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
More filters
Posted Content•
TL;DR: The HyperSurface tiles as discussed by the authors can effectively re-engineer electromagnetic waves, including steering towards any desired direction, full absorption, polarization manipulation, and more, by using planar meta-materials.
Abstract: Electromagnetic waves undergo multiple uncontrollable alterations as they propagate within a wireless environment. Free space path loss, signal absorption, as well as reflections, refractions and diffractions caused by physical objects within the environment highly affect the performance of wireless communications. Currently, such effects are intractable to account for and are treated as probabilistic factors. The paper proposes a radically different approach, enabling deterministic, programmable control over the behavior of the wireless environments. The key-enabler is the so-called HyperSurface tile, a novel class of planar meta-materials which can interact with impinging electromagnetic waves in a controlled manner. The HyperSurface tiles can effectively re-engineer electromagnetic waves, including steering towards any desired direction, full absorption, polarization manipulation and more. Multiple tiles are employed to coat objects such as walls, furniture, overall, any objects in the indoor and outdoor environments. An external software service calculates and deploys the optimal interaction types per tile, to best fit the needs of communicating devices. Evaluation via simulations highlights the potential of the new concept.
290 citations
01 May 2019
TL;DR: This paper contributes the software-programmable wireless environment, consisting of several HyperSurface tiles (programmable metasurfaces) controlled by a central server, which calculates and deploys the optimal electromagnetic interaction per tile, to the benefit of communicating devices.
Abstract: Wireless communication environments comprise passive objects that cause performance degradation and eavesdropping concerns due to anomalous scattering. This paper proposes a new paradigm, where scattering becomes software-defined and, subsequently, optimizable across wide frequency ranges. Through the proposed programmable wireless environments, the path loss, multi-path fading and interference effects can be controlled and mitigated. Moreover, the eavesdropping can be prevented via novel physical layer security capabilities. The core technology of this new paradigm is the concept of metasurfaces, which are planar intelligent structures whose effects on impinging electromagnetic waves are fully defined by their micro-structure. Their control over impinging waves has been demonstrated to span from 1 GHz to 10 THz. This paper contributes the software-programmable wireless environment, consisting of several HyperSurface tiles (programmable metasurfaces) controlled by a central server. HyperSurfaces are a novel class of metasurfaces whose structure and, hence, electromagnetic behavior can be altered and controlled via a software interface. Multiple networked tiles coat indoor objects, allowing fine-grained, customizable reflection, absorption or polarization overall. A central server calculates and deploys the optimal electromagnetic interaction per tile, to the benefit of communicating devices. Realistic simulations using full 3D ray-tracing demonstrate the groundbreaking performance and security potential of the proposed approach in 2.4 GHz and 60 GHz frequencies.
125 citations
12 Jun 2018
TL;DR: In this paper, the authors proposed a new paradigm, where indoor scattering becomes software-defined and, subsequently, optimizable across wide frequency ranges, where a central server calculates and deploys the optimal electromagnetic interaction per tile, to the benefit of communicating devices.
Abstract: Wireless communication environments are unaware of the ongoing data exchange efforts within them. Moreover, their effect on the communication quality is intractable in all but the simplest cases. The present work proposes a new paradigm, where indoor scattering becomes software-defined and, subsequently, optimizable across wide frequency ranges. Moreover, the controlled scattering can surpass natural behavior, exemplary overriding Snell's law, reflecting waves towards any custom angle (including negative ones). Thus, path loss and multi-path fading effects can be controlled and mitigated. The core technology of this new paradigm are metasurfaces, planar artificial structures whose effect on impinging electromagnetic waves is fully defined by their macro-structure. The present study contributes the software-programmable wireless environment model, consisting of several HyperSurface tiles controlled by a central, environment configuration server. HyperSurfaces are a novel class of metasurfaces whose structure and, hence, electromagnetic behavior can be altered and controlled via a software interface. Multiple networked tiles coat indoor objects, allowing fine-grained, customizable reflection, absorption or polarization overall. A central server calculates and deploys the optimal electromagnetic interaction per tile, to the benefit of communicating devices. Realistic simulations using full 3D ray-tracing demonstrate the groundbreaking potential of the proposed approach in 2.4GHz and 60GHz frequencies.
105 citations
TL;DR: In this article, the effect of large-scale deployment of RISs on the performance of cellular networks was studied using tools from stochastic geometry to derive the probability that a typical mobile user associates with a BS using an RIS.
