Dissertation
Dissertation > Industrial Technology > Radio electronics, telecommunications technology > Wireless communications > Radio relay communications,microwave communications

A Research on Spectrum Sensing in Cognitive Radio Over Short Wave Channel

Author QianFeng
Tutor LinJiMing
School Guilin University of Electronic Science and Technology
Course Communication and Information System
Keywords Cognitive Radio Spectrum Sensing Short-wave Channel
CLC TN925
Type Master's thesis
Year 2011
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Short-wave communication is widely used with its long-distance communication and easy network erection. But with the rapid growth of services, current short-wave communication networks are facing the problem of spectrum shortage. Cognitive radio(CR) is one of the today’s leading communication technologies. CR can interact with its surrounding electromagnetic environment. By changing its own parameters, CR can allow unauthorized users to share the authorized spectrum without causing interference to primer users. Therefore, CR can effectively improve the short-wave communication network’s spectrum efficiency and reliability. Spectrum sensing is one of the key technologies of cognitive radio. The majority of current studies of spectrum sensing target to fading channels, such as Rayleigh and Nakagami, while the study of sensing algorithm specifically for the short-wave channel is still in the initial stage. Hence how to achieve quick and accurate detection of prime user over short-wave channel is becoming an urgent problem to be solved at this stage.This thesis mainly focuses on the research of spectrum sensing technologies over short-wave channel. The study of single-node and multi-node spectrum sensing schemes based on the improved Watterson channel model are presented in the article.Firstly, a survey of characteristics of short-wave channel and its influence on the signal is given in the article and an improved Watterson model is also introduced to the follow-up investigation. Secondly, energy detection algorithm and cyclostationary feature detection algorithm in single-node architecture are analyzed and their performances over short-wave channel are obtained. Then a dual dynamic thresholds algorithm combining the merits of the previous two algorithms is proposed for noise uncertainty may exist in short-wave channel. It can adjust the thresholds adaptively to achieve the required detection requirements, and the simulation verifies that the new algorithm, compared to the classical ones, can achieve good detection performance with smaller computational complexity. According to IEEE 802.22 standard requirements for feature detection, a low complexity digital signal blind recognition algorithm combing characteristic parameters is offered in the paper. Finally, The collaborative sensing algorithms based on AND and OR fusion rules in multi-node architecture are studied, then two improved algorithms on the basis of SNR reliability and SNR weight combing cognitive node’s SNR status based on AND hard-decision algorithm are introduced; and a modified dual-threshold algorithm with the thought of threshold optimization based on OR hard-decision algorithm is also offered in this paper. The better detection performances of improved algorithms applied in cognitive networks over short-wave channel are acquired, which is proved by the simulation.The result of this paper contributes to further study of the spectrum sensing algorithms’performances over short-wave channel, and it also provides valuable references for future engineering application.

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