Frequency offset estimation method and frequency offset estimation system for frequency domain strong interference environment of OFDM (Orthogonal Frequency Division Multiplexing) system

Abstract

The invention relates to a frequency offset estimation method and a frequency offset estimation system for a frequency domain strong interference environment of an OFDM (Orthogonal Frequency DivisionMultiplexing) system. The frequency offset estimation method comprises the following steps: receiving and performing interference cancellation on an FFT (Fast Fourier Transform)-transformed subcarriersignal; performing integer frequency offset calculation and integer frequency offset adjustment on the subcarrier signal after the interference cancellation; and performing fractional frequency offset calculation on the subcarrier signal adjusted by the integer frequency offset according to the phase difference between the inter-symbol pilots to perform fractional frequency offset adjustment. Thefrequency offset estimation method and frequency offset estimation system provided by the invention directly perform interference cancellation on the FFT-transformed subcarrier signal firstly, then perform integer frequency offset calculation and adjustment on the interference-canceled subcarrier signal, and perform fractional frequency offset calculation on the subcarrier signal adjusted by theinteger frequency offset according to the phase difference between the inter-symbol pilots so as to perform fractional frequency offset adjustment, which is more accurate in calculation by using own characteristics of the OFDM system with no need to separately set a interference cancellation device, and saves resources and computational complexity.

Description

technical field [0001] The invention relates to the field of communication technology, in particular to a frequency offset estimation method and a frequency offset estimation system used in an OFDM system frequency domain strong interference environment. Background technique [0002] figure 1 It is a flow chart of the frequency domain interference elimination algorithm in the prior art OFDM system frequency domain strong interference environment, such as figure 1 As shown, the frequency domain interference removal algorithm process includes the following steps: receiving useful signals and interference signals, processing the useful signals and interference signals into zero-IF signals, and dividing the zero-IF signals into two channels for windowing, and the two window functions The phase difference between them is N / 2 points to form two data streams after windowing, where N is the number of window function points; the two data streams after windowing are respectively subj...

AI Technical Summary

Problems solved by technology

[0003] At present, generally after the ADC (Analog-to-Digital Converter, analog-to-digital converter) collects the signal, a device such as figure 1 The shown independent module performs interference elimination processing, which is independent of the interference elimination algorithm of the OFDM (Orthogonal Frequency Division Multiplexing, orthogonal frequency division multiplexing technology) system itself, consumes a lot of resources, and cannot fully adapt to OFDM-TDD (Orthogonal Frequency Division Multiplexing) system itself. Interfrequency division multiplexing-time division duplex) system burst characteristics, therefore, the existing frequency domain interference removal algorithm device is only suitable for continuous signal interference signal detection and removal, such as QPSK (Quadrature Phase Shift Keyin, which is continuously sent, is Cross-phase shift keying) signal, GMSK (Gaussian filtered minimum shift keying, Gaussian filtered minimum shift keying) signal or spread spectrum CDMA (Code Division Multiple Access, code division multiple access) signal, etc.

Images