Decentralized Cognitive MAC Based on Exploitation of Spatio-temporal Knowledge

0 pages , March 2006.

NESL Technical Report #: TR-UCLA-NESL-200603-04

We propose a decentralized MAC protocol for wireless networks that utilizes multiple frequency channels. This protocol allows users to optimize their local spectrum usage via intelligent channel selection. Channel selection takes place based on the spatio-temporal knowledge of each wireless node. Channel quality metrics that give a reliable metric for optimal channel selection are computed and updated for each of the frequency channels. This protocol requires only one transceiver per node and uses temporal synchronization between nodes to avoid the multi-channel hidden terminal problem. It also enables secondary users to opportunistically utilize the primary frequency channels. We describe the design of this protocol and further analyze its performance using simulation. We have compared the performance of our protocol with other multi channel MACs such as MMAC and DCA. Simulation results show that our scheme improves network throughput significantly. We also simulate our protocol when there are primary users transmitting their packets. The results show that secondary users can opportunistically switch their channels to the primary channels and increase the throughput of network.

• Sadaf Zahedi
• Mani B Srivastava

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• SDR : Software Defined Radio Research

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