Suppression method for single-frequency interference in OFDM (Orthogonal Frequency Division Multiplexing) communication system

Abstract

The invention discloses a suppression method for single-frequency interference in an OFDM (Orthogonal Frequency Division Multiplexing) communication system. The suppression method comprises the following steps of: filtering the detected single-frequency interference in a time domain by an IIR (Infinite Impulse Response) notching filter through a time domain and frequency domain processing combination method, and regulating the signal power based on digital automatic gain control to ensure that the signal input powder is stabilized in the optimal input power when subsequent digital signal processes are carried out; and carrying out shielding processing on subcarriers interfered by single frequency in a frequency domain to ensure that effective data are not transmitted by the subcarriers. According to the method provided by the invention, the single-frequency interference can be effectively resisted, the single-frequency interference resistance of the OFDM communication system is improved, and the throughput of the system is improved; and when the single-frequency interference exits in the OFDM communication system, the normal operation of the system is guaranteed.

Description

technical field [0001] The invention relates to the field of digital communication, in particular to a method for suppressing single-frequency interference in an OFDM (Orthogonal Frequency Division Multiplexing) communication system. Background technique [0002] As a multi-carrier modulation technique, OFDM transmits data through multiple mutually orthogonal low-speed subcarriers. OFDM modulation and demodulation can be processed by using inverse fast Fourier transform (IFFT) and fast Fourier respectively. Realized by FFT. Since the sub-carriers are orthogonal to each other, the modulated spectrum can partially overlap with each other, which greatly improves the utilization rate of the spectrum. In addition, because the use of cyclic prefix (CP, Cyclic Prefix) isolates the mutual interference between the front and back OFDM symbols, it has good anti-multipath interference ability; the bandwidth of each subcarrier is very small, and the channels experienced are all It can ...

AI Technical Summary

Problems solved by technology

The general disadvantage of these methods lies in the complexity and robustness of their algorithms

The feed-forward digital automatic gain control is faster than the feedback digital automatic gain control, but there is distortion when the amplitude changes suddenly, while the feedback automatic gain control circuit has a smooth output waveform, but the response speed is slow and there is instability. phenomenon (if the automatic gain control loop is controlled by the level change of the input signal, it will cause unstable attack and release time, resulting in deterioration of receiver performance)

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