisms for implementation of the proposed SMA scheme, including segmentation of long packets and contention resolution, which is working on top of power controlled Request-to-Send (RTS) and Clear-to-Send (CTS) exchanges in a multichannel environment. An analytical model is developed on the proposed SMA scheme using an absorbing Markov chain model to evaluate throughput of the secondary user network. Extensive simulation is conducted to study the impact of some important factors on the proposed SMA scheme, such as channel conditions and secondary traffic loads.