CENTAUR: realizing the full potential of centralized wlans through a hybrid data path
CENTAUR: realizing the full potential of centralized wlans through a hybrid data path
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DOI：
10.1145/1614320.1614353
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发表时间：
2009-09
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通讯作者：
Vivek Shrivastava;N. Ahmed;Shravan K. Rayanchu;Suman Banerjee;S. Keshav;K. Papagiannaki;Arunesh Mishra-Arunesh-M
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文献类型：
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作者：
Vivek Shrivastava;N. Ahmed;Shravan K. Rayanchu;Suman Banerjee;S. Keshav;K. Papagiannaki;Arunesh Mishra-Arunesh-M
最近，企业WLAN已经向集中式架构进行了巨大的转变。作出这一改变的原因是便于管理和更好地设计各种控制和安全功能。然而，WLAN的数据路径继续使用分布式随机接入模型，如由802.11标准的流行DCF机制所定义的。虽然理论结果表明，一个集中调度的数据路径可以实现更高的效率比它的分布式对应，这种解决方案的可能的复杂性抑制了实际的考虑。在本文中，我们采取了一个新的，实施和部署为导向，在理解企业无线局域网中的数据路径选择的观点。我们进行了广泛的测量，以表征各种设计选择的影响，如调度粒度对集中式调度器的性能，并确定这样的集中式调度器可以提供最佳增益的区域。我们对部署在两个不同无线测试平台上的调度原型的详细评估表明，DCF在许多场景中非常强大，但集中化可以在以下方面发挥独特作用：1）减轻隐藏终端-可能不经常发生的场景，但当它们发生时会成为痛点，2）利用暴露终端-发生频率更高的场景，并限制成功并发传输的潜力。受这些结果的激励，我们设计和实现CENTAUR -企业无线局域网的混合数据路径，结合了DCF的简单性和易用性，从一个独特的Vantage位置进行有限的集中式调度。我们的机制不需要客户端合作，可以支持传统的802.11客户端。
Enterprise WLANs have made a dramatic shift towards centralized architectures in the recent past. The reasons for such a change have been ease of management and better design of various control and security functions. The data path of WLANs, however, continues to use the distributed, random-access model, as defined by the popular DCF mechanism of the 802.11 standard. While theoretical results indicate that a centrally scheduled data path can achieve higher efficiency than its distributed counterpart, the likely complexity of such a solution has inhibited practical consideration. In this paper, we take a fresh, implementation and deployment oriented, view in understanding data path choices in enterprise WLANs. We perform extensive measurements to characterize the impact of various design choices, like scheduling granularity on the performance of a centralized scheduler, and identify regions where such a centralized scheduler can provide the best gains. Our detailed evaluation with scheduling prototypes deployed on two different wireless testbeds indicates that DCF is quite robust in many scenarios, but centralization can play a unique role in 1) mitigating hidden terminals - scenarios which may occur infrequently, but become pain points when they do and 2) exploiting exposed terminals - scenarios which occur more frequently, and limit the potential of successful concurrent transmissions. Motivated by these results, we design and implement CENTAUR - a hybrid data path for enterprise WLANs, that combines the simplicity and ease of DCF with a limited amount of centralized scheduling from a unique vantage point. Our mechanisms do not require client cooperation and can support legacy 802.11 clients.