EFD: an efficient low-overhead scheduler
NETWORKING'11 Proceedings of the 10th international IFIP TC 6 conference on Networking - Volume Part II
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Wireless LANs suffer from performance problems caused by insufficient medium access opportunity given to the access point. Consequently, the downlink buffer fills up, which often leads to packet losses. We propose to address this problem by using a size-based scheduling approach, which is known to favor short flows and the start up of new ones-a very appealing property from the user's perspective as interactive applications and new flows are serviced quickly. Still, size-based scheduling policies have a well-known Achilles heel: large flows can block each other for long periods of time and low rate multimedia transfers may end up with a low priority when their accumulated transferred volume becomes large. To solve the above deficiencies, we propose a new packet scheduling scheme called Least Attained Recent Service (LARS) that applies a temporal decay to the volume of data associated with each flow. In this way, its priority depends more on what has happened recently. With this strategy, LARS can bound the impact of a new arriving flow on ongoing flows, thus limiting lock out durations. It can also efficiently protect low rate multimedia transfers irrespectively of the load conditions.