Backpressure (BP) routing is a well-established framework for distributed routing and scheduling in wireless multi-hop networks. However, the basic BP scheme suffers from poor end-to-end delay due to the drawbacks of slow startup, random walk, and the last packet problem. Biased BP with shortest path awareness can address the first two drawbacks, and sojourn time-based backlog metrics were proposed for the last packet problem. Furthermore, these BP variations require no additional signaling overhead in each time step compared to the basic BP. In this work, we further address three long-standing challenges associated with the aforementioned low-cost BP variations, including optimal scaling of the biases, bias maintenance under mobility, and incorporating sojourn time awareness into biased BP. Our analysis and experimental results show that proper scaling of biases can be achieved with the help of common link features, which can effectively reduce end-to-end delay of BP by mitigating the random walk of packets under low-to-medium traffic, including the last packet scenario. In addition, our low-overhead bias maintenance scheme is shown to be effective under mobility, and our bio-inspired sojourn time-aware backlog metric is demonstrated to be more efficient and effective for the last packet problem than existing approaches when incorporated into biased BP.

翻译：反压（BP）路由是无线多跳网络中分布式路由与调度的重要框架。然而，基础BP方案因启动缓慢、随机游走和最后一包问题等缺陷，导致端到端延迟性能较差。具有最短路径感知的偏置BP可解决前两个缺陷，而基于逗留时间的积压度量则被提出用于解决最后一包问题。与基础BP相比，这些BP变体在每个时隙中无需额外信令开销。本研究进一步解决上述低成本BP变体相关的三个长期挑战，包括：偏置的最优缩放、移动环境下的偏置维护，以及将逗留时间感知融入偏置BP。我们的分析和实验结果表明，借助常见链路特征可实现偏置的合理缩放，通过缓解中低流量（含最后一包场景）下的数据包随机游走，有效缩短BP的端到端延迟。此外，我们提出的低开销偏置维护方案在移动环境下表现有效，而受生物启发的逗留时间感知积压度量在融入偏置BP后，于最后一包问题的处理上较现有方法更具高效性与有效性。