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中国地面数字电视广播系统采用了时域同步正交频分复用(TDS-OFDM)技术。在该系统中实现双天线发射分集时,不同天线发送的训练序列在独立链路上传输,到达接收端时相互之间存在干扰。该文提出了一种有效实现双天线发射分集的帧结构,将一组伪随机序列对经过空时编码后,分别作为双天线发射信号帧中二个帧时隙的帧头序列。基于该帧结构,给出了迭代的信道估计算法,提高了在衰落信道下系统的接收性能,可以改善电视信号的覆盖范围。
China terrestrial digital television broadcasting system uses time-domain synchronous orthogonal frequency division multiplexing (TDS-OFDM) technology. When implementing dual antenna transmit diversity in the system, the training sequences sent by different antennas are transmitted on independent links and interfere with each other when they reach the receiving end. This paper proposes a frame structure that effectively implements dual antenna transmit diversity. After a group of pseudo-random sequences are space-time coded, they are respectively used as the frame head sequence of two frame time slots in a signal transmission frame. Based on the frame structure, an iterative channel estimation algorithm is given, which improves the receiving performance of the system under the fading channel and improves the coverage of the television signal.