CR-MAC: A multichannel MAC protocol for cognitive radio ad hoc networks

TL;DR

This paper introduces CR-MAC, a multichannel MAC protocol for cognitive radio ad hoc networks that enhances throughput by dynamic channel switching, spectrum sensing, and temporal synchronization, while protecting primary users from interference.

Contribution

The paper presents a novel cross-layer MAC protocol that enables secondary users to efficiently utilize multiple channels in cognitive radio networks with a single transceiver.

Findings

Significantly improves network throughput in congested environments

Effectively exploits multiple channels for spectrum utilization

Protects primary users from interference even in hidden terminal scenarios

Abstract

This paper proposes a cross-layer based cognitive radio multichannel medium access control (MAC) protocol with TDMA, which integrate the spectrum sensing at physical (PHY) layer and the packet scheduling at MAC layer, for the ad hoc wireless networks. The IEEE 802.11 standard allows for the use of multiple channels available at the PHY layer, but its MAC protocol is designed only for a single channel. A single channel MAC protocol does not work well in a multichannel environment, because of the multichannel hidden terminal problem. Our proposed protocol enables secondary users (SUs) to utilize multiple channels by switching channels dynamically, thus increasing network throughput. In our proposed protocol, each SU is equipped with only one spectrum agile transceiver, but solves the multichannel hidden terminal problem using temporal synchronization. The proposed cognitive radio MAC (CR-MAC) protocol allows SUs to identify and use the unused frequency spectrum in a way that constrains the level of interference to the primary users (PUs). Our scheme improves network throughput significantly, especially when the network is highly congested. The simulation results show that our proposed CR-MAC protocol successfully exploits multiple channels and significantly improves network performance by using the licensed spectrum band opportunistically and protects PUs from interference, even in hidden terminal situations.