  In Cognitive Radio (CR) ad hoc networks, secondary users (SU) attempt to
utilize valuable spectral resources without causing significant interference to
licensed primary users (PU). While there is a large body of research on
spectrum opportunity detection, exploitation, and adaptive transmission in CR,
most existing approaches focus only on avoiding PU activity when making sensing
decisions. Since the myopic sensing strategy results in congestion and poor
throughput, several collision-avoidance sensing approaches were investigated in
the literature. However, they provide limited improvement. A channel-aware
myopic sensing strategy that adapts the reward to the fading channel state
information (CSI) of the SU link is proposed. This CSI varies over the CR
spectrum and from one SU pair to another due to multipath and shadow fading,
thus randomizing sensing decisions and increasing the network throughput. The
proposed joint CSI adaptation at the medium access control (MAC) and physical
layers provides large throughput gain over randomized sensing strategies and/or
conventional adaptive transmission methods. The performance of the proposed
CSI-aided sensing strategy is validated for practical network scenarios and
demonstrated to be robust to CSI mismatch, sensing errors, and spatial channel
correlation.
