SOQPSK (shaping offset quadrature phase shift keying) carrier synchronization method based on pilot frequency and soft information combined assistance

Abstract

The invention discloses an SOQPSK (shaping offset quadrature phase shift keying) carrier synchronization method based on pilot frequency and soft information combined assistance, mainly solves the problem in the existing short frame burst communication system carrier synchronization technique that the complexity is high and the carrier deviation estimation range is small. The implementation steps are as follows: firstly, according to pilot frequency assistant maximum likelihood carrier synchronization method, the rough estimation values of carrier frequency deviation and phase deviation are obtained, and the phase rough estimation value is used to revise the receiving signals; then, the frequency deviation one dimensional fine estimation interval, and phase deviation one dimensional fine estimation interval are respectively determined; and in the frequency deviation and phase deviation fine estimation intervals, according to the rule of maximizing the mean square value obtained during demodulation of soft information by SOQPSK, one dimensional search is performed to obtain the precise estimation value of carrier frequency deviation and phase deviation. A small amount of pilot frequency overhead is utilized, large carrier deviation with comparatively low operation complexity is revised, effective carrier synchronization is realized, nearly ideal bit-error performance of coherent demodulation is obtaind, and the method is suitable for the short frame burst communication system.

Description

technical field [0001] The invention belongs to the technical field of wireless communication, and relates to a method for acquiring synchronous information by using pilot frequency and demodulation soft information in digital communication. The carrier synchronization method is suitable for a SOQPSK short frame burst communication system using shaped offset quadrature phase shift keying, and can be used in military communication, satellite communication, telemetry communication and other fields. Background technique [0002] Short-frame burst communication systems are widely used in military communications, satellite communications, and telemetry communications. The working channels in these fields are both power- and bandwidth-limited channels, and there is a large carrier deviation. Shaped offset quadrature phase shift keying SOQPSK signal is one of the most commonly used modulation methods in the above-mentioned communication field because of its constant envelope and hi...

AI Technical Summary

Problems solved by technology

Its shortcoming is that the frequency offset estimation range of this method is limited, and it cannot resist the influence of large frequency offset, and its normalized frequency offset estimation range is only |ΔfT|-4 , where T is the symbol period, Δf is the frequency offset, and the phase offset estimation range is only |φ|<(π / 18). If there is a large carrier offset in the received signal, the bit error performance will suffer a great loss

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