# IEEE Communications Letters

## Filter Results

Displaying Results 1 - 25 of 52

Publication Year: 2014, Page(s):C1 - 1478
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• ### IEEE Communications Letters publication information

Publication Year: 2014, Page(s): C2
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• ### More on the Minimum Distance of Array LDPC Codes

Publication Year: 2014, Page(s):1479 - 1482
Cited by:  Papers (2)
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Array low-density parity-check (LDPC) codes are a special class of quasi-cyclic LDPC codes constructed from a pair of integers (m, q), where q is an odd prime, and m ≤ q. In this paper, an improved upper bound on the minimum distance of this class of codes is given. View full abstract»

• ### A Note on the Five Valued Conjectures of Johansen, Helleseth and Kholosha and Zeta Functions

Publication Year: 2014, Page(s):1483 - 1486
Cited by:  Papers (1)
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For the complete five-valued cross-correlation distribution between two m-sequences st and sdt of period 2m - 1 that differ by the decimation d = (22k + 1)/(2k + 1) where m is odd and gcd(k, m) = 1, Johansen and Helleseth expressed it in terms of some exponential sums. And two conjectures were presented about them. In this correspondence we st... View full abstract»

• ### Fault-Tolerant Probabilistic Gradient-Descent Bit Flipping Decoder

Publication Year: 2014, Page(s):1487 - 1490
Cited by:  Papers (22)
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We propose a gradient descent type bit flipping algorithm for decoding low density parity check codes on the binary symmetric channel. Randomness introduced in the bit flipping rule makes this class of decoders not only superior to other decoding algorithms of this type, but also robust to logic-gate failures. We report a surprising discovery that for a broad range of gate failure probability our ... View full abstract»

• ### Coding for Unreliable Flash Memory Cells

Publication Year: 2014, Page(s):1491 - 1494
Cited by:  Papers (8)
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In this work, the model introduced by Gabrys is extended to account for the presence of unreliable memory cells. Leveraging data analysis on errors taking place in a TLC Flash device, we show that memory cells can be broadly categorized into reliable and unreliable cells, where the latter are much more likely to be in error. Our approach programs unreliable cells only in a limited capacity. In par... View full abstract»

• ### A Clarification of the Proper-Integral Form for the Gaussian $Q$-Function and Some New Results Involving the $F$-Function

Publication Year: 2014, Page(s):1495 - 1498
Cited by:  Papers (5)
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We discuss the origin of the well-known integral form for the Gaussian Q-function. Although this form is originally attributed to Craig in his 1991 paper, it actually was inferred in previous communications theory references in the literature by Weinstein, and explicitly stated by Pawula, Rice and Roberts. Specifically, this form can be seen as a particular case of the general F-function, that is ... View full abstract»

• ### On the Concavity of the Sum-Rate Function in OFDM Systems

Publication Year: 2014, Page(s):1499 - 1502
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We study the power allocation problem for maximizing the sum rate in orthogonal frequency-division multiplexing systems, where multiple point-to-point links share a set of subcarriers. This problem is hard to solve, in general, due to its nonconvexity. In this letter, we characterize the conditions for the problem to be convex, in which case the problem can be solved efficiently using known algori... View full abstract»

• ### Space Shift Keying MIMO System Under Spectrum Sharing Environments in Rayleigh Fading

Publication Year: 2014, Page(s):1503 - 1506
Cited by:  Papers (17)
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This letter investigates the error performance for the space shift keying (SSK) system under spectrum sharing environments. The secondary network under consideration is equipped with multiple antennas at the transmitter and receiver. The primary network is composed of L primary users (PUs) equipped with multiple antennas. For the underlay spectrum sharing transmission with SSK modulation, the tran... View full abstract»

• ### High SNR BER Comparison of Coherent and Differentially Coherent Modulation Schemes in Lognormal Fading Channels

Publication Year: 2014, Page(s):1507 - 1510
Cited by:  Papers (7)
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Using an auxiliary random variable technique, we prove that binary differential phase-shift keying and binary phase-shift keying have the same asymptotic bit-error rate performance in lognormal fading channels. We also show that differential quaternary phase-shift keying is exactly 2.32 dB worse than quaternary phase-shift keying over the lognormal fading channels in high signal-to-noise ratio reg... View full abstract»

