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.
|Number of pages||10|
|Journal||Computer Communication Review|
|Publication status||Published - Apr 2015|