Abstract: The combining technology of HARQ are Chase combining and Incremental Redundancy（IR） generally.However，the performance of Chase combining is not excellent at low signal-to-noise channels and IR combining is complex to be realized.This paper proposes an adaptive combining algorithm based on signal-to-noise.With the real time estimation of channel signal-to-noise，this algorithm uses Chase combining and IR combining synthetically，which unifies performance and complexity of the system.The simulation results indicate that the new adaptive combining scheme is feasible.

Key words: Hybrid Automatic Repeat Request（HARQ）, Chase combining, incremental redundancy, adaptive combining

摘要： 目前无线通信中广泛使用的HARQ合并技术主要是Chase合并和递增冗余（IR）合并。针对Chase合并在低信噪比下性能受限，递增冗余（IR）合并实际应用复杂的问题，提出了一种基于信噪比的自适应合并算法，通过实时估计信道的信噪比，综合使用Chase合并和递增冗余（IR）合并，实现了系统性能和实现复杂度的统一。仿真结果表明，算法是切实可行的。

关键词: 混合自动重传请求（HARQ）, Chase合并, 递增冗余, 自适应合并