Application Of Compressive Sensing To FBMC In Cognitive Radio System

Cognitive radio (CR) is the key technology which can solve the problems of low utilization of the spectrum band and shortage of spectrum resource. In a licensed band, the main issue is the protection of the primary user, this means that the primary task in any CR network is to dynamically explore the spectrum holes and determine spectrum band that can be used without causing interference to other users. Due to the flexibility of the spectrum usage in CR, a multicarrier transmission technology in physical layer is needed. OFDM is absolutely the most prominent one, which has been developed maturely, because of the anti-multi-path interference, simple channel equalization, anti-ISI/ICI by cyclic prefix (CP) and so on. To the contrary, OFDM system still owns shortages that make its application to cognitive radio questionable for example:power leakage to outside band,cyclic prefix and so on. However, filter bank based multicarrier (FBMC), owning smaller outside band leakage, is considered as the candidate for the physical layer of CR, instead of OFDM. In this paper, firstly, we design a communication platform based on MATLAB, to simulate spectrum sensing and dynamic spectrum accessing. Then, we introduce a technology named FBMC, which can be the candidate for the physical layer of CR, instead of OFDM. At last, to solving the problem that impulse noise causing fatal degrade to the performance of multicarrier system, we propose a method based on compressed sensing to improve the immunity of FBMC signal to impulse noise.Firstly, we design a communication platform based on MATLAB, to simulate spectrum sensing and dynamic spectrum accessing. We pick up 802.11a as the the physical layer of the platform, spectrum sensing algorithm with energy detection and cyclostationary detection, and we make use of two different kinds of dynamic spectrum accessing model, a simple random accessing model and a accessing model based on learning algorithm.In view of the OFDM signal with large outside band leakage, in this paper we introduces a filter bank based multicarrier technology, FBMC inherit the advantage of multicarrier signal at the same time owning smaller outside band leakage. FBMC modulation and demodulation principle is described in detail. Then, we compare OFDM and FBMC from the aspect of outside band leakage and computation complexity. At last, we simply describe the problem which must be considered in synchronization an channel estimation.In the face of impulse noise, the performance of multi-carrier is deteriorated, in this paper, we analyze the impact of impulse noise to OFDM, and then we analyze FBMC. We introduce a method based on compressed sensing to improve the immunity of OFDM signal to impulse noise. Considering of the characteristic of FBMC, we propose a method based on compressed sensing to improve the immunity of FBMC signal to impulse noise.