By Topic

Communications Letters, IEEE

Issue 5 • Date May 2004

Filter Results

Displaying Results 1 - 25 of 28
  • Table of contents

    Publication Year: 2004 , Page(s): c1 - c4
    Request Permissions | PDF file iconPDF (37 KB)  
    Freely Available from IEEE
  • IEEE Communications Letters publication information

    Publication Year: 2004 , Page(s): c2
    Request Permissions | PDF file iconPDF (37 KB)  
    Freely Available from IEEE
  • An improved OCDMA/OCDMA scheme based on displaced orthogonal user sets

    Publication Year: 2004 , Page(s): 265 - 267
    Cited by:  Papers (10)
    Request Permissions | Click to expandAbstract | PDF file iconPDF (168 KB) |  | HTML iconHTML  

    We introduce a new type of OCDMA/OCDMA for oversaturated channels, by displacing in time the orthogonal signature sets of the users. A displacement by an integer multiple of a chip period considerably improves the performance of iterative detection of the user data, as compared to quasi-orthogonal sequences (QOS) and conventional random O/O sequences. An additional displacement by half a chip peri... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Blocking probability analysis for packet circuit emulation services

    Publication Year: 2004 , Page(s): 268 - 270
    Cited by:  Papers (1)
    Request Permissions | Click to expandAbstract | PDF file iconPDF (112 KB) |  | HTML iconHTML  

    Standardization of pseudo-wire and circuit emulation services on IP packet networks is underway. The ability to quickly find circuits in networks supporting circuit emulation is directly computed using blocking probability analysis. When all of the sequenced flows have the same maximum packet size, i.e., they are homogeneous, blocking probabilities are computed using Erlang's B formula. This paper... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A simple bound on the outage probability with lognormally distributed interferers

    Publication Year: 2004 , Page(s): 271 - 273
    Cited by:  Papers (31)  |  Patents (1)
    Request Permissions | Click to expandAbstract | PDF file iconPDF (184 KB) |  | HTML iconHTML  

    We consider the problem of determining the outage probability in a cellular radio system, where the interference is modeled by a sum of lognormal random variables. As no closed form expression is known, bounds can serve as a quick way of evaluating performance. By applying the arithmetic-geometric mean inequality, we give a lower bound, computationally simple as it is expressed by a single Q-funct... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Efficient cyclic prefix reconstruction for coded OFDM systems

    Publication Year: 2004 , Page(s): 274 - 276
    Cited by:  Papers (19)  |  Patents (2)
    Request Permissions | Click to expandAbstract | PDF file iconPDF (160 KB) |  | HTML iconHTML  

    This letter describes an improved method to mitigate interference when the cyclic prefix is not sufficient for coded orthogonal frequency-division multiplexing (OFDM) systems. The proposed method, based on the residual intersymbol interference cancellation (RISIC), efficiently restores the cyclicity of the ith received symbol by adding the weighted (i+1)th received symbol to the ith received symbo... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A new hybrid constraint-based approach for 3G network planning

    Publication Year: 2004 , Page(s): 277 - 279
    Cited by:  Papers (16)
    Request Permissions | Click to expandAbstract | PDF file iconPDF (224 KB) |  | HTML iconHTML  

    This letter proposes a novel constraint-based 3G network planning model and a novel hybrid approach for optimizing the 3G network planning problem. Computational results show that the model and the approach are more efficient than the mathematical model and the existing heuristics. Optimal solutions are always obtained for small and medium sized problems. For larger sized problems, the final resul... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Performance evaluation of GSM/GPRS networks with channel re-allocation scheme

    Publication Year: 2004 , Page(s): 280 - 282
    Cited by:  Papers (13)
    Request Permissions | Click to expandAbstract | PDF file iconPDF (168 KB) |  | HTML iconHTML  

    Previous work studying the channel allocation schemes in GSM/GPRS network commonly assume that one or two channels are required by a GPRS data for the sake of analytical simplicity. In this letter, we remove the assumption and generalize the GPRS data channel requirement (M channels). Additionally, we propose a channel re-allocation scheme (RAS), executed upon the channel release, by re-allocating... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • OXC port dimensioning strategies in optical networks-a nodal perspective

    Publication Year: 2004 , Page(s): 283 - 285
    Cited by:  Papers (2)  |  Patents (1)
    Request Permissions | Click to expandAbstract | PDF file iconPDF (216 KB) |  | HTML iconHTML  

