Dynamic dual threshold cooperative spectrum sensing for cognitive radio under noise power uncertainty

Abstract

The rapid development of wireless communications has brought endless new types of services or applications for human beings. The emergence of many kinds of communication equipments makes the public frequency band more and more crowded [1]. At present, most of the wireless communication systems employ fixed spectrum allocation mechanism. Only authorized users can be allowed to access the corresponding authorized spectrum resources, which will lead to inefficient usage of the licensed spectrum. From the report issued by International Telecommunication Union (ITU), there are still plenty of free spectrum resources within certain authorized bands at specific temporal and spatial scenarios. In cognitive radio (CR) system, by dynamically adjusting transmission power, carrier frequency, modulation and other parameters, SUs can utilize the spectrum holes as well as avoid interference with primary users (PUs). By applying cognitive radio technology, the SUs can fully access free authorized bands and apply suitable

Noise uncertainty effect on multi-channel cognitive radio networks

“…(c) at n=5, we observe when increasing noise by 30%,the throughput decreasing by 60%.From that we can say at n=10 ,this is the best number for CRs in this system under noise effect. Figure 5 shows a comparison with [17] under noise fluctuation β=1.3 we obtained that at t=3ms, P_f in reference system reaches to 0.55 which means it affected from noise with 30% but in our proposed system that reaches 0.43 which means it affected from noise with 14%. This means that our proposed system is better than reference system.…”

“…Studying n that represents the number of CRs in spectrum sensing. To compare this proposed system and [17] under noise fluctuation equation of the system will be Figure 1. Cognitive frame structure…”

“…Maximum throughput of the network has been studied for several numbers of optimal CR users. Ahead of the issue of threshold mismatch of energy detectors with noise power uncertainty, a cooperative spectrum sensing method with dynamic dual threshold is expressed in [17]. In [18] the optimal sensing technique has been offered maximizing channel throughput.…”

Combined Fusion Rules in Cognitive Radio Networks Using Different Threshold Strategies

“…However, the employment of hard decision reduces the accuracy of detection. To improve the performance of hard decision, two-bit scheme, i.e., softened hard decision scheme, has been developed such that detection performance improves with a little increase in the required bandwidth and complexity [18,24,25]. More details are provided below.…”

Cross Layer Based Cooperative Spectrum Sensing for Cognitive Radio Networks

“…The minimization function is used to minimize the probability of error in the spectrum. The author used the dual threshold for improving the results by considering the noise uncertainty factor in the signal [7]. The author addressed the problems of performance degradation of the licensed spectrum.…”