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Signals, Systems and Computers, 2001. Conference Record of the Thirty-Fifth Asilomar Conference on

Date 4-7 Nov. 2001

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  • The Thirty-Fifth Asilomar Conference on Signals, Systems & Computers

    Publication Year: 2001, Page(s):iii - xxii
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    Freely Available from IEEE
  • Enhanced user authentication through typing biometrics with artificial neural networks and k-nearest neighbor algorithm

    Publication Year: 2001, Page(s):911 - 915 vol.2
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (478 KB) | HTML iconHTML

    The emergence of global network access has promoted increased chances of malicious attack and intrusion. Password authentication has been known as the most commonly safeguard measure against these intrusions. Common it is, but the security measures that it provides have always been questionable. Thus, it gives rise to the need for a more secure and reliable authentication method in accessing compu... View full abstract»

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  • Space-time block codes: ML detection for unknown channels and unstructured interference

    Publication Year: 2001, Page(s):916 - 920 vol.2
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (453 KB) | HTML iconHTML

    Space-time coding (STC) schemes for communication systems employing multiple transmit and receive antennas have been attracting increased attention. The so-called linear space-time block codes (STBC) have been of particular interest due to their good performance and low decoding complexity. In this paper we take a systematic maximum-likelihood (ML) approach to the decoding of STBC for unknown prop... View full abstract»

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  • An adaptive semi-blind algorithm for channel identification in OFDM

    Publication Year: 2001, Page(s):921 - 925 vol.2
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (375 KB) | HTML iconHTML

    OFDM is a convenient vehicle for high rate transmission. However, this requires an accurate estimation of the channel at the receiver side. This paper proposes an iterative/adaptive algorithm for semi-blind channel estimation. An initial channel estimate is obtained by relying on the artificial constraint of pilots. The algorithm subsequently switches to the blind mode powered by the natural const... View full abstract»

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  • Beamspace MODE

    Publication Year: 2001, Page(s):926 - 930 vol.2
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (394 KB) | HTML iconHTML

    The polynomial parameterized method of direction estimation (MODE) is a popular algorithm for the direction-of-arrival (DOA) estimation of narrowband incident signals with a uniform linear array. It is desirable to apply the MODE method in beamspace so as to take advantage of the benefits of beamspace operations in terms of reduced computational complexity and improved resolution thresholds. The d... View full abstract»

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  • Wideband signal detection and maximum-likelihood source localization

    Publication Year: 2001, Page(s):931 - 935 vol.2
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (423 KB) | HTML iconHTML

    We present a signal detection scheme and maximum-likelihood source localization for wideband signals using a randomly distributed sensor array. The signal detection is based on a simple statistical test that sequentially detects the number of sources, or model order, with a theoretical probability of false alarm. The detection scheme requires the maximum-likelihood parameter estimation, in which a... View full abstract»

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  • Contravariant adaptation on structured parameter spaces

    Publication Year: 2001, Page(s):936 - 940 vol.2
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (414 KB) | HTML iconHTML

    The contravariant vector associated with the conventional gradient vector (covector) via the Riemannian metric is the appropriate direction for gradient descent learning. This fact is the basis for Amari's familiar natural gradient learning algorithms. The language of differential geometry is used to derive the contravariant gradient rule for parameterizations of invertible matrices as pullbacks o... View full abstract»

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  • On sampling planar curves

    Publication Year: 2001, Page(s):941 - 945 vol.2
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (412 KB) | HTML iconHTML

    In this paper we address the problem of sampling and perfect reconstruction of closed planar curves belonging to a certain class. We successively study the following problems: (1) identifying the class of curves yielding perfect reconstruction from their samples and establishing efficient class identification procedures, (2) sampling and reconstruction algorithms, (3) applicability of general samp... View full abstract»

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  • Polarization mode dispersion compensation for 10 Gbps over single mode fiber

    Publication Year: 2001, Page(s):946 - 950 vol.2
    Cited by:  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (484 KB) | HTML iconHTML

    The application of high-speed data transmission at a bit rate B>10 Gbps, through a single mode optical fiber (SMF) subject to polarization mode dispersion (PMD), is addressed in this paper. Two methods are proposed and compared for the mitigation of the induced and performance limiting intersymbol interference (ISI): the computationally simpler method of nonlinear threshold compensation (NLC), vs.... View full abstract»

