Richard Combes - Optimal Rate Sampling in 802.11 Systems

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Richard Combes


- Richard Combes, will give a talk Tuesday Jan. 7, 2014, 12h00, in room D102 LIG, campus, Ensimag building. Biography : Richard Combes received the Engineering Degree from ENST (Ecole Nationale Superieure des Telecommunications, Paris, France) in 2008, the Master Degree and the Ph.D. in Mathematics from the university of Paris VII (France) respectively in 2009 and 2013. He is currently a post-doctoral researcher at KTH. He received the best paper award at the Conference on Network and Service Management (CNSM) in 2011. His current research interests include communication networks, stochastic systems and machine learning

- The webpage of Richard Combes

In 802.11 systems, Rate Adaptation (RA) is a fundamental mechanism allowing transmitters to adapt the coding and modulation scheme as well as the MIMO transmission mode to the radio channel conditions, and in turn, to learn and track the (mode, rate) pair providing the highest throughput. So far, the design of RA mechanisms has been mainly driven by heuristics. In contrast, in this paper, we rigorously formulate such design as an online stochastic optimisation problem. We solve this problem and present ORS (Optimal Rate Sampling), a family of (mode, rate) pair adaptation algorithms that provably learn as fast as it is possible the best pair for transmission. We study the performance of ORS algorithms in both stationary and non stationary radio environments. We show that under ORS algorithms, the throughput loss due to the need to explore sub-optimal (mode, rate) pairs does not depend on the number of available pairs, which is a crucial advantage as evolving 802.11 ! standards offer an increasingly large number of (mode, rate) pairs. We illustrate the efficiency of ORS algorithms (compared to the state-of-the-art algorithms) using simulations and traces extracted from 802.11 test-beds.