# IEEE Transactions on Communications

## Filter Results

Displaying Results 1 - 25 of 31

Publication Year: 2007, Page(s):C1 - C4
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• ### IEEE Transactions on Communications publication information

Publication Year: 2007, Page(s): C2
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• ### Decoding Algorithms for Nonbinary LDPC Codes Over GF$(q)$

Publication Year: 2007, Page(s):633 - 643
Cited by:  Papers (383)  |  Patents (21)
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In this letter, we address the problem of decoding nonbinary low-density parity-check (LDPC) codes over finite fields GF(q), with reasonable complexity and good performance. In the first part of the letter, we recall the original belief propagation (BP) decoding algorithm and its Fourier domain implementation. We show that the use of tensor notations for the messages is very convenient for the alg... View full abstract»

• ### FFT-Based BP Decoding of General LDPC Codes Over Abelian Groups

Publication Year: 2007, Page(s):644 - 649
Cited by:  Papers (32)  |  Patents (1)
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We introduce a wide class of low-density parity-check (LDPC) codes, large enough to include LDPC codes over finite fields, rings, or groups, as well as some nonlinear codes. A belief-propagation decoding procedure with the same complexity as for the decoding of LDPC codes over finite fields is also presented. Moreover, an encoding procedure is developed View full abstract»

• ### Mapping Optimization for Space–Time Bit-Interleaved Coded Modulation With Iterative Decoding

Publication Year: 2007, Page(s):650 - 655
Cited by:  Papers (6)
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For space-time bit-interleaved coded modulation (ST-BICM) systems with iterative decoding, the overall performance is affected by the chosen mapping. In bit-error rate (BER) curves, one mapping reaches an error floor (EF) at a low signal-to-noise ratio (SNR), while other mappings result in a lower EF at a higher SNR. The constellation mappings are divided into groups where each group exhibits a di... View full abstract»

• ### Throughput Gains Using Rate and Power Control in Cooperative Relay Networks

Publication Year: 2007, Page(s):656 - 660
Cited by:  Papers (26)  |  Patents (1)
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In this letter, we use power and rate adaptation to maximize the throughput in cooperative relay networks when limited feedback links to the transmitter nodes exist. We observe that, for a finite rate of feedback, the throughput maximizing outage probability can be relatively high. This suggests using higher rate codes and allowing some outages in an effort to increase the overall network throughp... View full abstract»

• ### A New Segment Quantization Using Lempel–Ziv Algorithm and Its Application to Quantization of Line Spectral Frequencies

Publication Year: 2007, Page(s):661 - 664
Cited by:  Papers (1)
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A new segment quantization method using the Lempel-Ziv algorithm is proposed, and it is applied to quantize line spectral frequency parameters in speech codec. The proposed segment quantizer can save four bits per frame, compared with the ITU-T G.729 speech codec (18 bits/frame), without degradation of subjective or objective speech quality View full abstract»

• ### Recursive Code-Timing Estimation for DS-CDMA Signals in a Time-Varying Environment Through a Stochastic Optimization Approach

Publication Year: 2007, Page(s):665 - 669
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A modified simulated-annealing method is proposed for recursively minimizing the nonlinear cost function in the subspace-based code-timing estimation for direct-sequence code-division multiple-access signals over a multipath fading channel. The new algorithm has low complexity, because of the recursive updating of the final code-timing estimates together with the noise-subspace tracking View full abstract»

• ### Sequence Design for Data-Aided Estimation of Synchronization Parameters

Publication Year: 2007, Page(s):670 - 677
Cited by:  Papers (6)
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In this letter, we propose a systematic technique for optimum data-sequence design for data-aided (DA) estimation of synchronization parameters. It is assumed that the system operates in burst mode, transmitting a linearly modulated information signal over an additive white Gaussian noise channel. The method is based on the minimization of the corresponding Crameacuter-Rao lower bound subject to a... View full abstract»

