Optimization of a Decentralized Medium Access Control Scheme for Single Radio Cognitive Networks
The medium access control (MAC) of decentralized cognitive radio networks has been a topic of interest in the last years due to the lack of a central coordinator and the necessity of self-organizing procedures that effectively lead the nodes to act autonomously but efficiently. This work addresses a scenario where multiple non-licensed cognitive radios communicate with an access point when licensed users do not use the spectrum. We consider a MAC protocol for the non-licensed users which uses a double stage to schedule each node’s transmission. Non-licensed users perform spectrum sensing in a synchronous way and the proposed MAC is opportunistically employed when the channel is sensed idle. In the first stage the number of competing non-licensed nodes is decreased to reduce the number of collisions. In the second stage we adopt a reservation procedure to schedule the non-licensed users competing for the medium. Adopting a traditional energy-based sensing, we characterize the performance of the considered protocol by capturing the influence of the sensing in the MAC’s performance. Finally we present several results to evaluate the performance of the proposed scheme achieved in optimal conditions, which are compared to a cognitive ”slotted-aloha”-like protocol. The obtained results demonstrate the effectiveness of the proposed solution.
KeywordsCognitive Radio Distributed Medium Access Control Performance Analysis
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