Folded Chirp-Rate Shift Keying Modulation Technology For Anti Dual Dispersion Fading

With the emergence of platforms such as low earth orbit satellites and unmanned aerial vehicles,the problems of dynamic doppler and dual dispersion have brought new challenges to existing internet of things technologies.However,the chirp-rate has characteristics of natural time-frequency shift invariance,which is beneficial to resist the influence of dual dispersion channel.Therefore,in this paper,we investigate the multiple chirp-rates modulation and utilize the Folded Chirp-Rate Shift Keying(FCrSK)system with strong resistance to dynamic doppler to design the optimal decision criterion in a dual dispersion channel,and verify its feasibility by simulation.In addition,the model of FCrSK affected by fractional sampling time offsets(STO)is analyzed in detail.Then the estimated and compensation scheme is proposed,and there feasibility is verified by simulation.The main contents of this paper can be summarized as follows:(1)The basic principles of multiple chirp-rates modulation are presented and their performance against dynamic doppler is compared.Then,the process of proving that the demodulation terminal of the FCrSK system has energy aggregation decision criteria is described in detail.Design the optimal decision criterion for dual dispersion problems.Combined with FCrSK with dynamic doppler,a decision algorithm based on energy aggregation is proposed to obtain excellent detection performance.The theoretical derivation and simulation results show that the proposed decision algorithm is insensitive to the dual dispersion channel.(2)The folding chirp structure present in LoRa modulation is relatively sensitive to fractional STO,but further analysis and explanation have not been provided.Therefore,this article analyzes the model of folded chirp signals in FCrSK in the presence of fractional STO,a high-precision fractional STO estimation algorithm is proposed.This algorithm combines the idea of incoherent estimation,makes full use of phase information,and is more robust to AWGN.The simulation results show that compared with the current estimation method in LoRa-Chirp,the algorithm has a higher accuracy of estimation for fraction STO.Finally,a phase compensation scheme is designed to solve the fractional STO in FCrSK system.Theoretical derivation and simulation results show that the performance of FCrSK system is significantly improved through fractional STO estimation and compensation.