Beam diversity for indoor WLAN systems

Casas, E.; Chia, Tong; Silva, M. da; Yin, Hujun; Choi, Yang-Seok

doi:10.1109/vetecf.2003.1286206

Cited by 9 publications

(11 citation statements)

References 5 publications

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“…How does the directionality get affected with the characteristics of a beam such as main and side lobe width, front to side lobe ratio, and location of clients? The only research effort that we are familiar of in the indoor context is [5] that employs 10…”

Section: Introductionmentioning

confidence: 99%

On the Effectiveness of Switched Beam Antennas in Indoor Environments

Blanco

Kokku

Ramachandran

et al. 2008

Lecture Notes in Computer Science

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Switched beam antennas are an attractive extension to indoor wireless LANs due to their increased signal gain in a chosen direction; the gain can be exploited for improving wireless link quality, node localization and increasing spatial reuse. However, indoor environments are susceptible to multipath reflections that may reduce the degree of directionality of the antennas. To this end, in this paper, we address the following questions that have not been explored well in the open literature: how directional in reality is a beam with a switched beam antenna in a reflection-rich environment, and what are the implications of the observed directionality on spatial reuse and node localization? And how does the directionality get affected with the characteristics of a beam such as main and side lobe width, and front to side lobe ratio? We present results of measurements in a real office setting with a switched beam antenna built out of an 8-element phase array.

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Section: Introductionmentioning

confidence: 99%

On the Effectiveness of Switched Beam Antennas in Indoor Environments

Blanco

Kokku

Ramachandran

et al. 2008

Lecture Notes in Computer Science

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“…The performance of beamforming is related to the angular spread, or the directivity, of the indoor propagation channel where WLAN is used [4,8]. Therefore, first, we demonstrate the directivity of the indoor propagation channel through an analysis of IEEE 802.11n cluster channel models extracted from IEEE 802.11n MIMO channel models [5] and propagation measurements in a typical office environment.…”

Section: Directivity Of Indoor Propagation Channelmentioning

confidence: 99%

“…In this context, beamforming means the capability of steering a directive beam in the relevant direction of the access point. In contrast to existing research activities with beamforming focusing on the access point in WLAN, e.g., [4,3], we apply the beamforming capability at the wireless terminal to assure backwards compatibility with existing WLAN networks and to not force any change in existing wireless networks causing new investments for network providers. Furthermore, we propose to use radio frequency (RF) beamforming to achieve the vendor transparency to ease the system design process and achieve low complexity and costs.…”

Section: Introductionmentioning

confidence: 99%

“…As the current research on beamforming in WLAN focuses on investigating beam diversity -see, e.g., [4,8], we investigate signal to interference ratio (SIR) improvement as well as array gain through simulations with IEEE 802.11n cluster channel models and experiments with the demonstrator. Furthermore, the real capacity performance of terminal beamforming has been demonstrated in a typical office environment by experiments using the demonstrator.…”

Section: Introductionmentioning

confidence: 99%

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Capacity enhancement by terminal originated beamforming for wireless local area networks

Fitzek

Eggers

2007

Wireless Pers Commun

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In dense traffic areas, wireless local area networks (WLANs) suffer from interference problems due to the usage of the crowded unlicensed ISM band and the lack of available spectrum. To mitigate these problems, a terminal side beamforming framework is proposed-this beamforming is capable of focusing the transmission and the reception in the relevant direction of the access point to exploit the directivity of the indoor propagation channel. It provides network transparency to achieve the backwards compatibility to the existing WLAN networks, and vendor transparency to ease the system design process and thereby achieve low complexity and costs. The beamforming enabled terminal benefits in terms of capacity, energy efficiency, and security while it does not require any change on the network side costing network providers new investments. It will be an attractive value-added feature as well as low-cost solution for the future WLAN terminal design opening the door for WLAN terminal manufacturers to include the proposed solution into their product line.In this work, a WLAN terminal beamforming demonstrator has been developed to demonstrate the capacity enhancement in real environments. Signal to interference ratio (SIR) improvement as well as array gain were investigated by simulations with IEEE 802.11n cluster channel models and by experiments with the demonstrator in a typical office environment. The comparable results of simulations and experiments show significant array gain and SIR improvement. The significant capacity increase has been demonstrated in the experiments in both an interference free scenario and an interference limited scenario.

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“…Narrowband beam diversity selecting one beam (synthetic Butler matrix) was investigated in [18] and two beams in [19]. The work of Grau et al [20] and Onizawa et al [21], which were done independent of our investigation [22] showed analysis as well as measurement results of selection combing (one antenna selected) in combination with an implementation of a Butler matrix and Eigenbeam forming, respectively.…”

Section: Introductionmentioning

confidence: 96%

Antenna subset selection in measured indoor channels

Almers

Santos

Tufvesson

et al. 2007

IET Microw. Antennas Propag.

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Antenna subset selection can greatly reduce the implementation complexity of multiple input multiple output (MIMO) systems while retaining most of their benefits. This paper investigates the diversity gain and capacity of such systems in wireless personal area networks. Considered scenarios include both the communication between access point to a laptop, and between two hand held devices. We analyze the performance of different antenna selection algorithms and signal combining methods in measured dual-polarized narrow band and wide band propagation channels. We find that line-of-sight and non-line-of-sight situations have fairly similar behavior. Different polarizations result in similar signal-to-noise ratio gains when the multiple antennas are used for diversity, but result in noticeably different capacities in spatial-multiplexing systems. We also find that radio frequency (RF) preprocessing of the signals is less effective for hand held handsets with non-uniform antenna arrangements than for uniform linear arrays. For communications between hand held devices, simple selection (of one out of four antennas) shows extremely high performance gains compared to no-selection. Finally, we compare bulk selection (same antenna subset is used for all frequency sub-channels) to per-tone selection (different antenna subsets can be used for each frequency sub-channel) for wide band channels. Bulk selection together with RF preprocessing performs almost a s well as per-tone selection for some scenarios. IET Microwaves, Antennas & PropagationThis 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: Antenna subset selection can greatly reduce the implementation complexity of multiple input multiple output (MIMO) systems while retaining most of their benefits. This paper investigates the diversity gain and capacity of such systems in wireless personal area networks. Considered scenarios include both the communication between access point to a laptop, and between two handheld devices. We analyse the performance of different antenna selection algorithms and signal combining methods in measured dual-polarised narrowband and wideband propagation channels. We find that line-of-sight and non-line-of-sight situations have fairly similar behaviour. Different polarisations result in similar signal-to-noise ratio gains when the multiple antennas are used for diversity, but result in noticeably different ca...

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Beam diversity for indoor WLAN systems

Cited by 9 publications

References 5 publications

On the Effectiveness of Switched Beam Antennas in Indoor Environments

On the Effectiveness of Switched Beam Antennas in Indoor Environments

Capacity enhancement by terminal originated beamforming for wireless local area networks

Antenna subset selection in measured indoor channels

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