Automatic gain control system in orthogonal frequency division multiplexing receiver and method

Abstract

The invention belongs to the technical field of the wireless digital communication, particularly relates to an automatic gain control system in an orthogonal frequency division multiplexing receiver and a method. An antenna of the orthogonal frequency division multiplexing receiver system is sequentially connected with a band-pass filter, a radio-frequency amplifier, an orthogonal demodulator, an analog-to-digital converter, a time domain power processor, a gain controller, a baseband digital gain amplifier, a frame synchronic judger, a frequency domain balancer, a decoder, a frequency domain processor and a gain generator. The time domain power processor, the gain controller, the baseband digital gain amplifier, the frequency domain processor and the gain generator form an automatic gain control system. The frequency domain processor consists of a comparison judger and an energy estimator. The automatic gain control system can prevent the valid signal from being submerged by slowly-decreasing signals, overcomes the problems such as the invalidity of synchronic correlator caused by the signal oscillation because of the variation of the gain, obtains a stable gain value, and improves the frame detection rate and the decoding success rate.

Description

technical field [0001] The invention belongs to the technical field of wireless digital communication, and in particular relates to a frequency-domain automatic gain control system and a method of a time-domain synchronous Orthogonal Frequency Division Multiplexing system. Background technique [0002] OFDM (Orthogonal Frequency Division Multiplexing) is a multi-carrier modulation technology. The main idea is to convert high-speed data signals into parallel low-speed sub-data streams, and then modulate them into each orthogonal sub-channel for transmission. Ideally, the signals on the orthogonal channels do not interfere with each other. The signal bandwidth on each sub-channel is smaller than the relevant bandwidth of the channel, so the bandwidth on each sub-channel is only a small part of the original channel bandwidth, and channel equalization becomes relatively easy. Due to its high spectral efficiency and the ability to easily deal with intersymbol interference caused...

AI Technical Summary

Problems solved by technology

Due to the delay of the RF envelope detector, when the output of the RF envelope detector is greater than a certain reference voltage value of the bridge network, the system detects the transmission of the signal. It is not conducive to the frame synchronization and frequency synchronization of the OFDM receiving system

At the same time, RF analog devices are relatively susceptible to interference, and the device itself has a certain separation characteristic, which leads to insufficient detection accuracy of burst signals and is easily affected by the environment

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