Potholes Ahead: Impact of Transient Link Blockage on Beam Steering in Practical mm-Wave Systems
Potholes Ahead: Impact of Transient Link Blockage on Beam Steering in Practical mm-Wave Systems
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前方的坑洼：瞬态链路阻塞对实际毫米波系统中波束控制的影响
DOI：
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发表时间：
2016
期刊：
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通讯作者：
J. Widmer
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作者：
Adrian Loch;Irene Tejado;J. Widmer
在毫米波通信中，波束控制机制的实际实现对性能有很大影响。关键的挑战是找到一个务实的吞吐量性能和周期性波束扫描的开销之间的权衡，以提高链路质量的情况下，瞬时链路阻塞。这在商用现成设备中尤其重要，因为这些设备需要简单而高效的解决方案。首先，我们分析了这种商业设备的操作，以了解链路阻塞在实践中的影响。为此，我们测量TCP吞吐量为不同的流量负载，同时定期阻塞的链接。其次，我们根据实际见解推导出一个马尔可夫模型来计算瞬时阻塞情况下的吞吐量。我们使用这个模型来评估吞吐量和周期性波束扫描之间的权衡。最后，我们验证了我们的结果，使用上述商业设备收集的吞吐量痕迹。我们的模型和我们的实际测量表明，瞬态阻塞导致显着的信号波动，由于次优的光束重新排列。特别地，波动随着业务负载而增加，限制了可实现的吞吐量。我们表明，选择较低的流量负载，使我们能够减少41%的波动，同时实现相同的净吞吐量比更高的流量负载。
The practical realization of beam steering mechanisms in millimeter wave communications has a large impact on performance. The key challenge is to find a pragmatic trade-off between throughput performance and the overhead of periodic beam sweeping required to improve link quality in case of transient link blockage. This is particularly critical in commercial off-the-shelf devices, which require simple yet efficient solutions. First, we analyze the operation of such a commercial device to understand the impact of link blockage in practice. To this end, we measure TCP throughput for different traffic loads while blocking the link at regular intervals. Second, we derive a Markov model based on our practical insights to compute throughput for the case of transient blockage. We use this model to evaluate the trade-off between throughput and periodic beam sweeping. Finally, we validate our results using throughput traces collected using the aforementioned commercial device. Both our model and our practical measurements show that transient blockage causes significant signal fluctuation due to suboptimal beam realignment. In particular, fluctuations increase with traffic load, limiting the achievable throughput. We show that choosing lower traffic loads allows us to reduce fluctuations by 41% while achieving the same net throughput than with higher traffic loads.