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CSMA algorithms based on Gibbs sampling can achieve throughput optimality if appropriate attempt rates are employed. However, the problem of computing these attempt rates is NP-hard. Inspired by the well-known Kikuchi approximation, we propose a simple distributed algorithm, which obtains closed form estimates for the attempt rates. We also prove that our algorithm is exact for a class of graphs,...
In this paper, we consider an adaptive CSMA based scheduling algorithm for a single-hop wireless network under a realistic SINR (signal-to-interference-plus-noise ratio) model for the interference, and propose an efficient local optimization based algorithm to estimate certain parameters of the algorithm called fugacities. It is known that adaptive CSMA based algorithms can achieve throughput optimality,...
The increasing importance of networked control systems makes them inviting targets for cyber attacks. In a virus propagation attack, an adversary attempts to compromise a set of nodes in order to compromise their neighbors via software exploits. When the neighbor of a compromised node has already been compromised by a different virus, a newly-introduced virus can remove, co-exist with, or reinforce...
Motivated by recent high bandwidth communication systems, Inter-Symbol Interference (ISI) channels with 1-bit quantized output are considered under an average-power-constrained continuous input. While the exact capacity is difficult to characterize, an approximation that matches with the exact channel output up to a probability of error is provided. The approximation does not have additive noise,...
With the increasing popularity of complex network analysis through the use of graphs, a method for computing graph entropy has become important for a better understanding of a network's structure and for compressing large complex networks. There have been many different definitions of graph entropy in the literature which incorporate random walks, degree distribution, and node centrality. However,...
The wireless network medium has a large, but finite bandwidth. With increasing wireless network service providers, users, and applications, there is a need to optimise usage of even parts of the spectrum that are licensed. Dynamic spectrum access is an approach that is designed to enable unlicensed users to make use of licensed parts of the spectrum, opportunistically, when they are idle. To achieve...
Research has shown that fluid limits of Markov processes can be used to obtain closed form expressions for the evolution of the ripple-size. In this work we extend the above analysis to generalized LT (GLT) codes, which can be used to represent LT encoding (with priorities) over multiple data segments. In our analysis, we segregate the ripple into multiple colored ripples, where each color corresponds...
Reliable transmission is a challenging task over wireless links because wireless channels are susceptible to noise and interference. To address this problem various error control schemes have been introduced which are broadly categorized into automatic repeat request (ARQ)-based and forward error correction (FEC)-based techniques. In (S. Soltani et al., 2007), we introduced a channel adaptive error...
Contemporary wireless networks drop all corrupted packets at the receivers. Such a strategy adversely affects multimedia applications which have stringent throughput and delay constraints. Recently, a header estimation scheme was proposed to reduce packet drops at wireless receivers [1], [2]. These corrupted packets are recovered using FEC, which incurs lesser delay and bandwidth wastage than retransmissions...
Recent wireless measurement studies have revealed the presence of high-order memory in wireless bit-error channels. However, most wireless studies continue to employ the memory-less or 1st order Gilbert bit-error channels to design, analyze and verify wireless protocols and systems. The inaccuracies incurred by ignoring high-order channel memory are largely unexplored. This paper quantifies inaccuracies...
Bit-error rate (BER) modeling and prediction over residual wireless channels, which represent errors not corrected by the physical layer, has emerged as an active research area. Recently, it has been shown that signal to noise ratio (SNR) is a useful side-information that could be employed for BER prediction. In this paper, we propose a novel and accurate three-tier model that leverages a received...
Errors that are observed at the MAC layer of a wireless protocol are known as residue errors due to the failure of the physical layer to correct them. In this paper, based on experimentation with actual 802.11b wireless LANs (WLANs), it is shown that the 802.11b residue error process is a highly non-stationary process; and hence error models derived on the basis of observations at one time/environment...
Network impairments such as delay and packet losses have severe impact on the presentation quality of many predictive video sources. Prior researches have shown efforts to develop packet loss resilient coding methods to overcome such impairments for real-time streaming applications. Interleaved source coding (ISC) is one of the error resilient coding methods, which is based on an optimum interleaving...
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