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Information Theory and Applications Workshop, 2008

Date Jan. 27 2008-Feb. 1 2008

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Displaying Results 1 - 25 of 91
  • Author index

    Publication Year: 2008, Page(s):i - iii
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  • 2008 Information theory and applications workshop

    Publication Year: 2008, Page(s): c1
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  • Table of contents

    Publication Year: 2008, Page(s):1 - 4
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  • 2008 information theory and applications workshop

    Publication Year: 2008, Page(s): iv
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  • Adaptive rateless coding under partial information

    Publication Year: 2008, Page(s):5 - 11
    Cited by:  Papers (4)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (309 KB) | HTML iconHTML

    We present novel rateless codes that generalize and outperform LT codes (with respect to overall communication and computation complexity) when some input symbols are already available at the decoding host. This case can occur in data synchronization scenarios, or where feedback is provided or can be inferred from transmission channel models. We provide analysis and experimental evidence of this i... View full abstract»

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  • On power-of-choice in downlink transmission scheduling

    Publication Year: 2008, Page(s):12 - 17
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (336 KB) | HTML iconHTML

    A low-complexity guiding principle is considered for transmission scheduling from n homogeneous queues whose channel states fluctuate independently. The scheduler transmits from a longest queue within d randomly chosen queues with eligible channel states. A Markovian model is studied where mean packet transmission time is n-1 and packet arrival rate is lambda < 1 per queue. Equilibri... View full abstract»

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  • Reduction of ML decoding complexity for MIMO Sphere Decoding, QOSTBC, and OSTBC

    Publication Year: 2008, Page(s):18 - 25
    Cited by:  Papers (10)  |  Patents (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (270 KB) | HTML iconHTML

    In this paper, we discuss three applications of the QR decomposition algorithm to decoding in a number of Multi-Input Multi-Output (MIMO) systems. In the first application, we propose a new structure for MIMO Sphere Decoding (SD). We show that the new approach achieves 80% reduction in the overall complexity compared to conventional SD for a 2 times 2 system, and almost 50% reduction for the 4 tim... View full abstract»

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  • Optimal causal quantization of Markov Sources with distortion constraints

    Publication Year: 2008, Page(s):26 - 30
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (184 KB) | HTML iconHTML

    For Markov sources, the structure of optimal causal encoders minimizing the total communication rate subject to a mean-square distortion constraint is studied. The class of sources considered lives in a continuous alphabet, and the encoder is allowed to be variable-rate. Both the finite-horizon and the infinite-horizon problems are considered. In the finite-horizon case, the problem is non-convex,... View full abstract»

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  • A note on Kloosterman sums and its application

    Publication Year: 2008, Page(s):31 - 33
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (190 KB) | HTML iconHTML

    The number of times the trace of a certain function on an extension field assumes a fixed value in the base field is considered. It is shown that the set of all such values enjoys a Fourier transform like property with Kloosterman sums. The application of this property to coding and cryptography is briefly discussed. View full abstract»

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  • Spectrum-blind sampling and compressive sensing for continuous-index signals

    Publication Year: 2008, Page(s):547 - 554
    Cited by:  Papers (35)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (186 KB) | HTML iconHTML

    Spectrum-blind sampling (SBS), proposed in the mid-90psilas, is a sensing technique enabling minimum-rate sampling and reconstruction of signals with unknown but sparse spectra. SBS is applicable to continuous or discrete-index signals, finite or infinite length, in one or more dimensions. We revisit SBS and explore its relationship to compressive sensing (CS). On the one hand, recent results in C... View full abstract»

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  • Isoperimetrically Pareto-optimal shapes on the hexagonal grid

    Publication Year: 2008, Page(s):507 - 522
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (337 KB) | HTML iconHTML

    In the plane, the way to enclose the most area with a given perimeter and to use the shortest perimeter to enclose a given area, is to use a circle. If we replace the plane by a regular tiling of it, and construct polyforms i.e. shapes as sets of tiles, things become more complicated. We need to redefine the area and perimeter measures, and study the consequences carefully. In this paper we charac... View full abstract»

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  • Feedback schemes for multiuser MIMO-OFDM downlink

    Publication Year: 2008, Page(s):33 - 40
    Cited by:  Papers (1)  |  Patents (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (256 KB) | HTML iconHTML

    We consider a MIMO-OFDM broadcast channel and compare achievable ergodic rates under three channel state feedback schemes: analog feedback, direction quantized feedback and ldquotime-domainrdquo channel quantized feedback. The third scheme is new, and it is inspired by rate-distortion theory of Gaussian correlated sources. For each scheme we derive the conditions under which the system achieves fu... View full abstract»

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  • Can the storage capacity of memories built from unreliable components be determined?

    Publication Year: 2008, Page(s):41 - 43
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (136 KB) | HTML iconHTML

    A memory is a device in which information is stored at some time and retrieved at a later time . Let the information be stored in form of bits in registers (memory elements) each of which can store a single bit. The information storage capability of a memory is the number of information bits it stores. Building a memory with information storage capability of k bits with reliable memory elements re... View full abstract»

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  • Information rates for multiantenna systems with unknown fading

    Publication Year: 2008, Page(s):44 - 49
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (272 KB) | HTML iconHTML

    This work first presents a general technique to compute tight upper and lower bounds on the information rate of a multiuser Rayleigh fading channel with no channel state information (CSI) at the transmitters or the receivers. The paper then presents analytical upper and lower bounds on the information rate which converge in the limit of large number of transmitting users where the channel bandwidt... View full abstract»

