Canonical space-time processing for wireless communications (2000)

by E N Onggosanusi, A M Sayeed, B D Van Veen
Venue:IEEE Trans. Commun
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Detection, Classification and Tracking of Targets in Distributed Sensor Networks

by Dan Li, Kerry D. Wong, Yu H. Hu, Akbar M. Sayeed - IEEE Signal Processing Magazine , 2002
"... We outline a framework for collaborative signal processing in distributed sensor networks. The ideas are presented in the context of tracking multiple moving objects in a sensor field. The key steps involved in the tracking procedure include event detection, target classification, and estimation and ..."
Abstract - Cited by 99 (0 self) - Add to MetaCart
We outline a framework for collaborative signal processing in distributed sensor networks. The ideas are presented in the context of tracking multiple moving objects in a sensor field. The key steps involved in the tracking procedure include event detection, target classification, and estimation and prediction of target location. Algorithms for various tasks are discussed with an emphasis on classification. Results based on experiments with real data are reported which provide useful insights into the essential nature of the problems. Issues, challenges and directions for future research are identified.
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Orthogonal Multiple Access over Time- and Frequency-Selective Channels

by Geert Leus, Shengli Zhou, Georgios B. Giannakis - IEEE Trans. Inform. Theory , 2002
"... Suppression of Multi-User Interference (MUI) and mitigation of time- and frequency-selective (doubly-selective) channel effects constitute major challenges in the design of thirdgeneration wireless mobile systems. Relying on a Basis Expansion Model (BEM) for doubly-selective channels, we develop a c ..."
Abstract - Cited by 27 (6 self) - Add to MetaCart
Suppression of Multi-User Interference (MUI) and mitigation of time- and frequency-selective (doubly-selective) channel effects constitute major challenges in the design of thirdgeneration wireless mobile systems. Relying on a Basis Expansion Model (BEM) for doubly-selective channels, we develop a channel-independent block spreading scheme that preserves mutual orthogonality among single-cell users at the receiver. This alleviates the need for complex multi-user detection, and enables separation of the desired user by a simple code-matched channelindependent block despreading scheme that is Maximum Likelihood (ML)-optimal under the BEM plus white Gaussian noise assumption on the channel. In addition, each user achieves the maximum delay-Doppler diversity for Gaussian distributed BEM coefficients. Issues like links with existing multi-user transceivers, existence, user efficiency, special cases, backward compatibility with DS-CDMA, and error control coding, are briefly discussed. Index Terms--- Delay Diversity, Doppler Diversity, Multiple Access, Multi-User Detection, Time- and Frequency-Selective Channels.

A canonical space-time characterization of mobile wireless channels

by Akbar M. Sayeed, Eko N. Onggosanusi, Student Member, Barry D. Van Veen, Senior Member - IEEE Communications Letters , 1999
"... Abstract — A canonical space–time characterization of mobile wireless channels is introduced in terms of a fixed basis that is independent of the true channel parameters. The basis captures the essential degrees of freedom in the received signal using discrete multipath delays, Doppler shifts, and d ..."
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Abstract — A canonical space–time characterization of mobile wireless channels is introduced in terms of a fixed basis that is independent of the true channel parameters. The basis captures the essential degrees of freedom in the received signal using discrete multipath delays, Doppler shifts, and directions of arrival. This provides a robust representation of the propagation dynamics and dramatically reduces the number of channel parameters to be estimated. The resulting canonical space–time receivers deliver optimal performance at substantially reduced complexity compared to existing designs. Index Terms — Dimension reduction, dispersive channels, space–time sampling.
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Canonical Space-Time Coordinates For Multiuser Wireless Communications

by Eko N. Onggosanusi, Akbar M. Sayeed, Barry D. Van Veen - Proc. of the 1999 2nd IEEE Signal Proc. Workshop on Signal Proc. For Wireless Commun. SPAWC
"... We propose a space-time multiuser detection scheme for wireless communications that projects the received signal onto a fixed set of basis signals. The basis signals are dictated by a canonical characterization of channel propagation dynamics in terms of discrete multipath delays, Doppler shifts, an ..."
Abstract - Cited by 4 (4 self) - Add to MetaCart
We propose a space-time multiuser detection scheme for wireless communications that projects the received signal onto a fixed set of basis signals. The basis signals are dictated by a canonical characterization of channel propagation dynamics in terms of discrete multipath delays, Doppler shifts, and directions of arrival. They capture the essential degrees of freedom in the received signal. The canonical space-time coordinates induced by the underlying basis provide a natural framework for multi-access interference suppression and diversity processing. The signal of the desired user is concentrated in a subset of coordinates, while the interference generally occupies the entire space-time coordinate system. It is demonstrated that MAI suppression can be improved by incorporating a subset of coordinates where the desired user is absent. 1. INTRODUCTION The use of antenna arrays for enhancing the capacity and fidelity of multiuser wireless communication systems has spurred significant i...
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Low Complexity Space-Time Multiuser Detectors

