Spectrum Sensing With Active Cognitive Systems
Spectrum sensing is critical for cognitive systems to locate spectrum holes. In the IEEE 802.22 proposal, short quiet periods are arranged inside frames to perform a coarse intra-frame sensing as a pre-alarm for fine inter-frame sensing. However, the limited sample size of the quiet periods may not guarantee a satisfying performance and an additional burden of quiet-period synchronization is required. To improve the sensing performance, the authors first propose a quiet-active sensing scheme in which inactive Customer-Provided Equipments (CPEs) will sense the channels in both the quiet and active periods.