The Study And Implementation Of Adaptive Codec In Cognitive Radio

With the development of wireless communication, the wireless spectrum resources are becoming deficient, which becomes a new bottleneck of restricting the development of the wireless communication. This has given birth to cognitive radio, which can sense its environment to get the useful spectrum and use it to communication without interrupting the primary user. But the characteristic of bandwidth detected by the cognitive radio is multiplicity. All of these request an adaptive and reconfigurable communication module.The paper firstly introduces the developing process, the basic principles and key technologies of cognitive radio. Based on software radio, a project to realize a reconfigurable communication module of the cognitive radio is introduced. And the paper lays emphasis on the implementation of adaptive and reconfigurable codec. The cognitive system consists of cognitive module, communication module and radio module. My duty is to research on and realize the communication module on DSP+FPGA hardware platform. Then we introduce the design of the adaptive and reconfigurable codec in detail based on the platform. Finally, the test of the adaptive and reconfigurable codec in cognitive system is shown and some suggests will be given to improve the codec. We realize the MAC layer protocol in the communication module in detail based on DSP, and the adaptive and reconfigurable codec based on puncturing and de-puncturing on DSP+FPGA. The work of DSP in communication module is to exchange data with the cognitive module, to recognize and process the command and data from the radio module. In DSP+FPGA, we have realized adaptive modem with variable modulation, variable bandwidth and variable rate codec to meet the requirements of the cognitive system about its adaptive and reconfigurable capacity.