By Topic

Communications, IEEE Transactions on

Issue 12 • Date December 2010

Filter Results

Displaying Results 1 - 25 of 37
  • Table of contents

    Publication Year: 2010 , Page(s): c1 - c4
    Save to Project icon | Request Permissions | PDF file iconPDF (65 KB)  
    Freely Available from IEEE
  • [Staff list]

    Publication Year: 2010 , Page(s): c2
    Save to Project icon | Request Permissions | PDF file iconPDF (58 KB)  
    Freely Available from IEEE
  • Multiple-User Cooperative Communications Based on Linear Network Coding

    Publication Year: 2010 , Page(s): 3345 - 3351
    Cited by:  Papers (44)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (334 KB) |  | HTML iconHTML  

    We propose a new scheme for cooperative wireless networking based on linear network codes. The network consists of multiple (M ≥ 2) users having independent information to be transmitted to a common basestation (BS), assuming block-fading channels with independent fading for different codewords. The users collaborate in relaying messages. Because of potential transmission errors in links, resulting in erasures, the network topology is dynamic. To efficiently exploit the diversity available by cooperation and time-varying fading, we propose the use of diversity network codes (DNCs) over finite fields. These codes are designed such that the BS is able to rebuild the user information from a minimum possible set of coded blocks conveyed through the dynamic network. We show the existence of deterministic DNCs. We also show that the resulting diversity order using the proposed DNCs is 2 M - 1, which is higher than schemes without network coding or with binary network coding. Numerical results from simulations also show substantial improvement by the proposed DNCs over the benchmark schemes. We also propose simplified versions of the DNCs, which have much lower design complexity and still achieve the diversity order 2 M - 1. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Performance of Non-Ideal OT-MRC with Co-Channel Interference

    Publication Year: 2010 , Page(s): 3352 - 3357
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (268 KB) |  | HTML iconHTML  

    This paper studies the effect of non-ideal estimation of channel state information (CSI) on the performance of output-threshold maximal-ratio combining (OT-MRC) diversity scheme in the presence of co-channel interference as well as white noise. The channel fading envelopes are assumed to follow slowly varying flat Rayleigh model. New closed-form expressions for the combined signal-to-interference-plus-noise ratio (SINR) distribution and outage probability performance are presented. Performance comparisons between the conventional MRC and OT-MRC for the system model described above are provided. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Two-Way MIMO Relay Precoder Design with Channel State Information

    Publication Year: 2010 , Page(s): 3358 - 3363
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (225 KB) |  | HTML iconHTML  

    In this paper, a two-way relay precoder is designed for multiple-input multiple-output (MIMO) distributed cooperative relay systems. A constrained optimization problem with respect to (w.r.t.) the relay precoder is formulated for the most general relay and antenna scenario, namely, multiple relays each with multiple antennas, It is shown that due to the difficulty of two-way distributed relaying mechanism as well as the block-diagonal nature of the relay precoding matrix, this optimization problem cannot be solved by existing one-way relaying methods. It is then proved that with full channel state information available at relays, the underlying problem can be converted to a convex optimization w.r.t. the non-zero entries of the relay precoding matrix only, such that the Lagrangian multiplier method is applicable to the relay precoder design, leading to a closed-form relay precoding solution. A simulation study is conducted to justify the superior performance of the proposed two-way relaying scheme. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Some Notes on the Fourier Transform Methods for Error-Rate Analysis of Equal-Gain Combining

    Publication Year: 2010 , Page(s): 3364 - 3368
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (266 KB) |  | HTML iconHTML  

    Transform techniques based on moment generating functions (MGFs) and characteristic functions (CHFs) have recently provided efficient analytical tools for the performance evaluation of digital communication systems over fading channels. More recently, the convolution theorem of the Fourier transform has been employed to obtain unified expressions for the average error probabilities of equal gain combining (EGC) diversity reception in terms of the CHFs of the branches' amplitude gains. In this paper, we prove that these expressions include redundant terms. Furthermore, simpler analytical expressions for the average error rates of EGC diversity reception can be obtained when the convolutional theorem of the sine and cosine transforms are used instead of the conventional Fourier transform. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Linear MMSE Estimation of Large-Magnitude Symmetric Levy-Process Phase-Noise

    Publication Year: 2010 , Page(s): 3369 - 3374
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (311 KB) |  | HTML iconHTML  

