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Communication, Control, and Computing (Allerton), 2010 48th Annual Allerton Conference on

Date Sept. 29 2010-Oct. 1 2010

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Displaying Results 1 - 25 of 252
  • Foreword

    Publication Year: 2010 , Page(s): 1
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  • Table of contents

    Publication Year: 2010 , Page(s): 1 - 30
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  • Author index

    Publication Year: 2010 , Page(s): 1 - 14
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  • [Copyright notice]

    Publication Year: 2010 , Page(s): 1
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  • 48 years of Allerton conferences

    Publication Year: 2010 , Page(s): 1 - 3
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  • The design of rate-compatible protograph LDPC codes

    Publication Year: 2010 , Page(s): 1 - 5
    Cited by:  Papers (5)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (404 KB) |  | HTML iconHTML  

    This paper presents a simple yet powerful method for designing embedded rate-compatible families of LDPC codes. Rate compatible codes are essential for many communication applications, e.g. hybrid automatic repeat request (HARQ) systems, and their design is nontrivial due to the difficulty of simultaneously guaranteeing the quality of several related codes. Puncturing can be used to generate rate-compatible LDPC codes, but it produces a gap to capacity that, in practice, often significantly exceeds the gap of the mother code. We propose an alternative method based on successively extending a high-rate protograph. The resulting codes not only inherit the advantages of protograph codes, namely low encoding complexity and efficient decoding algorithms, but also cover a wide range of rates and have very good performance with thresholds that are all within 0.15 dB of their capacity limits. View full abstract»

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  • Low complexity Linear Programming decoding of nonbinary linear codes

    Publication Year: 2010 , Page(s): 6 - 13
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1060 KB) |  | HTML iconHTML  

    Linear Programming (LP) decoding of Low-Density Parity-Check (LDPC) codes has attracted much attention in the research community in the past few years. The aim of LP decoding is to develop an algorithm which has error-correcting performance similar to that of the Sum-Product (SP) decoding algorithm, while at the same time it should be amenable to mathematical analysis. The LP decoding algorithm has been derived for both binary and nonbinary decoding frameworks. However, the most important problem with LP decoding for both binary and nonbinary linear codes is that the complexity of standard LP solvers such as the simplex algorithm remain prohibitively large for codes of moderate to large block length. To address this problem, Vontobel et al. proposed a low complexity LP decoding algorithm for binary linear codes which has complexity linear in the block length. In this paper, we extend the latter work and propose a low-complexity LP decoding algorithm for nonbinary linear codes. We use the LP formulation for the nonbinary codes as a basis and derive a pair of primal-dual LP formulations. The dual LP is then used to develop the low-complexity LP decoding algorithm for nonbinary linear codes. The complexity of the proposed algorithm is linear in the block length and is limited mainly by the maximum check node degree. As a proof of concept, we also present a simulation result for a [80, 48] LDPC code defined over ℤ4 using quaternary phase-shift keying over the AWGN channel, and we show that the error-correcting performance of the proposed LP decoding algorithm is similar to that of the standard LP decoding using the simplex solver. View full abstract»

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  • Construction of turbo lattices

    Publication Year: 2010 , Page(s): 14 - 21
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (377 KB) |  | HTML iconHTML  

    In this work we introduce and establish the concept of turbo lattices. We employ a routine method for constructing lattices, called Construction D, to construct turbo lattices. This kind of construction needs a set of nested linear codes as its underlying structure. We benefit from turbo codes as our bases codes. Therefore, we first build a set of nested turbo codes based on nested interleavers and nested convolutional codes. Then by means of these codes, along with construction D, we construct turbo lattices. Several properties of Construction D lattices and specially many characteristics of turbo lattices including the minimum distance, coding gain, kissing number and the probability of error under a maximum likelihood decoder over AWGN channel are investigated. View full abstract»

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  • Self-inverse interleavers based on permutation functions for turbo codes

    Publication Year: 2010 , Page(s): 22 - 28
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (295 KB) |  | HTML iconHTML  

    In this work we introduce and study a set of new interleavers based on permutation functions with known inverses over a finite field Fq for using in turbo code structures. We use Möbius and Rédei functions in order to find new interleavers. As a byproduct we give an exact formula for finding the inverse of every Rédei function. The cycle structure of Rédei functions are also investigated. Finally, self-inverse versions of permutation functions are used to construct interleavers. These interleavers are their own de-interleavers and are useful for turbo coding and turbo decoding. Experiments carried out for self-inverse interleavers show excellent agreement with our theoretical results. View full abstract»

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  • Computing linear functions with linear network codes

    Publication Year: 2010 , Page(s): 29 - 35
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (455 KB) |  | HTML iconHTML  

