Showing papers by "Themistoklis Charalambous published in 2011"
01 Sep 2011
TL;DR: This paper analyzes the stability of asynchronous coordination protocols and studies their application to energy resource provisioning of ancillary services in power grids, and establishes the convergence properties of this asynchronous consensus protocol.
Abstract: This paper analyzes the stability of asynchronous coordination protocols and studies their application to energy resource provisioning of ancillary services in power grids. First, we consider and analyze a protocol that can be used to asymptotically reach average consensus in an asynchronous mode of operation. Once we establish the convergence properties of this asynchronous consensus protocol, we demonstrate its effectiveness by applying it towards energy resource provisioning of ancillary services in a power grid.
27 citations
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TL;DR: This framework encompasses as a special case several criteria previously investigated in the literature, while relations to universal coding is discussed, including a convex combination of the average of an exponential function of the codeword length and the average redundancy.
Abstract: This paper presents prefix codes which minimize various criteria constructed as a convex combination of maximum codeword length and average codeword length or maximum redundancy and average redundancy, including a convex combination of the average of an exponential function of the codeword length and the average redundancy. This framework encompasses as a special case several criteria previously investigated in the literature, while relations to universal coding is discussed. The coding algorithm derived is parametric resulting in re-adjusting the initial source probabilities via a weighted probability vector according to a merging rule. The level of desirable merging has implication in applications where the maximum codeword length is bounded.
2 citations
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TL;DR: A joint distributed power and rate control algorithm for each transmitter is proposed that dynamically adjusts the data rate to meet a target SINR at each channel, and to update the power levels allowing for variable desired SINRs.
Abstract: In this paper, we consider multiple channels and wireless nodes with multiple transceivers. Each node assigns one transmitter at each available channel. For each assigned transmitter the node decides the power level and data rate of transmission in a distributed fashion, such that certain Quality of Service (QoS) demands for the wireless node are satisfied. More specifically, we investigate the case in which the average SINR over all channels for each communication pair is kept above a certain threshold. A joint distributed power and rate control algorithm for each transmitter is proposed that dynamically adjusts the data rate to meet a target SINR at each channel, and to update the power levels allowing for variable desired SINRs. The algorithm is fully distributed and requires only local interference measurements. The performance of the proposed algorithm is shown through illustrative examples.
1 citations
03 Oct 2011
TL;DR: This framework encompasses as a special case several criteria previously investigated in the literature, while relations to universal coding is discussed, and an algorithm is presented to compute the weighting vector.
Abstract: This paper presents prefix codes which minimize various criteria constructed as a convex combination of maximum codeword length and average codeword length, or, a convex combination of the average of an exponential function of the codeword length and the average codeword length. This framework encompasses as a special case several criteria previously investigated in the literature, while relations to universal coding is discussed. The coding algorithm derived is parametric resulting in re-adjusting the initial source probabilities via a weighted probability vector according to a merging rule. An algorithm is presented to compute the weighting vector.
1 citations
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TL;DR: This paper presents lossless prefix codes optimized with respect to a payoff criterion consisting of a convex combination of maximum codeword length and average codewords length based on a new coding algorithm, which transforms the initial source probability vector into a new probability vector according to a merging rule.
Abstract: This paper presents lossless prefix codes optimized with respect to a pay-off criterion consisting of a convex combination of maximum codeword length and average codeword length. The optimal codeword lengths obtained are based on a new coding algorithm which transforms the initial source probability vector into a new probability vector according to a merging rule. The coding algorithm is equivalent to a partition of the source alphabet into disjoint sets on which a new transformed probability vector is defined as a function of the initial source probability vector and a scalar parameter. The pay-off criterion considered encompasses a trade-off between maximum and average codeword length; it is related to a pay-off criterion consisting of a convex combination of average codeword length and average of an exponential function of the codeword length, and to an average codeword length pay-off criterion subject to a limited length constraint. A special case of the first related pay-off is connected to coding problems involving source probability uncertainty and codeword overflow probability, while the second related pay-off compliments limited length Huffman coding algorithms.
1 citations