Enhancing wireless performance using reflectors
01 May 2017-pp 1-9
TL;DR: OptRe is proposed which optimally places metallic reflectors — providing a highly reflective surface that can reflect impinging signals almost 100% — in indoor environments to reduce the reflection loss and enhance wireless transmissions.
Abstract: Signal decay is the fundamental problem of wireless communications, especially in an indoor environment where line-of-sight (LOS) paths for signal propagation are often blocked and various indoor objects exacerbate signal fading. There are three reasons for signal decay: long transmission distance, signal penetration, and reflection. In this paper, we propose OptRe which optimally places metallic reflectors — providing a highly reflective surface that can reflect impinging signals almost 100% — in indoor environments to reduce the reflection loss and enhance wireless transmissions. It enhances both WiFi signal and low-power IoT devices without changing their configurations or network protocols. To enable OptRe, we first develop an empirical signal propagation model that can accurately estimate the signal strength and adapt itself to the reflectors' location. Using micro-benchmarks, our empirical signal propagation model is shown to be more accurate than the other existing path loss models. We also optimally place reflectors to maximize the worst-case signal coverage within the target indoor areas. Our extensive experimental evaluation results have shown OptRe to enhance signal strength for different types of wireless signals by almost 2x.
Citations
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08 Nov 2017
TL;DR: A low-cost, secure, and easy-to-configure approach that uses an easily-accessible, 3D-fabricated reflector to customize wireless coverage to improve signal reception and reduce harmful interference in built environments is presented.
Abstract: Judicious control of indoor wireless coverage is crucial in built environments. It enhances signal reception, reduces harmful interference, and raises the barrier for malicious attackers. Existing methods are either costly, vulnerable to attacks, or hard to configure. We present a low-cost, secure, and easy-to-configure approach that uses an easily-accessible, 3D-fabricated reflector to customize wireless coverage. With input on coarse-grained environment setting and preferred coverage (e.g., areas with signals to be strengthened or weakened), the system computes an optimized reflector shape tailored to the given environment. The user simply 3D prints the reflector and places it around a Wi-Fi access point to realize the target coverage. We conduct experiments to examine the efficacy and limits of optimized reflectors in different indoor settings. Results show that optimized reflectors coexist with a variety of Wi-Fi APs and correctly weaken or enhance signals in target areas by up to 10 or 6 dB, resulting to throughput changes by up to -63.3% or 55.1%.
18 citations
Cites background from "Enhancing wireless performance usin..."
...Additionally, [23] optimizes reflector locations, whereas our work optimizes reflector shape....
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...Similarly, a latest work [23] examined placing multiple metal plates in the environment to enhance wireless performance of a single AP....
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09 Aug 2021
TL;DR: LAVA as mentioned in this paper is a large array of vanilla amplifiers, which is a standard-agnostic cooperative mesh of elements, i.e., RF devices each consisting of several switched input and output antennas connected to fixed-gain amplifiers.
Abstract: Small IoT devices deployed in challenging locations suffer from uneven 3D coverage in complex environments. This work optimizes indoor coverage with LAVA, a Large Array of Vanilla Amplifiers. LAVA is a standard-agnostic cooperative mesh of elements, i.e., RF devices each consisting of several switched input and output antennas connected to fixed-gain amplifiers. Each LAVA element is further equipped with rudimentary power sensing to detect nearby transmissions. The elements report power readings to the LAVA control plane, which then infers active link sessions without explicitly interacting with the endpoint transmitter or receiver. With simple on-off control of amplifiers and antenna switching, LAVA boosts passing signals via multi hop amplify-and-forward. LAVA explores a middle ground between smart surfaces and physical-layer relays. Multi-hopping over short inter-hop distances exerts more control over the end-to-end trajectory, supporting fine-grained coverage and spatial reuse. Ceiling testbed results show throughput improvements to individual Wi-Fi links by 50% on average and up to 100% at 15 dBm transmit power (193% on average, up to 8x at 0 dBm). ZigBee links see up to 17 dB power gain. For pairs of co-channel concurrent links, LAVA provides average per-link throughput improvements of 517% at 0 dBm and 80% at 15 dBm.
8 citations
Posted Content•
TL;DR: This article uses tools from stochastic geometry to study the effect of large-scale deployment of RISs on the performance of cellular networks, and shows that deployment of riss highly improves the coverage regions of the BSs.