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  • On the single-slot capacity of random access over a Gaussian MAC

    Publication Year: 2008, Page(s):50 - 53
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (229 KB) | HTML iconHTML

    Consider a Gaussian multiple access channel (MAC) with two users, which do not always have a message to transmit. Neither user knows if the other is transmitting or not. Each user has two possible achievable rates depending on whether the other user is transmitting or not. Hence, in general, any coding scheme is characterized by a 4-tuple of rates. For given power constraints, we prove inner and o... View full abstract»

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  • Ergodic capacity maximizing MIMO ARQ precoder design based on channel mean information

    Publication Year: 2008, Page(s):58 - 62
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (228 KB) | HTML iconHTML

    In recent years, there has been broad research interest in the development of beamforming and precoding techniques for MIMO wireless communication systems. Most existing works focus on the single transmission session between transceivers. We expand the MIMO precoder design to take into account the significant role that ARQ (Automatic Repeat reQuest) may play in practical systems. We investigate th... View full abstract»

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  • Asymptotic ensemble enumerators for protograph-based generalized LDPC codes: Computational complexity

    Publication Year: 2008, Page(s):63 - 65
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (157 KB) | HTML iconHTML

    In earlier work, we presented a method for finding ensemble weight enumerator for protograph-based generalized LDPC (G-LDPC) codes, and leveraged this method to find ensemble stopping set enumerator and ensemble trapping set enumerator. The method is conceptually simple, but when the dimensionality of the constraint nodes (number of their code-words) grows, it becomes difficult to handle the compu... View full abstract»

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  • Buffering requirements for variable-iterations LDPC decoders

    Publication Year: 2008, Page(s):523 - 530
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (438 KB) | HTML iconHTML

    Low-density parity-check (LDPC) decoders, like iterative decoders for other block codes, can be designed to stop after a variable number of iterations, dependent on the difficulty of decoding particular noisy received words, also called frames. The number of iterations the decoder spends on a given frame determines both the probability of successful decoding, and the time expended. But whereas the... View full abstract»

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  • A note on convergence rate of constrained capacity estimation algorithms over ISI channels

    Publication Year: 2008, Page(s):66 - 69
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (399 KB) | HTML iconHTML

    It has recently become popular to use simulation-based algorithms to empirically estimate achievable information rates over intersymbol interference (ISI) channels with inputs from specific input constellations. Such algorithms are guaranteed to converge by invoking the Shannon-McMillan-Brieman theorem provided that the output sequence is stationary and ergodic. In this note, we establish a centra... View full abstract»

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  • Optimal multiple description and multiresolution scalar quantizer design

    Publication Year: 2008, Page(s):70 - 76
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (236 KB) | HTML iconHTML

    The author presents new algorithms for fixed-rate multiple description and multiresolution scalar quantizer design. The algorithms both run in time polynomial in the size of the source alphabet and guarantee globally optimal solutions. To the authorpsilas knowledge, these are the first globally optimal design algorithms for multiple description and multiresolution quantizers. View full abstract»

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  • Spectra and minimum distances of repeat multiple accumulate codes

    Publication Year: 2008, Page(s):77 - 86
    Cited by:  Papers (8)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (326 KB) | HTML iconHTML

    In this paper we consider ensembles of codes, denoted RAm, obtained by a serial concatenation of a repetition code and m accumulate codes through uniform random inter-leavers. We analyze their average spectrum functions for each m showing that they are equal to 0 below a threshold distance isinm and positive beyond it. One of our main results is to prove that these average sp... View full abstract»

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  • On the throughput of acyclic wired packet networks with finite buffers

    Publication Year: 2008, Page(s):87 - 93
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (250 KB) | HTML iconHTML

    In this paper, we study the effect of finite buffer sizes on the (unicast) throughput in directed acyclic wired erasure networks. First, we motivate the problem by presenting the underlying idea of throughput estimation in wireline networks. We observe that the problem of exact throughput estimation for wireline networks is equivalent to the calculation of steady state probabilities for a regular,... View full abstract»

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  • On information theoretic aspects of single- and multi-carrier communications

    Publication Year: 2008, Page(s):94 - 99
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (359 KB) | HTML iconHTML

    In this paper, we investigate the relation between the quadrature amplitude modulation (QAM) input information rates (IRs) of multi-carrier (MC) and single carrier (SC) systems transmitted over inter-symbol interference (ISI) channels with additive white Gaussian noise (AWGN). In particular, considering uniform power spectrum transmission, we conjecture that, for a given channel impulse response, ... View full abstract»

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  • Dynamic decentralized multi-channel MAC protocols

    Publication Year: 2008, Page(s):100 - 110
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (367 KB) | HTML iconHTML

    In this paper, we propose new dynamic decentralized multi-channel multiple access (MAC) protocols and study their performance. Our protocols build on slotted Aloha, but extend it in several ways to improve flow completion time and throughput, as follows: (i) channels are assigned to flows rather than packets to eliminate per packet collisions, thus the total number of collisions is reduced, and (i... View full abstract»

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  • The pre-log of Gaussian broadcast with feedback can be two

    Publication Year: 2008, Page(s):545 - 546
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (218 KB) | HTML iconHTML

    A generic intuition says that the pre-log, or multi-plexing gain, cannot be larger than the minimum of the number of transmit and receive dimensions. This suggests that for the scalar broadcast channel, the pre-log cannot exceed one. By contrast, in this note, we show that when the noises are anti-correlated and feedback is present, then a pre-log of two can be attained. In other words, in this sp... View full abstract»

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