• ### Improved Superorthogonal Codes Through Generalized Rotations

Publication Year: 2007, Page(s):678 - 682
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Concatenation of orthogonal space-time block codes (OSTBC) with an outer trellis has led to simple and powerful codes, known as superorthogonal codes or space-time block trellis-coded modulation. In this letter, we generalize these codes by finding new code supersets and corresponding set partitioning, resulting in improved coding gain. We provide design guidelines for the labeling of the generali... View full abstract»

• ### A Balancing Method for PMEPR Reduction in OFDM Signals

Publication Year: 2007, Page(s):683 - 691
Cited by:  Papers (5)
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A relation is established between the strength of a binary code over the alphabet {+1,-1}, and its ability to reduce peak-to-mean envelope power ratio (PMEPR) in n-subcarrier (OFDM) signals. Based on this relation, a method is proposed to deterministically bound PMEPR of such signals using coordinate-wise multiplication by a balancing vector (BV) chosen from a code of given strength. A practical p... View full abstract»

• ### Accumulate-Repeat-Accumulate Codes

Publication Year: 2007, Page(s):692 - 702
Cited by:  Papers (97)  |  Patents (4)
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In this paper, we propose an innovative channel coding scheme called accumulate-repeat-accumulate (ARA) codes. This class of codes can be viewed as serial turbo-like codes or as a subclass of low-density parity check (LDPC) codes, and they have a projected graph or protograph representation; this allows for high-speed iterative decoding implementation using belief propagation. An ARA code can be v... View full abstract»

• ### Coded Unitary Space–Time Modulation With Iterative Decoding: Error Performance and Mapping Design

Publication Year: 2007, Page(s):703 - 716
Cited by:  Papers (18)
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This paper studies the bit error probability of coded unitary space-time modulation with iterative decoding where neither the transmitter nor the receiver knows the channel fading coefficients. The tight error bound with respect to the asymptotic performance is first analytically derived for any given unitary constellation and mapping rule. Design criteria regarding the choice of unitary constella... View full abstract»

• ### Interference Analysis of Filtered Multitone Modulation Over Time-Varying Frequency- Selective Fading Channels

Publication Year: 2007, Page(s):717 - 727
Cited by:  Papers (26)
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We consider in this paper filtered multitone (FMT) modulation over frequency-selective time-varying fading channels. Due to the phase and amplitude distortion introduced by the fading channel, not only is the orthogonality among different subcarriers destroyed, but also the perfect Nyquist sampling condition of the baseband matched filters is no longer valid. Consequently, interchannel, as well as... View full abstract»

• ### Cross-Layer Scheduling and Power Control Combined With Adaptive Modulation for Wireless Ad Hoc Networks

Publication Year: 2007, Page(s):728 - 739
Cited by:  Papers (35)
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Efficient resource management is a major challenge in the operation of wireless systems, especially energy-constrained ad hoc networks. In this paper, we propose a cross-layer optimization framework to jointly design the scheduling and power control in wireless ad hoc networks. We study the system performance by combining scheduling, power control, and adaptive modulation. Specifically, the transm... View full abstract»

• ### Performance Analysis of an OFDMA Transmission System in a Multicell Environment

Publication Year: 2007, Page(s):740 - 751
Cited by:  Papers (27)
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The paper deals with design and performance analysis of orthogonal frequency-division multiple-access (OFDMA)-based downlink cellular wireless communications. Due to a high degree of user mobility, the base station is assumed to have only a statistical knowledge of the users' channels. Relying on the ergodic capacities connected to the user rates, a subcarrier and power allocation that minimizes t... View full abstract»

• ### An Integer-Programming Approach to the Bicriteria Multicasting Problem in Optical Networks

Publication Year: 2007, Page(s):752 - 765
Cited by:  Papers (2)
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We consider the problem of designing quality-of-service (QoS)-constrained routes for a set of multicast groups in an all-optical network. We present an integer goal programming formulation with the objectives of minimizing the cost of the multicast solution and minimizing the maximum link load of the network. Based on the structural properties of the problem, we develop a variable-fixing heuristic... View full abstract»

• ### Novel Clock Phase Offset and Skew Estimation Using Two-Way Timing Message Exchanges for Wireless Sensor Networks

