By Topic

Information Theory, IEEE Transactions on

Issue 3 • Date May 1982

Filter Results

Displaying Results 1 - 25 of 25
  • Comment on "Design of absolutely optimal quantizers for a wide class of distortion measures" by Sharma, D.K.

    Publication Year: 1982 , Page(s): 555
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (139 KB)  

    First Page of the Article
    View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Comment on "The capacity of the photon counting channel" by Pierce, J.R., et al.

    Publication Year: 1982 , Page(s): 556
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (154 KB)  

    The capacity of the photon counting channel with an average-power constraint equals P_{s}/(kT \ln2) bit/s at all noise temperatures T , where P_{s} is the average signal power and k is Boltzmann's constant. The channel can carry arbitrary orthogonal signals and is not restricted to the poise-position modulation (PPM) signals adduced in the above paper. ^{1} View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Review of 'A Second Course in Stochastic Processes' (Karlin, S., and Taylor, H.M.; 1981)

    Publication Year: 1982 , Page(s): 557 - 558
    Save to Project icon | Request Permissions | PDF file iconPDF (416 KB)  
    Freely Available from IEEE
  • Review of 'Advances in Computer System Security' (Turn, R.; 1981)

    Publication Year: 1982 , Page(s): 557
    Save to Project icon | Request Permissions | PDF file iconPDF (172 KB)  
    Freely Available from IEEE
  • Review of 'Protocols and Techniques for Data Communication Networks' (Kuo, F.F., Ed.; 1981)

    Publication Year: 1982 , Page(s): 558
    Save to Project icon | Request Permissions | PDF file iconPDF (187 KB)  
    Freely Available from IEEE
  • A new upper bound to the throughput of a multi-access broadcast channel

    Publication Year: 1982 , Page(s): 402 - 405
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (520 KB)  

    A new upper bound of 0.6126 packets/slot is established for the through-put of a time-slotted multi-access broadcast channel subject to an infinite population of user stations (whose transmissions are modeled by a Poisson process) using (0)-, (1)-, (e)-feedback to denote a slot with none, one, or at least two packets, respectively. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Information-singularity and recoverability of random processes

    Publication Year: 1982 , Page(s): 422 - 429
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1264 KB)  

    Two notions of information-singular and strong information-singular random processes were proposed by Berger as processes which are deterministic or negligible in a physically meaningful, information theoretic sense. This paper serves two purposes. First, it shows that strong information-singularity of a random process is equivalent to information-singularity plus a quite different property called recoverability. Secondly, it shows that these properties can be completely characterized in the case where the processes of interest are (jointly) stationary and satisfy a mild integrability condition. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Maximum likelihood detection and estimation of Bernoulli - Gaussian processes

    Publication Year: 1982 , Page(s): 482 - 488
    Cited by:  Papers (63)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (960 KB)  

    A new detection algorithm, single most likely replacement (SMLR), for detecting randomly located impulsive events which have Gaussian-distributed amplitudes is presented. This detector is designed for the case of severely overlapping wavelets. Estimation of the probability of events also is consider. Experimental results and comparisons with other detectors, using synthetic data, are provided. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Information rates and power spectra of digital codes

    Publication Year: 1982 , Page(s): 457 - 472
    Cited by:  Papers (40)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2392 KB)  

    The encoding of independent data symbols as a sequence of discrete amplitude, real variables with given power spectrum is considered. The maximum rate of such an encoding is determined by the achievable entropy of the discrete sequence with the given constraints. An upper bound to this entropy is expressed in terms of the rate distortion function for a memoryless finite alphabet source and mean-square error distortion measure. A class of simple dc-free power spectra is considered in detail, and a method for constructing Markov sources with such spectra is derived. It is found that these sequences have greater entropies than most codes with similar spectra that have been suggested earlier, and that they often come close to the upper bound. When the constraint on the power spectrum is replaced by a constraint On the variance of the sum of the encoded symbols, a stronger upper bound to the rate of dc-free codes is obtained. Finally, the optimality of the binary biphase code and of the ternary bipolar code is decided. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On the design of mean-square error channel coding systems using cyclic codes

    Publication Year: 1982 , Page(s): 406 - 413
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (912 KB)  

    Channel coding systems that employ linear block codes can be designed according to a mean-square error criterion. The optimum encoder and decoder pair is determined by selecting special elements in a generalized frequency domain based upon the values of key parameters called ratio weights. Systems may be designed that employ either hard or soft decision variables in the decoder. When cyclic codes are used, a minimal ideal decomposition of the code space shows that the ratio weights possess constant values on certain subsets in the frequency domain. This permits a drastic reduction in the number of ratio weights that need to be computed. For a cyclic code with t minimal ideals, this design procedure narrows the search for constancy subsets of the ratio weights to (2^{t}-1) subsets of the general space. Only one ratio weight needs to be computed for each constancy subset. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Modeling of high error rate binary communication channels (Corresp.)

