By Topic

IEEE Communications Letters

Issue 8 • Date Aug. 2002

Filter Results

Displaying Results 1 - 16 of 16
  • Partial transmit sequence arid selected mapping schemes to reduce ICI in OFDM systems

    Publication Year: 2002, Page(s):313 - 315
    Cited by:  Papers (35)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (223 KB) | HTML iconHTML

    Orthogonal frequency division multiplexing (OFDM) is sensitive to the carrier frequency offset (CFO). We introduce the peak interference-to-carrier ratio (PICR) to measure the resulting intercarrier interference (ICI). This paper shows that PICR can be reduced by selected mapping (SLM) and partial transmit sequence (PTS) approaches. These schemes are analyzed theoretically and their performances a... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Coding to reduce both PAR and PICR of an OFDM signal

    Publication Year: 2002, Page(s):316 - 318
    Cited by:  Papers (24)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (217 KB) | HTML iconHTML

    The two major drawbacks in orthogonal frequency-division multiplexing (OFDM) system are high peak-to-average power ratio (PAR) and intercarrier interference (ICI) due to frequency offset errors. Several techniques proposed in the literature treat these limitations as two separate problems. We introduce the peak interference-to-carrier ratio (PICR) to measure ICI. This paper shows the existence of ... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Delay analysis of integrated voice and data service for GPRS

    Publication Year: 2002, Page(s):319 - 321
    Cited by:  Papers (26)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (216 KB) | HTML iconHTML

    The quality-of-service (QoS) requirements of typical mobile packet data applications are very diverse. QoS profiles of the General Packet Radio Service (GPRS) are defined using the parameters service precedence, reliability, delay, and throughput. A one-dimensional decomposing Markov chain is used as the queueing model to analyze the GPRS performance in terms of the mean delay and 95% delay. In ad... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On optimum MIMO with antenna selection

    Publication Year: 2002, Page(s):322 - 324
    Cited by:  Papers (79)  |  Patents (17)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (233 KB) | HTML iconHTML

    Wireless communication systems with transmit and receive antenna arrays are studied when antenna selection is used. A case with very limited feedback of information from the receiver to the transmitter is considered, where the only information fed back is the selected subset of transmit antennas to be employed. It is shown that the optimum signaling, for largest ergodic capacity with antenna selec... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Capacity of multiple antenna systems in free space and above perfect ground

    Publication Year: 2002, Page(s):325 - 327
    Cited by:  Papers (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (202 KB) | HTML iconHTML

    Multiple input-multiple output (MIMO) systems are a promising technique for wireless applications that require high data rates. We theoretically study their capacity potential for propagation in free-space and over a ground surface. We investigate how this depends on the array geometry and the electric field polarization. Moreover, we validate our theoretical predictions with measurements above a ... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An entropy-based model for supporting and evaluating route stability in mobile ad hoc wireless networks

    Publication Year: 2002, Page(s):328 - 330
    Cited by:  Papers (40)  |  Patents (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (193 KB) | HTML iconHTML

    We propose an entropy-based modeling framework for supporting route stability in mobile ad hoc wireless networks. The basic motivations of the proposed modeling approach stem from the commonality observed in the location uncertainty in mobile ad hoc wireless networks and the concept of entropy. The corresponding results demonstrate that the proposed approach and parameters provide an accurate and ... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Modeling the channel time-variance for fixed wireless communications

    Publication Year: 2002, Page(s):331 - 333
    Cited by:  Papers (33)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (203 KB) | HTML iconHTML

    We propose a new stochastic model for the time-variance of channels for fixed wireless communications. In the classical Jakes' Doppler spectrum, the receiver (or the transmitter) is assumed to move at a certain speed. However, in fixed wireless communication systems, both the transmitter and the receiver are stationary and time-variations are actually due to moving scatterers. A novel stochastic m... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An intra-LA location update strategy for reducing paging cost

    Publication Year: 2002, Page(s):334 - 336
    Cited by:  Papers (10)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (194 KB) | HTML iconHTML

    The blanket paging strategy in current mobile networks may waste a lot of wireless bandwidth. While keeping the standard location area (LA) based location update (LU) strategy unchanged, we propose an intra-LA LU scheme to reduce the paging cost. While a mobile terminal (MT) is residing in an LA with a cell called anchor cell, where the MT usually stays for a significant period, an intra-LA LU is ... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On design of error-correcting reversible variable length codes

