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Communications Letters, IEEE

Issue 8 • Date Aug. 2006

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Displaying Results 1 - 25 of 27
  • IEEE Communications Letters - Aug. 2006 Vol. 10 No. 8 - Cover and table of Contents

    Publication Year: 2006 , Page(s): 01
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  • IEEE Communications Society

    Publication Year: 2006 , Page(s): 02
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  • Peak-to-average power ratio reduction in CDMA systems using metric-based symbol predistortion

    Publication Year: 2006 , Page(s): 577 - 579
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (220 KB) |  | HTML iconHTML  

    In this paper, we propose a simple peak-to-average power ratio (PAPR) reduction algorithm for code-division multiple access (CDMA) systems. The described algorithm is based on predistorting a set of symbols using an appropriate metric and does not need sending any side information to the receiver. Using binary phase-shift keying (BPSK) modulation, we show that performance of this algorithm approaches that of the optimum PAPR reduction procedure while avoiding its excessive complexity View full abstract»

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  • Breaking a remote user authentication scheme for multi-server architecture

    Publication Year: 2006 , Page(s): 580 - 581
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (104 KB) |  | HTML iconHTML  

    Lin et al., (2003) proposed a remote user authentication scheme for multi-server architecture. In this paper, we breaks this scheme by giving an attack. Our attack allows an adversary to impersonate any user in the system, as long as a single authentication message of that user is observed View full abstract»

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  • A new symbol-alphabet-aware multi-user detection scheme

    Publication Year: 2006 , Page(s): 582 - 584
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (255 KB) |  | HTML iconHTML  

    In this letter, a new multi-user detection scheme is proposed. It employs a novel nonlinear minimum mean square error (MMSE) estimator that exploits the knowledge of symbol alphabet to estimate the interfering signals. After cancelling the estimated interference, a conventional linear multi-user detector such as the MMSE detector or, simply, the matched-filter receiver (MFR) is then used to detect the desired user signal. Simulation results demonstrate that the proposed detector significantly outperforms the conventional linear MMSE detector View full abstract»

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  • q-Exponential product-form solution of packet distribution in queueing networks: maximization of Tsallis entropy

    Publication Year: 2006 , Page(s): 585 - 587
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (126 KB) |  | HTML iconHTML  

    A maximum Tsallis entropy solution is presented to examine the effect of long-range dependence (LRD) of packet traffic on network of queues. An important finding is that usual product form solution of queueing networks does not hold. However, it is possible to preserve the product like structure in terms of q-product of q-exponential functions. A special case is considered when normalized q-expectation values of first moment and queue utilization at each node are available as the constraint. The joint state probability distribution is shown to depict asymptotically power law behavior View full abstract»

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  • Analytical assessment of multi-user vs. spatial diversity trade-offs with delayed channel state information

    Publication Year: 2006 , Page(s): 588 - 590
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (236 KB) |  | HTML iconHTML  

    In this letter, we explore the combined use of spatial and multi-user diversity in a cellular system where channel state information is subject to delays in the feedback channel. First, we analytically derive the probability and cumulative density functions of the post-scheduling signal-to-noise ratio (SNR) for both a single-input single-output (SISO) and an orthogonal space-time block coding (OSTBC) transmission schemes. Then, we obtain the closed-form expressions of the corresponding average system capacities. By evaluating those expressions, we analytically show that the OSTBC scheme is far less sensitive to delays in the feedback channel View full abstract»

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  • Mutual information statistics for dual MIMO systems in correlated Rayleigh fading

    Publication Year: 2006 , Page(s): 591 - 593
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (225 KB) |  | HTML iconHTML  

    In this letter, we derive very simple and exact expressions for the mutual information (MI) distributions under isotropic Gaussian input of dual multiple-input multiple-output (MIMO) systems, where the minimum number of antennas at either side of the wireless link is two, in a semicorrelated Rayleigh fading environment with correlation at the dual-antenna side only. Furthermore, exact closed-form expressions for the MI moments (mean, variance), and other higher order statistics, such as the skewness and kurtosis, are derived. The proposed methodology for evaluating the MI statistics, is easily extendable to other multielement antenna settings such as single-input multiple-output (SIMO), multiple-input single-output (MISO) and dual MIMO systems for both uncorrelated and semicorrelated Rayleigh fading, where correlation can be assumed at the side with the largest number of antennas View full abstract»

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  • Elementary expressions for outage probability

    Publication Year: 2006 , Page(s): 594 - 595
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (98 KB) |  | HTML iconHTML  

    Elementary expressions are derived for the outage probabilities of maximal ratio combining in the presence co-channel interference considered by Zhang and Beaulieu. The branch gains of the desired user signal and interfering signals experience Rayleigh fading and have the same correlation matrix. The expressions are given as finite sums of the double integral View full abstract»

