Multi-Channel Opportunistic Access Based on Primary ARQ Messages Overhearing

We consider an opportunistic channel access problem over multiple primary bands. We exploit primary ACK/NAK packets overhearing to overlay secondary communications on top of permanently busy primary channels. Through the theory of multi-armed restless bandit processes (MARB), we prove optimality of the myopic policy with a simple structure that does not require channel state-transition probabilities knowledge at the secondary users under certain conditions.