基于ACK/NAK反馈的FDD-OFDM系统跨层设计
Cross-Layer Design of FDD-OFDM Systems based on ACK/NAK Feedbacks
摘要：
众所周知，跨层调度，自适应功率，速率和用户分配可以实现显着的增益系统容量。然而，传统的跨层设计都需要在基站处的信道状态信息（CSIT），这在实践中是难以获得的。在本文中，我们专注于跨层资源优化的基础上的ACK/NAK反馈流的OFDM系统中没有显式CSIT。虽然问题可以建模为马尔可夫决策过程（MDP），但通过策略迭代或值迭代的蛮力方法无法导致任何可行的解决方案。因此，我们推导出一个简单的封闭形式的解决方案的MDP跨层问题，这是渐近最佳的足够小的目标数据包出错率（PER）。所提出的解决方案也具有低复杂度，适合实时实现。它还示出，以实现显着的性能增益相比，不利用ACK/NAK反馈的跨层设计的系统或跨层系统，利用非常不可靠的CSIT的适应与CSIT错误统计不匹配。还提供了渐近分析，以获得有用的设计见解。
英文摘要：
It is well-known that cross-layer scheduling which adapts power, rate and user allocation can achieve significant gain on system capacity. However, conventional cross-layer designs all require channel state information at the base station (CSIT) which is difficult to obtain in practice. In this paper, we focus on cross-layer resource optimization based on ACK/NAK feedback flows in OFDM systems without explicit CSIT. While the problem can be modeled as Markov Decision Process (MDP), brute force approach by policy iteration or value iteration cannot lead to any viable solution. Thus, we derive a simple closed-form solution for the MDP cross-layer problem, which is asymptotically optimal for sufficiently small target packet error rate (PER). The proposed solution also has low complexity and is suitable for realtime implementation. It is also shown to achieve significant performance gain compared with systems that do not utilize the ACK/NAK feedbacks for cross-layer designs or cross-layer systems that utilize very unreliable CSIT for adaptation with mismatch in CSIT error statistics. Asymptotic analysis is also provided to obtain useful design insights.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
