Study On The Space-Time Coding For Frequency And Time Selective Fading Channels

As a key technique of Generation 4 wireless mobile communication, Space-TimeCoding (STC) combines the channels coding and transmission diversity, and it couldachieve high-rate and credibility data transmission without increasing transmissionpower and expanding bandwidth. When the signal is transmitted in the freedom space, itcould suffer from the influence of landform, weather and high speed move of the mobileend, which results in many kinds of fading, and the quality of the wirelesscommunication falls severity. So it is necessary to investigate the space-time codingmethod for fading channels.The concept of the space-time coding was brought forward in 1996. From then on,researchers have devoted themselves to investigation on the space-time coding for flatfading. But in practice wireless communication system the signal suffers from theinfluence of multi-path spread and Doppler spread, so the fading is not always the idealflat fading. In this thesis, the model of the frequency selective fading channels and timeselective fading channels is studied. The improved space-time coding scheme ofselective fading channels is put forward, and their performance is compared to that ofthe existing schemes.This thesis mainly consists of the following research works.The three space-time schemes of the frequency selective fading channels such asthe orthogonal frequency-division multiplexing space-time block coding, frequencydomain equivalence space-time block coding and time-reverse space-time block codingare systematically discussed and compared. The process of coding and decoding of thefrequency domain equivalence space-time block coding is formulated in the form ofmatrix.Two new space-time schemes of the time selective fading channels is proposed.One is based on the double differential coding, which chooses a group of orthogonalspreading sequences as the weight of the STC transmit array. The receiver suppressesinterferences from other antennas by the orthogonality of the transmitted signals.Another uses the fuzzy Kalman filter to estimate the parameters of the time-varyingchannels. Simulation results illustrate that these two new schemes achieve goodperformance.The existing space-time schemes of the time-frequency selective fading channelsare analyzed briefly, and the bit error rate, the difficulty of coding and decoding and thecomplexity of the implementation are studied. The performance of space-time coding...