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

Abstract

Carrier frequency estimation is completed in three phases: (1) receiver carries out coarse frequency estimation, (CFE) in order to locate frequency deviation correction within a small region; (2) non coherent auto frequency estimation (AFC) is carried out under obtained timing information is not completed; (3) coherent AFC is carried out under obtained timing information is completed i.e. the receiver enters into locking state, carrier frequency correction of data is completed by using a tracking loop in first order. The invention is realized at FPGA of Tsinghua DMB - T, ASIC version receiver. Favorable effect is obtained through actual try out broadcasting and testing, and performance is better than existing other system evidently.

Description

technical field [0001] The invention belongs to the technical field of digital information transmission, and in particular relates to a carrier recovery method for a Time Domain Synchronous OFDM (TDS-OFDM) digital television receiver. Background technique [0002] In the digital communication or broadcasting system of synchronous transmission, due to the influence of Doppler frequency shift and local carrier error, the received signal will have a slow frequency drift, which will cause the received signal to have a phase drift, which will cause problems for the communication system using coherent demodulation. produce adverse effects and degrade system performance. Especially for an OFDM signal composed of many orthogonal sub-carriers, the sub-channel bandwidth is much smaller than the entire bandwidth, and the introduction of inter-carrier interference (ICI) by the carrier frequency offset will destroy the orthogonality between different sub-carriers of the OFDM signal. A s...

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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