Buffer-Aided Relaying With Outdated CSI
Buffer-Aided Relaying With Outdated CSI
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DOI：
10.1109/twc.2015.2497342
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发表时间：
2016-03
影响因子：
10.4
通讯作者：
T. Islam;D. Michalopoulos;R. Schober;V. Bhargava
中科院分区：
文献类型：
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作者：
T. Islam;D. Michalopoulos;R. Schober;V. Bhargava
当完美的信道状态信息（CSI）可用于链路选择时，与具有固定传输调度的传统中继相比，缓冲器辅助中继的自适应链路选择可以提供显着的性能增益。然而，在实践中，由于CSI反馈不频繁和/或反馈延迟，可能必须基于过时的CSI来执行链路选择。在本文中，我们研究了过时的 CSI 对固定速率传输的三节点解码转发（DF）中继网络自适应链路选择错误率性能的影响。特别是，我们提出了两种基于 CSI 估计的可靠性是否已知的链路选择协议。对于这两种协议，我们根据决策阈值 β 提供统一的错误率分析，可以调整该阈值以保持缓冲区稳定性，并导出渐近近似，从而揭示多样性和编码增益。由于数据包传输延迟对于机会性链路选择是不可避免的，因此我们考虑有限和无限缓冲区大小来分析平均延迟和吞吐量。平均延迟和吞吐量是决策阈值β的函数，可以对其进行优化以最小化错误率，同时满足平均延迟和/或吞吐量约束。数值结果表明，即使使用过时的 CSI，自适应链路选择也比传统 DF 中继提供显着的编码增益优势。此外，我们还表明，对于完美的 CSI，可以实现 2 的分集增益，并且可以通过小延迟和/或高吞吐量来达到最佳错误率。
Adaptive link selection for buffer-aided relaying can provide significant performance gains compared to conventional relaying with fixed transmission schedule, when perfect channel state information (CSI) is available for link selection. However, in practice, link selection may have to be performed based on outdated CSI, because of infrequent feedback of CSI and/or feedback delay. In this paper, we study the effect of outdated CSI on the error rate performance of adaptive link selection for a three node decode-and-forward (DF) relay network with fixed-rate transmission. In particular, we propose two protocols for link selection based on whether the reliability of the CSI estimates is known or not. For both protocols, we provide a unified error-rate analysis in terms of a decision threshold β, which can be adjusted to maintain buffer stability, and derive asymptotic approximations, which reveal the diversity and coding gains. Since packet transmission delay is unavoidable for opportunistic link selection, we analyze the average delay and throughput considering both finite and infinite buffer size. The average delay and throughput are functions of the decision threshold β, which can be optimized to minimize the error rate while satisfying average delay and/or throughput constraints. Numerical results manifest that even with outdated CSI, adaptive link selection provides a significant coding gain advantage over conventional DF relaying. Furthermore, we show that a diversity gain of two can be achieved for perfect CSI and the optimum error rate can be approached with small delay and/or high throughput.