  One of the major challenges in the medium access control (MAC) protocol
design over cognitive Ad Hoc networks (CAHNs) is how to efficiently utilize
multiple opportunistic channels, which vary dynamically and are subject to
limited power resources. To overcome this challenge, in this paper we first
propose a novel diversity technology called \emph{Multi-Channel Diversity}
(MCD), allowing each secondary node to use multiple channels simultaneously
with only one radio per node under the upperbounded power. Using the proposed
MCD, we develop a MCD based MAC (MCD-MAC) protocol, which can efficiently
utilize available channel resources through joint power-channel allocation.
Particularly, we convert the joint power-channel allocation to the
Multiple-Choice Knapsack Problem, such that we can obtain the optimal
transmission strategy to maximize the network throughput through dynamic
programming. Simulation results show that our proposed MCD-MAC protocol can
significantly increase the network throughput as compared to the existing
protocols.