    In this letter, we investigate optical cross-connect (OXC) port dimensioning strategies for supporting bandwidth-on-demand (BoD) services in optical networks. At a given node, the bandwidth-on-demand traffic load consists of two components; an access component, which is generated by demands originating at that node, and a transit component, which is generated by demands that transit electronically... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Reduced complexity Schnorr-Euchner decoding algorithms for MIMO systems

    Publication Year: 2004 , Page(s): 286 - 288
    Cited by:  Papers (27)  |  Patents (2)
    Request Permissions | Click to expandAbstract | PDF file iconPDF (160 KB) |  | HTML iconHTML  

    A new reduced-complexity Schnorr-Euchner decoding algorithm is proposed in this letter for uncoded multi-input multi-output systems with q-QAM (q=4,16,...) modulation. Furthermore, a Fano-like metric bias is introduced to the algorithm from the perspective of sequential decoding, as well as an early termination technique. Simulation results show that these modifications reduce the algorithm comple... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Outage performance for maximal ratio combiner in the presence of unequal-power co-channel interferers

    Publication Year: 2004 , Page(s): 289 - 291
    Cited by:  Papers (42)
    Request Permissions | Click to expandAbstract | PDF file iconPDF (152 KB) |  | HTML iconHTML  

    Outage probability for maximal ratio combining (MRC) is usually tackled in the framework of Rayleigh or Nakagami faded co-channel interferers with equal power, which allows for the treatment of the total interference power as a single gamma distributed variable to simplify the analysis. The more general case with unequal-power co-channel interferers is formulated and solved differently in this pap... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Adaptive stochastic iterative rate selection for wireless channels

    Publication Year: 2004 , Page(s): 292 - 294
    Cited by:  Papers (7)  |  Patents (5)
    Request Permissions | Click to expandAbstract | PDF file iconPDF (184 KB) |  | HTML iconHTML  

    A stochastic algorithm for channel adaptive rate selection (modulation and coding scheme or MCS) is proposed. The algorithm learns the optimal policy by iteratively augmenting a rate selection probability vector. While simple to implement, this technique requires no explicit channel estimation phase. The single bit ACK/NACK signal feedback from the data link layer is used as the input to the stoch... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Comments on "Spatial fading correlation function of circular antenna arrays with Laplacian energy distribution"

    Publication Year: 2004
    Cited by:  Papers (3)
    Request Permissions | Click to expandAbstract | PDF file iconPDF (76 KB) |  | HTML iconHTML  

    For original paper see Tsai et al. (IEEE Commun. Lett., vol.6, p.178-80, 2002 May). This comment points out three inaccurate formulae and the problems in results of the numerical simulations. The correct formulae and results of the voltage correlation coefficients are provided. Our simulations have shown the simulation results exhibit good agreement with the analytical results as long as the items... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A soft-detector based on multiple symbol detection for double differential modulation

    Publication Year: 2004 , Page(s): 296 - 298
    Cited by:  Papers (1)
    Request Permissions | Click to expandAbstract | PDF file iconPDF (192 KB) |  | HTML iconHTML  

    We consider the problem of soft-detection for communication systems employing double differential modulation and forward error correction codes, for example, a convolutional code. We propose a soft-detector with low computational complexity. Simulation results are provided to show the superior performance of the new soft-detector. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A tight upper bound on the BER of linear systematic block codes

    Publication Year: 2004 , Page(s): 299 - 301
    Cited by:  Papers (2)
    Request Permissions | Click to expandAbstract | PDF file iconPDF (192 KB) |  | HTML iconHTML  

    We present in this letter new upper bounds for linear and systematic block codes. Both perfect and quasi-perfect codes are considered. Numerical results show that our new bounds give much tighter results compared to the classical union-Chernoff bound. In addition, these bounds are more accurate than the leading term approximations especially at low signal-to-noise ratio. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Systematic recursive construction of LDPC codes

    Publication Year: 2004 , Page(s): 302 - 304
    Cited by:  Papers (17)
    Request Permissions | Click to expandAbstract | PDF file iconPDF (240 KB) |  | HTML iconHTML  

    This letter presents a systematic and recursive method to construct good low-density parity-check (LDPC) codes, especially those with high rate. The proposed method uses a parity check matrix of a quasi-cyclic LDPC code with given row and column weights as a core upon which the larger code is recursively constructed with extensive use of pseudorandom permutation matrices. This construction preserv... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Diversity performance of precoded orthogonal space-time block codes using limited feedback

