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FiniteState Markov Modeling of Fading Channels—A Survey of Principles and Applications
 IEEE Sign. Process. Mag
"... [A survey of principles and applications] © MASTER SERIES In late 1950s and early 1960s, Gilbert and Elliott at Bell Labs were modeling burstnoise telephone circuits with a very simple twostate channel model with memory. This simple model allowed them to evaluate channel capacity and error rate pe ..."
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[A survey of principles and applications] © MASTER SERIES In late 1950s and early 1960s, Gilbert and Elliott at Bell Labs were modeling burstnoise telephone circuits with a very simple twostate channel model with memory. This simple model allowed them to evaluate channel capacity and error rate performance through bursty wireline telephone circuits. However, it took another 30 years for the socalled GilbertElliott channel (GEC) and its generalized finitestate Markov channel (FSMC) to be applied in the design of secondgeneration (2G) wireless communication systems. Since the mid 1990s, the GEC and FSMC models have been widely used for modeling wireless flatfading channels in a variety of applications, ranging from modeling channel error bursts to decoding at the receiver. FSMC models are versatile, and with suitable choices of model parameters, can capture the essence of timevarying fading channels. This article’s goal is to provide an indepth understanding of the principles of FSMC modeling of fading channels with its applications in wireless communication systems. Digital Object Identifier 10.1109/MSP.2008.926683 10535888/08/$25.00©2008IEEE IEEE SIGNAL PROCESSING MAGAZINE [57] SEPTEMBER 2008While the emphasis is on frequency nonselective or flatfading channels, this understanding will be useful for future generalizations of FSMC models for frequencyselective fading channels. The target audience of this article include both theory and practiceoriented researchers who would like to design accurate channel models for evaluating the performance of wireless communication systems in the physical or media access control layers, or those who would like to develop more efficient and reliable transceivers that take advantage of the inherent memory in fading channels. Both FSMC models and flatfading channels will be formally introduced. However, a background in timevarying fading communication channels is beneficial.
A generalization of the BlahutArimoto algorithm to finitestate channels
 IEEE TRANS. INF. THEORY
, 2008
"... The classical Blahut–Arimoto algorithm (BAA) is a wellknown algorithm that optimizes a discrete memoryless source (DMS) at the input of a discrete memoryless channel (DMC) in order to maximize the mutual information between channel input and output. This paper considers the problem of optimizing f ..."
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The classical Blahut–Arimoto algorithm (BAA) is a wellknown algorithm that optimizes a discrete memoryless source (DMS) at the input of a discrete memoryless channel (DMC) in order to maximize the mutual information between channel input and output. This paper considers the problem of optimizing finitestate machine sources (FSMSs) at the input of finitestate machine channels (FSMCs) in order to maximize the mutual information rate between channel input and output. Our main result is an algorithm that efficiently solves this problem numerically; thus, we call the proposed procedure the generalized BAA. It includes as special cases not only the classical BAA but also an algorithm that solves the problem of finding the capacityachieving input distribution for finitestate channels with no noise. While we present theorems that characterize the local behavior of the generalized BAA, there are still open questions
Smart meter privacy using a rechargeable battery: Minimizing the rate of information leakage
 in Proc. IEEE Int. Conf. Acoust. Speech Sig. Proc
, 2011
"... A rechargeable battery may be used to partially protect the privacy of information contained in a household’s electrical load profile. We represent the system as a finite state model to make tractable the computation of the rate of information leakage. Specifically, we use a trellis algorithm to est ..."
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A rechargeable battery may be used to partially protect the privacy of information contained in a household’s electrical load profile. We represent the system as a finite state model to make tractable the computation of the rate of information leakage. Specifically, we use a trellis algorithm to estimate the mutual information rate between the battery’s input and output loads. We show that stochastic battery policies can leak 26 % less information than a socalled besteffort algorithm (that holds the output load constant whenever possible). We finally describe the extension of the technique to more realistic models of the battery system. Index Terms — information security, data privacy, smart grids, energy storage, batteries 1.
