Channel estimating and balancing method for suppressing long echo waves and high Doppler of DTMNB (Digital Terrestrial Multimedia Broadcasting) system

Abstract

The invention belongs to the technical field of radio digital communication and broadcast, in particular to a channel estimating and balancing method for suppressing long echo waves and high Doppler of a DTMNB (Digital Terrestrial Multimedia Broadcasting) system. The method comprises the followings steps of: eliminating trailing introduced after a frame head and a frame body pass through a channel through reconstructing and balancing a previous frame body on the basis of obtaining the channel impulse response of a current frame through rough estimation so as to more accurately estimate the channel impulse response, wherein the obtained channel impulse response not only can reflect the quick change of the channel, but also can eliminate errors caused by long echo waves to the estimation; and finally, reconstructing and balancing the frame before the previous frame by utilizing the frame body impulse response obtained by simple average to obtain output data so as to eliminate the influence of long multipath and high-speed mobile environment on transmitted data. The method has excellent channel estimation property and moderate complexity and can be used for receiving in a high-speed mobile environment and resisting overlong echo waves.

Description

technical field [0001] The invention belongs to the technical field of wireless digital communication and broadcasting, and in particular relates to a channel estimation and equalization method oriented to the national standard for digital television terrestrial transmission. Background technique [0002] The time-domain synchronous OFDM technology proposed by Tsinghua University is an important part of China's digital TV terrestrial transmission standard (DTMB). The standard was proposed in 2006, including two modes of single carrier and multi-carrier. Among them, the multi-carrier mode uses the orthogonal frequency division multiplexing technology to modulate the frame body. Compared with the traditional frequency division multiplexing, this technology improves the spectrum utilization rate and has excellent anti-multipath ability. This mode uses the PN sequence and its cyclic prefix and cyclic suffix as the frame header, which not only acts as a guard interval, but also ...

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Problems solved by technology

[0006] In the DTMB system, the simplest channel estimation method is to use the quasi-cyclic characteristics of the frame header PN sequence in the multi-carrier mode, and only need simple time-domain correlation to obtain the channel impulse response (refer to the Chinese invention patent "time-based Domain-related channel estimator for terrestrial digital multimedia broadcasting system", the authorization number is 200710044718.0), and this method also has better mobile reception performance, but when the channel length is large, this method shows its disadvantages, In addition, this algorithm is not suitable for single-carrier mode and does not meet the national standard fusion standard design

At this time, we can use the iterative elimination algorithm to perform channel estimation (refer to the Chinese invention patent "An Iterative Elimination Method for Pseudo-random Sequence Filling in OFDM Modulation System" applied by Tsinghua University, the authorization number is 200510012127.6, and the document F.Yang etal.Channel Estimation for the Chinese DTTB System Based on a Novel Iterative PNSequence Reconstruction, ICC, 2008, 54(4): 1583-1589), this method has a great advantage in combating long echoes, but these algorithms cannot It supports high-speed mobile reception. In addition, there is an algorithm that has a certain performance in supporting long echoes, but cannot support ultra-long echoes. In the case of short channel lengths, this algorithm degenerates into a simple PN sequence correlation algorithm (reference L.Gui, Q.Li, B.Liu et al.Low Complexity Channel Estimation Method for TDS-OFDM Based Chinese DTTB System.IEEE TRANSACTIONS ONCONSUMER ELECTRONICS, 2009, 55(3):1135-1140)

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