Spatio-temporal radio channel characteristics in urban macrocells

Martin, U.

doi:10.1049/ip-rsn:19981780

Cited by 75 publications

(32 citation statements)

References 7 publications

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“…Measurement results have also shown that in some environments, multipath components are not always uniformly spread out. Instead, due to the presence of far scatterers, they arrive in clusters [13]- [15], whose relative delays depend on the position of the mobile. Therefore, the delay profile, and consequently the OF, can be quite different for locations spaced far apart.…”

Section: Introductionmentioning

confidence: 99%

Macrocell-Wide Behavior of the Orthogonality Factor in WCDMA Downlinks

Mehta

Molisch

Greenstein

2006

IEEE Trans. Wireless Commun.

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The orthogonality factor (OF) quantifies the loss of orthogonality between the signals transmitted simultaneously on a wideband code division multiple access (WCDMA) downlink due to multipath dispersion. It is one of the fundamental parameters that determines the signalto-interference-plus-noise ratio at the output of the Rake receiver and, consequently, it has a significant impact on downlink system capacity. The OF depends greatly on the delay profile of the multipath channel between the mobile and its serving base station; this profile varies considerably from one location in the cell to another. In this paper, we study how the statistical properties of the small-scale-fading-averaged OF vary over the entire macrocellular area. We use an ensemble of channel profiles at different locations in a cell generated from an implementation of the comprehensive COST259 channel model, which incorporates results from several experimental investigations. We show that the small-scale-fading-averaged OF is itself a random variable whose statistics depend on the mobile's distance from its serving base station. The large observed variance of the OF indicates that using a single value for all users in downlink capacity analyses and simulations, as has been the practice, may lead to erroneous conclusions. Finally, we propose a simple model that closely matches the statistics of the OF as a function of mobileto-base distance, thus obviating the need to set up the complicated channel model every time OF values are to be generated. IEEE Transactions on Wireless Communications (2006)This work may not be copied or reproduced in whole or in part for any commercial purpose. Permission to copy in whole or in part without payment of fee is granted for nonprofit educational and research purposes provided that all such whole or partial copies include the following: a notice that such copying is by permission of Mitsubishi Electric Research Laboratories, Inc.; an acknowledgment of the authors and individual contributions to the work; and all applicable portions of the copyright notice. Copying, reproduction, or republishing for any other purpose shall require a license with payment of fee to Mitsubishi Electric Research Laboratories, Inc. All rights reserved. Abstract-The orthogonality factor (OF) quantifies the loss of orthogonality between the signals transmitted simultaneously on a wideband code division multiple access (WCDMA) downlink due to multipath dispersion. It is one of the fundamental parameters that determines the signal-to-interference-plus-noise ratio at the output of a Rake receiver and, consequently, it has a significant impact on downlink system capacity. The OF depends greatly on the delay profile of the multipath channel between the mobile and its serving base station; this profile varies considerably from one location in the cell to another.In this paper, we study how the statistical properties of the small-scale-fading-averaged OF vary over the entire macrocellular area. We use an ensemble of channel profiles ...

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Section: Introductionmentioning

confidence: 99%

Macrocell-Wide Behavior of the Orthogonality Factor in WCDMA Downlinks

Mehta

Molisch

Greenstein

2006

IEEE Trans. Wireless Commun.

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“…In outdoor propagation environments, the BS is typically positioned higher than the surrounding scatterers so that the transmitted signals propagate through a multipath channel with a moderate angular spread [23], [24]. In this case, the fading that impairs the channels to different users is often spatially correlated so that scheduling algorithms can be designed to efficiently arrange the users into groups (or clusters).…”

Section: A Related Workmentioning

confidence: 99%

A Comparative Analysis of Spatial Multiplexing Techniques for Outdoor MIMO-OFDM Systems with a Limited Feedback Constraint

Savazzi

Nicoli

Sternad

2009

IEEE Trans. Veh. Technol.

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Abstract-In this paper, we analyze spatial multiplexing techniques for the downlink of a multiple-input-multiple-output (MIMO) orthogonal frequency-division multiplexing (OFDM) system. Our study is focused on outdoor environments characterized by a moderate angular spread. We consider two techniques that are able to separate the downlink data streams associated with different users and to guarantee a fixed error probability by exploiting limited feedback from each user. The grid of beams (GoBs) and the proposed adaptive GoB (AGoB) differ in the way the precoders are designed (by adaptive or fixed processing) and in their scheduling policy. The new AGoB is able to harness partial knowledge of the downlink channel spatial structure to better select the users and adjust their precoders for downlink transmission. The performances of GoB and AGoB are compared in this paper in terms of throughput and cell coverage capability. The radio interface is adapted to fit the requirements for the adaptive modulation and coding with advanced antenna system (AMC-AAS) mode of the IEEE 802.16-2005 standard. Numerical results show that, as long as the channel exhibits a limited angular spread at the base station, the AGoB technique is able to provide significant throughput gains compared with the fixed GoB approach. On the other hand, large angular spreads are proved to have a substantial impact on system performance as the benefits of adaptation are significantly reduced.Index Terms-MIMO-OFDM systems, multiuser diversity, spatial multiplexing, zero-forcing beamforming.

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“…Since multipath channels in urban, suburban, and rural macro-cell are usually characterized by angular spread ranging from 10 deg to 30 deg [5]- [6], we chose for the angular spread Φ k at the BS a one-sided Gaussian random variable, Φ k ∼ N (15 deg, σ 2 Φ ), Φ k ≥ 0, with mean 15 deg and standard deviation σ Φ = 5 deg. Spatial correlation of the channel gains at the transmitter and the receiver is modelled according to [6].…”

Section: B Lower-bound Sinrmentioning

confidence: 99%

“…that transmitted signals propagate through a multipath channel with moderate angular spread [5], [6]. For the allocation of a specific time-frequency resource unit, a scheduler at the BS exploits quantized partial CSI on all the active users in order to maximize the cell throughput at a given limited feedback rate and minimize the multi-user interference (MUI) within the unit.…”

Section: Introductionmentioning

confidence: 99%

Spatial multiplexing for outdoor MIMO-OFDM systems with limited feedback costraint

Savazzi

Nicoli

Sternad

2006

2006 IEEE International Conference on Communications

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Abstract-In this paper we propose a spatial multiplexing technique for the downlink of a multiple-input-multiple-output (MIMO) orthogonal-frequency-division-multiplexing (OFDM) system. For outdoor environments with a limited angular spread at the base station, the proposed technique is able to separate the users' streams through a joint spatial processing at both the transmitter and the receiver requiring only a limited feedback from each user. Adaptive transmission is adopted on each stream to set a fixed probability of error. Numerical simulations show that the proposed technique is able to provide significant throughput gains compared to fixed-beams based approaches proposed in the literature.

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Spatio-temporal radio channel characteristics in urban macrocells

Cited by 75 publications

References 7 publications

Macrocell-Wide Behavior of the Orthogonality Factor in WCDMA Downlinks

Macrocell-Wide Behavior of the Orthogonality Factor in WCDMA Downlinks

A Comparative Analysis of Spatial Multiplexing Techniques for Outdoor MIMO-OFDM Systems with a Limited Feedback Constraint

Spatial multiplexing for outdoor MIMO-OFDM systems with limited feedback costraint

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