Method for estimating integer multiple frequency deviation with timing error during communication synchronization process

Abstract

The invention provides a method for estimating integer frequency offset with timing error during the communication synchronization, which comprises the following steps: a constant-amplitude Chu sequence with ideal autocorrelation characteristics is selected as a frequency domain difference sequence C(k),a first element S(0) in a frequency domain training sequence is defined to be equal to 1, the frequency domain training sequence S(k) with a length of N is obtained according to the recursion formula S(k)=C(k-1)S(k-1), and the S(k) is transformed into a time domain training sequence s(n) through an IFFT; after a receiving sequence finishes the fractional frequency offset compensation, two sections of receiving sequences with a length of N are taken out according to a coarse timing sequence, and two sections of receiving sequences are added to obtain a receiving sequence r(n) with a length of N; the frequency domain of the sequence r(n) is transformed into R(k) through FFT, the formula D(k)=R(k+1)(R(k))<*> is utilized to calculate a receiving frequency domain difference sequence D(k), the cyclic shift correlation is performed through the conjugation of the received sequence D(k) and the sequence C(k), and a related peak value corresponds to the integer frequency offset estimation epsilon int of a system, as shown in the right formula. The method strengthens the frequency offset estimation performance and improves the transmission efficiency of the system on the premise of not affecting the timing synchronous performance.

Description

technical field [0001] The invention relates to a method for realizing synchronization in the field of digital communication, and mainly relates to a method for estimating integer multiple frequency offset in the receiving synchronization process. Background technique [0002] OFDM technology has the advantages of strong anti-multipath fading ability, high spectrum utilization rate and high data transmission rate, and has been widely used in military and civil communication systems. Carrier frequency offset has a great influence on the correct reception of system signals. How to quickly and accurately estimate frequency offset is the premise and basis for OFDM system to realize reliable and effective data transmission. The frequency deviation is divided into a fractional multiple frequency deviation and an integer multiple frequency deviation of the subcarrier spacing. [0003] Based on repeated training sequences, Moose proposed a maximum likelihood frequency offset estima...

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Problems solved by technology

When viewing the training sequence as repeating two segments, figure 2 It is impossible for the training sequence structure to have ideal autocorrelation chara

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