In this paper we study the problem of jointly performing scheduling and congestion control in mobile adhoc networks so that network queues remain bounded and the resulting flow rates satisfy an associated network utility maximization problem. In recent years a number of papers have presented theoretical solutions to this problem that are based on combining differential-backlog scheduling algorithms with utility-based congestion control. However, this work typically does not address a number of issues such as how signaling should be performed and how the new algorithms interact with other wireless protocols.In this paper we address such issues. In particular:• We define a specific network utility maximization problem that we believe is appropriate for mobile adhoc networks.
• We describe a wireless Greedy Primal Dual(wGPD) algorithm for combined congestion control and scheduling that aims to solve this problem. • We show how the wGPD algorithm and its associated signaling can be implemented in practice with minimal disruption to existing wireless protocols. • We show via OPNET simulation that wGPD significantly outperforms standard protocols such as 802.11 operating in conjunction with TCP.This work was supported by the DARPA CBMANET program.This full text paper was peer reviewed at the direction of IEEE Communications Society subject matter experts for publication in the IEEE INFOCOM 2008 proceedings. 978-1-4244-2026-1/08/$25.00
Proper display and accurate recognition of document images are often hampered by degradations caused by poor scanning or transmission conditions. We propose a method to enhance such degraded document images for better display quality and recognition accuracy. The essence of the method is in finding and averaging bitmaps of the same symbol that are scattered across a text page. Outline descriptions of the symbols are then obtained that can be rendered at arbitrary resolution. The paper describes details of the algorithm and an experiment to demonstrate its capabilities using fax images.
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