    The linear minimum-mean-square error (LMMSE) estimator is herein derived to estimate phase-noise of Levy statistics (including Wiener phase-noise) and of arbitrarily large magnitude. This estimator may be pre-set to any latency and any number of tabs. This estimator depends only on the signal-to-(additive)-noise ratio and the phase-noise variance, but requires no matrix-inversion. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Cooperative Beamforming with Mobile Wireless Sensor Nodes: Performance Analysis and Optimal Node Locations

    Publication Year: 2010 , Page(s): 3375 - 3380
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (303 KB) |  | HTML iconHTML  

    In this paper, cooperative beamforming in the context of wireless sensor networks with random mobile nodes is analyzed. In the first part, we use two dimensional Brownian motion to model mobile nodes, which are assumed to follow Gaussian distribution at every time. The concept of overall outage probability is introduced, and its lower and upper bounds are derived theoretically. In the second part, we extend the Brownian motion to any form and prove the beampattern with minimum mainlobe as well as maximum three-dB sidelobe region can be got simultaneously, then we design a low complexity algorithm to arrange sensor node locations to produce this optimum beampattern. Simulation results show that the overall outage probability and its lower and upper bounds are in good agreement, and compared with uniform and Gaussian distribution, the beampattern produced by the algorithm has sharpest mainbeam and significantly small sidelobe peaks. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Generalized Maximum-Likelihood Sequence Detection for Photon-Counting Free Space Optical Systems

    Publication Year: 2010 , Page(s): 3381 - 3385
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (280 KB) |  | HTML iconHTML  

    We investigate detection methods for on-off keying (OOK) photon-counting Free Space Optical (FSO) systems in the presence of turbulence-induced fading, assuming no channel state information at the receiver. To recover the performance loss which is associated with symbol-by-symbol detection in such a scenario, we consider sequence detection techniques, exploiting the temporal correlation of the FSO channel. Due to its high complexity in the calculation of its metric, optimal maximum likelihood sequence detection (MLSD) is infeasible for most practical purposes. Hence, we propose a suboptimal low-complexity detection rule, which is based on the generalized maximum-likelihood sequence estimation. The proposed scheme allows the detection of sequence lengths that are prohibitive for conventional MLSD, without using any kind of channel knowledge. Monte Carlo simulation results show its performance to be very close to the optimum for large sequence lengths and various fading models. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Performance of an AFC Loop in the Presence of a Single Interferer in a Fading Channel

    Publication Year: 2010 , Page(s): 3386 - 3391
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (278 KB) |  | HTML iconHTML  

    The performance of an automatic frequency control (AFC) loop is investigated using two measures, the mean time to loss of lock and the average switching rate. The AFC is considered to operate in fading while a single interferer is also present at its input. Channels are modeled using independent non-identically distributed Rayleigh, Rician and Nakagami-m fading while the special case of independent identically distributed channels is also considered. Closed-form expressions and integral form formulas are derived for the general case of modulated signals as well as important special cases of similar modulations and unmodulated signals. The considered scenarios include previous results from the literature as special cases. Corresponding numerical examples are provided and discussed to illustrate the performance of an AFC in such scenarios. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Modulo Loss Reduction for Vector Perturbation Systems

    Publication Year: 2010 , Page(s): 3392 - 3396
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (233 KB) |  | HTML iconHTML  

    In this letter, we present an improved precoding technique which reduces a modulo loss in vector perturbation with low complexity. Instead of searching perturbation vectors in the infinite lattice, the proposed scheme restricts the search range by utilizing the distribution of the perturbation vector depending on transmitted data. As a result, we can achieve significant complexity savings at the transmitter while providing better performance compared to the original vector perturbation. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Receiver Multiuser Diversity Aided Multi-Stage Minimum Mean-Square Error Detection for Heavily Loaded DS-CDMA and SDMA Systems

    Publication Year: 2010 , Page(s): 3397 - 3404
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (270 KB) |  | HTML iconHTML  

    By investigating the conditions required for successive interference cancellation multiuser detectors (SIC-MUD) to achieve near-optimum BER performance, we propose and investigate a so-called receiver multiuser diversity aided multi-stage minimum mean-square error MUD (RMD/MS-MMSE MUD), which is operated in the SIC principles. The BER performance of the RMD/MS-MMSE MUD is investigated in association with both the direct-sequence code-division multiple-access (DS-CDMA) over either Gaussian or Rayleigh fading channels, and the space-division multiple-access (SDMA) over Rayleigh fading channels. Furthermore, we consider both full-load and overload scenarios in comparison with the spreading factor N of DS-CDMA and the number of receive antennas N in SDMA. Our studies show that the RMD/MS-MMSE MUD is highly efficient for both full-load and overload systems. Specifically, the RMD/MS-MMSE MUD for the full-load systems of moderate size is capable of attaining the BER performance similar to that of the optimum maximum likelihood MUD (ML-MUD). For the overload systems, it can allow a DS-CDMA or SDMA system to support K=2N users and still achieve much better BER performance than a corresponding DS-CDMA or SDMA system using conventional MMSE-MUD to support K=N users. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • MIMO Systems Based on Modulation Diversity

