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Communications Letters, IEEE

Issue 10 • Date Oct. 2005

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Displaying Results 1 - 25 of 36
  • Table of contents

    Publication Year: 2005 , Page(s): 01 - 04
    Cited by:  Papers (1)
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    Freely Available from IEEE
  • IEEE Communications Society

    Publication Year: 2005 , Page(s): 02 - 022
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    Freely Available from IEEE
  • NCTU SLT: a socket-layer translator for IPv4-IPv6 translation

    Publication Year: 2005 , Page(s): 865 - 867
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (131 KB) |  | HTML iconHTML  

    Based on Bump-In-the-API (BIA) architecture, this letter proposes a Socket-layer Translator called NCTU SLT that translates IPv4 applications to IPv4/IPv6-capable applications on dual-stack hosts. Like previously proposed approaches, NCTU SLT can translate NAT-friendly applications (e.g., HTTP and TELNET) without modifying the source codes of the IPv4 applications. Furthermore, NCTU SLT has the advantages over the previous approaches for translating non-NAT friendly applications (i.e., SIP and FTP). View full abstract»

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  • Low-complexity Low-PAR transmission for MIMO-DSL

    Publication Year: 2005 , Page(s): 868 - 870
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (139 KB) |  | HTML iconHTML  

    This letter considers clip-limited transmission over multiple-input multiple-output digital subscriber lines (MIMO-DSL). We show that a recent low complexity, low peak-to-average-ratio (PAR) single-input modulation technique can be applied to the case of multiple cross-talking channels in a bonded-DSL system. Unfortunately however the direct initialization procedure is computationally infeasible. In this paper, we provide a novel low-complexity initialization procedure. Simulations confirm that the proposed approach has superior performance in clip-limited conditions, compared with both discrete matrix multitone and vectored discrete multitone. View full abstract»

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  • Switched diversity receivers over generalized gamma fading channels

    Publication Year: 2005 , Page(s): 871 - 873
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (340 KB) |  | HTML iconHTML  

    A versatile envelope distribution which generalizes several commonly used fading models is the generalized Gamma (GG) distribution. This letter deals with the performance analysis of switch and stay combining (SSC) receivers operating over not necessarily identical GG fading channels. For these receivers, novel analytical expressions for the moments of the output signal-to-noise ratio (SNR) (including average SNR and amount of fading), outage probability, average bit error probability (ABEP), and Shannon average spectral efficiency (ASE) are derived. Moreover, closed-form expressions are obtained for the optimal average SNR, ABEP, and ASE switching thresholds. Special cases of the derived expressions agree with known results. View full abstract»

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  • Effective VoIP call routing in WLAN and cellular integration

    Publication Year: 2005 , Page(s): 874 - 876
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (153 KB) |  | HTML iconHTML  

    In cellular-WLAN integration, a dual-mode mobile station (MS) typically disables the WLAN module for power saving. A major problem is that for an incoming VoIP call (or data session), the MS will not be able to receive this call from the WLAN. It turns out that the call is directed to the cellular network. This letter proposes a simple push solution where an MS can accurately detect a VoIP call from paging signaling of the cellular network. Then the WLAN module of the MS is turned on and the VoIP call is connected to the MS through the relatively inexpensive WLAN. View full abstract»

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  • Minimum ON requirements for DRM reception based on field trials

    Publication Year: 2005 , Page(s): 877 - 879
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (191 KB) |  | HTML iconHTML  

    This paper presents field measurements results of minimum signal to noise ratio required to achieve a threshold BER based on the first medium wave Digital Radio Mondiale (DRM) measurement campaign in Spain. The main goal of these measurements has been to compare the laboratory simulated values recommended by the ITU with field measurements using real transmission and reception systems and real propagation and reception environments. View full abstract»

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  • On multi-hop routing for energy efficiency

    Publication Year: 2005 , Page(s): 880 - 881
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (177 KB) |  | HTML iconHTML  

    We compare two multi-hop routing schemes: the first maximizes the minimum lifetime of the nodes; the second minimizes total energy consumption. We consider both the transmission energy and circuit energy spent in transmission, as well as the receiver energy. The comparison reveals that multihop routing is preferred by the first scheme when the ratio of transmission energy to circuit energy is low and by the second scheme when this ratio is high. In order to balance the load, the first scheme limits the range of multi-hop routing. View full abstract»

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  • Decision feedback detection with error compensation for hybrid space-time block codes

    Publication Year: 2005 , Page(s): 882 - 884
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (186 KB) |  | HTML iconHTML  

    Spatial division multiplexing (SDM) techniques increase the total throughput by transmitting independent information streams through multiple transmit antennas whereas space time coding (STC) techniques utilize diversity gain. Hybrid space-time block code (STBC) schemes proposed combine the above two techniques to maximize the link performance. We propose a decision feedback detection method to improve the performance of the hybrid STBC scheme for orthogonal frequency division multiplexing (OFDM). In this scheme, we take the error propagation effect into account to enhance the detection performance. Simulation results show that the proposed method outperforms the conventional hybrid STBC detection algorithm by more than 3dB at 1% frame error rate for frequency selective fading channels. View full abstract»