Timefrequency packing for linear modulations: spectral efficiency and practical detection schemes
 IEEE Trans. Commun
, 2009
"... Abstract — We investigate the spectral efficiency, achievable by a lowcomplexity symbolbysymbol receiver, when linear modulations based on the superposition of uniformly time and frequencyshifted replicas of a base pulse are employed. Although orthogonal signaling with Gaussian inputs achieves ..."
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Abstract — We investigate the spectral efficiency, achievable by a lowcomplexity symbolbysymbol receiver, when linear modulations based on the superposition of uniformly time and frequencyshifted replicas of a base pulse are employed. Although orthogonal signaling with Gaussian inputs achieves capacity on the additive white Gaussian noise channel, we show that, when finiteorder constellations are employed, by giving up the orthogonality condition (thus accepting interference among adjacent signals) we can considerably improve the performance, even when a symbolbysymbol receiver is used. We also optimize the spacing between adjacent signals to maximize the achievable spectral efficiency. Moreover, we propose a more involved transmission scheme, composed by the superposition of two independent signals and a receiver based on successive interference cancellation, showing that it allows a further increase of the spectral efficiency. Finally, we show that a more involved equalization algorithm, based on soft interference cancellation, allows to achieve an excellent biterrorrate performance, even when errorcorrecting codes designed for the Gaussiannoiselimited channel are employed, and thus does not require a complete redesign of the coding scheme. I.
Information Capacity of an Energy Harvesting Sensor Node
, 1212
"... Energy harvesting sensor nodes are gaining popularity due to their ability to improve the network life time and are becoming a preferred choice supporting “green communication”. In this paper we focus on communicating reliably over an AWGN channel using such an energy harvesting sensor node. An impo ..."
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Energy harvesting sensor nodes are gaining popularity due to their ability to improve the network life time and are becoming a preferred choice supporting “green communication”. In this paper we focus on communicating reliably over an AWGN channel using such an energy harvesting sensor node. An important part of this work involves appropriate modeling of the energy harvesting, as done via various practical architectures. Our main result is the characterization of the Shannon capacity of the communication system. The key technical challenge involves dealing with the dynamic (and stochastic) nature of the (quadratic) cost of the input to the channel. As a corollary, we find close connections between the capacity achieving energy management policies and the queueing theoretic throughput optimal policies.
Binary energy harvesting channel with finite energy storage.
 In IEEE ISIT,
, 2013
"... AbstractA noiseless binary energy harvesting channel with onoff fading is considered. When causal fading state information is available at the transmitter only, an equivalent timing channel with additive geometric noise and noise information known at the transmitter is obtained. In this channel, ..."
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AbstractA noiseless binary energy harvesting channel with onoff fading is considered. When causal fading state information is available at the transmitter only, an equivalent timing channel with additive geometric noise and noise information known at the transmitter is obtained. In this channel, the transmitter's strategy is a stopping rule with respect to the channel fade levels given the message and the additive noise. Next, capacity when energy arrival information is available at the receiver and capacity when both energy arrival and fading information are available at the receiver are obtained. Additionally, several achievable schemes are proposed and evaluated.
Determining and approaching achievable rates of binary intersymbol interference channels using multistage decoding
 IEEE Trans. Information Theory
, 2007
"... Abstract—By examining the achievable rates of a multistage decoding system on stationary ergodic channels, we derive lower bounds on the mutual information rate corresponding to independent and uniformly distributed (i.u.d.) inputs, also referred to as the i.u.d. information rate. For binary intersy ..."
