Clear channel assessment in energyconstrained wideband wireless networks

This is intended as a tutorial review of the clear channel assessment (CCA) component of typical data link layers in wideband wireless networks that employ some form of channel sensing as part of their medium access mechanism. While channel sensing - the core component within CCA module - is implemented at the physical layer, its primary impact is on MAC throughput and energy efficiency, and this impact has not yet been adequately highlighted in the existing literature. We provide a description of CCA methods for wideband wireless networks like IEEE 802.11 and IEEE 802.15 followed by illustrations of their impact on the respective MAC protocols. We also demonstrate the need for a cross-layer consideration of MAC and CCA to optimize the performance of CSMA protocols.