ABSTRACT

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Abstract-Spectrum sensing is an important functional unit of the cognitive radio networks. The spectrum sensing is one of the main challenges encountered by cognitive radio. This paper presents a survey of spectrum sensing techniques and they are studied from a cognitive radio perspective. The challenges that go with spectrum sensing are reviewed. Two sensing schemes, namely; cooperative sensing and eigenvalue-based sensing are studied. The various advantages and disadvantages are highlighted. Based on this study, the cooperative spectrum sensing is proposed for employment in spectrum sensing in wideband based cognitive radio systems.

Cognitive radio networks has been known to be a technique to enhance the utilization of spectrum, where a secondary user can utilize the spectrum of a primary user without causing harmful interference. This paper we have presents an interference model implementing power, contention and hybrid control management schemes. Furthermore; we have investigated how the hidden primary receiver problem on affects the three schemes. The power and contention control scheme were assessed analytically. However, the hybrid scheme was analyzed numerically. The results presented in this paper show the sensitivity of the power control method to the radius of interference region when compared to the results obtained from the contention and the hybrid control schemes. Finally, we examined the effects of the hidden primary user on the interference.

Abstract-Due to the ever growing need for spectrum, the cognitive radio (CR) has been proposed to improve the radio spectrum utilization. In this scenario, the secondary users (SU) are permitted to share spectrum with the licensed primary users (SU) with a strict condition that they do not cause harmful interference to the cognitive network. In this work, we have proposed an interference model for cognitive radio network that utilizes power or contention control interference management schemes. We derived the probability density function (PDF) with the power control scheme, where the power of transmission of the CR transmitter is guided by the power control law and also with contention control scheme that has a fixed transmission power for all CR transmitter controlled by a contention control protocol. This protocol makes a decision on which CR transmitter can transmit at any point in time. In this work, we have shown that power and contention control schemes are good candidates for interference modeling in cognitive radio system. The impact of the unknown location of the primary receiver on the resulting interference generated by the CR transmitters was investigated and the results shows that the challenges of the hidden primary receivers lead to higher CR-primary interference in respect to higher mean and variance. Finally, the presented results show power control and the contention control scheme are good candidates in reducing the interference generated by the cognitive radio network.