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 article, 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/km2 to 490 RISs/km2 when the density of the blockages is 700 blockage/km2.
105 citations
Proceedings Article•
01 Jan 2019TL;DR: This work instrument the environment with a large array of inexpensive antenna (LAIA) elements, and design algorithms to configure LAIA elements in real time, and designs a channel decomposition algorithm to quickly estimate the wireless channel due to the environment alone, which leads to a process to align the phases of theLAIA elements.
Abstract: Conventional thinking treats the wireless channel as a constraint, so wireless network designs to date target endpoint designs that best utilize the channel. Examples include rate and power control at the transmitter, sophisticated receiver decoder designs, and high-performance forward error correction for the data itself. We instead explore whether it is possible to reconfigure the environment itself to facilitate wireless communication. In this work, we instrument the environment with a large array of inexpensive antenna (LAIA) elements, and design algorithms to configure LAIA elements in real time. Our system achieves a high level of programmability through rapid adjustments of an on-board phase shifter in each LAIA element. We design a channel decomposition algorithm to quickly estimate the wireless channel due to the environment alone, which leads us to a process to align the phases of the LAIA elements. Variations of our core algorithm then improve wireless channels on the fly for singleand multi-antenna links, as well as nearby networks operating on adjacent frequency bands. We implement and deploy a 36-element LAIA array in a real indoor home environment. Experiments in this setting show that, by reconfiguring the wireless environment, we can achieve a 24% TCP throughput improvement on average and a median improvement of 51.4% in Shannon capacity over baseline single-antenna links. Over baseline multi-antenna links, LAIA achieves an improvement of 12.23% to 18.95% in Shannon capacity.
44 citations
Cites background or result from "Enhancing wireless performance usin..."
...In a similar spirit, there have been several attempts at making the environment more amenable to wireless communications, for example, by adding 3D-printed static reflectors around the sender or receiver to shape outgoing or incoming signals [8, 41] or deploying static reflectors away from the AP [16]....
[...]
...For this reason, our vision qualitatively differs from recent proposals to cover walls with conductive paint [43], add static reflectors [8, 16, 41, 44], or programmable phasedarray reflectors [1, 2] for 60 GHz links in the environment....
[...]
References
More filters
04 Oct 2010
TL;DR: This paper proposes 3D ray tracing as a way for automatically generating a highly accurate radiomap and compares this method to previously used propagation modeling-based methods like the Wall Attenuation Factor and 2D Ray tracing models, and quantifies the accuracy- complexity trade-off.
Abstract: WLAN RSS-based localization has been a hot research topic for the last years. To obtain high accuracy in the noisy wireless channel, WLAN location determination systems usually use a calibration phase, where a radio map, capturing the signal strength signatures at different locations in the area of interest, is built. The radio map construction process takes a lot of time and effort, reducing the value of WLAN localization systems. In this paper, we propose 3D ray tracing as a way for automatically generating a highly accurate radiomap. We compare this method to previously used propagation modeling-based methods like the Wall Attenuation Factor and 2D ray tracing models. We evaluate the performance of each method and its computational cost in a typical residential environment. We also examine the sensitivity of the localization accuracy to inaccurate material parameters. Our results quantify the accuracy- complexity trade-off of the different proposed techniques with 3D ray tracing giving the best localization accuracy compared to measurements with acceptable computational requirements on a typical PC.
103 citations
"Enhancing wireless performance usin..." refers background in this paper
...Considering the walls and other objects as homogeneous dielectric slabs, and assuming parallel polarization [14], the reflection coefficient R is:...
[...]
15 Jun 2009
TL;DR: A site-specific validation of the ITU indoor path loss model at 2.4 GHz is presented, for the first time, to provide values for the model's parameters that concern specifically this frequency band, which is of utmost importance for wireless networks.
Abstract: This paper presents a site-specific validation of the ITU indoor path loss model at 2.4 GHz. Based on measurements acquired in a recent experiment for a WLAN indoor office environment, we are able to accomplish a numerical adjustment of the Site-general ITU model to the specific measured data that reflect the intrinsic characteristics of the complex indoor topology, thus validating the Site-Specific ITU model at 2.4 GHz. For the first time, we are in position to provide values for the model's parameters that concern specifically this frequency band, which is of utmost importance for wireless networks, mostly for WLAN channels. This marks a major step towards an even greater degree of precision and reliability in the usage of indoor RF models for link budget design in modern wireless communications.
