Date Added: Jun 2010
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.