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  • Transmit antenna shuffling for quasi-orthogonal space-time block codes with linear receivers

    Publication Year: 2006 , Page(s): 596 - 598
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (279 KB) |  | HTML iconHTML  

    In this letter, we propose a transmit antenna shuffling scheme for quasi-orthogonal space-time block codes (QO-STBCs). We show that by adaptively mapping the space-time sequences of the QO-STBC to the appropriate transmit antennas depending on the channel condition, the proposed scheme can improve its transmit diversity with limited feedback information. The performance of the scheme with various numbers of shuffling patterns is analyzed. The bit error probability of the schemes is evaluated by simulations. It is demonstrated that with the linear zero-forcing (ZF) and the minimum mean squared error (MMSE) receivers, the closed-loop QO-STBC using two feedback bits can achieve almost the same performance as the ideal 4-path diversity and it is about 4-5 dB better than the open loop schemes View full abstract»

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  • Closed form expression and improved bound on pairwise error probability for performance analysis of turbo codes over Rician fading channels

    Publication Year: 2006 , Page(s): 599 - 601
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (247 KB) |  | HTML iconHTML  

    This letter provides derivations for an exact expression and a bound on pair wise error probability over fully interleaved Rician fading channels under the assumption of ideal channel state information. The derivation which is based on the probability distribution of the sum of squared Rician random variables leads to an improved upper bound in comparison with the only known bound in literature. Pairwise error probability plots together with average union upper bounds for turbo codes having (1,7/5,7/5) and (1,5/7,5/7) generator polynomials are presented to demonstrate the effectiveness of the new results View full abstract»

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  • Channel allocation for priority packets in the GPRS network

    Publication Year: 2006 , Page(s): 602 - 604
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (167 KB) |  | HTML iconHTML  

    As the general packet radio service (GPRS) network begins to provide such as "push-to-talk" (PTT) service, delay-sensitive packets should be given higher priority in transmission. In this paper, we study two channel allocation schemes that implement priority queues for priority packets in the GPRS network: bitmap channel allocation (BCA) and uplink state flag channel allocation (USFCA). Our study shows that the transmission delay of priority packets in the GPRS network can be better guaranteed using USFCA View full abstract»

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  • New performance results for MDPSK with noncoherent diversity in fast Rayleigh fading

    Publication Year: 2006 , Page(s): 605 - 607
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (210 KB) |  | HTML iconHTML  

    The error performance for M-ary differential phase-shift keying (MDPSK) with non-coherent diversity in fast fading was recently tackled, ending up with a very general formula applicable to various operational environments. The only drawback of this formula is its expression with a double integral which, alongside a singularity existing in the integrand, poses considerable burdens in numerical calculation. In this correspondence, by restricting to the case of independent fast Rayleigh fading channels with equal power, we show how to obtain a much simpler solution with only one integral View full abstract»

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  • A novel hidden station detection mechanism in IEEE 802.11 WLAN

    Publication Year: 2006 , Page(s): 608 - 610
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (190 KB) |  | HTML iconHTML  

    The popular IEEE 802.11 wireless local area network (WLAN) is based on a carrier sense multiple access with collision avoidance (CSMA/CA), where a station listens to the medium before transmission in order to avoid collision. If there exist stations which can not hear each other, i.e., hidden stations, the potential collision probability increases, thus dramatically degrading the network throughput. The RTS/CTS (request-to-send/clear-to-send) frame exchange is a solution for the hidden station problem, but the RTS/CTS exchange itself consumes the network resources by transmitting the control frames. In order to maximize the network throughput, we need to use the RTS/CTS exchange adaptively only when hidden stations exist in the network. In this letter, a simple but very effective hidden station detection mechanism is proposed. Once a station detects the hidden stations via the proposed detection mechanism, it can trigger the usage of the RTS/CTS exchange. The simulation results demonstrate that the proposed mechanism can provide the maximum system throughput performance View full abstract»

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  • Tuning of 802.11e network parameters

    Publication Year: 2006 , Page(s): 611 - 613
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (135 KB) |  | HTML iconHTML  

    This paper introduces a mechanism which dynamically tunes the parameters of the 802.11e contention-based access method. The proposed mechanism aims at providing QoS as well as ameliorating the problem of delay asymmetry View full abstract»

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  • Simple precise approximations to Weibull sums

    Publication Year: 2006 , Page(s): 614 - 616
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (274 KB) |  | HTML iconHTML  

