Improved Energy Detection Spectrum Sensing Method for OFDM-Based Cognitive Radio System
The spectrum sensing scheme which is used for detecting primary users in a licensed spectrum are essential to utilize the spectrum effectively for cognitive radio communication systems. As a matter of fact, sensing accuracy is regarded as the most importa
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Improved Energy Detection Spectrum Sensing Method for OFDM-Based Cognitive Radio System Min Jia, Hao Yang, and Xuemai Gu
Abstract The spectrum sensing scheme which is used for detecting primary users in a licensed spectrum are essential to utilize the spectrum effectively for cognitive radio communication systems. As a matter of fact, sensing accuracy is regarded as the most important factor for spectrum sensing with the intension of sufficient protection for the primary user. A novel spectrum sensing scheme which exploits the cyclic prefix of an orthogonal frequency-division multiplexing (OFDM) symbol as well as idle period containing no information symbols is proposed in this chapter. From the analysis and simulation results, it shows that the proposed scheme can improve sensing accuracy and increase system throughput compared with the conventional scheme which uses only idle period. Keywords OFDM • Cognitive radio • Cyclic prefix • Energy detection
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Introduction
The rapid growth of wireless services and devices tends to exhaust the available radio spectrum. Consequently, cognitive radio technology has been suggested with an effort to use the spectrum more efficiently [1]. A cognitive radio system that can learn from and adapt to the external radio environment potentially maximizes the spectrum utilization. Since the secondary user is required to return the occupied spectrum whenever the primary user appears, thus it is necessary that the secondary user can sense the availability of the licensed spectrum periodically. OFDM is a newly appearing transmitting technique, by dividing the channel into several orthogonal sub-channels, the signal is transmitted in some of the sub-channels.
M. Jia (*) • H. Yang • X. Gu (*) Communication Research Center, School of Electronics and Information Engineering Harbin Institute of Technology, Harbin 150001, China e-mail: [email protected]; [email protected]; [email protected] Q. Liang et al. (eds.), Communications, Signal Processing, and Systems, Lecture Notes in Electrical Engineering 202, DOI 10.1007/978-1-4614-5803-6_13, # Springer Science+Business Media New York 2012
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This transmitting method boasts lots of advantages like high efficiency of spectrum exploit, restrain of multi-path interference and easy to be realized in hardware layer. Nowadays, the OFDM is becoming the most prevalent technique in cognitive radio system. Applying the OFDM in cognitive radio will bring benefits in shaping the spectrum so as to make the secondary user be easy to access the available spectrum and enhance the efficiency of the whole system in spectrum usage. There are plenty of schemes for spectrum sensing. And the performance of sensing scheme is mainly depended on the sensing time as well as the accurate. The traditional energy detection scheme does not require any information of the primary user and has a relatively short sensing period, making it one of the most popular spectrum sensing method in usage. In [2, 3], Zengyou Sun and Refik Fatih made some
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