by Eko N. Onggosanusi, Akbar M. Sayeed, Barry D. Van Veen - Proceedings of the 1999 IEEE Wireless Commun. and Network Conf . WCNC , 1999
"... A design framework for space-time multiuser detectors is introduced based on the recently introduced notion of canonical space-time coordinates (CSTC). The CSTC system employs a fixed set of basis signals which eliminates the need for estimating direction of arrivals (DOAs) and delays of the channel ..."
Abstract - Cited by 2 (2 self) - Add to MetaCart
A design framework for space-time multiuser detectors is introduced based on the recently introduced notion of canonical space-time coordinates (CSTC). The CSTC system employs a fixed set of basis signals which eliminates the need for estimating direction of arrivals (DOAs) and delays of the channel, thereby allowing significant reduction in receiver complexity. The proposed framework is based on a hybrid structure for multiuser detection which combines the power of centralized processing and the flexibility of decentralized reception. In the first stage, a subset of users whose spreading codes are assumed known are suppressed in a centralized fashion. The remaining interference is suppressed via the second stage in an adaptive decentralized mode. The hybrid scheme offers a flexible design framework by offering lower complexity compared to fully centralized receivers and improved adaptive performance compared to fully decentralized schemes. I. Introduction The use of antenna arrays...
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Multiaccess interference suppression in canonical space-time coordinates for mobile communications," to be submitted

by E N Onggosanusi, B D Van Veen, A M Sayeed , 1999
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Abstract - Cited by 1 (1 self) - Add to MetaCart
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Space–Time Fading Channel Estimation and Symbol Detection in Unknown Spatially Correlated Noise

by Ar Dog, Arye Nehorai
"... Abstract—We present maximum likelihood (ML) methods for space–time fading channel estimation with an antenna array in spatially correlated noise having unknown covariance; the results are applied to symbol detection. The received signal is modeled as a linear combination of multipath-delayed and Dop ..."
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Abstract—We present maximum likelihood (ML) methods for space–time fading channel estimation with an antenna array in spatially correlated noise having unknown covariance; the results are applied to symbol detection. The received signal is modeled as a linear combination of multipath-delayed and Doppler-shifted copies of the transmitted waveform. We consider structured and unstructured array response models and derive the Cramér–Rao bound (CRB) for the unknown directions of arrival, time delays, and Doppler shifts. We also develop methods for spatial and temporal interference suppression. Finally, we propose coherent matched-filter and concentrated-likelihood receivers that account for the spatial noise covariance and analyze their performance. Index Terms—Array processing, coherent matched-filter detec-tion, noncoherent detection, time-varying channel estimation. I.
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Exploiting Directional Antennas for Reduced-Dimension Space–Time RAKE Receiving

by Peng Jin, Nathan A. Goodman, Kathleen L. Melde
"... Abstract—We propose to combine directional antennas in a conformal array configuration with a matching two-stage receiver architecture to improve performance of code-division multiple-access (CDMA) communi-cation systems in time-varying channels. We propose a reduced-dimension space–time (ST) RAKE a ..."
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Abstract—We propose to combine directional antennas in a conformal array configuration with a matching two-stage receiver architecture to improve performance of code-division multiple-access (CDMA) communi-cation systems in time-varying channels. We propose a reduced-dimension space–time (ST) RAKE architecture that matches the ST correlation structure of the data received by a circular array. In time-varying chan-nels, this reduced-dimension architecture outperforms the full-dimension architecture due to improved convergence of its adaptive processor. Index Terms—Multipath, multiuser detection, RAKE receiver, space– time beamforming.

A Canonical Space-Time Characterization of Mobile Wireless Channels

by Akbar Sayeed Eko, Akbar M. Sayeed, Eko N. Onggosanusi, Barry D. Van Veen
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Constrained Space-Time MOE Detection for CDMA Wireless Systems

by Zhi Tian, Kristine L. Bell, Harry L. Van Trees , 2001
"... This paper provides a comprehensive treatment of space-time blind minimum output energy (MOE) detection in multipath code division multiple access (CDMA) channels with receiver antenna arrays. Assuming no knowledge of the spatial response characteristic of the propagation channel, we investigate con ..."
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This paper provides a comprehensive treatment of space-time blind minimum output energy (MOE) detection in multipath code division multiple access (CDMA) channels with receiver antenna arrays. Assuming no knowledge of the spatial response characteristic of the propagation channel, we investigate constrained space-time MOE detection schemes, present a series of constraint strategies, and develop both centralized and decentralized space-time receiver structures, using fixed and optimized constraints. Under each receiver structure, the detection design is based on a generic constraint design framework that illustrates the tradeo#s between performance and computational complexity in a unified manner. Di#erent constraint parameters for temporal and spatial combining are derived to minimize the performance degradation due to imprecise knowledge of the space-time multipath channel. Adaptive recursive least squares implementations are provided for each of the spacetime detectors. Simulations are provided to compare the performance of the derived detectors.