    Publication Year: 2004 , Page(s): 305 - 307
    Cited by:  Papers (21)
    Request Permissions | Click to expandAbstract | PDF file iconPDF (152 KB) |  | HTML iconHTML  

    Orthogonal space-time block codes (OSTBCs) are simple space-time codes that can be used for open-loop transmit diversity systems. OSTBCs, however, can only be designed for certain numbers of transmit antennas. Channel-dependent linear precoders have been proposed to overcome this deficiency, but it is not clear what conditions the precoder design must satisfy to guarantee full diversity order. In ... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Improving voice over IP subjective call quality

    Publication Year: 2004 , Page(s): 308 - 310
    Cited by:  Papers (6)
    Request Permissions | Click to expandAbstract | PDF file iconPDF (272 KB) |  | HTML iconHTML  

    Adaptive playout algorithms rely on estimates of network delays to calculate playout times of voice packets. Typically, network estimators are either able to react quickly to delay variations or to ignore transient noise conditions, but cannot do both. In our solution, the weighting factor that controls the estimation process is dynamically adjusted according to the observed delay variations. This... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Performance analysis of M-PAM signaling with Tomlinson-Harashima precoding over ISI channels

    Publication Year: 2004 , Page(s): 311 - 313
    Cited by:  Papers (3)
    Request Permissions | Click to expandAbstract | PDF file iconPDF (128 KB) |  | HTML iconHTML  

    An analytical method is developed to evaluate the symbol error probability of multilevel pulse amplitude modulation system using Tomlinson-Harashima precoding over inter-symbol interference channels. Analytical and simulation results are in an excellent agreement for different values of M. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On evil-twin routing in Clos networks

    Publication Year: 2004 , Page(s): 314 - 316
    Request Permissions | Click to expandAbstract | PDF file iconPDF (152 KB) |  | HTML iconHTML  

    The evil twin randomized routing algorithm is successfully applied to three-stage Clos networks in packet-switching platforms. Here we show the essence of evil twin permutations and how to construct evil twin permutations. The concept of evil twin permutations is also generalized in this letter. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Efficient and reliable link state information dissemination

    Publication Year: 2004 , Page(s): 317 - 319
    Cited by:  Papers (15)  |  Patents (3)
    Request Permissions | Click to expandAbstract | PDF file iconPDF (112 KB) |  | HTML iconHTML  

    Distributing link state information may place a heavy burden on the network resource. In this letter, based on the tree-based reliable topology (TRT), we propose a simple but efficient and reliable scheme for disseminating link state information. We show that the computational complexity of computing the subnet topology over which link state information is distributed is the same as that of comput... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Proportional differentiated admission control

    Publication Year: 2004 , Page(s): 320 - 322
    Cited by:  Papers (3)
    Request Permissions | Click to expandAbstract | PDF file iconPDF (168 KB) |  | HTML iconHTML  

    This letter presents a new admission control policy inspired in the framework of proportional differentiated services (PDS). While most of previous PDS has focused on average queueing delays and packet drops to differentiate the performance of adaptive applications, the proportional differentiation admission control (PDAC) differentiates inelastic traffic in terms of blocking probabilities. The PD... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Modified RED gateways under bursty traffic

    Publication Year: 2004 , Page(s): 323 - 325
    Cited by:  Papers (10)
    Request Permissions | Click to expandAbstract | PDF file iconPDF (152 KB) |  | HTML iconHTML  

    We propose modified random early detection (MRED) gateways for congestion avoidance in TCP/IP networks. MRED aims at providing better control over the burstiness level while remaining the advantages of RED. We use ns2 to simulate a series of network configurations and the numerical results demonstrate that MRED can achieve higher link utilization compared to RED without sacrificing its advantages ... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Performance comparison of local area video streaming systems

    Publication Year: 2004 , Page(s): 326 - 328
    Cited by:  Papers (5)
    Request Permissions | Click to expandAbstract | PDF file iconPDF (200 KB) |  | HTML iconHTML  

    The performance of our Quality Oriented Adaptation Scheme (QOAS) for multimedia streaming in local networks is compared with other existing solutions (TFRCP, LDA+, and non-adaptive). This comparison is done in terms of bandwidth utilization, number of concurrent clients, loss rate, and end-user perceived quality. Simulation results show that for the same average end-user quality, our QOAS system c... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • IEEE Communications Letters Edics

    Publication Year: 2004 , Page(s): 329
    Request Permissions | PDF file iconPDF (17 KB)  
    Freely Available from IEEE

Aims & Scope

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. 

 

 

Full Aims & Scope

Meet Our Editors

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