    Publication Year: 2010 , Page(s): 3405 - 3409
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (269 KB) |  | HTML iconHTML  

    This letter proposes a new approach to achieve the maximum diversity gain in the vertical Bell Laboratories Layered Space-Time (V-BLAST) system over multiple-input multiple-output (MIMO) Rayleigh channels. First, we will briefly review the modulation diversity scheme based on real-valued multidimensional rotated constellations that has been proposed to obtain high diversity orders for single-input single-output (SISO) systems. Then, this letter extends the modulation diversity scheme to V-BLAST MIMO systems in order to achieve the maximum diversity gain without additional power or bandwidth consumption. The proposed method is particularly suitable for MIMO applications which employ channel codes with high rate in order to support high spectral efficiency. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Fast and Robust Spectrum Sensing via Kolmogorov-Smirnov Test

    Publication Year: 2010 , Page(s): 3410 - 3416
    Cited by:  Papers (12)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (621 KB) |  | HTML iconHTML  

    A new approach to spectrum sensing in cognitive radio systems based on the Kolmogorov-Smirnov (K-S) test is proposed. The K-S test is a non-parametric method to measure the goodness of fit. The basic procedure involves computing the empirical cumulative distribution function (ECDF) of some decision statistic obtained from the received signal, and comparing it with the ECDF of the channel noise samples. A sequential version of the K-S-based spectrum sensing technique is also proposed. Extensive simulation results demonstrate that compared with the existing spectrum detection methods, such as the energy detector and the eigenvalue-based detector, the proposed K-S detectors offer superior detection performance and faster detection, and is more robust to channel uncertainty and non-Gaussian noise. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Joint Relay-and-Antenna Selection in Multi-Antenna Relay Networks

    Publication Year: 2010 , Page(s): 3417 - 3422
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (268 KB) |  | HTML iconHTML  

    For the decode-and-forward protocol in relay networks, opportunistic relaying (OR) and selection cooperation (SC) are two major relay selection schemes, which have been studied only for single antenna terminals. We study OR and SC in a multi-antenna relay network where each terminal has multiple antennas. To fully exploit multiple antennas without incurring high feedback overhead, we adopt transmit antenna selection (TAS). Specifically, we first propose two joint relay-and-antenna selection schemes which combine OR and SC, respectively, with TAS: joint OR-TAS and joint SC-TAS. For each joint selection scheme, a single best transmit antenna at the source, a single best relay, and a single best transmit antenna at this selected relay are jointly determined in an optimum sense. In this network, at the first time slot, the selected antenna at the source transmits a symbol to the selected relay; at the second time slot, the selected antenna at the selected relay retransmits the detected symbol to the destination. We derive the outage probability of joint OR-TAS. Also, we obtain the outage probability of joint SC-TAS by proving that the outage probability of joint SC-TAS is identical to that of joint OR-TAS. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Partial Information Relaying with Per Antenna Superposition Coding

    Publication Year: 2010 , Page(s): 3423 - 3427
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (735 KB) |  | HTML iconHTML  

    In this letter we propose per antenna superposition coding (PASC) by which partial information can be relayed instead of full information, to exploit the higher capacity of source-relay-destination link. Here, the PASC is designed across antennas, producing basic layer and superposed layer for each data stream per antenna. It is shown that an overall data rate of partial information relaying with PASC can be increased beyond that offered by full information relaying by virtue of fast forwarding of partial information over relatively better link. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Signal Shaping for Bit-Interleaved Coded Modulation on the AWGN Channel

    Publication Year: 2010 , Page(s): 3428 - 3435
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (725 KB) |  | HTML iconHTML  

    In this paper a coded modulation method for the additive white Gaussian noise channel is presented which incorporates signal shaping. The scheme uses a modulation map to map bits to channel inputs. A modulation map is considered that has the advantage it is can easily be combined with binary error-correcting codes. The decoding strategy is a combination of bit-interleaved coded modulation and multistage decoding. The number of required decoding stages is only small compared to other multistage decoding schemes for coded modulation. It is shown that modulation maps can be designed with a constrained capacity limit very close to the capacity of the AWGN channel. When combined with low-density parity-check codes, simulation results show that a near-capacity performance is achieved for high spectral efficiencies. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Large-Girth Nonbinary QC-LDPC Codes of Various Lengths