85 citations
"Enhancing wireless performance usin..." refers methods in this paper
...We compare OptRe with the widely used propagation models: (i) log-distance path loss model [9], and (ii) site-specific ITU indoor path loss model [10]....
[...]
...The representative models range from a simple uniform path-loss model [9] to sophisticated models such as empirical models for indoor signal propagation (ITU model [10]) and ray-tracing models [11]....
[...]
27 Jul 2015
TL;DR: This work proposes the first computational model for simulating hydrographic printing process, and extends the method to enable multiple immersions, each with a different object orientation, so the combined colors of individual immersion form a desired texture on the object surface.
Abstract: Hydrographic printing is a well-known technique in industry for transferring color inks on a thin film to the surface of a manufactured 3D object. It enables high-quality coloring of object surfaces and works with a wide range of materials, but suffers from the inability to accurately register color texture to complex surface geometries. Thus, it is hardly usable by ordinary users with customized shapes and textures. We present computational hydrographic printing, a new method that inherits the versatility of traditional hydrographic printing, while also enabling precise alignment of surface textures to possibly complex 3D surfaces. In particular, we propose the first computational model for simulating hydrographic printing process. This simulation enables us to compute a color image to feed into our hydrographic system for precise texture registration. We then build a physical hydrographic system upon off-the-shelf hardware, integrating virtual simulation, object calibration and controlled immersion. To overcome the difficulty of handling complex surfaces, we further extend our method to enable multiple immersions, each with a different object orientation, so the combined colors of individual immersions form a desired texture on the object surface. We validate the accuracy of our computational model through physical experiments, and demonstrate the efficacy and robustness of our system using a variety of objects with complex surface textures.
52 citations
"Enhancing wireless performance usin..." refers background or methods in this paper
...Numerous efforts have been made to improve radio propagation models [11]....
[...]
...The representative models range from a simple uniform path-loss model [9] to sophisticated models such as empirical models for indoor signal propagation (ITU model [10]) and ray-tracing models [11]....
[...]
03 Nov 2014
TL;DR: A revision of the current CSI feedback scheme is suggested and a novel CSI feedback system is proposed to prevent CSI forging without requiring any modification at the client side, thus facilitating its deployment.
Abstract: Multiple-In-Multiple-Out (MIMO) offers great potential for increasing network capacity by exploiting spatial diversity with multiple antennas. Multiuser MIMO (MU-MIMO) further enables Access Points (APs) with multiple antennas to transmit multiple data streams concurrently to several clients. In MU-MIMO, clients need to estimate Channel State Information (CSI) and report it to APs in order to eliminate interference between them. We explore the vulnerability in clients' plaintext feedback of estimated CSI to the APs and propose two advanced attacks that malicious clients can mount by reporting forged CSI: (1) sniffing attack that enables concurrently transmitting malicious clients to eavesdrop other ongoing transmissions; (2) power attack that enables malicious clients to enhance their own capacity at the expense of others?. We have implemented and evaluated these two attacks in a WARP testbed. Based on our experimental results, we suggest a revision of the current CSI feedback scheme and propose a novel CSI feedback system, called the CSIsec, to prevent CSI forging without requiring any modification at the client side, thus facilitating its deployment.
48 citations
"Enhancing wireless performance usin..." refers background in this paper
...Numerous researchers discussed defense mechanisms against DoS attack [22], [23], and sniffing attack [24], [25]....
[...]
11 Sep 2015
TL;DR: A new computational approach to control wireless coverage by mounting signal reflectors in carefully optimized shapes on wireless routers is proposed, which is low-cost, adapts to different wireless routers and physical environments, and has a far-reaching impact by interweaving computational techniques to solve key problems in wireless communication.
Abstract: Directing wireless signals and customizing wireless coverage is of great importance in residential, commercial, and industrial environments. It can improve the wireless reception quality, reduce the energy consumption, and achieve better security and privacy. To this end, we propose
ame, a new computational approach to control wireless coverage by mounting signal reflectors in carefully optimized shapes on wireless routers. Leveraging 3D reconstruction, fast-wave simulations in acoustics, computational optimization, and 3D fabrication, our method is low-cost, adapts to different wireless routers and physical environments, and has a far-reaching impact by interweaving computational techniques to solve key problems in wireless communication.
15 citations
Additional excerpts
...Wiprint [12] customized a wireless signal map using reflectors, but it required 3D printing to get the reflector which requires special and expensive equipment....
[...]
...As in [12], [13], we focus on modeling the average of RSS over time, and ignore the phase differences among rays which are usually used to study the variance of RSS over time....
[...]