Spread-response precoding for communication over fading channels

Wornell, Gregory W.

doi:10.1109/18.485719

Cited by 50 publications

(36 citation statements)

References 15 publications

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“…A similar convergence result has also been shown in [10], where the asymptotic behavior of a system with time-spread symbols is considered. In [10], the fading channel with infinite time-spreading (and hence, infinite temporal diversity) converges to a marginally Gaussian channel with a lower SNR than due to an additional noise variance term.…”

Section: Asymptotic Behavior Of the Systemsupporting

confidence: 58%

“…We note that a system design approach similar to the one presented in this paper has been recently proposed in [10] and [11]. In particular, the signaling strategy proposed in this paper is very similar in spirit to the one in [10] and [11], except that our scheme employs standard binary spreading codes as opposed to the real-valued codes used in [10] and [11].…”

mentioning

confidence: 80%

“…In particular, the signaling strategy proposed in this paper is very similar in spirit to the one in [10] and [11], except that our scheme employs standard binary spreading codes as opposed to the real-valued codes used in [10] and [11]. However, our receiver structure, inspired by the canonical multipath-Doppler channel decomposition, is fundamentally different from the design proposed in [10].…”

mentioning

confidence: 88%

“…In [10], the fading channel with infinite time-spreading (and hence, infinite temporal diversity) converges to a marginally Gaussian channel with a lower SNR than due to an additional noise variance term. However, the diversity signaling and reception based on the canonical channel representation enable our system to achieve the SNR of the corresponding nonfading AWGN channel.…”

Section: Asymptotic Behavior Of the Systemmentioning

confidence: 99%

“…However, our receiver structure, inspired by the canonical multipath-Doppler channel decomposition, is fundamentally different from the design proposed in [10]. As we will see, the overall system proposed in this paper is optimally matched to the fast fading channel and can deliver improved performance compared to the scheme presented in [10]. Overlapping signature sequences have also been studied in [12] for other advantageous system characteristics, such as increased resistance to impulse noise and increased number of available signature sequences.…”

mentioning

confidence: 99%

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Time-selective signaling and reception for communication over multipath fading channels

Bhashyam

Sayeed

Aazhang

2000

IEEE Trans. Commun.

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Abstract-The mobile wireless channel affords inherent diversity to combat the effects of fading. Existing code-division multiple-access systems, by virtue of spread-spectrum signaling and RAKE reception, exploit only part of the channel diversity via multipath combination. Moreover, their performance degrades under fast fading commonly encountered in mobile scenarios. In this paper, we develop new signaling and reception techniques that maximally exploit channel diversity via joint multipath-Doppler processing. Our approach is based on a canonical representation of the wireless channel, which leads to a time-frequency generalization of the RAKE receiver for diversity processing. Our signaling scheme facilitates joint multipath-Doppler diversity by spreading the symbol waveform beyond the intersymbol duration to make the channel time-selective. A variety of detection schemes are developed to account for the intersymbol interference (ISI) due to overlapping symbols. However, our results indicate that the effects of ISI are virtually negligible due to the excellent correlation properties of the pseudorandom codes. Performance analysis also shows that relatively small Doppler spreads can yield significant diversity gains. The inherently higher level of diversity achieved by time-selective signaling brings the fading channel closer to an additive white Gaussian noise channel, thereby facilitating the use of powerful existing coding techniques for Gaussian channels.

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Section: Asymptotic Behavior Of the Systemsupporting

confidence: 58%

mentioning

confidence: 80%

mentioning

confidence: 88%

Section: Asymptotic Behavior Of the Systemmentioning

confidence: 99%

mentioning

confidence: 99%

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Time-selective signaling and reception for communication over multipath fading channels

Bhashyam

Sayeed

Aazhang

2000

IEEE Trans. Commun.

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Joint intersymbol and multiple‐access interference suppression algorithms for CDMA systems

Beheshti

Wornell

Isabelle³

1998

Trans Emerging Tel Tech

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Two promising classes of techniques are developed for e cient m ultiuser detection in codedivision multiple-access CDMA communication systems subject to fading due to time-varying multipath propagation. Both are designed to jointly suppress both intersymbol and multipleaccess interference inherent in such systems, and exploit all available time and frequency diversity.The rst is a family of linear receivers for time-varying multiuser channels that generalize familiar linear equalizers designed for traditional single-user linear time-invariant c hannels. Minimum mean-square error, zero-forcing, and matched-lter versions of such m ultiuser detectors are all developed within a common state-space framework, and have convenient recursive implementations. Performance issues as well as natural decision-feedback v ariants of the detector structure are both discussed.The second is a family of nonlinear receivers that are speci cally designed for use with spread-signature CDMA systems on time-varying multipath channels. These multiuser detectors employ a batch-iterative m ultipass decoding algorithm based on a successive-cancellation strategy. Several aspects of the performance of this algorithm are developed, including its monotonic convergence property.Collectively, these two classes of algorithmic structures for joint equalization, interference suppression, demodulation, and detection are representative of several emerging and interrelated approaches to receiver design for next-generation CDMA systems.

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OTFS: A New Modulation Scheme for High-Mobility Use Cases

2020

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Introduction Next-generation wireless networks (including 5G networks) are expected to see the emergence of several new use cases and business models driven by the emerging needs of users and system operators. This will be enabled by the maturity of current technologies and emergence of new technologies. The variety of applications and the corresponding performance requirements in these scenarios will be vastly different. Several use case families such as broadband access everywhere (e.g., pervasive video), extreme real-time communications (e.g., tactile internet with sub-millisecond latency), ultra-reliable communications (e.g., e-health services), massive internet of things

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Spread-response precoding for communication over fading channels

Cited by 50 publications

References 15 publications

Time-selective signaling and reception for communication over multipath fading channels

Time-selective signaling and reception for communication over multipath fading channels

Joint intersymbol and multiple‐access interference suppression algorithms for CDMA systems

OTFS: A New Modulation Scheme for High-Mobility Use Cases

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