Abstract: This paper discusses adaptive feedback resource allocation schemes in OFDM systems under time-varying fading channels.The adaptive schemes are presented：Adjust the power based on the increment in the coherence time and adaptively feedback based on the capacity change.Through simulation，it compares the capacity of adaptive scheme with the capacity of water-filling in OFDM system，proves the methods can preserve the performance，reduce the system complexity，and improve the system efficiency.

Key words: time-varying fading channels, Orthogonal Frequency Division Multiplexing（OFDM）, adaptive resource allocation, system capacity

摘要： 讨论了在任意衰落的时变信道中自适应反馈的资源分配方法，提出了基于相干时间周期检测的增量调整及基于容量变化自适应反馈信道状态的自适应功率分配方法，仿真了多径衰落信道中这种自适应分配方式的OFDM系统容量，通过与理想情况下的注水原理资源分配容量比较，证明了自适应分配方法的性能与最佳分配基本一致，同时大大降低了系统的复杂度，减少了迭代次数，提高了系统效率，并保证了各用户的长期公平性。

关键词: 时变衰落信道, 正交频分复用, 自适应资源分配, 系统容量