    Publication Year: 2010 , Page(s): 3436 - 3447
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (692 KB) |  | HTML iconHTML  

    In this paper, we construct nonbinary quasi-cyclic low-density parity-check (QC-LDPC) codes whose parity check matrices consist of an array of square sub-matrices which are either zero matrices or circulant permutation matrices. We propose a novel method to design the shift offset values of the circulant permutation sub-matrices, so that the code length can vary while maintaining a large girth. Extensive Monte Carlo simulations demonstrate that the obtained codes of a wide range of rates (from 1/2 to 8/9) with length from 1000 to 10000 bits have very good performance over both AWGN and Rayleigh fading channels. Furthermore, the proposed method is extended to design multiple nonbinary QC-LDPC codes simultaneously where each individual code can achieve large girth with variable lengths. The proposed codes are appealing to practical adaptive systems where the block length and code rate need to be adaptively adjusted depending on traffic characteristics and channel conditions. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On the Decomposition Method for Linear Programming Decoding of LDPC Codes

    Publication Year: 2010 , Page(s): 3448 - 3458
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (860 KB) |  | HTML iconHTML  

    In this paper, we focus on solving the linear programming (LP) problem that arises in the decoding of low-density parity-check (LDPC) codes by means of the revised simplex method. In order to take advantage of the structure of the LP problem, we reformulate the dual LP and apply the idea of Dantzig-Wolfe (D-W) decomposition method to solve the problem. Each subproblem in the D-W decomposition method is an LP over a convex polyhedral cone. We define the convex polyhedral cone as local parity-check cone and discuss its special structures. Then, we enumerate its extreme rays and use these extreme rays to design an efficient method for the general LP decoding problem. The proposed method exhibits advantages in reducing both the storage and computational requirements. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Early-Elimination Modification for Priority-First Search Decoding

    Publication Year: 2010 , Page(s): 3459 - 3469
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (571 KB) |  | HTML iconHTML  

    In order to release the growing demand for computational complexity with respect to increasing information sequence length in the priority-first search decoding algorithm, a path elimination modification is proposed and also analyzed in this work. Specifically, we propose to directly eliminate all paths whose end nodes are Δ-level prior to the farthest node among those that have been visited thus far by the priority-first search. Following the argument on random coding, we then analyze the path elimination window Δ that results in a larger exponent for additional decoding error caused by path elimination than the exponent of the maximum-likelihood error performance, and hence guarantees exponentially negligible performance degradation. Our analytical results indicate that under additive white Gaussian noise (AWGN) channels, the path elimination window required for exponentially negligible performance degradation is just three times the code constraint length for rate one-half convolutional codes. It can be further reduced to 1.7-fold of the code constraint length when rate one-third convolutional codes are considered instead. Simulation results confirm these analytical window sizes. As a consequence, the priority-first search decoding algorithm can considerably reduce its computation burden and memory consumption by directly eliminating a large number of paths with nearly no performance degradation. This makes the priority-first search decoding algorithm with path elimination suitable for applications that demand low-complexity software implementation with near optimal performance. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • LDPC Decoders with Informed Dynamic Scheduling

    Publication Year: 2010 , Page(s): 3470 - 3479
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (383 KB) |  | HTML iconHTML  

    Low-Density Parity-Check (LDPC) codes are usually decoded by running an iterative belief-propagation (BP), or message-passing, algorithm over the factor graph of the code. The traditional message-passing scheduling, called flooding, consists of updating all the variable nodes in the graph, using the same pre-update information, followed by updating all the check nodes of the graph, again, using the same pre-update information. Recently, several studies show that sequential scheduling, in which messages are generated using the latest available information, significantly improves the convergence speed in terms of number of iterations. Sequential scheduling introduces the problem of finding the best sequence of message updates. We propose Informed Dynamic Scheduling (IDS) strategies that select the message-passing schedule according to the observed rate of change of the messages. In general, IDS strategies require computation to select the message to update but converge in fewer message updates because they focus on the part of the graph that has not converged. Moreover, IDS yields a lower error-rate performance than either flooding or sequential scheduling because IDS strategies overcome traditional trapping-set errors. This paper presents IDS strategies that address several issues including performance for short-blocklength codes, complexity, and implementability. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Spectral Efficient Cooperative Diversity Technique with Multi-Layered Modulation

    Publication Year: 2010 , Page(s): 3480 - 3490
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (664 KB) |  | HTML iconHTML  

