Research On Technology In Cognitive Radio Receiver System Based On Wireless Optical Access Network

Due to the fast development of communication system and the enlarging size of the mobile users, the traditional allocation of frequency zone is an obstacle to the sustainable development of communication industry. In this circumstance, the Cognitive Radio, which is an intelligent sharing technology on the frequency and takes full use of the whole frequency span, appears as an effective solution.This paper discussed the cognitive radio system and focused on the related technologies in the receiver for military use, such as the frequency detection algorithms and how to recognize the modulation types. And a novel recognition method is provided based on the cyclostionarity algorithm, and this method is available for both analogy and digital signals. The recognition method is made of three parts. The first part is the implement of the Cyclic Autocorrelation Density (CAD) in project level, in which the FAM is decided to use finally by comparing several methods. And the second part is the feature extraction, in which 6 feature vectors were finally extracted from the CAD by serious analysis, such as the spectrum line number and standard deviation value. In the final part, the extracted feature vectors are inputted into SVM classifier which has trained by a large amount of samples previously, and the corresponded modulation type is outputted. In experiment, there are 10 sorts of modulated signal with Signal-Noise-Rate from 9dB to 13dB emulated, which are AM, DSB, SSB, BPSK, QPSK, BFSK, QFSK, MSK,16QAM and ASK. The result is satisfying and the accuracy reaches expressively 97.5%, which proves the effectiveness of this method.In the paper, the related technologies in optical access network, which is based on the radio-over-fiber (ROF), are explored. And the network deployment solution is offered, by combining the optical access network and cognitive radio network. The bandwidth of access network is always the bottleneck problem to the whole mobile communication network. However, the deployment solution can successfully solve this problem and bring the system many other merits, such as immunity to the radio frequency interference, low power consumption, low attenuation loss, easy installation and maintenance and so on.In the last part of the paper, the whole cognitive radio receiver system design and the process procedure are introduced. The system is separated into several modules which are examined both in technology choice and in process procedure.