| Compared with traditional communication methods,frequency hopping burst communication technology has the characteristics of high spectrum utilization,good confidentiality,anti-interception,anti-interference,and so on.In the modern society where digital wireless communication is rapidly developing,frequency band resources are increasingly crowded,and high-speed information transmission and high-reliability transmission naturally become the two main aspects of information transmission.Therefore,in order to further improve the efficiency and reliability of the information transmission system in frequency hopping burst communication,the key technologies of the frequency hopping burst transmission system under low signal-to-noise ratio are studied in this paper.Some common carrier parameter estimation methods,including the commonly used timedomain autocorrelation function algorithm and frequency-domain periodogram algorithm,are first introduced and analyzed,and the impact of each parameter of the RPA algorithm on the estimation performance is also analyzed in this paper.Secondly,the effects of different channel codes—RS code,Turbo code and TPC code on the entire frequency hopping communication system are studied,and the anti-interference performance of each code is analyzed.Then the performance of frequency hopping anti-jamming system based on the cascade of RS with Turbo is studied and analyzed.Then,the transmission performances of frequency hopping systems of different channel coding cascaded with linear modulation(QPSK)and nonlinear modulation(SOQPSK)are studied and analyzed.The simulation results show that when the code rate and code length parameters are basically the same,for QPSK modulation,the performance of Turbo code is better than TPC code,and for SOQPSK modulation,TPC code is better than Turbo code.Finally,the influence of the frame format on the entire communication system is studied,and a carrier frequency offset estimation algorithm,MSA-RPA algorithm based on the frame format design of equal interval pilot interpolation,is proposed.The corresponding frame structure of the algorithm is splitting the pilot sequence into multiple blocks throughout the data burst,where the pilot blocks are separated by the same number of data blocks.Based on the traditional RPA algorithm,the MSA-RPA algorithm reduces the variance of erroneous estimation and improves the estimation performance by performing a frequency shift and periodogram averaging on multi-segment pilots.Simulation results show that without the increase of the number of pilot blocks,when the normalized frequency offset is less than half of the symbol rate and the number of pilots is sufficient,the estimation result is more accurate,and the performance of frequency offset estimation is improved as the number of pilot blocks increases.In addition,based on the MSA-RPA algorithm,a 2SA-RPA-time domain correlation algorithm using a two-segment pilot block structure is further proposed.Compared with the MSA-RPA algorithm,this algorithm only operates on two pilot blocks,which saves a lot of frequency shifts and multi-segment averaging operations,and avoids a large number of tentative searches during the frequency offset fine estimation stage.And it can also achieve the BER performance equivalent to the MSA-RPA algorithm. |
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