    Publication Year: 1982 , Page(s): 549 - 555
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (952 KB)  

    Most of the existing mathematical models for binary communication channels describe low error rate wire lines satisfactorily. For typical high error rate channels, like the ultrahigh frequency (UHF) or very high frequency (VHF) wideband data channel encountered in military uses, finite-state as well as denumerable infinite state Markov chain models do not achieve an accurate characterization. The above models, including some more recent compound models, are compared against data from the actual channel using the multigap distribution as a tool. A modification of a compound model is shown that allows more accurate modeling of a wider class of channels including the high error rate radio channel. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Good codes can be produced by a few permutations

    Publication Year: 1982 , Page(s): 430 - 443
    Cited by:  Papers (16)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1864 KB)  

    Our main result is that good codes, even those meeting the random coding bound, can be produced with relatively few (linear in the block length) permutations from a single codeword. This cutdown in complexity may be of practical importance. The motivation for looking at such codes came from Ahlswede's covering lemma, which makes it possible to build correlated source codes from channel codes via permutations. In Appendix I we show that the problem of finding the best error exponents for coding sources with full side information at the decoder, which has received attention in the recent literature, can easily be reduced to the familiar one for the discrete memoryless channel (DMC). Finally, in Appendices II and III we give rather precise double exponentially small bounds on the probabilities that a randomly chosen code will fail to meet the random coding or expurgated bound for the DMC. According to these results, good codes are hard to miss if selected at random. This also explains why good codes of a Iow complexity (such as those produced by View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On the convexity of some divergence measures based on entropy functions

    Publication Year: 1982 , Page(s): 489 - 495
    Cited by:  Papers (26)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (952 KB)  

    Three measures of divergence between vectors in a convex set of a n -dimensional real vector space are defined in terms of certain types of entropy functions, and their convexity property is studied. Among other results, a classification of the entropies of degree \alpha is obtained by the convexity of these measures. These results have applications in information theory and biological studies. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 17 does not divide the order of the group of a (72,36,16) doubly even code (Corresp.)

    Publication Year: 1982 , Page(s): 537 - 541
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (872 KB)  

    It is an interesting open question whether an extremal (72, 36, 16) doubly even code C exists. In [3] the odd prime numbers which can divide the order of the group of C were determined. The largest of these, 23, was eliminated by finding weight 12 vectors in 384 codes [8]. The next largest prime remaining is 17. It is shown that 17 is also not possible by reducing the problem to the consideration of 16.17^{3} codes and then finding a weight 12 vector, by computer, in each of these codes. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Coding for a class of nonprobabilistic channels with nonzero memory

    Publication Year: 1982 , Page(s): 414 - 422
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1576 KB)  

    A class of finite-alphabet discrete-time nonprobabilistic communication channels with finite nonzero memory is defined. The unknown input/output mapping is required to stay fixed for a specified number of channel uses and then can change arbitrarily within a given set of mappings. The frequency with which the input/output mapping can change gives a rate of time-variation for the channel. The class of channels is parametrized by this rate of time-variation, by alphabet size, by memory duration, and by the set of permissible mappings. Zero-error capacity in the sense of Shannon is computed for a collection of special cases within this class. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Minimal permutation sets for decoding the binary Golay codes (Corresp.)

    Publication Year: 1982 , Page(s): 541 - 543
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (528 KB)  

    For permutation decoding of an e error-correcting linear code, a set of permutations which move all error vectors of weight \leq e out of the information places is needed. A method of finding minimal decoding sets is given, along with minimal sets obtained with this method for the binary Golay codes. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Global identification of continuous-time-systems with unknown noise covariance (Corresp.)

    Publication Year: 1982 , Page(s): 531 - 536
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1040 KB)  

    Global convergence pf the maximum likelihood estimates of unknown parameters of a continuous-time stochastic linear dynamical system is investigated when the observation noise covariance is unknown. The unknown parameter set is assumed to be finite. The situation where the true parameter does not belong to the unknown parameter set is considered as well as the situation where the true model is included in the unknown parameter set. Convergence is proved under a certain sufficient condition called the identifiability condition. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Computing automorphism groups of error-correcting codes

    Publication Year: 1982 , Page(s): 496 - 511
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2520 KB)  

    An algorithm is described for computing the automorphism group of an error correcting code. The algorithm determines the order of the automorphism group and produces a set of monomial permutations which generate the group. It has been implemented on a computer and has been used successfully on a great number of codes of moderate length. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Alphabet-constrained data compression

    Publication Year: 1982 , Page(s): 443 - 457
    Cited by:  Papers (20)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2312 KB)  

    The optimal data compression problem is posed in terms of an alphabet constraint rather than an entropy constraint. Solving the optimal alphabet-constrained data compression problem yields explicit source encoder/decoder designs, which is in sharp contrast to other approaches. The alphabet-constrained approach is shown to have the additional advantages that (1) classical waveform encoding schemes, such as pulse code modulation (PCM), differential pulse code modulation (DPCM), and delta modulation (DM), as well as rate distortion theory motivated tree/trellis coders fit within this theory; (2) the concept of preposterior analysis in data compression is introduced, yielding a rich. new class of coders: and (3) it provides a conceptual framework for the design of joint source/channel coders for noisy channel applications. Examples are presented of single-path differential encoding, delayed (or tree) encoding, preposterior analysis, and source coding over noisy channels. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The merit factor of long low autocorrelation binary sequences (Corresp.)