    We study the problem of computing linear functions over a finite field in arbitrary networks with a single receiver node. We follow an algebraic approach similar to the one developed by Koetter and Médard for conventional network coding problems. First, we find a necessary and sufficient condition for the existence of a linear solution; then we identify a class of linear functions over the binary field that are solvable whenever the network min-cut is at least one. For linear functions outside this class, we shown that there always exists a network of min-cut one which has no linear solution. View full abstract»

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  • Relaxed half-stochastic decoding of LDPC codes over GF(q)

    Publication Year: 2010 , Page(s): 36 - 41
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (329 KB) |  | HTML iconHTML  

    The error-correcting performance of non-binary LDPC codes has been shown to be better than most codes currently used for a variety of applications. However, due to the very high complexity of decoding these codes, they are not ubiquitously used. Moreover, an SPA decoder is so prohibitively complex, that a fully parallel implementation is not feasible even with simplified algorithms. In this paper we present a new algorithm which approaches the low complexity of stochastic decoding with the high performance of SPA decoding by combining elements from both algorithms and applying successive relaxation. We study its performance using a number of codes and show that it matches that of the SPA. We also analyze its complexity compared to the SPA and conclude that it has lower per iteration complexity and can have comparable average complexity per codeword. Due to the lower per iteration complexity, RHS has the potential of being implemented as a parallel, or partially parallel, decoder that is faster than a feasible SPA decoder. View full abstract»

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  • Coupling of day ahead and real-time power markets for energy and reserves incorporating local distribution network costs and congestion

    Publication Year: 2010 , Page(s): 42 - 49
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (478 KB) |  | HTML iconHTML  

    Acknowledging that increasing intermittent clean energy generation is likely to impose a bottleneck in the demand for regulation reserves, we investigate potential increases in the supply of regulation service through enhanced participation of loads in electricity markets. Moreover, we focus on future markets where Loads connected at the distribution network participate extensively and in direct competition with centralized generation whole sale market participants. We focus our analysis to distributed PHEV loads and develop a decision support algorithm for optimal bidding to the existing wholesale as well as to prospective retail/distribution market. We argue that generalization to a broad range of load types is reasonably straight forward. View full abstract»

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  • Volatility and efficiency in markets with friction

    Publication Year: 2010 , Page(s): 50 - 57
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1716 KB) |  | HTML iconHTML  

    We consider a game theoretic model where multiple suppliers and consumers interact continuously by setting prices in a dynamic market with friction. Using stochastic differential equations to model the dynamics with friction, we investigate the equilibrium, and analyze the efficiency of the market under an integrated expected cost function. We provide an intriguing efficiency-volatility tradeoff theorem. View full abstract»

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  • Distributed energy resources in electricity markets: The price droop mechanism

    Publication Year: 2010 , Page(s): 58 - 65
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (595 KB) |  | HTML iconHTML  

    Distributed energy resources (DER), including small-scale generation, renewable energy technologies, and demand response, are disadvantaged with respect to central generating facilities as a consequence of being excluded from regional energy and ancillary services markets. This paper proposes a price-based open-loop control signal to facilitate significantly increasing DER penetration in the power system by coordinating their participation in electricity markets while also maintaining the local system energy balance. The proposed signal introduces the concept of “price droop” that is based upon the concepts of frequency droop and own price elasticity. The use of this signal is demonstrated in a variety of scenarios with DER in a microgrid operating in islanded mode. View full abstract»

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  • Repeated games in electricity spot and forward markets - An equilibrium modeling and computational framework

    Publication Year: 2010 , Page(s): 66 - 71
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (376 KB) |  | HTML iconHTML  

    It has long been recognized that repeated interactions among strategic firms can lead to tacit collusion, a form of market power abuse that can cause more market inefficiencies than in a static game. Harrington et al. formulated the tacit collusion model into a nonlinear optimization problem, and Liu extended the collusion model into electricity markets with transmission constraints. This paper presents another extension of the collusion model into a marketplace consisting of the repetition of a forward and a spot market, such as two-settlement system (a day-ahead and a real-time market) in some deregulated electricity markets. This paper is to establish an optimization model to study firms' strategies when they engage in tacit collusion in both forward and spot markets. A numerical example based on the modeling approach is presented and the results show that repetition of forward markets can help firms sustain collusion, which is contrary to the common belief that forward markets can increase market efficiency. In addition, the numerical results indicate that market power abuse is intensified when firms can take long position in forwards than just taking short positions. View full abstract»

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  • Bidirectional multi-pair network with a MIMO relay: Beamforming strategies and lack of duality

    Publication Year: 2010 , Page(s): 72 - 77
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (431 KB) |  | HTML iconHTML  

