Improved Spectrum Access Control of Cognitive Radios Based on Primary ARQ Signals
Cognitive radio systems capable of opportunistic spectrum access represent a new paradigm for improving the efficiency of current spectrum utilization. In this paper, the authors present a novel cognitive channel access method based on learning from both primary channel transmissions and the receiver ARQ feedback signals. This new sensing-plus-confirmation scheme constitutes a non-trivial generalization of the more traditional "Listen-Before-Talk" (LBT) strategy that merely listens to and yields to primary transmissions regardless of primary receiver responses. Their new method exploits the bi-directional and interactive nature of most wireless communication links to facilitate better opportunistic secondary access while achieving primary receiver protection.