    This paper proposes a spectral efficient cooperative diversity technique with multi-layered modulation for high data rate transmissions. The proposed system transmits with different cyclic delay and phase rotation patterns, in order to achieve cooperative diversity gain for all transmit signals from the source. Since these patterns increase the interference between the layers, we derive optimal cyclic delay and phase rotation patterns to minimize mean square error. With the optimal patterns, the proposed system still suffers from inter-layer interference, especially in high-order modulations. To overcome this problem, multiple layers are separately interleaved by layer-specific interleavers and are mapped by hierarchical symbol mapping for the high data rate transmission with cooperative diversity. A destination structure with iterative equalization is also presented to separate each layer and extract diversity gain for high data rate transmissions. The proposed system can use reliable feedback from the layers and effectively remove the inter-layer interference. To estimate the performance of the proposed system, we develop a density evolution technique. It is shown that the predicted performances agree with simulated performances. Simulation results indicate that the proposed system achieves cooperative diversity and has better performance than conventional cooperative systems. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Semiblind Iterative Data Detection for OFDM Systems with CFO and Doubly Selective Channels

    Publication Year: 2010 , Page(s): 3491 - 3499
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (281 KB) |  | HTML iconHTML  

    Data detection for OFDM systems over unknown doubly selective channels (DSCs) and carrier frequency offset (CFO) is investigated. A semiblind iterative detection algorithm is developed based on the expectation-maximization (EM) algorithm. It iteratively estimates the CFO, channel and recovers the unknown data using only limited number of pilot subcarriers in one OFDM symbol. In addition, efficient initial CFO and channel estimates are also derived based on approximated maximum likelihood (ML) and minimum mean square error (MMSE) criteria respectively. Simulation results show that the proposed data detection algorithm converges in a few iterations and moreover, its performance is close to the ideal case with perfect CFO and channel state information. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Relay Selection with ANC and TDBC Protocols in Bidirectional Relay Networks

    Publication Year: 2010 , Page(s): 3500 - 3511
    Cited by:  Papers (30)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (486 KB) |  | HTML iconHTML  

    We study relay selection (RS) with the analog network coding (ANC) and time division broadcast (TDBC), which are two major amplify-and-forward (AF)-based protocols in bidirectional relay networks. We consider a bidirectional network consisting of two different end-sources and multiple relays, where each terminal has a single antenna and operates in a half-duplex mode. In this network, a single best relay is selected depending on channel conditions to help bidirectional communication between the two end-sources. Specifically, we first consider RS schemes for the ANC and TDBC protocols based on a max-min criterion to minimize the outage probabilities. Then, for the RS in the ANC protocol, we derive a closed-form expression of the outage probability; for the RS in the TDBC protocol, we derive a one-integral form of the outage probability and its lower bound in closed-form. Numerical results confirm that the closed-form expression of the ANC protocol and the one-integral form of the TDBC protocol are very accurate, and that the closed-form lower bound of the TDBC protocol is also tight. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On the Computation of the Capacity Region of the Discrete MAC

    Publication Year: 2010 , Page(s): 3512 - 3525
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (618 KB) |  | HTML iconHTML  

    The computation of the channel capacity of discrete memoryless channels is a convex problem that can be efficiently solved using the Arimoto-Blahut (AB) iterative algorithm. However, the extension of this algorithm to the computation of capacity regions of multiterminal networks is not straightforward since it gives rise to non-convex problems. In this context, the AB algorithm has only been successfully extended to the calculation of the sum-capacity of the discrete memoryless multiple-access channel (DMAC). Thus, the computation of the whole capacity region still requires the use of computationally demanding search methods. In this paper, we first give an alternative reformulation of the capacity region of the DMAC which condenses all the non-convexities of the problem into a single rank-one constraint. Then, we propose efficient methods to compute outer and inner bounds on the capacity region of the two-user DMAC by solving a relaxed version of the problem and projecting its solution onto the original feasible set. Targeting numerical results, we first take a randomization approach. Focusing on analytical results, we study projection via minimum divergence, which amounts to the marginalization of the relaxed solution. In this case we derive sufficient conditions and necessary and sufficient conditions for the bounds to be tight. Furthermore, we are able to show that the class of channels for which the marginalization bounds match exactly the capacity region includes all the two-user binary-input deterministic DMACs as well as other non-deterministic channels. In general, however, both methods are able to compute very tight bounds as shown for various examples. 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 Communications focuses on all telecommunications including telephone, telegraphy, facsimile, and point-to-point television by electromagnetic propagation.

 

 

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Robert Schober
University of British Columbia