Research On Synchronization Technologies Of SOQPSK Signal

With the rapid development of wireless communication technology in recent years,the available spectrum resources have become less and less.How to make spectrum utilization more efficient and have less impact on adjacent channels has become a hot issue in the current communication field.The Shaped Offset QPSK(SOQPSK)signal that appeared in 2000 is a novel continuous phase modulation(CPM)signal.Its characteristics of continuous phase and constant envelope make it have Excellent spectrum efficiency and power efficiency,currently mainly used in major aviation telemetry standards.The SOQPSK signal's symbol timing,carrier synchronization,and simplification of its receiver are the main research contents of SOQPSK signal.This paper mainly focuses on two aspects,SOQPSK signal's symbol timing synchronization and carrier phase synchronization.This article first analyzes the principle and mathematical model of the SOQPSK signal,deeply analyzes the modulation and demodulation method of the SOQPSK signal,and also deeply studies the current timing algorithm and phase synchronization algorithm of the SOQPSK signal.Both types of synchronization can be divided into two categories:data-aided algorithms and non-data-aided algorithms.Since data-aided algorithms will occupy additional traffic channels,this paper mainly studies non-data-assisted algorithms.In terms of symbol timing algorithm,this article focuses on the problem of high computational complexity in the implementation of the maximum likelihood(Maximum Likelihood,ML)joint estimation algorithm with the best performance among the current non-data-aided non-decision-directed symbol timing algorithms.Analysis and simulation have proved the relationship between parameter selection and estimation accuracy,and then a quantification method of the h function in the ML joint estimation algorithm is proposed.Under the premise of ensuring that the algorithm still maintains the same estimation performance,the complexity of convolution calculation is significantly reduced,the overall calculation complexity of the algorithm is reduced fromo(N ²L₀)too(NL₀).In terms of phase synchronization algorithm,this article addresses the problem of the current SOQPSK signal phase synchronization algorithms is few and some algorithms are not widely applicable.This article represents the SOQPSK signal as a binary CPM signal.And a quadratic joint estimation algorithm is proposed based on phase estimation algorithm suitable for the binary CPM signal.After the phase error is estimated and compensated,the algorithm can directly estimate the symbol timing error using the intermediate parameters in the algorithm implementation process.After simulation verification,the algorithm has better symbol timing performance than the fourth power joint estimation algorithm under the same implementation complexity,and the phase synchronization performance is better than the fourth power joint estimation algorithm under the condition of low signal-to-noise ratio.