Research On Single Channel Blind Separation Of PCMA Signals

Paired Carrier Multiple Access(PCMA)technology is a new type of capacity augmentation technology,which has attracted much attention because of its high frequency band utilization and strong anti-interception ability.This research starts with two aspects:modulation recognition of PCMA signals and single-channel blind separation based on Per-Survivor Processing(PSP).The main tasks completed include the following aspects:1.Summarizes the working principle and system model of PCMA satellite communication,and introduces two mixed-signal models,symmetric and asymmetric.According to the definition of blind separation,the difference between single-channel blind separation and multi-channel blind separation is introduced,which provides a theoretical basis for studying the problem of single-channel blind separation of PCMA symmetric mixed signals.To solve the problem of unknown parameters of PCMA signals,several common traditional algorithms for rough estimation of parameters are introduced to provide algorithm support for the follow-up.2.Regarding the identification of the modulation mode of the PCMA signal,first perform a series of preprocessing on the signal to eliminate channel effects such as frequency offset and inter-code crosstalk.Then several common PCMA signal modulation recognition algorithms are introduced,and several algorithms applied to single-signal modulation recognition are extended to mixed-signal modulation recognition,and their feasibility is verified.The characteristic parameters are constructed,thresholds are set through a large number of simulations,the modulation recognition algorithms are compared horizontally,an efficient and feasible recognition process is designed,and finally the influence of parameters such as frequency offset and amplitude ratio on the performance of the algorithm is analyzed longitudinally.The algorithm shows that when the signal-to-noise ratio is greater than 5dB,the correct rate of modulation recognition of the PCMA signal can reach 95%,and the algorithm is not sensitive to the influence of frequency offset.When the amplitude ratio of the mixed signal is greater than 0.8,the overall recognition performance Better,when the amplitude ratio is equal,the algorithm performance is the best.3.Regarding the single-channel blind separation of PCMA signals,for the situation where the received signal lacks prior information,a per-retention path processing algorithm based on the Viterbi algorithm is studied to achieve single-channel blind separation of PCMA signals.The PSP algorithm integrates unknown parameter estimation technology into the Viterbi algorithm.By calculating the state path metric,a small number of surviving paths are selected,so that the number of states that need to be processed at each moment is small,thereby reducing the computational complexity and the process of calculation requirements for storage.This algorithm is suitable for separating the mixed signal when the channel parameters are unknown,that is,recovering the symbol sequence of the two upstream signals.The simulation results show that under the condition of normal communication signal-to-noise ratio of 1OdB?22dB,the BPSK modulation type PCMA signal can achieve a better separation effect.The separation performance becomes better as the signal-to-noise ratio increases has different effects.