SampleLite: A Hybrid Approach to 802.11n Link Adaptation
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CCR April 2015 We consider the link adaptation problem in 802.11n wireless LANs that involves adapting MIMO mode, channel bonding, modulation and coding scheme, and frame aggregation level with varying channel conditions. Through measurement-based analysis, we find that adapting all available 802.11n features results in higher goodput than adapting only a subset of features, thereby showing that holistic link adaptation is crucial to achieve best performance. We then design a novel hybrid link adaptation scheme termed SampleLite that adapts all 802.11n features while being efficient compared to sampling-based open-loop schemes and practical relative to closed loop schemes. SampleLite uses sender-side RSSI measurements to significantly lower the sampling overhead, by exploiting the monotonic relationship between best settings for each feature and the RSSI. Through analysis and experimentation in a testbed environment, we show that our proposed approach can reduce the sampling overhead by over 70% on average compared to the widely used Minstrel HT scheme. We also experimentally evaluate the goodput performance of SampleLite in a wide range of controlled and realworld interference scenarios. Our results show that SampleLite, while performing close to the ideal, delivers goodput that is 35– 100% better than with existing schemes.
Public Review By:
Aline Carneiro Viana Public Review for SampleLite: A Hybrid Approach to 802.11n Link Adaptation Lito Kriara and Mahesh K. Marina In the context of 802,11n, link adaptation brings the possibility to increase application performance if MAC and PHY features are well configured to deal with varying channel and interference conditions. This paper deals with link adaptation in 802.11n WLANs and aims to overcome existing schemes incurring high sampling overhead or using sub-optimal settings for extended periods. For this, a practical hybrid approach, named SampleLite, is proposed. The considered features at the adaptation are channel bonding, MIMO mode, and modulation and coding scheme. The work relies on sender-side RSSI measurements to significantly lower the sampling overhead, by exploiting the monotonic relationship between best settings for each feature and the RSSI, thus improving performance. In the first round of review, reviewers found the paper interesting but in order to be considered complete some changes were still required to make the ideas more concise, as well as to clarify explanations. Authors have then answered all concerns of reviewers and improved the quality of their contribution. Reviewers then considered the paper had met the contributions authors were listing in the introduction, though some few comments to improve the presentation of the paper were still requested in the final notification.
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