A Survey of Positioning Systems Using Visible LED Lights

© 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.As Global Positioning System (GPS) cannot provide satisfying performance in indoor environments, indoor positioning technology, which utilizes indoor wireless signals instead of GPS signals, has grown rapidly in recent years. Meanwhile, visible light communication (VLC) using light devices such as light emitting diodes (LEDs) has been deemed to be a promising candidate in the heterogeneous wireless networks that may collaborate with radio frequencies (RF) wireless networks. In particular, light-fidelity has a great potential for deployment in future indoor environments because of its high throughput and security advantages. This paper provides a comprehensive study of a novel positioning technology based on visible white LED lights, which has attracted much attention from both academia and industry. The essential characteristics and principles of this system are deeply discussed, and relevant positioning algorithms and designs are classified and elaborated. This paper undertakes a thorough investigation into current LED-based indoor positioning systems and compares their performance through many aspects, such as test environment, accuracy, and cost. It presents indoor hybrid positioning systems among VLC and other systems (e.g., inertial sensors and RF systems). We also review and classify outdoor VLC positioning applications for the first time. Finally, this paper surveys major advances as well as open issues, challenges, and future research directions in VLC positioning systems.Peer reviewe

Coded Index Modulation for Non-DC-Biased OFDM in Multiple LED Visible Light Communication

Use of multiple light emitting diodes (LED) is an attractive way to increase spectral efficiency in visible light communications (VLC). A non-DC-biased OFDM (NDC OFDM) scheme that uses two LEDs has been proposed in the literature recently. NDC OFDM has been shown to perform better than other OFDM schemes for VLC like DC-biased OFDM (DCO OFDM) and asymmetrically clipped OFDM (ACO OFDM) in multiple LEDs settings. In this paper, we propose an efficient multiple LED OFDM scheme for VLC which uses {\em coded index modulation}. The proposed scheme uses two transmitter blocks, each having a pair of LEDs. Within each block, NDC OFDM signaling is done. The selection of which block is activated in a signaling interval is decided by information bits (i.e., index bits). In order to improve the reliability of the index bits at the receiver (which is critical because of high channel correlation in multiple LEDs settings), we propose to use coding on the index bits alone. We call the proposed scheme as CI-NDC OFDM (coded index NDC OFDM) scheme. Simulation results show that, for the same spectral efficiency, CI-NDC OFDM that uses LDPC coding on the index bits performs better than NDC OFDM

Control speculation for energy-efficient next-generation superscalar processors

Conventional front-end designs attempt to maximize the number of "in-flight" instructions in the pipeline. However, branch mispredictions cause the processor to fetch useless instructions that are eventually squashed, increasing front-end energy and issue queue utilization and, thus, wasting around 30 percent of the power dissipated by a processor. Furthermore, processor design trends lead to increasing clock frequencies by lengthening the pipeline, which puts more pressure on the branch prediction engine since branches take longer to be resolved. As next-generation high-performance processors become deeply pipelined, the amount of wasted energy due to misspeculated instructions will go up. The aim of this work is to reduce the energy consumption of misspeculated instructions. We propose selective throttling, which triggers different power-aware techniques (fetch throttling, decode throttling, or disabling the selection logic) depending on the branch prediction confidence level. Results show that combining fetch-bandwidth reduction along with select-logic disabling provides the best performance in terms of overall energy reduction and energy-delay product improvement (14 percent and 10 percent, respectively, for a processor with a 22-stage pipeline and 16 percent and 13 percent, respectively, for a processor with a 42-stage pipeline).Peer ReviewedPostprint (published version

Permutation and sampling with maximum length CA for pseudorandom number generation

In this paper, we study the effect of dynamic permutation and sampling on the randomness quality of sequences generated by cellular automata (CA). Dynamic permutation and sampling have not been explored in previous CA work and a suitable implementation is shown using a two CA model. Three different schemes that incorporate these two operations are suggested - Weighted Permutation Vector Sampling with Controlled Multiplexing, Weighted Permutation Vector Sampling with Irregular Decimation and Permutation Programmed CA Sampling. The experiment results show that the resulting sequences have varying degrees of improvement in DIEHARD results and linear complexity compared to the CA

