Timing jitter, frequency offset, carrier phase jitter and sampling clock frequency offset are the main synchronization errors encountered by OFDM systems. As many literatures have proved, OFDM systems are very sensitive to frequency errors. In this paper, an improved method to do decimal frequency offset estimation in time domain is proposed. In addition, lots of simulations have proved that when the decimal frequency offset in data streams approaches to 0.5 of the subcarrier spacing, a wrong estimated frequency offset with inverse polarity will be presented, therefore, a novel adjusting model to deal with this problem is also proposed in this paper. Simulation results show that the mean square error (MSE) can be significantly improved by over three order of magnitude at high SNR with the proposed method compared with the conventional method [1], [2]. The correspondent Field Programmable Gate Array (FPGA) circuit through test in HDTV prototype in Team of Engineering Expert Group (TEEG) proves its feasibility and availability.

Most existing methods for HPA predistortion with memory effects are based on polynomial or indirect learning structures. Few papers concern about the memory predistortion with LUT based techniques. Based on the previously presented method, we propose an improved two-dimensional LUT indexing method for HPA predistortion with memory. Computer simulations and corresponding analysis demonstrate that the proposed method has more effective predistortion capabilities but lower computational complexity.

针对由正交多项式设计的功率放大器预失真系统，提出一种系数可变的多项式预失真器，并给出相应的实现结构．该预失真多项式有多组系数组合，随着输入信号幅度的不同，多项式选取不同的系数组合，从而降低估计误差．仿真分析表明，当使用2，4和8组系数时，相对于传统的正交多项式，采用该算法得到的估计误差可达到6.0dB，23.6dB和42.7dB的增益，对应得到10dB，30dB和50dB的带外谱抑制增益．该方法降低了预失真器设计中对多项式阶数的要求，提高了设计的灵活性，降低了预失真器后低通滤波器的设计难度。

通过对欧洲OFDM接收方案的分析，提出了一种易于FPGA实现的同步解决方案。结合计算机仿真和工程实现，提出了一种新的符号定时同步算法。该法克服了常规ML方法估计出的符号同步位置波动较大的缺点，弥补了门限估计方法中实际同步起始位置与估计位置相差大的不足，可以较好地实现符号定时同步。

提出了一种宽带数字电视地面广播（BDB-T）系统的同步解决方案重点研究了频域中的频率同步部分通过对各种算法的仿真分析比较给出易于实现节省资源的频域频率同步算法并完成了相应的FPGA 硬件电路设计经BDB-T 功能样机在实际无线环境中的传输测试证明了算法及其电路的良好实际工作性能。