针对地面数字多媒体广播演进方案(DTMB-A)中由于采用了较大FFT长度而带来的高峰均比问题,提出一种基于动态星座图扩展的自适应峰均比降低算法。首先介绍了针对APSK调制方式的动态星座图扩展算法,明确了星座点可扩展区域的选择方式; 随后基于峰值抵消信号推导了动态星座图扩展算法的最优时域系数; 最后针对现有动态星座图扩展算法对初始限幅门限值敏感的问题,提出一种在迭代中自适应调整限幅门限值的方法。仿真结果表明: 所提算法的降峰均比性能优于现有动态星座图扩展算法,同时在初始限幅门限值设置不理想的情况下具有较好的鲁棒性。

This paper describes an adaptive peak-to-average power ratio (PAPR) reduction algorithm using the active constellation extension (ACE) for DTMB-A systems with large FFT lengths. The implementation of ACE algorithm for APSK constellation is introduced with the feasible extension region for the APSK constellation. An optimal time-domain factor for the ACE algorithm is then given based on the peak-cancellation signal. Since the original active constellation extension is sensitive to the initial clipping threshold, a method is given to adaptively adjust the clipping threshold. Simulations show that the algorithm has better performance than the original algorithms and is more robust to the initial clipping threshold.