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为提高数字电视地面广播(DTTB)系统的传输性能,在传统的串行级联编码结构中,引入Turbo码的思想,同时结合16QAM映射和多载波正交频分复用(OFDM)调制,构造了一种新的并行级联格型码(PCTC)作为内码方案。在接收端采用基于MAX-LOG-MAP准则的“滑动窗”迭代Turbo译码算法,以达到性能和复杂度的折衷并避免了归零处理。在加性高斯白噪声信道下的误码率性能仿真证明:在视觉门限下该方案所需的比特信噪比Eb/N0仅为3.4dB,比参考方案有约1.8dB的增益。在此场强水平下,该系统可提供净信息速率约为12.5Mb/s的可靠视频广播。
In order to improve the transmission performance of digital terrestrial television (DTTB) system, the idea of Turbo code is introduced in the traditional serial concatenated coding structure, combined with 16QAM mapping and multi-carrier orthogonal frequency division multiplexing (OFDM) modulation, A new parallel concatenation lattice code (PCTC) is used as the inner code scheme. A “sliding window” iterative Turbo decoding algorithm based on the MAX-LOG-MAP criterion is used at the receiving end to achieve a compromise between performance and complexity and to avoid zeroing. Simulation of BER performance under additive white Gaussian noise channel shows that the bit-to-noise ratio Eb / N0 of this scheme is only 3.4dB under the visual threshold, and has a gain of about 1.8dB compared with the reference scheme. At this level of field strength, the system provides a reliable video broadcast with a net message rate of about 12.5 Mb / s.