Energy/bandwidth-saving cooperative spectrum sensing for two-hop WRAN

A two-hop wireless regional area network (WRAN) providing monitoring services using Television White Space (TVWS), i.e., IEEE p802.22b, is now under development. A great number of subscriber customer-premises equipments (S-CPEs) may be connected to a base station with relaying of a relay CPE (R-CPE) in p802.22b. Cost-effective and power-saving S-CPEs are needed due to the its large volume and the possibility of absence of main power supply. This paper proposes cooperative spectrum sensing (CSS) employing energy detection to IEEE p802.22b. With the proposal, a number of S-CPEs are instructed to cooperatively sense TV channels and a R-CPE serves as fusion center. We further propose that when an S-CPE without upstream detects the presence of primary users it does not report to the R-CPE if it detects a signal-to-noise ratio (SNR) less than a pre-defined threshold, for purpose of saving energy and bandwidth consumption. Numerical results show that with the proposed energy/bandwidth-saving scheme the fused error probability changes very little while the fused miss-detection probability and false alarm probability are lower than 10% that is required by 802.22. With 10 S-CPEs participating CSS, it is possible to save more than 40% of the energy/bandwidth in a Rayleigh fading channel.