Publication Year: 2007, Page(s):766 - 777
Cited by:  Papers (123)  |  Patents (1)
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Recently, a few efficient timing synchronization protocols for wireless sensor networks (WSNs) have been proposed with the goal of maximizing the accuracy and minimizing the power utilization. This paper proposes novel clock skew estimators assuming different delay environments to achieve energy-efficient network-wide synchronization for WSNs. The proposed clock skew correction mechanism significa... View full abstract»

• ### Optimal Signaling and Selection Verification for Single Transmit-Antenna Selection

Publication Year: 2007, Page(s):778 - 789
Cited by:  Papers (13)
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In marked contrast with the ideal error-free feedback assumption that is common in the literature, practical systems are likely to have severely bandwidth-limited, error-prone feedback channels. We consider the scenario where feedback from the receiver is used by the transmitter to select the best antenna, out of many available antennas, for data transmission. Feedback errors cause the transmitter... View full abstract»

• ### A Family of Distributed Space-Time Trellis Codes With Asynchronous Cooperative Diversity

Publication Year: 2007, Page(s):790 - 800
Cited by:  Papers (93)  |  Patents (1)
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In current cooperative communication schemes, to achieve cooperative diversity, synchronization between terminals is usually assumed, which may not be practical since each terminal has its own local oscillator. In this paper, based on the stack construction proposed by Hammons and El Gamal, we first construct a family of space-time trellis codes for BPSK modulation scheme that is characterized to ... View full abstract»

• ### A Reduced-CP Approach to SC/FDE Block Transmission for Broadband Wireless Communications

Publication Year: 2007, Page(s):801 - 809
Cited by:  Papers (14)
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For conventional cyclic prefix (CP)-assisted single-carrier/frequency-domain equalization (SC/FDE) implementations, as well as for orthogonal frequency-division multiplexing (OFDM) implementations, the CP length is known to be selected on the basis of the expected maximum delay spread. Next, the data block size can be chosen to be large enough to minimize the CP overhead, yet small enough to make ... View full abstract»

• ### Noncoherent Ultra-Wideband (De)Modulation

Publication Year: 2007, Page(s):810 - 819
Cited by:  Papers (17)
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Ultra-wideband (UWB) radios have received increasing attention recently for their potential to overlay legacy systems, their low-power consumption and low-complexity implementation. Because of the pulsed or duty-cycled nature of the ultra-short transmitted waveforms, timing synchronization and channel estimation pose major, and often conflicting, challenges and requirements. In order to address (o... View full abstract»

• ### On the Expected Rate of Slowly Fading Channels With Quantized Side Information

Publication Year: 2007, Page(s):820 - 829
Cited by:  Papers (93)
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We study a multiple-layer variable-rate system employing quantized feedback to maximize the expected rate over a single-input single-output slowly fading Gaussian channel. The transmitter uses partial channel-state information, which is obtained via an optimized resolution-constrained feedback link, to adapt the power and to assign code layer rates, subject to different power constraints. To syste... View full abstract»

• ### Performance of Optimum and Suboptimum Combining Diversity Reception for Binary and Quadrature DPSK Over Independent, Nonidentical Rayleigh Fading Channels

Publication Year: 2007, Page(s): 830
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dThis paper is concerned with the error-performance analysis of binary and quadrature differential phase-shift keying with differential detection over the nonselective, Rayleigh fading channel with combining diversity reception. The diversity channels are independent, but have nonidentical statistics. The fading process in each channel is assumed to have an arbitrary Doppler spectrum with a... View full abstract»

• ### On the Teletraffic Capacity of Optical CDMA

Publication Year: 2007, Page(s): 830
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The capacity of an optical CDMA (OCDMA) network has traditionally been defined as the number of continuously transmitting circuits supported by the network. In this paper, we use teletraffic models to determine the teletraffic capacity of a circuit-switched OCDMA network where circuits carry bursty traffic. Our analysis is independent of the OCDMA implementation or spreading code. In conven... View full abstract»

## 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
Naofal Al-Dhahir
University of Texas at Dallas