Channel estimation method for four-phase modulation system

Abstract

The invention discloses a channel estimation method for a four-phase modulation system, which belongs to the digital communication field. The method comprises the following steps: a sending terminal performing four-phase modulation to a binary sequence Bt(m) to obtain a frequency-domain symbol sequence Xt(k), performing the FFT or the DFT to the symbol sequence Xt(k) to obtain a transmitted time-domain sequence xt(n), a receiving terminal performing FFT or DFT to the received time-domain sequence xt(n) to obtain a received frequency-domain sequence Yr(k), calculating the amplitude and the phase of the frequency-domain sequence Yr(k) to obtain an amplitude sequence AH(k) and a phase sequence Phi(k), the amplitude sequence AH(k) being namely the amplitude of a channel response H, performing the phase rotation to the phase sequence Phi(k) to obtain a phase sequence Theta H<0>(k), performing the phase correction to the phase sequence Theta H<0>(k) to obtain a corrected phase sequence Theta H(k) which is namely the phase of the channel response H. The invention directly utilizes the received four-phase modulation symbol to perform channel estimation without decision feedback and avoids the influence of wrong judgment to the channel estimation accuracy.

Description

technical field [0001] The invention belongs to the field of digital communication, and in particular relates to a channel estimation method used in a four-phase modulation OFDM system. Background technique [0002] In an Orthogonal Frequency Division Multiplexing (OFDM) system, the accuracy of channel estimation directly affects the equalization effect of frequency domain signals, and further affects the performance of the entire OFDM system. Traditional channel estimation methods in OFDM systems include non-blind channel estimation methods and blind channel estimation methods. Non-blind channel estimation methods usually use the method of inserting training sequences or inserting pilots to perform channel estimation. This method increases redundant information and reduces system transmission efficiency, but it can track channel changes in real time. In order to achieve the highest possible data transmission efficiency, some OFDM systems do not send training sequences and...

AI Technical Summary

Problems solved by technology

However, since this method needs to judge the data, the accuracy of channel estimation depends on the correctness of the judgment data

When a subcarrier is in deep fading for a long time or is affected by single-frequency interference for a long time, error propagation is prone to occur, resulting in a large channel estimation error

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