Method for self-elimination of inter-subcarrier interference of differential OFDM (orthogonal frequency division multiplexing) system

Abstract

The invention discloses a method for self-elimination of inter-subcarrier interference of a differential OFDM (orthogonal frequency division multiplexing) system. In comparison with a primal differential OFDM system, a zero insertion algorithm and a displacement offsetting algorithm are added, wherein the zero insertion algorithm enables adjacent carriers of a subcarrier carrying information to return to zero, so that, the interference of the adjacent carriers on the information carrying carrier is effectively reduced. In a process of transmitting the information to a receiving terminal through a wireless channel, orthogonality cannot be completely formed under influence of Doppler frequency shift caused by carrier synchronous error and movement, and the subcarriers generate mutual interference; and by the displacement offsetting algorithm, the subcarriers carrying the information are amplified, a signal-to-noise ratio of the subcarrier to the adjacent subcarriers is increased, and the adjacent subcarriers are further subtracted, so that the inter-subcarrier interference is effectively eliminated.

Description

technical field [0001] The invention relates to a differential OFDM system, in particular to a subcarrier interference elimination method. Background technique [0002] OFDM technology has been widely used in broadband wireless mobile communication systems because of its good ability to resist channel frequency selective fading. However, the OFDM system requires strict orthogonality between subcarriers, and puts forward very strict requirements on frequency offset. The generation of frequency offset includes carrier synchronization error and motion-induced Doppler frequency shift. Frequency synchronization error can be reduced by a well-designed carrier synchronization algorithm, and Doppler frequency shift causes time-selective fading of the channel, especially for high-speed In the case of motion, the ICI caused by fast channel fading will lead to a rapid decline in system performance. [0003] Current methods to reduce the impact of ICI include frequency domain equaliza...

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Problems solved by technology

[0004] Among them, although the frequency domain equalization method and the time domain windowing method have a certain improvement on the impact on ICI, the out-of-band leakage power increases, and the utilization rate of the system is greatly reduced; the frequency offset estimation and compensation method is in a fast fading environment, The estimated error becomes larger, and the improvement effect on ICI is not obvious; the implementation of the iterative elimination method is too complicated, and the delay is also relatively large. After receiving one or more OFDM symbols, complex matrix operations or FFT transformations are required, and the calculation amount Very large, not conducive to practical application

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