Abstract: One of the promising technologies for the next generation wireless networks is the reconfigurable intelligent surfaces (RISs). This technology provides planar surfaces the capability to manipulate the reflected waves of impinging signals, which leads to a more controllable wireless environment. One potential use case of such technology is providing indirect line-of-sight (LoS) links between mobile users and base stations (BSs) which do not have direct LoS channels. Objects that act as blockages for the communication links, such as buildings or trees, can be equipped with RISs to enhance the coverage probability of the cellular network through providing extra indirect LoS-links. In this paper, we use tools from stochastic geometry to study the effect of large-scale deployment of RISs on the performance of cellular networks. In particular, we model the blockages using the line Boolean model. For this setup, we study how equipping a subset of the blockages with RISs will enhance the performance of the cellular network. We first derive the ratio of the blind-spots to the total area. Next, we derive the probability that a typical mobile user associates with a BS using an RIS. Finally, we derive the probability distribution of the path-loss between the typical user and its associated BS. We draw multiple useful system-level insights from the proposed analysis. For instance, we show that deployment of RISs highly improves the coverage regions of the BSs. Furthermore, we show that to ensure that the ratio of blind-spots to the total area is below 10^5, the required density of RISs increases from just 6 RISs/km2 when the density of the blockages is 300 blockage/km^2 to 490 RISs/km^2 when the density of the blockages is 700 blockage/km^2.
6 citations
Cites background from "Enhancing wireless performance usin..."
...Authors in [6] introduced the idea of utilizing metallic reflectors in indoor environments to enhance the communication performance....
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01 Dec 2021
TL;DR: This work offers a novel, backscatter radio-based, blind beamforming technique that assists the reception of signals in multipath conditions and shows that increased number of assistive tags offers higher beamforming gain, at the expense of increased delay.
Abstract: This work offers a novel, backscatter radio-based, blind beamforming technique that assists the reception of signals in multipath conditions. The technique is based on simple, assistive backscattering tags, implemented without any means of signal amplification. These tags can blindly (i.e., without feedback) modify the phase of the associated wireless channels, leading to constructive addition of the multipath components (i.e, alignment). Such alignment events offer distributed beamforming gain. Analysis is performed and an expression for the probability of alignment is offered, along with an expression for the achievable gain, corroborated by simulations and experimental results. It is shown that increased number of assistive tags offers higher beamforming gain, at the expense of increased delay. The effectiveness of the proposed beamforming technique is highlighted with experiments and measurements on the radio frequency identification (RFID) Gen2 standard. Commercial RFIDs that initially could not be interrogated due to insufficient impinged power, were successfully interrogated hundreds of times/minute with the assistance of the beamforming tags. It was experimentally shown that the proposed beamforming tags can offer power gains in the range of 0.4-3.7 dB. While the technique was tested on commercial RFIDs, it is not limited to a specific communication standard.
5 citations
27 Mar 2022
TL;DR: Experimental results show that in the presence of the passive reflector, the path loss can be reduced up to 24 dB and this type of configuration could be an economical solution to expand the mmWave coverage area.
Abstract: Millimeter wave (mmWave) coverage is relatively limited due to high path loss (PL), that makes radio frequency planning difficult, especially for the non-line-of-sight (NLOS) scenarios. In this work, we are looking to improve mmWave signal coverage in NLOS indoor scenario using passive reflectors. Measurements have been performed in L-shaped hallway using a vector network analyzer (VNA) and the path loss is evaluated with and without reflector. Experimental results show that in the presence of the passive reflector, the path loss can be reduced up to 24 dB. This type of configuration could be an economical solution to expand the mmWave coverage area. Moreover, a study is provided to compare the path loss when the reflector is placed horizontally to the path loss obtained when the reflector was placed vertically.
4 citations
References
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Proceedings Article•
01 Jan 2005
TL;DR: This book aims to provide a chronology of key events and individuals involved in the development of microelectronics technology over the past 50 years and some of the individuals involved have been identified and named.
