Hardware-constrained multi-channel cognitive MAC

Open spectrum systems allow unlicensed secondary users equipped with cognitive radio to opportunistically access the spectrum underutilized by primary users. Cognitive radio has many advanced features, such as agilely sensing the signal of primary users and utilizing multiple spectrum bands simultaneously, etc. However, the capability of practical cognitive radios is constrained by hardware cost, resulting in partial spectrum sensing and spectrum aggregation limit. In this paper, we take such constraints into consideration and investigate efficient spectrum management in ad hoc cognitive networks with single cognitive radio. A hardware-constrained cognitive MAC, HC-MAC, is proposed to conduct accurate spectrum sensing and spectrum access decision. We identify the optimal spectrum sensing decision for a single secondary transmission pair, and formulate it as an optimal stopping problem. A decentralized MAC protocol is then proposed for the ad hoc cognitive network. Simulation results are given to demonstrate the effectiveness of our proposed protocol.