    Publication Year: 2002, Page(s):337 - 339
    Cited by:  Papers (41)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (236 KB) | HTML iconHTML

    We propose an algorithm for construction of reversible variable length codes (RVLCs) with good error-correcting properties. The error-correcting properties are evaluated by a metric called the free distance, which is always greater than one in the case of the proposed RVLCs. Since variable length codes (VLCs) typically have free distance equal to one, the proposed RVLCs exhibit significant improve... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Sum capacity of the OCDMA/OCDMA signature sequence set

    Publication Year: 2002, Page(s):340 - 342
    Cited by:  Papers (15)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (210 KB) | HTML iconHTML

    The sum capacity of the OCDMA/OCDMA (O/O) signature sequence set is investigated under the assumption of equal average-input-energy constraints and perfect synchronization of the users. It is shown that the spectral efficiency of the O/O signature sequence set is only dependent on the SNR and load, but independent of the choice of the orthogonal bases. Moreover, this sequence set is found to be on... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Blind frequency-offset estimator for OFDM systems transmitting constant-modulus symbols

    Publication Year: 2002, Page(s):343 - 345
    Cited by:  Papers (41)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (236 KB) | HTML iconHTML

    We address the problem of carrier frequency offset (CFO) synchronization in OFDM communications systems in the context of frequency-selective fading channels. We consider the case where the transmitted symbols have constant modulus, i.e., PSK constellations. A novel blind CFO estimation algorithm is developed. The new algorithm is shown to greatly outperform a previously published blind technique ... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Performance analysis of optical composite burst switching

    Publication Year: 2002, Page(s):346 - 348
    Cited by:  Papers (20)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (187 KB) | HTML iconHTML

    In this letter, we introduce a queueing model to study the performance enhancement in a so-called optical composite burst switching network (OCBS). Based on our model, we develop a simple analytical method to calculate the packet loss probability and we provide numerical results to compare the performance of OCBS versus the traditional optical burst switching (OBS) technique. We then provide expla... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Flexible multicasting in high-capacity switches

    Publication Year: 2002, Page(s):349 - 351
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (183 KB) | HTML iconHTML

    Since packet switches with input queueing require low-speed buffers and simple cross-bar fabrics, they potentially provide high switching capacities. In these switches, the port that is a source of a multicast session might easily get congested with the increasing popularity of this session. We propose the protocol for scheduling packets in switches with input buffers for varying popularity of dif... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Collision-free operation in ad hoc carrier sense multiple access wireless networks

    Publication Year: 2002, Page(s):352 - 354
    Cited by:  Papers (8)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (189 KB) | HTML iconHTML

    The CSMA/CA algorithm proposed in the IEEE 802.11 standard does not exclude collisions between transmitted packets. Regardless of whether RTS/CTS packets are used or not, these collisions do always have a more or less negative effect on system performance, especially at high loads. In this letter a method of avoiding collisions by using busy energy bursts is proposed. The algorithm used is based o... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Throughput and delay limits of IEEE 802.11

    Publication Year: 2002, Page(s):355 - 357
    Cited by:  Papers (214)  |  Patents (16)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (208 KB) | HTML iconHTML

    The IEEE 802.11 protocol family provides up to 54-Mbps data rate, whereas the industry is seeking higher data rates. This paper shows that a theoretical throughput upper limit and a theoretical delay lower limit exist for the IEEE 802.11 protocols. The existence of such limits indicates that by simply increasing the data rate without reducing overhead, the enhanced performance, in terms of through... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Impersonation attacks on software-only two-factor authentication schemes

    Publication Year: 2002, Page(s):358 - 360
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (182 KB) | HTML iconHTML

    Two-factor authentication is favorable to securely identifying remote users in a communications network. Lately cryptographic camouflage was applied for the purpose by software-only techniques. However it can be vulnerable to impersonation attacks via interleaved sessions if a single server is compromised. This article brings to light such a hidden weak point and suggests a possible solution. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

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

Meet Our Editors

Editor-in-Chief
Octavia Dobre
Memorial University, Canada