Flow-level performance and user mobility in wireless data networks
Flow-level performance and user mobility in wireless data networks
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无线数据网络中的流级性能和用户移动性
DOI：
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发表时间：
2008
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通讯作者：
S. Borst
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作者：
S. Borst
无线网络中的信道条件在空间和时间上表现出巨大的变化，从而引起传输速率的巨大波动。通道感知调度策略提供了一种有效的机制，可以通过利用这种速率变化来提高吞吐量性能，这些已经在静态用户配置的数据包级别上进行了广泛的研究。在本文中，我们讨论了动态用户群体在流水平上的性能影响，同时考虑了较慢时间尺度和大范围用户移动性的变化。首先，我们给出了流级稳定的简单必要条件，并证明这些条件实际上（接近）足以满足一系列基于效用的调度策略。进一步展示了如何通过具有状态依赖服务率的处理器共享模型来评估比例公平调度策略的流级性能。此外，我们研究了变化在较慢的时间尺度上的影响，并建立了所谓的流体和准平稳状态产生明确的，不敏感的性能界限。最后，我们将注意力转向由多个基站（BSs）组成的网络，其中活动会话的切换由广泛的用户移动性控制。证明了移动性不仅在全局最优调度的情况下，而且在每个BSs遵守局部公平共享原则的情况下，都增加了运力。
Channel conditions in wireless networks exhibit huge variations across space and time, giving rise to vast fluctuations in the transmission rates. Channel-aware scheduling strategies provide an effective mechanism for improving throughput performance by exploiting such rate variations, and these have been extensively examined at the packet level for a static user configuration. In this paper, we discuss the performance implications at the flow level for a dynamic user population, taking into account variations on a slower time scale and wide-range user mobility as well. First of all, we present simple necessary conditions for flow-level stability and prove that these are in fact (near) sufficient for a wide family of utility-based scheduling strategies. It is further shown how the flow-level performance of the proportional fair scheduling strategy may be evaluated by means of a processor-sharing model with a state-dependent service rate. In addition, we examine the impact of variations on a slower time scale, and establish that the so-called fluid and quasi-stationary regimes yield explicit, insensitive performance bounds. Finally, we turn our attention to a network of several base stations (BSs) with handoffs of active sessions governed by wide-range user mobility. It is demonstrated that mobility increases the capacity, not only in the case of globally optimal scheduling but also when each of the BSs adheres to a local fair-sharing discipline.