A Phase Compensation Method of Sampling Frequency Offset in OFDM System

Abstract

The invention relates to a phase compensation method for sampling frequency offset in an OFDM system, which belongs to the field of communication technology. The method utilizes that after channel equalization is performed on each OFDM symbol 1 of a received load frame, a phase is correspondingly set for each OFDM symbol 1 Twiddle factor φ l ; using the phase rotation factor φ l Phase compensation is performed for each symbol. The phase compensation method of the present invention does not need to directly estimate the estimated value of sampling frequency offset, but uses multiple subcarrier information to combine and reduce noise, obtain an approximate phase offset information of sampling frequency offset, and determine a phase rotation factor accordingly , to realize the phase correction of each symbol, the principle is simple, and the calculation is convenient. Moreover, because the method has the effect of reducing noise, a good correction effect can be obtained even under low signal-to-noise ratio, and the noise resistance is strong.

Description

technical field [0001] The invention belongs to the technical field of communication, and in particular relates to a phase compensation method for sampling frequency offset in an OFDM system. Background technique [0002] In a broadband communication system, in order to eliminate the frequency selective fading of the broadband communication channel, the multi-carrier modulation technology divides the broadband channel into multiple sub-channels, uses a sub-carrier for modulation on each sub-channel, and transmits each sub-carrier in parallel. Thus, although the overall channel is non-flat and frequency selective, each sub-channel is relatively flat. Orthogonal frequency division multiplexing (OFDM) is a kind of multi-carrier modulation technology, its sub-carriers are orthogonal to each other, and has a high spectrum utilization rate; and it can use inverse discrete Fourier transform / discrete Fourier transform ( IDFT / DFT) instead of multi-carrier modulation and demodulation...

AI Technical Summary

Problems solved by technology

[0003] Usually, in an OFDM communication system, due to cost control, the error of the crystal oscillator will be relatively large, resulting in a large sampling deviation during the analog-to-digital conversion process after signal reception, and a large deviation will lead to a serious decline in system performance

Or, even if the sampling deviation is not very large, due to the long time difference between the pilot position and the useful data in some communication systems, the channel estimation value of the pilot cannot reflect the channel characteristics of the useful data in real time, and there is a serious phase deviation

In order to enhance the receiving performance of the OFDM communication system, the same source is usually sent multiple times, and the receiving end performs diversity and combined reception to improve the signal-to-noise ratio. If multiple diversity still has a large phase deviation after equalization, it will instead Reduced system reception performance

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