Design And Implementation For Signal Detection And Recognition In Cognitive Radio

In recent years, cognitive radio has been attached a growing emphasis by academic and IEEE standards organization. At the same time, cognitive radio was known as a'next big event'in the future of wireless communication field. Cognitive radio as a smart radio technology was concerned not only by academics but also industrial circles. Its role is mainly reflected in several aspects as follows. First of all, cognitive radio enhances the capacity of communications systems by dynamic use of spectrum resources. Secondly, cognitive radio greatly enhances the flexibility and efficiency of spectrum management of communication system through sensing the electromagnetic environment, simultaneously detecting available spectrum in the bandwidth required for own communication systems and automatically and reasonably allocating spectrum resources. Thirdly, cognitive radio find a fundamental solution to the problem of interconnection of communications equipment through the use of existing software radio technology to quickly configure with different communicate network protocols and services to support the fundamental solution to the communications system.Based on the above important role of cognitive radio in communication, it has a great significance to design and implement a set cognitive radio system whose features and performance can meet the certain communication needs. On the basis of extensive investigation and research of cognitive radio and functional requirements of system, this paper gives overall software platform architecture of cognitive radio system and finishes the design and implementation of the spectrum sensing module, the direct sequence spread spectrum signal detection module and the signal modulation recognition module. Simulation results show that signal detection and recognition module is reasonably practicable and the test results meet the system requirements.The main work done and results are as follows:1) Gives the demand analysis of cognitive radio systems and designs the overall program of system;2) Investigates existing spectrum sensing techniques, designs and implements the spectrum sensing module of the system, and gives the test results;3) A decision method based on peak-to-average ratio was proposed in the autocorrelation detection algorithm in time domain for direct sequence spread spectrum signal detection, designs and implements direct sequence spread spectrum signal detection module of system, and gives the test results;4) Investigates existing modulation recognition algorithm and takes the breadth of modulation recognition, signal to noise ratio tolerance and computational complexity into consideration; designs and implements modulation recognition module of system, and test results are given;5) Finally, the thesis shows the deficiencies of the speech recognition modules and the goals in the future.