Hacia una arquitectura pragmática. El caso de Tous y Fargas

[EN] Tous & Fargas were a unique case in the field of Spanish architecture of the second half of the 20th century. From the technical and industrial experimentation of their first works, they developed a nonconformist architecture within the realistic conditions characteristic of the time, propitiated by the economic, political and social context. Despite of this, they achieved a remarkable success carrying out designs of technological type and giving support to the industrial innovation of constructive systems. However, during the last stage of their collaboration, traits characteristic of the pragmatic drift are visible to which much of the architecture of the last quarter of the 20th century was subjected. The excess of mercantile concern for the real estate product, the excessive systematization of the typological models and the constructive systems, the lack of a consistent theoretical discourse or the abandonment of the technical investigation as a priority of innovation are some of the symptoms that characterize the pragmatic architecture of their latest works.[ES] Tous y Fargas fueron un caso singular en el ámbito de la arquitectura española de la segunda mitad del siglo XX. Desde la experimentación técnica e industrial de sus primeros trabajos, desarrollaron una arquitectura inconforme con los condicionantes realistas característicos de la época, propiciados por el contexto económico, político y social. Pese a ello, alcanzaron un éxito notable con realizaciones de corte tecnológico y dando soporte a la innovación industrial de sistemas constructivos. Sin embargo, durante la última etapa de su colaboración son visibles rasgos propios de la deriva pragmática a la que se veía sometida buena parte de la arquitectura del último cuarto del siglo XX. El exceso de preocupación mercantil por el producto inmobiliario, la sistematización excesiva de los modelos tipológicos y los sistemas constructivos, la carencia de un discurso teórico consistente o el abandono de la investigación técnica como premisa de innovación son algunos de los síntomas que caracterizan la arquitectura pragmática de sus últimos trabajosHernandez Falagan, D. (2017). Towards a pragmatic architecture. The case of Tous & Fargas. VLC arquitectura. Research Journal. 4(2):119-147. doi:10.4995/vlc.2017.6952SWORD11914742Ábalos, I-aki. La buena vida. Visita guiada a las casas de la modernidad. Barcelona: Gustavo Gili, 2000.Allen, Stan. "Pragmatismo en la práctica". Bau – Arquitectura, Urbanismo, Arte y Dise-o 21 (2001): 38.Coca, Joaquim and David Lladó. "Baròmetres de l'arquitectura catalana. Veterans a peu d'obra". INDE Informació i Debat 10/04 (2004): 62.De Fusco, Renato. Historia del dise-o. Barcelona: Santa & Cole, 2005.Dorfles, Guillo. El dise-o industrial y su estética. Barcelona: Editorial Labor, 1968.Ellwood, Craig. "The Machine and Architecture". Arts and Architecture 75-6 (1958): 19.Fargas Falp, Josep Maria. "Así proyectan". In XII Congreso Mundial de la Unión Internacional de Arquitectos, edited by Rafael de la Hoz, 55-56. Madrid: UIA, Departamento de Publicaciones, 1975.Fargas Falp, Josep Maria. "Proyectar pensando en el mantenimiento: los edificios de oficinas". In El mantenimiento de los edificios. Desde el inicio del proyecto al final de la vida útil, 84. Barcelona: COAC-UPC, Colección Papers Sert, 1999.Ferrater Mora, José. Diccionario de filosofía. Buenos Aires: Editorial Sudamericana, 1964.Gausa, Manuel. OPOP. Optimismo operativo en arquitectura. Barcelona: Actar, 2005.Giménez Serrano, Carmen. "Banco Exterior de Espa-a". Arquitectura bancaria en Espa-a, 255. Madrid: Electa-Ministerio de Fomento, 1998.James, W. (1907). Pragmatism: A new name for some old ways of thinking. doi:10.1037/10851-000Jameson, Fredric. Postmodernism or the Cultural Logic of Late Capitalism. Durham: Duke University Press, 1991.Koolhaas, Rem. Delirious New York: a retroactive manifesto for Manhattan. New York: Monacelli Press, 1994.Kwinter, Sanford. Far from Equilibrium. Barcelona: Actar, 2008.Martínez Calzón, Julio. Puentes, estructuras, actitudes. Madrid: Turner, 2006.Massip-Bosch, Enric. "Formas del pragmatic". Bau – Arquitectura, Urbanismo, Arte y Dise-o 21 (2001): 24.Mu-oz, Josep M. "Enric Tous. L'altra modernitat". L'Avenç 392 (2013): 20.Muschamp, Hebert. "The Temple of Marketing". Hearts of the city: the selected writings of Herbert Muschamp. Nueva York: Alfred A. Knopf, 2009.Ockman, Joan. "Pragmatismo y arquitectura". AV Monografías 91 (2001): 4-7.Rajchman, John. "Arquitectura y pragmatismo: una nueva introducción". Bau – Arquitectura, Urbanismo, Arte y Dise-o 21 (2001): 16.Venturi, Robert; Scott Brown, Denise and Izenour, Steven. Learning from Las Vegas. Cambridge, Mass; London, England: The MIT Press, 1972.Wolf, Tom. ¿Quién teme al Bauhaus feroz? El arquitecto como mandarín. Barcelona: Anagrama, 1982

