Research On Wireless Transmission With Efficient Modulations

With diversification of wireless multimedia communication information,demand for spectrum increases gradually,but spectrum resource is limited and cannot regenerate.Efficient modulations improve demodulation efficiency on the basis of UNB(Ultra Narrow Band)modulation,thus it not only keeps high spectrum efficiency of UNB modulation,but also improves the status quo of spectrum scarcity and has higher comprehensive efficiency.Along with rapid development of urban construction,wireless channel become more complex,therefore research on wireless transmission with efficient modulations is of great significance.This article mainly use EBPSK(Extended Binary Phase Shift Keying)and MPPSK(M-ary Position Phase Shift Keying)to research wireless transmission with efficient modulations.It mainly has two aspects of regular application and "fill-in" transmission to explore.First of all,it summarizes EBPSK/MPPSK theory,and expounds the principle of impacting filter and realization.Then it gives EBPSK/MPPSK modulation receiver structure based on impacting filter,and simulates transmission performance of efficient modulation system on the additive white gaussian noise channel.Secondly,it introduces concepts and development prospects of digital interphone,then researches DMR standard for representative and simulates its transmitter and receiver system on physical layer.According to spectrum characteristics of efficient modulations,a new kind of digital interphone based on MPPSK is put forward and its transmitter and receiver are realized.The simulation results show that MPPSK digital interphone relative to other interphone has high transmission rate,high frequency utilization and better demodulation performance,which improves the state of spectrum shortage in digital interphone.Then,from AWGN channel extended to multipath fading channel,it researches multipath fading resistance method of efficient modulation.With interpolation idea,two interpolation algorithms based on estimated fading factor and estimated decision threshold are given,which promote demodulation performance to varying degree.It researches efficient modulation anti-multipath algorithm based on frequency domain linear equilibrium.Combined with channel estimation,it simulates error rate of four kinds of frequency domain linear equilibrium and analyzes results,which show that performance of MMSE equalization is best,greatly enhances demodulation performance of efficient modulations.Then,from general to specific,it analyzes characteristics of multipath fading channel in digital interphone.The performance of MPPSK digital intercom in multipath fading channel without any measures is declined.Thus anti-multipath fading algorithm of MPPSK digital interphone is proposed,and the simulation of error rate is realized.Results show that proposed algorithm can achieve multipath separation without complex structure,and better demodulation performance is at the expense of transmission rate.In practical application,the algorithm needs good compromise between transmission rate and demodulation performance.Finally,With extremely narrow "spectrum tree" and wider "spectrum grass" of efficient modulations,spectrum gap communication of effective modulations based on traditional rectangular spectrum division mode is put forward,and "fill-in" data transmission of MPPSK digital inteiphone is proposed.Combining with "rate" domain filtering,receiver structure of MPPSK interphone is given.The simulation of error rate under same frequency interference and adjacent frequency interference is realized,which shows that "fill-in" data transmission of MPPSK digital interphone has high frequency utilization and good demodulation performance,good compatibility,less interference of adjacent channel,high frequency interference isolation,to verify feasibility of "fill-in" transmission with efficient modulations.