Design And Performance Analysis Of M-ary Orthogonal Code Spread Spectrum Scheme In Millimeter Wave Communication

With the development of wireless communication technology,5G communication has become the hotspot.Meantime,millimeter wave communication technology is considered as one of the key technologies of 5G communication.To improve spectral efficiency and transmission performance,we propose a novel M-ary orthogonal spread spectrum millimeter wave communication scheme.We construct the transmission symbols with different pseudo-random sequences,analyze the bit error performance in AWGN channel and different fading channels.The simulation results demonstrate the advantages of the proposed system scheme.The main contribution can be concluded as follows:(1)On the basis of summarizing the spread spectrum communication techniques,a novel M-ary orthogonal spread spectrum millimeter wave communication scheme is proposed.In the proposed communication scheme,the M-ary orthogonal codes are constructed by cyclic shift processing on the basic pseudo-random sequence,which simplify the complexity of the receiver.The advantage of transmission scheme is proved by theoretical analysis and simulation experiments.The effects of different cyclic shift lengths and different M values on the bit error rate at the receiver are verified.We also analysis and compare the BER performance of the M-ary orthogonal signal group with different spread spectrum codes in AWGN channel.(2)We summarize several common fading channels and their respective distribution characteristics.The transmission performance of M-ary orthogonal spread spectrum millimeter wave signal is analyzed in detail in AWGN channel,Rayleigh fading channel and Nakagami-m fading channel.We derive the transmission bit error rate expression in a closed form and conduct the numerical simulation using MATLAB.(3)Maximum-Ratio Combining(MRC),Equal-Gain Combining(EGC)and Selective Combining(SC)are introduced in the thesis,considering the reception performance of the signal in the fading channel.After that,the bit error rate expressions of M-ary orthogonal spread spectrum millimeter wave signal under different diversity reception techniques are deduced in theory.The bit error ratio expression in closed form is obtained,and the numerical simulation is conducted in MATLAB.Finally,the advantages and disadvantages of the above methods are discussed.(4)We summarize the research work in the thesis,point out the shortcomings of the work,and propose the direction for future works.