Research Of High Efficient Receiver Synchronization Techniques In Burst Communication Systems

In the burst-mode communications,it is required that the synchronization system can estimate and compensate the large timing error,large Doppler extension(frequency offset)and random phase jitter(phase offset)for obtaining quick accurate extraction,estimation and compensation in various scenarios.This will require a comprehensive consideration of the three bad factors to design one or more efficient(such as high accuracy and low complexity,etc.)receiver synchronization algorithms(including timing recovery algorithms and carrier synchronization algorithms).Combined with related studies of receiver synchronization techniques in recent years,this paper has made some contributions.Aiming at the problem of timing recovery,we discuss the classical timing error detection algorithms proposed by Mueller & Muller,Gardner and Oerder,i.e.,the M&M algorithm,Gardner algorithm and square algorithm.Combined with non-binary LDPC(NB-LDPC)code and high-order QAM,an iterative scheme of joint demodulation,decoding and timing recovery(M&M)algorithm is given.According to the difference of decoding feedback information,iterative strategies can be divided into two iterative kinds:one is based on feedback of the decoding hard information and the other is based on feedback of the decoding soft information.In this way,M&M algorithm can be used to iteratively correct the timing errors in the symbol period.Finally the simulation results show that under the conditions of low signal-to-noise ratio(SNR)and different timing errors,the performance of the timing recovery algorithm based on two iterative methods is close to the ideal performance with a fast convergence speed,which is suitable for engineering implementation.Among them,the timing recovery algorithm based on the decoding soft information iteration has more complete probability information than the other one,thus obtaining better performance.For carrier synchronization problems,we discuss the classical carrier synchronization algorithms including the fast Fourier transformation(FFT)and its extension,the L&R and its extension,and the maximum likelihood(ML).In this paper,a time-domain correlation frequency offset estimation algorithm is proposed based on the pilot symbol assisted modulation(PSAM)frame format.Its main principle is that by using the idea of the auto-correlation(AC)algorithm and the thought of algebra knowledge,a partial cross-correlation(PCC)frequency offset estimation algorithm is designed,which caneliminate its complex multiplication operation;And combining with a proposed phase-unwrapping algorithm based on Monte-Carlo simulations and dichotomy method,the problem of phase ambiguity of the frequency offset estimation is solved,which can adapt to the large frequency offset.So,an improved partial cross-correlation(IPCC)frequency offset estimation algorithm is derived.The final simulation results show that compared with the existing classical time-domain algorithms with a large estimation range,the proposed algorithm has higher estimation precision and lower computational complexity.In addition,in order to achieve the compromise of the performance and complexity,the proposed or existing synchronization algorithms needs to be improved for reducing the system complexity with a small performance loss,which can adapt to engineering implementation.