Signal design for dispersive channels

Kennedy, Robert S.; Lebow, Irwin

doi:10.1109/mspec.1964.6500650

Cited by 22 publications

(7 citation statements)

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“…• We analyze the impact of delay spread and power delay profile (PDP) on noncoherent SFC performance from an error probability point-of-view and show that unlike in the coherent case, the presence of additional channel taps does not monotonically improve performance. Instead, we observe the notion of an optimum diversity order, an effect previously found in single-antenna wideband fading channels [23], [24], and recently also reported for the MIMO case from a capacity point-of-view [25].…”

Section: A Contributionsmentioning

confidence: 49%

“…In [5], a simplified design criterion for the frequency-flat fading case is derived, which aims at minimizing the so-called correlation . In the frequencyselective case (uniform PDP), this simplified criterion generalizes to a minimization of the corresponding metric in terms of the pseudocodewords (23) Similarly to [5], we can interpret as a measure related to the chordal distance between the "induced" subspaces spanned by the columns of and or, equivalently, and , which consist of the codewords along with their cyclically shifted versions [cf. (21)].…”

Section: H Code Design Criteriamentioning

confidence: 99%

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Noncoherent space-frequency coded MIMO-OFDM

Borgmann

Bölcskei

2005

IEEE J. Select. Areas Commun.

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Recently, the use of coherent space-frequency coding in orthogonal frequency-division multiplexing (OFDM)-based frequency-selective multiple-input multiple-output (MIMO) fading channels has been proposed. Acquiring knowledge of the fading coefficients in a MIMO channel is already very challenging in the frequency-flat (fast) fading case. In the frequency-selective case, this task becomes significantly more difficult due to the presence of multiple paths, which results in an increased number of parameters to be estimated. In this paper, we address code design for noncoherent frequency-selective MIMO-OFDM fading links, where neither the transmitter nor the receiver knows the channel. We derive the code design criteria, quantify the maximum achievable diversity gain, and provide explicit constructions of full-diversity (space and frequency) achieving codes along with an analytical and numerical performance assessment. We also demonstrate that unlike in the coherent case, noncoherent space-frequency codes designed to achieve full spatial diversity in the frequency-flat fading case can fail completely to exploit not only frequency diversity but also spatial diversity when used in frequency-selective fading environments. We term such codes "catastrophic." Index Terms-Diversity, frequency-selective fading channels, multiple-input multiple-output (MIMO) systems, noncoherent communications, orthogonal frequency-division multiplexing (OFDM), pairwise error probability (PEP), Rayleigh fading, space-frequency coding. I. INTRODUCTION AND OUTLINE S PACE-TIME coding has emerged as a promising technique for realizing spatial diversity gains in multiple-input-multiple-output (MIMO) wireless systems. The design criteria for space-time codes (STCs) in the coherent case, where the receiver has perfect channel state information (CSI), were derived in [1] and [2]. While the coherent setup is representative for fixed or low mobility wireless systems, future mobile wireless access systems are expected to operate at high vehicle speeds and will, hence, experience fast fading. Estimating the MIMO channel in a fast-fading environment is very challenging and often not possible at all. Addressing this problem, noncoherent communication, where neither the transmitter nor the receiver has CSI, was considered recently for the frequency-flat fading case in [3]-[6]. The design criteria for space-time unitary codebooks were derived in [4]. A simple systematic code construction was given in [5]. Different code designs were proposed, among Manuscript

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Section: A Contributionsmentioning

confidence: 49%

Section: H Code Design Criteriamentioning

confidence: 99%

Noncoherent space-frequency coded MIMO-OFDM

Borgmann

Bölcskei

2005

IEEE J. Select. Areas Commun.

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“…The underwater communication channel is different from these channels in several aspects, and one important difference is that refraction of the ray paths is a first order effect that can seldom be neglected. Another differen ce is that The received signal from this transmission is amplitude modulated [58), and the received signal spectrum is broader than the transmitted signal spectrum.…”

Section: The Problem Of Underwater Communicationmentioning

confidence: 99%

Underwater acoustic communication over Doppler spread channels

Eggen¹

1997

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“…An early model that describes signal distortion in dispersive channels is due to Kennedy [7,8]. The dispersive channel is assumed to be linear and time-varying.…”

Section: Approach To Investigating the Problemmentioning

confidence: 99%

The Detection and Classification of Broadband Signals in Reverberant Dispersive Environments

Lynch

Kirsteins

Kelly

2005

2005 IEEE Aerospace Conference

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The use of broadband waveforms has been suggested as a means of improving active sonar performance against slow moving or stationary targets in littoral waters. In principle, the use of a wide spectrum permits the design of waveforms with nearly ideal "thumbtack-like" ambiguity functions. However, the ocean has dispersive characteristics in both time and frequency that can prevent the idealized broadband gains from being realized. These dispersive effects or coherence losses result in non-idealized signalecho cross-ambiguity function properties. At present, it is not well understood how coherence losses affect the crossambiguity function. The objectives of this paper are to investigate the study and quantify the effects of coherence loss on detection in reverberation-limited environments and provide insight into the maximum tolerable coherence losses and optimum sonar receiver design.

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Signal design for dispersive channels

Cited by 22 publications

References 0 publications

Noncoherent space-frequency coded MIMO-OFDM

Noncoherent space-frequency coded MIMO-OFDM

Underwater acoustic communication over Doppler spread channels

The Detection and Classification of Broadband Signals in Reverberant Dispersive Environments

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