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Communications Letters, IEEE

Issue 3 • Date March 2009

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Displaying Results 1 - 17 of 17
  • IEEE Communications Letters - Table of contents

    Publication Year: 2009 , Page(s): c1
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  • Fault localization in data networks

    Publication Year: 2009 , Page(s): 161 - 163
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (136 KB) |  | HTML iconHTML  

    In this letter we show a fault localization system implemented by using policy-based thresholds for triggering alarms or self-healing mechanisms. Alarms are collected and organized within a codebook, which is a fundamental component of our fault management system. The relevant performance is analyzed by using a real network deploying VoIP services. View full abstract»

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  • Analysis of the impact of background traffic on the performance of 802.11 power saving mechanism

    Publication Year: 2009 , Page(s): 164 - 166
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (226 KB) |  | HTML iconHTML  

    In our previous work, we have identified the issue that the performance of 802.11 power saving mechanism degrades significantly with the presence of background traffic. In this letter, we propose a simple model to theoretically analyze the impact of background streams on the power performance of an individual mobile station in power saving mode (PSM). By reasonable assumptions on medium access details, we develop a set of mathematical formulas which gives the ratio of prolonged data retrieval time under condition of background traffic within a beacon period. Simulation results demonstrate the validity of the proposed model for analysis of 802.11 PSM. View full abstract»

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  • Symbol-based processing with balanced subcarrier performance for MIMO-OFDM systems

    Publication Year: 2009 , Page(s): 167 - 169
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (260 KB) |  | HTML iconHTML  

    Recently, symbol-based beamforming/combining has been introduced for OFDM systems with multiple transmit and receive antennas. Despite the complexity reduction, the resultant SNR values of different subcarriers are often not balanced, and it limits the system performance. In this letter, we propose to use the max-min criterion to overcome the problem. Simulation results show that the error-rate performance of the proposed symbol-based processing scheme can be improved as compared with that of the conventional one. View full abstract»

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  • On the anonymity of some authentication schemes for wireless communications

    Publication Year: 2009 , Page(s): 170 - 171
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (183 KB) |  | HTML iconHTML  

    In 2004, Zhu and Ma proposed a new and efficient authentication scheme claiming to provide anonymity for wireless environments. Two years later, Lee et al. revealed several previously unpublished flaws in Zhu-Ma's authentication scheme and proposed a fix. More recently in 2008, Wu et al. pointed out that Lee et al.'s proposed fix fails to preserve anonymity as claimed and then proposed yet another fix to address the problem. In this paper, we use Wu et al.'s scheme as a case study and demonstrate that due to an inherent design flaw in Zhu-Ma's scheme, the latter and its successors are unlikely to provide anonymity. We hope that by identifying this design flaw, similar structural mistakes can be avoided in future designs. View full abstract»

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  • On the performance of selection decode-and-forward relay networks over Nakagami-m fading channels

    Publication Year: 2009 , Page(s): 172 - 174
    Cited by:  Papers (43)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (762 KB) |  | HTML iconHTML  

    In this paper, we present the performance of fixed decode-and-forward cooperative networks with relay selection over independent but not identically distributed Nakagami-m fading channels, with integer values of the fading severity parameter m. Specifically, closed-form expressions for the symbol error probability and the outage probability are derived using the statistical characteristic of the signal-to-noise ratio. We also perform Monte-Carlo simulations to verify the analytical results. View full abstract»

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  • Throughput analysis considering coupling effect in ieee 802.11 networks with hidden stations

    Publication Year: 2009 , Page(s): 175 - 177
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (346 KB) |  | HTML iconHTML  

    This letter investigates the throughput performance of the IEEE 802.11 networks with hidden stations. Note that the decoupling approximation of the Bianchi's Markov chain model is valid for the IEEE 802.11 networks with a large number of the hidden stations. Hence, we propose a new analytic model to accommodate the effect of the hidden stations and estimate the network throughput based on the analytic model. View full abstract»