    Publication Year: 1982 , Page(s): 543 - 549
    Cited by:  Papers (31)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1112 KB)  

    The asymptotic "merit factor," i.e, the ratio of central to sidelobe energy of extremely long, optimally Iow autocorrelation sequences, formerly calculated as 2e^{2}=14.778 \cdots with the use of an ergodicity hypothesis and a convenient, but faulty, approximation, is recalculated without that approximation and is established at 12.32 \cdots . View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Spectral analysis of variable-length coded digital signals

    Publication Year: 1982 , Page(s): 473 - 481
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (840 KB)  

    Spectral analysis is performed for a digital message produced by a variable-length encoder driven by a stationary memoryless source. In particular, closed form expressions are derived for both the continuous and the discrete part of the spectral density. The continuous part turns out to be a rational function of z=\exp (j2\pi fT) ,where T is the symbol period, whereas the discrete part exhibits in general spectral lines at multiple integers of (\lambda _{0}T)^{-1} , where \lambda _{0} is the greatest common divisor of the codeword lengths. As an application of the theory explicit formulas are derived for the spectra of B n ZS and HDB n codes. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On the capacity of infinite population multiple access protocols

    Publication Year: 1982 , Page(s): 396 - 401
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (968 KB)  

    We present bounds on the maximum channel utilization (with finite average delay) of synchronous multiple access communications protocols serving an infinite population of homogeneous stations. Messages arrive to the system as a series of independent Bernoulli trials in discrete time, with probability p of an arrival at each arrival point (the Poisson limit is explicitly included) and are then randomly distributed among the stations. Pippenger showed that the channel utilization cannot exceed \xi_{p} , where \xi_{l}=1 and \lim_{p \rightarrow 0} \xi_{p} \approx 0.744 . Using a "helpful genie" argument, we find the exact capacity for all p \geq 0.568 (where we find optimal protocols that obey first-come first-served); for smaller values of p, we present an improved upper bound that decreases monotonically to \approx 0.6731 in the Poisson limit as p \rightarrow 0 . View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A new series of concatenated codes subject to matrix type- B codes

    Publication Year: 1982 , Page(s): 522 - 530
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1088 KB)  

    Some important aspects of a series of concatenated codes subjected to matrix type- B codes are investigated. Concatenated matrix codes and the concatenated quadratic residue codes especially are emphasized. An analysis of the error patterns, which can be corrected with the matrix coding, also is given. These codes are suitable for compound channels with memory (i.e., channels on which burst, cluster, and random errors occur). Explicit formulas are given for the number of bursts, cluster, and random errors that can be corrected with these codes. Decoding schemes and techniques for studying error propagation in the proposed codes are given. In particular a new decoding algorithm for a concatenated matrix code is given. The performance of coding and decoding schemes of the various types of concatenated codes can be tested in practice. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The capacity of the semideterministic relay channel (Corresp.)

    Publication Year: 1982 , Page(s): 536
    Cited by:  Papers (92)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (160 KB)  

    The capacity of the class of relay channels with sender x_{1} , a relay sender x_{2} , a relay receiver y_{1}=f(x_{1},x_{2}) , and ultimate receiver y is proved to be C = {\hbox{max min} \atop p(x_{1},x_{2})} \{ I(X_{1}, X_{2}; Y), H(Y_{1}|X_{2})+I(X_{1};Y|X_{2},Y_{1}) \}. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Automorphisms of codes with applications to extremal doubly even codes of length 48

    Publication Year: 1982 , Page(s): 511 - 521
    Cited by:  Papers (26)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1896 KB)  

    General results on automorphisms of self-dual binary codes are given. These results are applied to the study of extremal self-dual doubly even binary codes of length 48 . The main theorem proved is that an extremal self-dual doubly even code of length 48 with a nontrivial automorphism of odd order is equivalent to the extended quadratic residue code. Interesting constructions of the binary extended Golay code as well as a conjecture about a possible connection between an extremal self-dual doubly even code of length 72 and an extremal quaternary code of length 24 arc yielded by techniques used in the proof. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

Aims & Scope

IEEE Transactions on Information Theory publishes papers concerned with the transmission, processing, and utilization of information.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Frank R. Kschischang

Department of Electrical and Computer Engineering