The Search And Implementation Of Software Radio Multi-mode Modem On FPGA

Software radio in the wireless communications known as the transition from analog communication to digital commucation again after revolution in military and civilian aspects have a wide range of application.It is a new wireless communication technology.Programmable hardware based on a common platform,the communication function as much as possible with software,making system improvements and upgrades are very convenient and easy to achieve compatibility between different communication systems.The basic idea of Software Radio is to construct a general hardware platformwith openness,standardization and modularization.The generalization of SR must bringthe multi-modularization,so the automatic multi-mode modulation recognition methodcomes into necessity to ensure correct demodulation.As a result,the automaticmodulation recognition is one of the necessary functions.How to make the method ofautomatic modulation recognition adaptive to thedemodulation method and realize theautomatic reception and demodulation is one of the key technologies and must have a wide application.In digital communication systems,all-digital receivers become more popular.It hasbecome an important technology that realizes the modulator and demodulator of communication system in digitalization method.GMSK Minimum Gaussian frequency shiftkeying is a typical continuous phase modulation method,which has the characteristics of constant envelope,compact spectrum,and anti-jamming performance.GMSK can effectively reduce inter-channel interference,improve the efficiency of non-linear power amplifier,and has been widely used in mobile system and others systems.In the GMSK modem used in the FPGA implementation of programmable logic devices,analog system flexibility not only to overcome the shortcomings of bad,and easy system modifications and upgrades.In allusion to the status mentioned above,the contents finished in the dissertationare listed as follows:1 The three Software Radio architectures were introduced and the wideband and band-passsample architecture was proved as the practical one now in the present design condition. 2 The extraction method of character parameter including envelope,frequency and phase was analyzed and three classification method of digital modulationwere also discussed.When channel condition is good,the parameter histogramdistribution method was introduced to make a statistics of the three basic characterparameters.According to the peak number,the 2ASK,4ASK,2PSK,4PSK,2FSK and 4FSK can be classified well.In the channel condition that is not so good,the decisiontheory method was adopted to extract four character parameters so that the classificationof 2ASK,4ASK,2PSK,4PSK,2FSK and 4FSK was realized.3 The recognition of modulation signals under the low SNR condition is alwaysthe important research content of signal recognition.In the dissertation,the high ordercumulants method was adopted to realize successfully the classification of 2ASK,4ASK,2PSK,4PSK,2FSK and 4FSK by extracting four character parameters based onseveral high order cumulants calculated.4 Finally Matlab carried out on software radio GMSK modulation and demodulation of the simulation,and FPGA to achieve the modulation and demodulation.