    Simple and precise closed-form approximations to the probability density function and cumulative distribution function of the sum of independent identically distributed Weibull variates are derived. The new approximations find applicability in several wireless communications issues such as equal-gain combining, signal detection, linear equalizers, outage probability, intersymbol interference, and phase jitter View full abstract»

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  • A Markov-Kronecker model for analysis of closed-loop MIMO systems

    Publication Year: 2006 , Page(s): 617 - 619
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (183 KB) |  | HTML iconHTML  

    Closed-loop MIMO systems have gained much interest recently due to their ability in improving performance. Although many spatial-temporal MIMO channel models have been proposed, system limitations are not considered and the effects of a time varying channel on MIMO systems with a realistic feedback delay are also not available in an analytically tractable form. In this letter, we propose a composite model where both propagation and system factors are considered thus providing a simple and analytically tractable model for the performance evaluation and design of closed-loop MIMO systems View full abstract»

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  • System load model for the OFDMA network

    Publication Year: 2006 , Page(s): 620 - 622
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (114 KB) |  | HTML iconHTML  

    In this letter we introduce our system load model for the orthogonal frequency division multiple access (OFDMA) network. We formulate the requirements to the system load model and present its definition. The system load model comprises the uplink load, the downlink load, the sector load, and the network load. We describe our approach to combine the time-frequency and power shared system resources in the OFDMA network View full abstract»

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  • Cryptanalysis of two password authenticated key exchange protocols based on RSA

    Publication Year: 2006 , Page(s): 623 - 625
    Cited by:  Papers (3)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (112 KB) |  | HTML iconHTML  

    In 2002, Zhu et al. proposed a password-based authenticated key exchange protocol based on RSA. Many researchers pointed out that Zhu et al.'s protocol is vulnerable to off-line dictionary attack. In 2003, Yeh et al. proposed an improved protocol. Recently, Lo and Yang-Wang pointed out that Yeh et al.'s improved protocol is also vulnerable to offline dictionary attack. To avoid this weakness existed in Yeh et al.'s protocol, Lo and Yang-Wang proposed two improved protocols. However, in this letter, we show that the Lo protocol is vulnerable to an active off-line dictionary attack and the Yang-Wang protocol is vulnerable to a passive off-line dictionary attack View full abstract»

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  • Performance analysis of dual pulse transmission in UWB channels

    Publication Year: 2006 , Page(s): 626 - 628
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (190 KB) |  | HTML iconHTML  

    A dual pulse transmission scheme with autocorrelation detector has recently been proposed for robust and low complexity UWB communications. This letter present bit error rate expressions of the binary pulse amplitude modulated dual pulse scheme in realistic UWB channels. The semi-analytical solutions are verified by simulation results for IEEE 802.15.3a channels View full abstract»

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  • Efficient ISI cancellation for STBC OFDM systems using successive interference cancellation

    Publication Year: 2006 , Page(s): 629 - 631
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (217 KB) |  | HTML iconHTML  

    In this letter, we propose an efficient detection scheme for space-time block coded (STBC) orthogonal frequency-division multiplexing (OFDM) with insufficient cyclic prefix (CP). The proposed scheme employs successive interference cancellation (SIC) and cyclic prefix reconstruction (CPR) concepts. Simulation results present that the proposed scheme outperforms the conventional scheme for STBC OFDM systems View full abstract»

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  • A long-range dependent model for Internet traffic with power transformation

    Publication Year: 2006 , Page(s): 632 - 634
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (206 KB) |  | HTML iconHTML  

    Internet traffic has been shown to have long-range dependence, and is often modeled by using the fractional Gaussian noise model. The fractional Gaussian noise model can capture the autocorrelation of a real trace, but cannot fit the marginal distribution when the trace has a non-Gaussian marginal distribution. In this letter, we use the inverted Box-Cox transformation to establish a long-range dependent Internet traffic model that can simultaneously capture both the long-range dependence parameter and the marginal distribution of a real trace View full abstract»

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  • Modeling 802.11 mesh networks

    Publication Year: 2006 , Page(s): 635 - 637
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (168 KB) |  | HTML iconHTML  

    We introduce a tractable analytic model of throughput performance for general 802.11 multi-hop multi-radio networks subject to finite loads. The model's accuracy and utility is illustrated by comparison with simulation View full abstract»

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  • Analysis of an efficient group key agreement protocol

    Publication Year: 2006 , Page(s): 638 - 639
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (89 KB) |  | HTML iconHTML  

    Recently, Jung (2006), proposed an efficient group key agreement protocol over authenticated channel. In this letter, we present a critique of the protocol. In particular, we show that Jung's protocol is vulnerable to attacks of malicious insiders View full abstract»

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  • Advertisement - IEEE Order form for reprints

    Publication Year: 2006 , Page(s): 640
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