• ### Bandwidth and Latency Aware Contribution Estimation in P2P Streaming System

Publication Year: 2014, Page(s):1511 - 1514
Cited by:  Papers (1)
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In this article, a bandwidth and latency aware contribution estimation (BLACE) mechanism is proposed to enhance the efficiency of content distribution in a mesh peer-to-peer (P2P) streaming system. This is because the mesh P2P streaming system outperforms others in many aspects, but most content distribution mechanisms use only one of upload bandwidth and link latency as a factor, several contribu... View full abstract»

• ### Labeling Non-Square QAM Constellations for One-Dimensional Bit-Metric Decoding

Publication Year: 2014, Page(s):1515 - 1518
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A new modulation scheme is proposed that combines the advantages of APSK and QAM constellations, namely, the low peak power of APSK and the independent processing of the real and imaginary components of QAM. The new scheme consists of a Gray-labeled non-square QAM constellation and a bit-metric decoder. At a spectral efficiency of 3.5 bits/s/Hz, the new scheme saves 1.35 dB of peak power compared ... View full abstract»

• ### A Fast Anticollision Algorithm for the EPCglobal UHF Class-1 Generation-2 RFID Standard

Publication Year: 2014, Page(s):1519 - 1522
Cited by:  Papers (6)
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In this letter, a fast anticollision algorithm has been proposed to improve the read performance of the EPCglobal UHF Class-1 Generation-2 protocol. Our algorithm is based on the early adjustment of frame length. To reduce the computation complexity of interrogators, the proposed algorithm resorts to only one examination of current frame length in each read round. As compared with the case of exam... View full abstract»

• ### Fault-Tolerant Two-Stage Open Queuing Systems With Server Failures at Both Stages

Publication Year: 2014, Page(s):1523 - 1526
Cited by:  Papers (3)
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Two-stage open queuing systems are used to model and evaluate interaction between two systems in computer and communication networks. Application areas include two-stage internetworking mechanisms, memory servers, and interaction of wireless communication systems. Realistic features, such as finite capacities, feedback from one stage to another, and failures of servers usually complicate analytic ... View full abstract»

• ### Modeling Alien-Line Impedance Mismatch in Wideband Vectored Wireline Systems

Publication Year: 2014, Page(s):1527 - 1530
Cited by:  Papers (3)
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Sudden changes of channel coefficients in a wideband vectored wireline system (such as G.fast) due to changes in the terminating impedance of lines outside the vectored group can seriously degrade stability and throughput. This letter presents a model that predicts the impact of termination mismatch based exclusively on crosstalk data for the properly-terminated state. Experimental results confirm... View full abstract»

• ### Energy-Efficient Elastic Optical Interconnect Architecture for Data Centers

Publication Year: 2014, Page(s):1531 - 1534
Cited by:  Papers (24)
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To address the urgent need for high-capacity, scalable and energy-efficient data center solutions, we propose a novel data center network architecture realized by combining broadcast-and-select approach with elastic channel spacing technology. We demonstrate that the proposed architecture is able to scale efficiently with the number of servers and offers lower energy consumption at a competitive c... View full abstract»

• ### Efficient Generalized Engset Blocking Calculation

Publication Year: 2014, Page(s):1535 - 1538
Cited by:  Papers (1)
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Engset's model of resource blocking with a finite population has recently been generalized to allow blocked users to have a recovery time before they re-enter contention for the resources. We propose an algorithm to find the stationary distribution of the resulting level-dependent quasi-birth-and-death (LDQBD) process, and hence the blocking probability. Its running time is linear in the number of... View full abstract»

• ### Flow-Aware Multi-Topology Adaptive Routing

Publication Year: 2014, Page(s):1539 - 1542
Cited by:  Papers (9)  |  Patents (1)
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Internet routing processes currently rely on protocols that were developed more than ten years ago. Today, we have far more computational power and memory at our disposal, and it is possible to take advantage of these resources in order to greatly increase the efficiency of routing protocols. Therefore, we propose a new approach to routing packets in IP-based networks: Flow-Aware Multi-Topology Ad... View full abstract»

