The Study And Implementation Of Adaptive Modem In Cognitive Radio

With the development of wireless communication, the wireless spectrum resources are becoming deficient along with the requirement of the ever-increasing data transmission. Cognitive Radio can sense its environment, learn from the environment and then alter its power, frequency, modulation and other parameter to dynamically reuse available spectrum. But the characteristic of bandwidth detected by the Cognitive radio is multiplicity. All of these request an adaptive and reconfigurable communication module.Firstly, the paper introduces the developing process, the basic principles and key technologies of cognitive radio. Software radio is an ideal platform for implementing the cognitive radio. Based on Software radio, a project to realize a reconfigurable communication module of the cognitive radio is introduced. Then interpolation and decimation in multi-rate signal processing, sampling, digital up/down converter, and digital filtering are discussed, which is the key technologies of Software radio. The communication platform of the Cognitive radio system based on DSP+FPGA is studied; we will discuss the modem technology and the digital up/down converter in detail based on FPGA. According to these results, the project to demonstrate the Cognitive radio and the adaptive modem with variable modulation and variable bandwidth will be given. After this, we will get the data from the NCO and demodulator, analyze it and get the result of the performance evaluation. Finally, some suggests will be given to resolve the problem of the project.