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  • SINR estimation for power control in systems with transmission beamforming

    Publication Year: 2005 , Page(s): 885 - 887
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (148 KB) |  | HTML iconHTML  

    This paper takes a unified approach to the downlink transmission power control, while a transmission beamforming is applied in the base station. The proposed scheme is based on the estimation of signal-to-interference-and-noise-ratios (SINRs) by antenna array measurement and using this estimate in transmission power control. Hence power control algorithms needing SINR-levels can be applied instead of the simple relay power control. The SINR estimation technique does not require any additional measurements compared to a separate adaptive beamforming and power control, since the required measurements are needed for the adaptive beamforming update. The estimation is based on the knowledge of the level of caused interference to the multiple access links in the same cell, and the utilization of relay power control commands in SINR estimation. View full abstract»

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  • Adaptive beamforming algorithm based on eigen-space method for smart antennas

    Publication Year: 2005 , Page(s): 888 - 890
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (251 KB) |  | HTML iconHTML  

    This paper presents an adaptive beamforming technique based on the eigen-space method for computing the optimal weight vector that does not degrade the receiving performance even in wide angle spread circumstances. By exploiting the diversity gain, which is available in the signal environments of the wide angle spread, the proposed technique rather enhances the performance as the angle spread increases. It is also confirmed in this paper that performance of the proposed technique is almost identical to that of which has been obtained through the exact solution of the eigen-space method. View full abstract»

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  • Aperiodic complementary sets of sequences-based MIMO frequency selective channel estimation

    Publication Year: 2005 , Page(s): 891 - 893
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (258 KB) |  | HTML iconHTML  

    Accurate estimation of MIMO frequency selective fading channels is important for reliable communication. In this letter, a new channel estimator which relies on aperiodic complementary sets of sequences is proposed. Theoretical analysis and Monte-Carlo simulation have shown that it achieves the minimum possible Cramer-Rao lower bound. A low-complexity hardware implementation of the estimator is also provided. View full abstract»

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  • Pairwise error probability of space-time codes in frequency selective Rician channels

    Publication Year: 2005 , Page(s): 894 - 896
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (138 KB) |  | HTML iconHTML  

    In this letter, we investigate the performance of space-time codes in frequency selective correlated Rician channels. An exact expression has been derived for the pairwise error probability (PEP) of space-time trellis codes over frequency selective Rician fading channel, which is in the form of a single finite range integral. We also obtain a closed form expression for the PEP when the signal matrices are drawn from some special design and the performance upper bound. View full abstract»

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  • Single-channel imaging receiver for optical wireless communications

    Publication Year: 2005 , Page(s): 897 - 899
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (179 KB) |  | HTML iconHTML  

    A novel and simple single-channel imaging receiver for high-speed portable wireless infrared communications is proposed. The receiver is able to aim automatically at the ceiling areas with better signal-to-noise ratio. The self-orienting capability, together with the very narrow field of view employed, drastically reduces the path loss, background noise and multipath distortion. Moreover, its single-channel structure minimizes hardware complexity in contrast to conventional angle diversity receivers. Our simulation results indicate that the proposed receiver, operating in a multispot diffusing configuration, offers significant gains in power requirements and channel bandwidth compared to angle diversity receivers. View full abstract»

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  • A preferential attachment gathering mobility model

    Publication Year: 2005 , Page(s): 900 - 902
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (274 KB) |  | HTML iconHTML  

    In this letter we propose a mobility model using preferential attachment via objects called attractors. We introduce a new kind of mobility we call Gathering Mobility, where nodes, although independent, exhibit a collective behavior. We show that this model, called Pragma, achieves a scale-free spatial distribution in the situation of population growth. View full abstract»

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  • New rate control scheme BSased on adaptive RateLimit for 1xEV-DO reverse link traffic channels

    Publication Year: 2005 , Page(s): 903 - 905
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (213 KB) |  | HTML iconHTML  

    cdma2000 UEV-130 standard has a distributed rate control scheme on a reverse link. In this paper, we propose an adaptive rate control scheme based on the control of Rate Limit, which is a maximum possible data rate in the reverse link. From numerical and simulation results, it is shown that our proposed scheme achieves significant capacity gain in reverse link compared to 1xEV-D0 rate control scheme. View full abstract»

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  • Multiuser detection for continuous phase modulation over Rayleigh fading channels

    Publication Year: 2005 , Page(s): 906 - 908
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (169 KB) |  | HTML iconHTML  

    We study multiuser (MU) continuous phase modulation (CPM) over Rayleigh fading channels with a receiver antenna array. An optimum symbol-by-symbol MU detector is derived and its practical implementation with reduced-complexity is considered. According to the numerical results, the MU detector performs very close to a system free of interference by other users, when each user has more than one receiving antenna. For three receiving antennas, this difference is less than 0.25 dB, 0.4 dB, and 0.6 dB for two, three and four users, respectively. Moreover, the proposed system is bandwidth efficient as CPM is a bandwidth efficient modulation scheme, and the MU system only uses the single user CPM bandwidth. View full abstract»

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  • Error restricted fast MAP decoding of VLC

