摘要(英) |
DVB-T is an OFDM system, which exhibits outstanding characteristics in terms of simplicity in combating multi-path transmission and efficiency in spectral utilization. The ISI effect results from the multi-path interference could be successfully eliminated by the insertion of cyclic-prefix and the use of multi-carriers. In high-mobility environment, DVB-T signals pass the time-varying channel, and a loss of sub-carrier orthogonality due to Doppler spread of received signals leads to inter-carrier interference (ICI).This ICI effect degrades the maximum allowed velocity of reception. For eliminating this ICI effect due to high-mobility reception, this thesis modifies other’s methods and introduces a method about channel estimation and equalization, which is suitable high-mobility reception.
Some ICI estimation schemes, which using first order linear model to approximate the channel variations, have been developed. This thesis compares three different schemes of ICI estimation, which two is first order model and the other is second order model, and iteratively repeats ICI cancellation to improve the maximum allowed velocity of reception. This modified method improves the normalized Doppler frequency from 8.6% to 13% for DVB-T signals in 8K mode、16QAM、code-rate=1/2. |
參考文獻 |
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