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A New Adaptive Sensing Scheme for Low SNR and Random Arrival of PU Environment

Xianzhong Xie, Ting Song, Bin Ma, and Xiaofeng Hu
Chongqing Key Lab of Mobile Communications Technology, Chongqing University of Posts and Telecommunications, Chongqing 400065, China

Abstract—Cognitive radio (CR) networks facing with difficulties caused by the low SNR environment and the random arrival of primary users (PUs) application traffic. The existing studies focus on the unilateral processing on weak PU signal or random departure/arrival of PU problems. In this paper, we propose an adaptive sensing scheme which is applicable under certain adverse conditions by jointly optimize sensing and transmission period. At first the adaptive sensing state model is established. On this basis, secondary users (SUs) perform collaborative detection in the sensing period and an optimal sensing duration is determined to obtain adaptability and detection reliability. At the end of each period, a decision-making system predicts PU’s activity based on the previous observations and adaptively chooses whether to perform spectrum sensing, data transmission or channel switching. Both the impact of non-ideal sensing and the imperfect ACK/NACK feedback are being fully considered when designing the decision-making algorithm. Numerical results show that our optimal scheme significantly increases SU utility while avoiding interference to PU in the adverse environment, and it reduces detection difficulty and computational complexity.

Index Terms—Cognitive radio, low SNR, random departure/arrival of PU, POMDP, adaptive spectrum sensing

Cite: Xianzhong Xie, Ting Song, Bin Ma, and Xiaofeng Hu, "A New Adaptive Sensing Scheme for Low SNR and Random Arrival of PU Environment," Journal of Communications, vol. 9, no. 3, pp. 262-270, 2014. Doi: 10.12720/jcm.9.3.262-270