Abstract: The DVB-C2 standard utilizes QAM constellation sizes up to 4096-QAM to achieve a frequency utilization efficiency of up to 12（bit/s）/Hz over coax cable. However, while using high order Quadrature Amplitude Modulation（QAM）, it becomes more sensitive to channel estimation errors due to the densely distributed QAM constellation. This paper analyzes the impact of channel estimation errors on high order QAM modulated OFDM signals and proposes a channel equalization method suitable for the slow time-varying multipath channel characteristics of DVB-C2 system. The Mean Square Error（MSE） and the Bit Error Rate（BER） performance of the proposed algorithm are verified by the simulation results.

Key words: DVB-C2, Orthogonal Frequency Division Multiplexing（OFDM）, channel estimation, 4096-QAM

摘要： DVB-C2系统采用了4096-QAM调制，并结合OFDM技术在同轴电缆上获得接近12 （bit/s）/Hz的频谱利用率。然而相对于低阶调制，高阶QAM密集的星座点分布更容易受到信道估计误差的影响。分析了高阶QAM调制对OFDM信道估计精度的要求，针对同轴电缆信道的慢时变特性，提出了一种噪声抑制的信道均衡方法。计算机仿真结果表明，与传统的信道均衡方法相比，在高信噪比时，提出方法的误比特率性能优于传统方法约3 dB。

关键词: 欧洲第二代有线数字电视, 正交频分复用, 信道估计, 正交幅度调制