• ### Active Interference Cancellation for OFDM Spectrum Sculpting: Linear Processing Is Optimal

Publication Year: 2014, Page(s):1543 - 1546
Cited by:  Papers (2)
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Active interference cancellation (AIC) is a multicarrier spectrum sculpting technique, which reduces the power of undesired out-of-band emissions by adequately modulating a subset of reserved cancellation subcarriers. In most schemes, online complexity is a concern, and thus, cancellation subcarriers have traditionally been constrained to linear combinations of the data subcarriers. Recent AIC des... View full abstract»

• ### New Constructions of Perfect Gaussian Integer Sequences of Even Length

Publication Year: 2014, Page(s):1547 - 1550
Cited by:  Papers (5)
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Perfect sequences have wide application fields, including spread spectrum communication, synchronization techniques, channel estimation, and cell search. In this letter, two kinds of (almost) perfect Gaussian integer sequences of length N=2 (mod4) and N=0 (mod4) are proposed and constructed by complex transformations and interleaving techniques, using the perfect Gaussian integer sequences of odd ... View full abstract»

• ### Clock Synchronization Over Communication Paths With Queue-Induced Delay Asymmetries

Publication Year: 2014, Page(s):1551 - 1554
Cited by:  Papers (3)
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Timing protocols such as the IEEE 1588 Precision Time Protocol and the Network Time Protocol require an accurate measurement of the communication path delay between the time server (master) and the client (slave) in order to provide a precise timing synchronization. The precise time at the client's site is then estimated using an assumption that forward and backward delays due to physical propagat... View full abstract»

• ### Is a Large Bandwidth Mandatory to Maximally Exploit the Transmit Matched-Filter Structure?

Publication Year: 2014, Page(s):1555 - 1558
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Transmitted signals can be focused in time or space, i.e., at a particular receiver location, by introducing a prefilter in the transmitter. Prefiltering also allows containing intersymbol and multiuser interference. Performance bounds in terms of signal-to-noise ratio gain, which is achievable by prefiltering, depend on both transmitted signal bandwidth and channel characteristics. This paper ana... View full abstract»

• ### Energy-Efficient Precoder Design for MIMO Wiretap Channels

Publication Year: 2014, Page(s):1559 - 1562
Cited by:  Papers (31)
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In this letter, we study energy-efficient precoder design in a three-node MIMO wiretap channel. Different from previous works in this area that mainly focus on secrecy rate maximization or power minimization problems, here, we aim to maximize the energy efficiency (EE) of the system subject to the secret rate and transmit power constraints, which is a nonconvex optimization and hard to tackle. To ... View full abstract»

• ### Throughput Scaling of MIMO Channels With Imperfect CSIT in the Low-SNR Regime

Publication Year: 2014, Page(s):1563 - 1566
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We study the effect of channel estimation error on the performance of water-filling in point-to-point multiple-input- multiple-output (MIMO) channels at low signal-to-noise ratios (SNRs). In this regard, we derive the water-filling throughput of a MIMO channel in the presence of imperfect channel state information at the transmitter (CSIT). The asymptotic growth rate for the throughput, i.e., R, i... View full abstract»

• ### A Theorem on the Asymptotic Outage Behavior of Fixed-Gain Amplify-and-Forward Relay Systems

Publication Year: 2014, Page(s):1567 - 1570
Cited by:  Papers (1)
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A theorem that describes the high signal-to-noise ratio outage behavior of fixed-gain amplify-and-forward relay systems is given. Qualitatively, the theorem states that the outage probability decays according to a power law, where the power is dictated by the poles of the moments of the underlying per-hop fading distributions. The power-law decay is dampened by a logarithmic factor when the leadin... View full abstract»

## Aims & Scope

IEEE Communications Letters publishes letters on the frontiers of research within the field of interest of the IEEE Communications Society in a timely manner.

Full Aims & Scope

Editor-in-Chief
Octavia Dobre