Simulation On Slow Frequency Hopping System Over Multipath Fading Channels

With the development of wireless communication technology and the accelerated process of information globalization, a lot of convenience has brought to mankind. At the same time, the growing frequency interferences generated by various electronic products had become more seriously. So signal communication bands are constantly exhausted. In this case, the development of wireless communications technology tends to on how to improve the anti-jamming performance. Frequency hopping spread spectrum communication is a kind of spread spectrum communication technology, which by "randomly" changing the signal carrier frequency, to escape it away from interference.Firstly, the research background and the development of frequency hopping technology, especially the research and development of slow frequency hopping(SFH) communication technology have been introduced in thesis. Secondly, a brief introduction of the basic principle for frequency hopping communication technologies, system architecture and the main parameters affecting the performance are presented. Then, the wireless channel, especially on frequency selective fading channel of small-scale fading channels is described in detail. And finally, the worst case of ISI impact on the signal bit error rate in slow frequency-hopping MFSK communication system (SFH/MFSK) in multipath Rayleigh fading channel is analyzed theoretically.System simulation is based on MATLAB7.1 platform. The simulation framework of SFH/MFSK communication system is given and a detailed description of the important modules is presented.The BER performances of SFH/MFSK system under AWGN channel and multi-path fading channel are simulated respectively The simulation results shown that the BER performance of SFH/MFSK system is affected badly by the index M in FSK modulation, but affected slightly by the size of frequency set K and the number of transmission symbol in each hop L over AWGN channels. The simulation results also shown that the BER performance of SFH/MFSK system influence heavily by the parameters M, K and L on multipath fading channels, especially the multipath delay.In order to study how influence the system performance by multipath delay, an ideal model is given by receiver. The simulation results show that the BER performance is improved significantly by that model. Above all works have given a better basis for study the performance of quasi-synchronous frequency hopping systems over multipath fading channels.