Modulation Of The Wireless Communication Systems And Software Radio

Zhang Xiaozhen (Communication and Information System)Directed by Wang zhensongThe inter-symbol interference in wireless communication systems and the software radio were studied in this thesis.The OFDM system was studied widely in the modern wireless systems. A general system module of the OFDM system in Non-frequency Rayleigh Channels, which is a practical system suited for wireless communications, was proposed in this paper. We analyze the effect of fading channels and noises on the system performance with QAM, propose the formula and draw conclusions.The technique of the Linear Frequency Modulation was proposed to solve the problems of the inter-symbol interference in this paper. For comparing with other modulation techniques, we analyze the BER , and present the simulation results. The theoretical prediction and the simulation results indicate that the Linear FM is very useful to depress the inter-symbol interference. The high transmitting speed is holding in some areas where the average of the multi-path time dispersion is larger. Merits of the Linear FM are that it is not necessary to have an equalizer or the spread spectrum code modulation.The architecture of the software radio for studying the communication technique was proposed in this thesis. This architecture uses DSP and CPLD to achieve the modulation scheme, protocols, equalization etc.