Carrier-wave recovering method for time-domain synchronous orthogonal frequency-division duplex receiver and system thereof

Abstract

A carrier recovery method for a TDS-OFDM digital television receiver belongs to the technical field of digital information transmission. The carrier frequency estimation is completed in three stages: a) the receiver performs coarse frequency estimation (Coarse Frequency Estimation, CFE) to correct the frequency offset to a smaller range; b) when the timing information is not fully obtained, perform Non-coherent AFC (Auto Frequency Estimation, AFC); c) Coherent AFC estimation is performed when the timing information is fully obtained, that is, when the receiver enters a locked state. The resulting frequency estimate is corrected for the carrier frequency of the data using a first-order tracking loop. The present invention has been realized in FPGA and ASIC version receivers of Tsinghua DMB-T system, and the actual trial broadcast and test prove that its performance is obviously better than other existing systems.

Description

technical field [0001] The invention belongs to the technical field of digital information transmission, and in particular relates to a carrier recovery method of a time domain synchronous orthogonal frequency division multiplexing (Time Domain Synchronous OFDM, TDS-OFDM) digital television receiver. Background technique [0002] In a digital communication or broadcasting system with synchronous transmission, due to the influence of Doppler frequency shift and local carrier error, the received signal will have a slow frequency drift, so that the phase drift of the received signal will occur, which will affect the communication system using coherent demodulation. Produce adverse effects and degrade system performance. Especially for OFDM signals composed of many orthogonal sub-carriers, the sub-channel bandwidth is much smaller than the entire bandwidth, and the introduction of carrier frequency offset into inter-carrier interference (ICI) will destroy the orthogonality betwe...

AI Technical Summary

Problems solved by technology

But in practice, the ISI introduced by the multipath channel has destroyed this repetitive structure, so the estimation performance is affected

The second algorithm can provide better estimation results, but because inserting pilots reduces the information rate, the number of inserted pilots must be small relative to the data

In addition, OFDM will cause ICI due to the influence of frequency offset. If there is ICI, it will definitely destroy the performance of frequency estimation.

Moreover, this algorithm can generally be used only after obtaining correct timing information, so its synchronization time is relatively long.

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