Abstract: Alhussein Abouzeid Rensselaer Polytechnic Institute Raviraj Adve University of Toronto Dharma Agrawal University of Cincinnati Walid Ahmed Tyco M/A-COM Sonia Aissa University of Quebec, INRSEMT Huseyin Arslan University of South Florida Nallanathan Arumugam National University of Singapore Saewoong Bahk Seoul National University Claus Bauer Dolby Laboratories Brahim Bensaou Hong Kong University of Science and Technology Rick Blum Lehigh University Michael Buehrer Virginia Tech Antonio Capone Politecnico di Milano Javier Gómez Castellanos National University of Mexico Claude Castelluccia INRIA Henry Chan The Hong Kong Polytechnic University Ajit Chaturvedi Indian Institute of Technology Kanpur Jyh-Cheng Chen National Tsing Hua University Yong Huat Chew Institute for Infocomm Research Tricia Chigan Michigan Tech Dong-Ho Cho Korea Advanced Institute of Science and Tech. Jinho Choi University of New South Wales Carlos Cordeiro Philips Research USA Laurie Cuthbert Queen Mary University of London Arek Dadej University of South Australia Sajal Das University of Texas at Arlington Franco Davoli DIST University of Genoa Xiaodai Dong, University of Alberta Hassan El-sallabi Helsinki University of Technology Ozgur Ercetin Sabanci University Elza Erkip Polytechnic University Romano Fantacci University of Florence Frank Fitzek Aalborg University Mario Freire University of Beira Interior Vincent Gaudet University of Alberta Jairo Gutierrez University of Auckland Michael Hadjitheodosiou University of Maryland Zhu Han University of Maryland College Park Christian Hartmann Technische Universitat Munchen Hossam Hassanein Queen's University Soong Boon Hee Nanyang Technological University Paul Ho Simon Fraser University Antonio Iera University "Mediterranea" of Reggio Calabria Markku Juntti University of Oulu Stefan Kaiser DoCoMo Euro-Labs Nei Kato Tohoku University Dongkyun Kim Kyungpook National University Ryuji Kohno Yokohama National University Bhaskar Krishnamachari University of Southern California Giridhar Krishnamurthy Indian Institute of Technology Madras Lutz Lampe University of British Columbia Bjorn Landfeldt The University of Sydney Peter Langendoerfer IHP Microelectronics Technologies Eddie Law Ryerson University in Toronto
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Book•
01 Jan 1993TL;DR: In this paper, the Lagrangian relaxation and dual ascent tree search were used to solve the graph bisection problem and the graph partition problem, and the traveling salesman problem scheduling problems.
Abstract: Part 1 Introduction: combinatorial problems local and global optima heuristics. Part 2 Simulated annealing: the basic method enhancements and modifications applications conclusions. Part 3 Tabu search: the tabu framework broader aspects of intensification and diversification tabu search applications connections and conclusions. Part 4 Genetic algorithms: basic concepts a simple example extensions and modifications applications conclusions. Part 5 Artificial neural networks: neural networks combinatorial optimization problems the graph bisection problem the graph partition problem the travelling salesman problem scheduling problems deformable templates inequality constraints, the Knapsack problem summary. Part 6 Lagrangian relaxation: overview basic methodology Lagrangian heuristics and problem reduction determination of Lagrange multipliers dual ascent tree search applications conclusions. Part 7 Evaluation of heuristic performance: analytical methods empirical testing statistical inference conclusions.
2,571 citations
"Enhancing wireless performance usin..." refers methods in this paper
...SA is used to search for the optimal solution based on the way that a metal cools down to the optimal state (the annealing process from an initial temperature T to minimal Tmin at a certain cooling rate) [17]....
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01 Jan 1993
TL;DR: The principles of radio propagation in indoor environments are reviewed, the channel is modeled as a linear time-varying filter at each location in the three-dimensional space, and the properties of the filter's impulse response are described.
1,735 citations
"Enhancing wireless performance usin..." refers background in this paper
...Indoor radio propagation has been an active subject of research [6], [7]....
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01 Jul 1993
TL;DR: In this paper, a tutorial survey of radio propagation in indoor environments is presented, where the channel is modeled as a linear time-varying filter at each location in the 3D space, and the properties of the filter's impulse response are described.
Abstract: In this tutorial survey the principles of radio propagation in indoor environments are reviewed. The channel is modeled as a linear time-varying filter at each location in the three-dimensional space, and the properties of the filter's impulse response are described. Theoretical distributions of the sequences of arrival times, amplitudes and phases are presented. Other relevant concepts such as spatial and temporal variations of the channel, large-scale path losses, mean excess delay and RMS delay spread are explored. Propagation characteristics of the indoor and outdoor channels are compared and their major differences are outlined. Previous measurement and modeling efforts are surveyed, and areas for future research are suggested. >
1,696 citations