Blocking equalizing method for OFDM system under Quick-Change channel condition

Abstract

The invention provides a block balancing method for an orthogonal frequency division multiplexing (OFDM) system on the condition of a fast time variant channel. The method comprises the following: at a sending terminal, a bit signal subjected to cyclic redundancy codification is subjected to channel codification, interlacement, symbol map, serial / parallel conversion and IFFT conversion to be converted to a time domain signal; the time domain signal which is subjected to serial / parallel conversion and is inserted with a cyclic prefix is sent to a radio channel; at a receiving terminal, the signal is received by a traditional first-order frequency domain equalizer, and the signal guess value is checked after the signal is subject to serial / parallel conversion, demap, deinterlacement and signal path decoding; if the check is correct, the signal is outputted; if the check is not correct, the block balancing process is performed, during which, firstly, a time domain OFDM sending signal is restructured; secondly, the received time domain OFDM symbol is divided into a plurality of equilong signal receiving subblocks, the loop restructuring and the interference removing processes are performed by a time domain OFDM restructured signal; and finally, each subblock is subjected to frequency domain balance, the balanced guess values of sub blocks are merged to obtain the block balance output serving as the input of the serial / parallel conversion.

Description

technical field [0001] The invention belongs to the technical field of Orthogonal Frequency Division Multiplexing (OFDM) mobile communication. Background technique [0002] Orthogonal Frequency Division Multiplexing (OFDM, Orthogonal Frequency Division Multiplexing) technology has attracted more and more attention due to its high spectrum utilization rate and low implementation complexity. Since the 1980s, OFDM technology has not only been widely used in broadcast digital audio and video fields, but also has become a part of the wireless local area network standard. With the increase of people's demand for communication data, broadband, personalization and mobility, OFDM technology has been applied in many high-speed information transmission fields. At present, people are considering using OFDM technology in the next generation wireless cellular mobile communication system in the future. However, the OFDM mobile system working under the condition of high carrier frequency ...

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Problems solved by technology

However, this method requires special precoding at the sending end, which reduces the frequency band utilization of the system

In addition, Philip Schniter published "Low-Complexity Equalization of OFDM in Doubly Selective Channels" in "IEEE Trans.On Signal Processing" vol.52, no.4, pp.1002-1011, April 2004 (Journal of IEEE Signal Processing in 2004 April, Volume 52, Issue 4, pages 1002 to 1011, OFDM Low Complexity Equalization under Dual Selective Channels), this method first uses time-domain windowing to filter the time-varying channel, and uses iterative MMSE to estimate the signal, Its disadvantage is that it is necessary to accurately know the statistical information of the channel and the channel state information at each time point, which is not easy to realize for the channel estimator of the actual OFDM system

Li Wei et al. proposed to use block frequency domain equalization method in single-carrier frequency domain equalization system and OFDM system to combat time-varying channels, but this method simply divides the received signal into multiple sub-blocks for processing, without considering the interference between sub-blocks problem, resulting in a decrease in equalization performance

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