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Abstract—By examining the achievable rates of a multistage decoding system on stationary ergodic channels, we derive lower bounds on the mutual information rate corresponding to independent and uniformly distributed (i.u.d.) inputs, also referred to as the i.u.d. information rate. For binary intersymbol interference (ISI) channels, we show that these bounds become tight as the number of decoding stages increases. Our analysis, which focuses on the marginal conditional output densities at each stage of decoding, provides an information rate corresponding to each stage. These rates underlie the design of multilevel coding schemes, based upon lowdensity paritycheck (LDPC) codes and message passing, that in combination with multistage decoding approach the i.u.d. information rate for binary ISI channels. We give example constructions for channel models that have been commonly used in magnetic recording. These examples demonstrate that the technique is very effective even for a small number of decoding stages. Index Terms—Bahl–Cocke–Jelinek–Raviv (BCJR) algorithm, coset codes, density evolution, finitestate channels, information rates, intersymbol interference (ISI) channels, lowdensity paritycheck (LDPC) codes, magnetic recording, multilevel coding, multistage decoding. I.
SpectrallyEfficient Continuous Phase Modulations
 IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS
, 2009
"... Abstract—We investigate the spectral efficiency of continuous phase modulations (CPMs). To this end, we need an effective bandwidth definition for a CPM signal, whose power spectral density has in principle an infinite support. The definition we adopt is based on the spacing between adjacent carrier ..."
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Abstract—We investigate the spectral efficiency of continuous phase modulations (CPMs). To this end, we need an effective bandwidth definition for a CPM signal, whose power spectral density has in principle an infinite support. The definition we adopt is based on the spacing between adjacent carriers in a frequency division multiplexed CPM system. We consider the interchannel interference, which depends on the channel spacing, and we evaluate the spectral efficiency achievable by a singleuser receiver in the considered multichannel scenario. We then optimize the channel spacing with the aim of maximizing the spectral efficiency, showing that impressive improvements with respect to the spectral efficiencies reported in the literature and obtained by heuristic approaches can be achieved. Index Terms—Continuous phase modulation, interchannel interference, multiuser channels, information rate, spectral efficiency. I.
Asymptotics of the inputconstrained binary symmetric channel capacity
 Annals of Applied Probability
, 2009
"... We study the classical problem of noisy constrained capacity in the case of the binary symmetric channel (BSC), namely, the capacity of a BSC whose inputs are sequences chosen from a constrained set. Motivated by a result of Ordentlich and Weissman [In Proceedings of IEEE Information Theory Workshop ..."
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We study the classical problem of noisy constrained capacity in the case of the binary symmetric channel (BSC), namely, the capacity of a BSC whose inputs are sequences chosen from a constrained set. Motivated by a result of Ordentlich and Weissman [In Proceedings of IEEE Information Theory Workshop (2004) 117–122], we derive an asymptotic formula (when the noise parameter is small) for the entropy rate of a hidden Markov chain, observed when a Markov chain passes through a BSC. Using this result, we establish an asymptotic formula for the capacity of a BSC with input process supported on an irreducible finite type constraint, as the noise parameter tends to zero. 1. Introduction and background. Let X,Y be discrete random variables with alphabet X,Y and joint probability mass function pX,Y (x,y) △ = P(X = x,Y = y), x ∈ X,y ∈ Y [for notational simplicity, we will write p(x,y) rather than pX,Y (x,y), similarly p(x),p(y) rather than pX(x),pY (y), resp., when it
Joint Iterative Decoding of LDPC Codes and Channels with Memory
, 2003
"... This paper considers the joint iterative decoding of irregular lowdensity paritycheck (LDPC) codes and channels with memory. It begins by introducing a new class of erasure channels with memory, known as generalizederasure channels. For these channels, a single parameter recursion for the density ..."
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This paper considers the joint iterative decoding of irregular lowdensity paritycheck (LDPC) codes and channels with memory. It begins by introducing a new class of erasure channels with memory, known as generalizederasure channels. For these channels, a single parameter recursion for the density evolution of the joint iterative decoder is derived. This provides a necessary and sucient condition for decoder convergence, and allows the algebraic construction of sequences of LDPC degree distributions. Under certain conditions, these sequences can achieve the symmetric information rate (SIR) of the channel using only iterative decoding. Example code sequences are given for two channels, and it is conjectured that they each achieve the respective SIR. Keywords: joint iterative decoding, erasure channel, capacityachieving, LDPC codes 1.