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  • Decoupling data dissemination from mobile sink's trajectory in wireless sensor networks

    Publication Year: 2009 , Page(s): 178 - 180
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (210 KB) |  | HTML iconHTML  

    We propose an efficient proactive data dissemination approach that allows a mobile sink to effectively gather a representative view of a monitored region covered by n sensor nodes by visiting any m nodes, where m << n. Moreover, the proposed strategy allows the mobile sink to follow any trajectory through the deployment region, thus decoupling the data dissemination management from the mobile sink's trajectory. View full abstract»

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  • On the connectivity of wireless multi-hop networks with arbitrary wireless channel models

    Publication Year: 2009 , Page(s): 181 - 183
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (156 KB) |  | HTML iconHTML  

    Considering a wireless multi-hop network where a total of n nodes are randomly, independently and uniformly distributed in a unit square in R2 and each node has a uniform transmission power, a fundamental problem is to investigate the connectivity of such networks. In this letter, we prove that the probability of having a connected network and the probability of having no isolated node asymptotically converges to the same value as n goes to infinity for an arbitrary wireless channel model satisfying certain intuitively reasonable conditions. View full abstract»

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  • Cyclic delay diversity with frequency domain turbo equalization for uplink fast fading channels

    Publication Year: 2009 , Page(s): 184 - 186
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (225 KB) |  | HTML iconHTML  

    Cyclic delay diversity (CDD) is an attractive diversity technique due to its low complexity and compatibility to existing wireless communication systems. This letter proposes a CDD with frequency domain turbo equalization (FDTE) for single carrier (SC) transmission, in order to achieve the full spatial diversity of frequency-selective multi-antenna channels. The frequency diversity inherent in SC is picked up from the increased channel selectivity of CDD. The noise or intersymbol interference enhanced by equalization for highly selective channels is then mitigated through applying FDTE at the receiver. Simulation results show that the performance of proposed system approaches the corresponding orthogonal spacetime block coding (STBC) system in slowly fading channels without any data rate loss, and considerably outperforms the STBC system in fast fading channels. View full abstract»

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  • Practical determination of impulse sample power boosting factor in impulse postfix OFDM systems

    Publication Year: 2009 , Page(s): 187 - 189
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (307 KB) |  | HTML iconHTML  

    An impulse postfix OFDM (IP-OFDM) system, which performs channel estimation in time-domain by exploiting the IP instead of pilot tones, has recently been proposed by Chang et al. Although the proposed system can achieve the enhanced bit error rate (BER) performance compared to that of conventional OFDM systems, there is an important peak-to-average power ratio (PAPR) issue of using the IP that needs to be resolved. In this letter, we propose decision criteria for determining the power boosting factor (PBF) of IP in practical IP-OFDM systems with a high power amplifier (HPA). The analysis is performed with two criteria, the complementary cumulative distribution function of signal PAPR and the input back-off to determine the PBF of IP. The best PBF can be the one which gives an equal power to the IP and the rest of the OFDM symbol. From the analytic results, however, the PBF maximizing the power of the IP out of the HPA turns out to be the best one due to the non-linearities of the HPA. Simulation results demonstrate the effectiveness of the proposed decision criteria for IP-OFDM systems. View full abstract»

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  • Seamless spectrum handover considering differential path-loss in cognitive radio systems

    Publication Year: 2009 , Page(s): 190 - 192
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (268 KB) |  | HTML iconHTML  

    In cognitive radio systems, spectrum handover occurs when a secondary user changes frequency due to the appearance of a primary user. Spectrum handover may result in degraded system performance because of the different propagation loss of the different frequency. In this case, data transmission is disrupted and it is more difficult to provide seamless service. Here, we propose a seamless handover scheme based on the prediction of cell coverage. The proposed handover scheme can avoid service disruption and can reduce redundant handovers. The efficiency of the scheme is validated by simulation results. View full abstract»