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  • Segmented equalizers with dynamic length selection

    Publication Year: 2001, Page(s):951 - 955 vol.2
    Cited by:  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (407 KB) | HTML iconHTML

    Adaptive linear equalizers are commonly used in wireless systems to reduce the distorting effects of the channel. One of the key parameters to be determined is the number of taps of the equalizer. In a time varying scenario, the optimum number of taps may vary as a result of changes in the environment. In this paper we introduce a reconfigurable filter structure and a low complexity algorithm that... View full abstract»

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  • Receiver design for type-I hybrid ARQ scheme in frequency-selective fading channels

    Publication Year: 2001, Page(s):959 - 963 vol.2
    Cited by:  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (492 KB) | HTML iconHTML

    This paper proposes a new receiver design for a type-I hybrid automatic repeat request (ARQ) scheme in wireless packet data services. To achieve reliable transmission under a multipath fading channel environment, temporal diversity from retransmissions is utilized to facilitate channel equalization and error correction via low density parity check (LDPC) codes. A linear equalization receiver struc... View full abstract»

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  • On the general form of FIR MIMO biorthogonal partners

    Publication Year: 2001, Page(s):964 - 968 vol.2
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (468 KB) | HTML iconHTML

    The concept of biorthogonal partners has previously been shown to provide a unifying link for various applications in digital signal processing. In particular, the multiple input multiple output (MIMO) case has been associated with several different contexts such as multiwavelet theory and MIMO channel equalization, especially with fractionally spaced equalizers. In most of these applications, the... View full abstract»

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  • MIMO communication capacity using infinite dimension random matrix eigenvalue distributions

    Publication Year: 2001, Page(s):969 - 974 vol.2
    Cited by:  Papers (10)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (422 KB) | HTML iconHTML

    Wireless communication using multiple-input multiple-output (MIMO) systems enables increased spectral efficiency for a given total transmit power. MIMO capacity is a strong function of the singular value distribution of the channel matrix, the receive antenna to transmit antenna transfer matrix. In this paper the capacity is calculated using an asymptotic large random matrix approach. Bounds on th... View full abstract»

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  • On MIMO decoding algorithms for UMTS

    Publication Year: 2001, Page(s):975 - 979 vol.2
    Cited by:  Papers (10)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (416 KB) | HTML iconHTML

    With the understanding of the channel capacity in wireless systems that allows much higher data rates in high scattering environments, transmission over multiple antenna systems has become an attractive option. In this paper we present candidate algorithms for decoding multiple-input-multiple-output (MIMO) systems and study their behavior and implementation for a 4-by-4 antenna system in a UMTS en... View full abstract»

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  • Performance of maximal ratio transmission with two receive antennas

    Publication Year: 2001, Page(s):980 - 983 vol.2
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (271 KB) | HTML iconHTML

    Maximal ratio transmission (see Lo, T.K.Y., IEEE Trans. Comm., vol.47, no.10, p.1458-61, 1999) is a transmit beamforming technique where multiple antennas are used both for transmission and reception. It can effectively increase the diversity order without modifying the receiver. An expression for the error probability for maximal ratio transmission is derived for the special case of two receive a... View full abstract»

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  • Subspace-based channel identification and multiuser detection for space-time coded DS-CDMA systems

    Publication Year: 2001, Page(s):984 - 988 vol.2
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (494 KB) | HTML iconHTML

    In order to accommodate high data-rate applications, there is a significant interest in extending space-time (ST) coding, originally proposed for frequency-nonselective channels assumed known to the receiver, to unknown multipath channels. In this paper, we consider the problem of blind channel identification and linear multiuser receiver design for ST coded CDMA (code-division multiple-access) sy... View full abstract»

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  • Joint channel estimation and co-channel interference suppression for space-time block coded systems

    Publication Year: 2001, Page(s):989 - 993 vol.2
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (394 KB) | HTML iconHTML

    We consider the problem of interference suppression for wireless TDMA systems equipped with multiple transmit antennas and receive antennas in frequency-selective fading channels. A novel scheme with space-time block coding is presented herein to jointly estimate the multipath channel, coherently demodulate information symbols, and meanwhile suppress radio interference. The proposed scheme is simp... View full abstract»

