Research On Application Of High Spectrum Efficiency Non-orthogonal Signal In Wireless Communication

With the development of science and technology and the improvement of quality of life,people will also have a sharply increasing demand for the quality and data transmission rate of mobile communication networks.At present,the spectrum resources of mobile communications are very limited,the higher data rate means that we need a wider spectrum,which has always been a major contradiction that constrains the development of communications.In order to transmit more data in the limited spectrum resources which increases the transmission data rate in the same spectrum bandwidth,we need to use more effective signals to improve the spectrum efficiency.In order to improve the bit sent in unit time and improve the spectral efficiency,highorder modulation and MIMO technology are used.With the increase of modulation order,the distance between constellation symbols becomes smaller and the error tolerance between symbols will be reduced,so that the performance of the system will be reduced.MIMO technology needs multiple antennas,while terminal equipment has fewer applications due to factors such as size and power consumption.Overlapping time division multiplexing can improve the efficiency of transmission and spectrum efficiency by compressing the time interval of pulse shaping transmission.This kind of non orthogonal signal is the focus of this paper.Firstly,in this paper,We will elaborate the principle of overlapping time division multiplexing system is introduced in detail.Overlapping time division multiplexing can be equivalent to a convolutional encoder at the transmitter,maximum likelihood detection can be used at the receiver,such as the Viterbi decoding algorithm and the maximum posterior probability decoding algorithm to recover the information sent by the source.Secondly,Secondly,compared with M-QAM system,the performance of overlapping time division multiplexing system is better under the same spectrum efficiency.In order to improve the anti-interference ability of the system,the cascaded convolutional code is studied as the overlapping time division multiplexing system of channel coding.From the results,we can see that the performance of the system is improved after the cascaded channel coding,which can also improve the performance of the system when the overlapping time division multiplexing system has a large overlapping multiplexing coefficient.For the square wave and the rising cosine roll down waveform,the weight of the system is increased stack time division multiplexing is used for performance simulation.With the increase of system overlap,the system spectrum efficiency is improved,but the system performance is decreased.Thirdly,on the basis of the previous research,under the condition of white noise,different sampling positions have almost no effect on the system performance.When the rising cosine roll-off is used as pulse shaping,the system performance gradually improves as the rolling factor increases.From a practical point of view,this paper makes up for the previous research gap only under white noise,and studies that under the same spectral efficiency,the system performance is better than the traditional QAM system in the case of band limited noise,the system performance is better than the traditional QAM system in the case of band limited noise.Overlapping time division multiplexing does not extend the bandwidth of the system.Finally,in order to further improve the spectrum efficiency of the system,overlapping time division multiplexing is applied to the MIMO system,and a signal detection scheme based on the trellis structure is proposed.Simulation analysis shows that the performance of the scheme is better than the traditional ZF and MMSE performance.Compared with ML detection of OvTDM signal at the receiver,the computational complexity is similar,but the bit error rate is lower,and the system performance is better.