    Publication Year: 2005 , Page(s): 909 - 911
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (228 KB) |  | HTML iconHTML  

    Joint source channel techniques based on Variable-Length Coding (VLC) have been widely used. One of the most famous VLC decoders is optimal Maximum A Posteriori (MAP) decoder based on directed graph search and soft-input theory. Due to the high complexity of directed graph search, many reduced complexity methods have been proposed. In this paper, we propose two error restricted algorithms for fast MAP decoding of VLC and compare them with three existing methods. Simulation results show that our methods outperform existing methods in terms of decoding complexity with nearly the same performance on Symbol Error Rate (SER) of optimal decoding. When used in a larger codeword set, the superiority in decoding complexity of our methods is more remarkable. View full abstract»

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  • Simple maximum-likelihood decoding of generalized first-order Reed-Muller codes

    Publication Year: 2005 , Page(s): 912 - 914
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (170 KB) |  | HTML iconHTML  

    An efficient decoder for the generalized first-order Reed-Muller code RMq (1, m) is essential for the decoding of various block-coding schemes for orthogonal frequency-division multiplexing with reduced peak-to-mean power ratio. We present an efficient and simple maximum-likelihood decoding algorithm for RMq (1, m). It is shown that this algorithm has lower complexity than other previously known maximum-likelihood decoders for RMq (1, m). View full abstract»

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  • Carrier phase tracking from turbo and LDPC coded signals affected by a frequency offset

    Publication Year: 2005 , Page(s): 915 - 917
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (101 KB) |  | HTML iconHTML  

    This contribution considers carrier phase estimation from coded signals, affected by a frequency offset at low operating signal-to-noise ratio (SNR). We derive a maximum likelihood (ML) based iterative code-aided feedback phase-tracker suited for receivers with iterative maximum-a-posteriori (MAP) detection. Simulations indicate that the proposed synchronizer is considerably more robust against frequency offsets than a feedforward synchronizer. View full abstract»

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  • A simple and fast carrier recovery algorithm for high-order QAM

    Publication Year: 2005 , Page(s): 918 - 920
    Cited by:  Papers (5)  |  Patents (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (255 KB) |  | HTML iconHTML  

    We propose a new carrier recovery algorithm for high-order quadrature amplitude modulation (QAM). The proposed solution relies on two phase detectors, combined with a novel track and hold algorithm for faster frequency acquisition. Compared to previous works, a tenfold improvement or better is achieved in terms of acquisition speed, while keeping a low residual phase noise. View full abstract»

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  • Effects of the nonlinearity of a Mach-Zehnder modulator on OFDM radio-over-fiber transmission

    Publication Year: 2005 , Page(s): 921 - 923
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (400 KB) |  | HTML iconHTML  

    Radio-over-Fiber (RoF) techniques enable transmission of microwave and millimeter-wave signals for long distances with small loss. Due to the limited signal handling capabilities of electrical/optical components, proper leveling is necessary in order to achieve the highest dynamic range while maintaining distortion at acceptable level. This paper investigates the nonlinear distortion of Orthogonal Frequency-Division Multiplex (OFDM) signals caused by a Radio-over-Fiber stage in the transmission chain if a Mach-Zehnder electro-optical modulator is employed. View full abstract»

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  • Iteratively decodable codes from orthogonal arrays for optical communication systems

    Publication Year: 2005 , Page(s): 924 - 926
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (225 KB) |  | HTML iconHTML  

    A novel family of low-density parity-check codes is proposed based on orthogonal arrays. Codes from this family have high code rate, girth of at least six, large minimum distance, and significantly outperform the error correction schemes based on turbo product codes proposed for optical communication systems. View full abstract»

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  • Some remarks regarding asymptotic packet loss in the Pareto/M/1/K queueing system

    Publication Year: 2005 , Page(s): 927 - 929
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (288 KB) |  | HTML iconHTML  

    Many asymptotic results and numerical techniques have appeared in literature to evaluate the packet loss of GI/M/1/K queueing systems and some of them are applicable to heavy-tail distributed interarrival times. We have found a closed-form expression for the Laplace transform of Pareto probability distributions and it allows us to have a better setting to evaluate different performance measures of Pareto queueing systems. Particularly, in this paper we consider the evaluation of the asymptotic packet loss for the Pareto distributed interarrival times, i.e., Pareto/M/1/K queueing systems, through the use of the Pareto Laplace transform and its derivative. View full abstract»

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  • Protection switching for optical bursts using segmentation and deflection routing

    Publication Year: 2005 , Page(s): 930 - 932
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (275 KB) |  | HTML iconHTML  

    Burst segmentation in OBS networks can significantly reduce the amount of data that is lost due to contention events by dropping or deflecting only the portion of a burst that overlaps another contending burst. In this letter, we demonstrate how segmentation combined with deflection routing can be used to reduce the amount of data that is lost when network elements fail. By enabling an OBS switch to deflect the tail-end segments of bursts that are in transmission as soon as it becomes aware of a downstream link failure, the retransmission of lost data can be reduced. View full abstract»

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Editor-in-Chief
George K. Karagiannidis
Aristotle University of Thessaloniki
Greece