    We address the problem of a multi-user relay network, where multiple single-antenna node pairs want to exchange information by using a multiple antenna relay node. Due to the half-duplex constraint of the relay, the exchange of information takes place in two steps. In the first step, the nodes transmit their data to the relay, while in the second step, the relay is broadcasting the data by using linear and non-linear precoding strategies. We focus on the second step in this paper. We first consider the problem of maximizing the overall rate achievable using linear and dirty-paper type precoding strategies at the relay. Then, we consider minimizing the total power at the relay subject to individual SINR constraints using the same strategies at the relay. We show that the downlink-uplink duality does not hold for the setup considered here, which is a somewhat surprising result. We also show that the beamforming strategy which is optimal in the single-pair case performs very well in the multi-pair case for practically relevant SNR. The results are illustrated by numerical simulations. View full abstract»

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  • On the DMT optimality of the rotate-and-forward scheme in a two-hop MIMO relay channel

    Publication Year: 2010 , Page(s): 78 - 85
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (432 KB) |  | HTML iconHTML  

    The rotate-and-forward scheme was introduced in (Yang-Belfiore, 2010) to recover spatial diversity in multi-hop MIMO relay networks. It was shown that this scheme achieves the optimal diversity-multiplexing (DMT) trade-off in a two-hop relay network, with two antennas at the relay node. In this paper, it is shown that the scheme is DMT optimal for arbitrary number of antennas at the source, relay, and destination node. View full abstract»

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  • Asymptotic capacity of the separated MIMO two-way relay channel with linear precoding

    Publication Year: 2010 , Page(s): 86 - 93
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (438 KB) |  | HTML iconHTML  

    A multiple-input multiple-output two-way relay channel consisting of two communication nodes and a full-duplex relay node is considered, assuming that no direct link exists between the two communication nodes. We propose an achievable scheme using lattice codes combined with generalized singular value decomposition-based precoding for the first phase and vertically encoded structural bining for the second phase. We show that the proposed scheme achieves the cut-set bound asymptotically as the signal-to-noise ratio tends to infinity. View full abstract»

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  • The capacity region of the class of Gaussian MIMO three-receiver multilevel broadcast channels with degraded message sets

    Publication Year: 2010 , Page(s): 94 - 101
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (440 KB) |  | HTML iconHTML  

    Nair and Gamal established the capacity region for the class of three-receiver multilevel broadcast channels (MBC) with degraded message sets. In this channel, the output at receiver 2 is a degraded version of the output at receiver 1. The transmitter sends a common message to all three receivers and a private message to receiver 1. By considering a specific discrete-memoryless example, they showed that a direct extension of the Körner-Marton region (for the two-receiver broadcast channels with degraded message sets) is strictly suboptimal. They also considered a three-receiver Gaussian product MBC and showed that, restricted to Gaussian inputs, a direct extension of the Körner-Marton region is again strictly suboptimal. However, the question as to whether Gaussian inputs are optimal remained unresolved. In this paper, we show that Gaussian inputs, along with time-sharing between rate points obtained with Gaussian inputs, achieves the capacity region of the class of three-receiver Gaussian MIMO MBC with degraded message sets. View full abstract»

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  • Decomposing the MIMO broadcast channel

    Publication Year: 2010 , Page(s): 102 - 106
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (361 KB) |  | HTML iconHTML  

    The problem of transmitting a common message over a multiple-input multiple-output (MIMO) Gaussian broadcast channel with multiple receivers is well understood in terms of capacity. Nevertheless, existing optimal (capacity-achieving) schemes for this scenario require joint decoding of the multiple streams transmitted, entailing high computational complexity. In this paper, a low-complexity scheme requiring only single stream decoding is proposed. The scheme uses a matrix decomposition, which allows, by linear pre- and post-processing, to simultaneously transform both channel matrices to triangular forms, where the diagonal entries of both channels are equal. In conjunction with successive interference cancellation at each receiver, parallel channels are created, over each of which scalar coding and decoding may be used. We prove that this channel transformation conserves mutual information, and hence any sub-optimality of the proposed scheme is governed solely by the gap-to-capacity of the scalar coding scheme over the parallel channels. View full abstract»

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  • Divergence-based characterization of fundamental limitations of adaptive dynamical systems

    Publication Year: 2010 , Page(s): 107 - 114
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (361 KB) |  | HTML iconHTML  

    Adaptive dynamical systems arise in a multitude of contexts, e.g., optimization, control, communications, signal processing, and machine learning. A precise characterization of their fundamental limitations is therefore of paramount importance. In this paper, we consider the general problem of adaptively controlling and/or identifying a stochastic dynamical system, where our a priori knowledge allows us to place the system in a subset of a metric space (the uncertainty set). We present an information-theoretic meta-theorem that captures the trade-off between the metric complexity (or richness) of the uncertainty set, the amount of information acquired online in the process of controlling and observing the system, and the residual uncertainty remaining after the observations have been collected. Following the approach of Zames, we quantify a priori information by the Kolmogorov (metric) entropy of the uncertainty set, while the information acquired online is expressed as a sum of information divergences. The general theory is used to derive new minimax lower bounds on the metric identification error, as well as to give a simple derivation of the minimum time needed to stabilize an uncertain stochastic linear system. View full abstract»

