Frequency Multiplexed Spectrum Sensing for Enhanced Primary User Protection

Robust spectrum sensing techniques are required to maximize wireless spectrum utilization by secondary cognitive radio users while protecting the primary licensed users from any undesired interference. Existing spectrum sensing techniques assume a time multiplexed frame structure, where the first part of the frame is for spectrum sensing and the rest of the frame is reserved for secondary user data transmission. Our results show that in the practical scenario, when accurate time synchronization between primary and secondary users is not available, time multiplexed sensing fails to provide the required protection for primary users. We propose a novel frequency multiplexed cognitive radio frame structure for enhanced primary user protection in case of asynchronous secondary user operation. We optimize our proposed frame structure to maximize the secondary user throughput while not affecting the primary user throughput. Our results show that our proposed spectrum sensing technique is robust to time misalignment.