The Realization Of Multi Rate Modem Based On FPGA

With the development of new technology of wireless communication and keen need for high speed data services, the shortage of spectrum resources is becoming increasingly serious. What's more, the shortage of wireless spectrum resources has become the bottleneck of the development of the advanced wireless technology .Cognitive radio technology has changed the way of the traditional government-authorized use of the radio spectrum, which is with the aim at efficiently utilizing the spectrum.In order to improve the efficiency of the spectrum utilization, it provide non-authorized users the opportunity to use transmission spectrum that authorize users have not used temporally and geographically. The main objective of this thesis is implementing the conmmunication based on cognitive radio technology by using software programming based on the platform of FPGA + DSP .Software wireless radio is an ideal platform for implementing Cognitive radio technology. This thesis describes the basic theory and main algorithms of software wireless radio at first. Then the technologies of interpolation extraction, bandpass sampling, digital conversion in the multi-rate signal processing which are the basic ideas for designing the system of modulation and demodulation are analyzed. Then the flatform of system hardware based on the platform of DSP+FPGA with the aid of the software radio is introduced. Some parts of the hardware and their initialization are described which is followed by a study of modem technology, including the basic concepts and principles ofπ/4-DQPSK, 8PSK, 16QAM. Based on the program of the three modem system, their detailed process and data which is from debugging are given. Finally, we introduce how to choose mode ofπ/4-DQPSK, 8PSK, 16QAM adaptively with the help of the spectrum sensing broad and how to realizing the FPGA part of the process.