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  • Two-staged informed dynamic scheduling for sequential belief propagation decoding of LDPC codes

    Publication Year: 2009 , Page(s): 193 - 195
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (303 KB) |  | HTML iconHTML  

    Recent studies have shown that sequential belief propagation decoding of low-density parity-check codes can increase the decoding convergence speed while simultaneously improving the asymptotic performance compared to the conventional flooding scheme. Two of the practical sequential decoding schemes known are the ones by Casado et al. (2007) in which informed dynamic scheduling is used for scheduling the sequential updates of the messages. In this letter, we propose a two-staged informed dynamic scheduling that unifies and outperforms the two schemes of Casado et al. View full abstract»

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  • A minimum mean-squared error relay for the two-way relay channel with network coding

    Publication Year: 2009 , Page(s): 196 - 198
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (217 KB) |  | HTML iconHTML  

    In this letter, we consider the two-way relay channel (TWRC) employing network coding. In TWRC, a conventional relay first decodes symbols from each user and combines (network coding) them using, for example, the XOR (eXclusive OR) operation. However, it may be suboptimal for the relay to use this concatenated approach, when the channels are noisy and the cost criterion is source distortion. Instead, we propose a new relay scheme that generates network coded symbols by performing symbol estimation and network coding operation jointly, in order to minimize the source distortion at the users. View full abstract»

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  • Group-synchronized polling algorithm in WDM-EPON

    Publication Year: 2009 , Page(s): 199 - 201
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (335 KB) |  | HTML iconHTML  

    Wavelength division multiplexing-ethernet passive optical network (WDM-EPON) technology yields evolutionary advantages which enable next generation broadband access networks to overcome the bandwidth limit of EPON. To effectively share uplink resources of inter-optical network units (ONUs) in WDM-EPON, we propose a group-synchronized polling algorithm (GSPA). In GSPA, ONUs are partitioned into g (> 2) groups and each group fully uses one among m (ges 2) uplink wavelengths during a predetermined time TRef. Since the starting times of groups are inter-weaved with different wavelengths to enable groups to transmit frames to an optical line terminator (OLT), the GSPA can perform dynamic bandwidth allocation (DBA) in parallel without wasting uplink resources. Comprehensive simulation results show that GSPA yields better performance compared with both the existing offline and on-the-fly algorithms. View full abstract»

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  • Improved global stability conditions of the tuning parameter in FAST TCP

    Publication Year: 2009 , Page(s): 202 - 204
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (170 KB) |  | HTML iconHTML  

    In this letter, we present a correction of the theorem for the global stability of FAST TCP developed by Koo et al. in 2008. Furthermore, an analysis is carried out to determine an improved parameter condition for global stability than the existing conditions in the literature. The parameter condition is verified by the ns-2 simulation. View full abstract»

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  • An off-line dictionary attack on a simple three-party key exchange protocol

    Publication Year: 2009 , Page(s): 205 - 207
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (137 KB) |  | HTML iconHTML  

    Key exchange protocols allow two or more parties communicating over a public network to establish a common secret key called a session key. Due to their significance in building a secure communication channel, a number of key exchange protocols have been suggested over the years for a variety of settings. Among these is the so-called S-3PAKE protocol proposed by Lu and Cao for password-authenticated key exchange in the three-party setting. In the current work, we are concerned with the password security of the S-3PAKE protocol. We first show that S-3PAKE is vulnerable to an off-line dictionary attack in which an attacker exhaustively enumerates all possible passwords in an off-line manner to determine the correct one. We then figure out how to eliminate the security vulnerability of S-3PAKE. View full abstract»

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IEEE Communications Letters  is aimed at satisfying the need for rapid dissemination of information, offering a vehicle for authors to expose their results to be used in future developments. This ensures early recognition of work. 

 

 

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Meet Our Editors

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