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  • Correlation properties of MIMO radio channels for indoor scenarios

    Publication Year: 2001, Page(s):994 - 998 vol.2
    Cited by:  Papers (13)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (484 KB) | HTML iconHTML

    Multiple input- multiple output (MIMO) systems have the potential to achieve very high capacities, depending on the propagation environment. Capacity increases as signal correlation decreases. We present the measurements of a MIMO system under strong and weak line-of-sight conditions. The system capacity decreases as the separation from the transmitter increases; indeed the transmitter correlation... View full abstract»

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  • Semiblind channel estimation for MIMO spatial multiplexing systems

    Publication Year: 2001, Page(s):999 - 1003 vol.2
    Cited by:  Papers (8)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (501 KB) | HTML iconHTML

    We analyze the semiblind mutual information (MI) between the input and output of a MIMO channel. To that end we consider the popular block fading model. We assume that some training/pilot symbols get inserted at the beginning of each burst. We show that the average MI over a transmission burst can be decomposed into symbol position dependent contributions. The MI component at a certain symbol posi... View full abstract»

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  • Layered MIMO transceivers with enhanced capacities: a new coding strategy

    Publication Year: 2001, Page(s):1004 - 1008 vol.2
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (520 KB) | HTML iconHTML

    This paper describes a novel encoding strategy for the existing layered space-time architectures used in multiple element antenna (MEA) transmission systems. Layered architectures like V-BLAST regard a MEA channel as a set of independent mutually interfering scalar channels (layers) which are decoded subsequently so that a hefty fraction of the total MEA capacity may be achieved with a moderate co... View full abstract»

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  • Design of multiple antenna coding schemes with channel feedback

    Publication Year: 2001, Page(s):1009 - 1013 vol.2
    Cited by:  Papers (14)  |  Patents (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (480 KB) | HTML iconHTML

    We derive multiple antenna transmission strategies in the presence of limited channel information at the transmitter and the receiver. In, particular, we look at the cases of complete channel information, channel phase information and channel amplitude information at the transmitter. We highlight that transmission along the eigenvector of the channel corresponding to the maximum eigenvalue minimiz... View full abstract»

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  • Beamforming vs. transmit diversity in the downlink of a cellular communications system

    Publication Year: 2001, Page(s):1014 - 1018 vol.2
    Cited by:  Papers (5)  |  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (422 KB) | HTML iconHTML

    Transmit diversity and beamforming are two complementary techniques for using multiple antennas in the forward link of a cellular communication system. The first provides the benefit of diversity with no array gain, while the second provides array gain, but no diversity. We present a comparative analysis of the two systems, using outage capacity as the performance measure. The effects of handoff a... View full abstract»

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  • Optimal space-time block codes for reduced complexity DS-CDMA decoders

    Publication Year: 2001, Page(s):1021 - 1025 vol.2
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (485 KB) | HTML iconHTML

    Space-time coding promises greater insensitivity to wireless channel fading and improved channel capacity. In the current work, decoders based on the minimum mean squared error (MMSE) criterion are investigated. Two different MMSE-based decoders are developed based on knowledge about the residual error statistics. The performance of the decoders are evaluated in terms of achievable diversity level... View full abstract»

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  • Per-survivor based detection of DPSK modulated high rate turbo codes over Rayleigh fading channels

    Publication Year: 2001, Page(s):1026 - 1030 vol.2
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (506 KB) | HTML iconHTML

    We investigate the performance of a new method for implementing high rate turbo codes over complex fading channels with unknown states. The proposed system features the serial concatenation of an outer punctured turbo code and an inner accumulator separated by a nonuniform interleaver. Per-survivor based a posteriori probability (APP) demodulation and turbo processing are applied to achieve iterat... View full abstract»

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  • Outage in adaptive wireless communication systems

    Publication Year: 2001, Page(s):1031 - 1035 vol.2
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (543 KB) | HTML iconHTML

    Adaptive signaling schemes are derived that attempt to minimize the outage probability for wireless systems with strict delay constraints, under the assumption of perfect causal channel state information (CSI) at the transmitter and receiver. Using the channel characterization and delay constraint parameters imposed by the application, a recursive set of equations is derived for the outage probabi... View full abstract»

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