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  • Optimism in reinforcement learning and Kullback-Leibler divergence

    Publication Year: 2010 , Page(s): 115 - 122
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (410 KB) |  | HTML iconHTML  

    We consider model-based reinforcement learning in finite Markov Decision Processes (MDPs), focussing on so-called optimistic strategies. In MDPs, optimism can be implemented by carrying out extended value iterations under a constraint of consistency with the estimated model transition probabilities. The UCRL2 algorithm by Auer, Jaksch and Ortner (2009), which follows this strategy, has recently been shown to guarantee near-optimal regret bounds. In this paper, we strongly argue in favor of using the Kullback-Leibler (KL) divergence for this purpose. By studying the linear maximization problem under KL constraints, we provide an efficient algorithm, termed KL-UCRL, for solving KL-optimistic extended value iteration. Using recent deviation bounds on the KL divergence, we prove that KL-UCRL provides the same guarantees as UCRL2 in terms of regret. However, numerical experiments on classical benchmarks show a significantly improved behavior, particularly when the MDP has reduced connectivity. To support this observation, we provide elements of comparison between the two algorithms based on geometric considerations. View full abstract»

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  • Information utility in active sequential hypothesis testing

    Publication Year: 2010 , Page(s): 123 - 129
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (813 KB) |  | HTML iconHTML  

    This paper considers a broad spectrum of applications in cognition, communications, design of experiments, and sensor management. In all of these applications, a decision maker is responsible to control the system dynamically so as to enhance his information in a speedy manner about an underlying phenomena of interest while accounting for the cost of communication, sensing, or data collection. In addition, due to the sequential nature of the problem, the decision maker relies on his current information state to constantly (re-)evaluate the information utility of various actions. In this paper, using a dynamic programming interpretation, an optimal notion of information utility is derived. Inspired by this view of the problem, a set of heuristic policies for dynamic selection of actions are proposed. The construction of these heuristics relate various notions of information utility with the statistical properties of the outcome, such as Kullback-Leibler divergence and mutual information. Via numerical and asymptotic analysis, the performance of these policies, hence the utility of the statistical quantities such as divergence and mutual information, in the context of the active hypothesis testing is investigated. View full abstract»

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  • Multiuser detection in asynchronous on-off random access channels using lasso

    Publication Year: 2010 , Page(s): 130 - 137
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (552 KB) |  | HTML iconHTML  

    This paper considers on-off random access channels where users transmit either a one or a zero to a base station. Such channels represent an abstraction of control channels used for scheduling requests in third-generation cellular systems and uplinks in wireless sensor networks deployed for target detection. This paper introduces a novel convex-optimization-based scheme for multiuser detection (MUD) in asynchronous on-off random access channels that does not require knowledge of the delays or the instantaneous received signal-to-noise ratios of the individual users at the base station. For any fixed number of temporal signal space dimensions N and maximum delay τ in the system, the proposed scheme can accommodate M ≲ exp(O(N1/3)) total users and k ≲ N/ log M active users in the system-a significant improvement over the k ≤ M ≲ N scaling suggested by the use of classical matched-filtering-based approaches to MUD employing orthogonal signaling. Furthermore, the computational complexity of the proposed scheme differs from that of a similar oracle-based scheme with perfect knowledge of the user delays by at most a factor of log(N+τ). Finally, the results presented in here are non-asymptotic, in contrast to related previous work for synchronous channels that only guarantees that the probability of MUD error at the base station goes to zero asymptotically in M. View full abstract»

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  • Optimal signaling for detection in doubly dispersive multipath

    Publication Year: 2010 , Page(s): 138 - 145
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1478 KB) |  | HTML iconHTML  

    In this paper, we revisit the problem of signal detection in multipath scattering. Specifically, we explore the effect of bandwidth and signaling duration on non-coherent signal detection in doubly dispersive non-uniform multipath scattering environments. In such environments, we conjecture that detection performance is optimized if two conditions are met: C1) the number of independent degrees of freedom induced by the transmit signal on the channel is approximately SNR/2, and C2) the variance of the channel coefficients (each corresponding to a degree of freedom) is equal. In uniform multipath, the second condition is inherent. In non-uniform scattering, the variance of the channel coefficients depends on the transmit signal which critically impacts detection performance. As such, non-uniform doubly selective channels afford us an additional design parameter; we can design packets for detection of a specific aspect ratio, the ratio of bandwidth to signaling duration. If our packets meet the two criteria above, numerical and analytical results indicate detection performance is maximized. When the above conditions cannot be met, we present an algorithm for finding the signaling duration and bandwidth that maximize detection performance. View full abstract»

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