'Mediterranean' dietary pattern for the primary prevention of cardiovascular disease

It is well established that diet plays a major role in cardiovascular disease risk. The traditional Mediterranean dietary pattern is of particular interest because of observations from the 1960s that populations in countries of the Mediterranean region, such as Greece and Italy, had lower mortality from cardiovascular disease compared with northern European populations or the US, probably as a result of different eating habits. This review assessed the effects of providing dietary advice to follow a Mediterranean-style dietary pattern to healthy adults or people at increased risk of cardiovascular disease in order to prevent the occurrence of cardiovascular disease and reduce the risk factors associated with it. Definitions of a Mediterranean dietary pattern vary and we included only randomised controlled trials (RCTs) of interventions that reported at least two of the following components: (1) high monounsaturated/saturated fat ratio, (2) low to moderate red wine consumption, (3) high consumption of legumes, (4) high consumption of grains and cereals, (5) high consumption of fruits and vegetables, (6) low consumption of meat and meat products and increased consumption of fish, and (7) moderate consumption of milk and dairy products. The control group was no intervention or minimal intervention. We found 11 RCTs (15 papers) that met these criteria. The trials varied enormously in the participants recruited and the different dietary interventions. Four trials were conducted in women only, two trials were in men only and the remaining five were in both men and women. Five trials were conducted in healthy individuals and six trials were in people at increased risk of cardiovascular disease or cancer. The number of components relevant to a Mediterranean dietary pattern ranged from two to five and only seven trials described the intervention as a Mediterranean diet. The largest trial, which recruited only postmenopausal women and was not described as a Mediterranean diet meeting only two of the criteria described above, reported no difference in the occurrence of cardiovascular disease between the dietary advice group and the control group. The other trials measured risk factors for cardiovascular disease. As the studies were so different, it was not possible to combine studies for most of the outcomes. Where it was possible to combine studies, we found small reductions in total cholesterol levels as well as in the harmful low-density lipoprotein (LDL) cholesterol concentrations. The reductions in total cholesterol were greater in the studies that described themselves as providing a Mediterranean diet. None of the trials reported side effects. The review concludes that, from the limited evidence to date, a Mediterranean dietary pattern reduces some cardiovascular risk factors. However, more trials are needed to look at the effects of the different participants recruited and the different dietary interventions to see which interventions might work best in different populations

Anticipatory Buffer Control and Quality Selection for Wireless Video Streaming

Video streaming is in high demand by mobile users, as recent studies indicate. In cellular networks, however, the unreliable wireless channel leads to two major problems. Poor channel states degrade video quality and interrupt the playback when a user cannot sufficiently fill its local playout buffer: buffer underruns occur. In contrast to that, good channel conditions cause common greedy buffering schemes to pile up very long buffers. Such over-buffering wastes expensive wireless channel capacity. To keep buffering in balance, we employ a novel approach. Assuming that we can predict data rates, we plan the quality and download time of the video segments ahead. This anticipatory scheduling avoids buffer underruns by downloading a large number of segments before a channel outage occurs, without wasting wireless capacity by excessive buffering. We formalize this approach as an optimization problem and derive practical heuristics for segmented video streaming protocols (e.g., HLS or MPEG DASH). Simulation results and testbed measurements show that our solution essentially eliminates playback interruptions without significantly decreasing video quality