Domain-specific integrated development environments can help capture specifications in the form of domain models. These tools support the design process by automating analysis and simulating essential system behavior. In addition, they can automatically generate, configure, and integrate target application components. The high cost of developing domain-specific, integrated modeling, analysis, and application-generation environments prevents their penetration into narrower engineering fields that have limited user bases. Model-integrated computing (MIC), an approach to model-based engineering that helps compose domain-specific design environments rapidly and cost effectively, is particularly relevant for specialized computer-based systems domains-perhaps even single projects. The authors describe how MIC provides a way to compose such environments cost effectively and rapidly by using a metalevel architecture to specify the domain-specific modeling language and integrity constraints. They also discuss the toolset that implements MIC and describe a practical application in which using the technology in a tool environment for the process industry led to significant reductions in development and maintenance costs.

Smart Dust: communicating with a cubic-millimeter computer

Solid-state lighting is a rapidly growing area of research and applications, due to the reliability and predicted high efficiency of these devices. The white LED sources that are typically used for general illumination can also be used for data transmission, and Visible Light Communications (VLC) is a rapidly growing area of research. One of the key challenges is the limited modulation bandwidth of sources, typically several MHz. However, as a room or coverage space would typically be illuminated by an array of LEDs there is the potential for parallel data transmission, and using optical MIMO techniques is potentially attractive for achieving high data rates. In this paper we investigate non-imaging and imaging MIMO approaches: a non-imaging optical MIMO system does not perform properly at all receiver positions due to symmetry, but an imaging based system can operate under all foreseeable circumstances. Simulations show such systems can operate at several hundred Mbit/s, and up to Gbit/s in many circumstances.

High data rate multiple input multiple output (MIMO) optical wireless communications using white led lighting

Visible Light Communication (VLC) is an emerging field in Optical Wireless Communication (OWC) which utilizes the superior modulation bandwidth of Light Emitting Diodes (LEDs) to transmit data. In modern day communication systems, the most popular frequency band is Radio Frequency (RF) mainly due to little interference and good coverage. However, the rapidly dwindling RF spectrum along with increasing wireless network traffic has substantiated the need for greater bandwidth and spectral relief. By combining illumination and communication, VLC provides ubiquitous communication while addressing the shortfalls and limitations of RF communication. This paper provides a comprehensive survey on VLC with an emphasis on challenges faced in indoor applications over the period 1979–2014. VLC is compared with infrared (IR) and RF systems and the necessity for using this beneficial technology in communication systems is justified. The advantages of LEDs compared to traditional lighting technologies are discussed and comparison is done between different types of LEDs currently available. Modulation schemes and dimming techniques for indoor VLC are discussed in detail. Methods needed to improve VLC system performance such as filtering, equalization, compensation, and beamforming are also presented. The recent progress made by various research groups in this field is discussed along with the possible applications of this technology. Finally, the limitations of VLC as well as the probable future directions are presented.

LED Based Indoor Visible Light Communications: State of the Art

Wireless Optical Communication Systems addresses the problem of designing efficient signaling and provides a link between the areas of communication theory and modem design for amplitude constrained linear optical intensity channel. Topics include historical perspective, channel impairments, amplitude constraints and the characteristics of popular optoelectronic components. A variety of wireless optical channel topologies are presented along with a survey and analysis of present day signalling techniques employed for these channels. The author provides a unifying framework for signalling design which allows the channel constraints to be represented geometrically and permits the use of modem design principles from electrical channels. Modulation schemes are designed using the formalism of lattice codes and a design process for signalling sets is specified. The use of multiple-input/multiple-output (MIMO) wireless optical channels to improve the spectral efficiency of links is explored. The basic spatio-temporal modem design problem is specified and a spatial multiplexing gain is quantified. New spatial discrete multitone modulation is proposed and the unique features are discussed. Based on measurements on an experimental prototype, a channel model is formulated and a realizable spatio-temporal coding scheme is simulated to quantify performance gains. This volume is organized for professional and academic readers engaged in modem design for wireless optical intensity channels. Significant background material is presented on both the properties as well as on fundamental communications principles. Wireless Optical Communication Systems can be used by physicists and experimentalists as an introduction to signalling design as well as communication systems designers.

Wireless Optical Communication Systems

A method for interpreting at least two consecutive gestures includes providing a sensing assembly having at least one photoreceiver and a plurality of phototransmitters, wherein each phototransmitter is positioned to emit infrared light away from the electronic device about a corresponding central transmission axis, wherein each central transmission axis is oriented in a different direction with respect to the others, and controlling emission of infrared light by each of the phototransmitters during each of a plurality of time periods. During each of the plurality of phototransmitters and for each of the plurality of time periods, a corresponding measured signal is generated which is indicative of a respective amount of infrared light which originated from that phototransmitter during that time period and was reflected by the external object prior to being received by a photoreceiver. The measured signals are evaluated to identity a first gesture, and the electronic device is controlled in response to identification of the first gesture according to a first mode of operation. A parameter of a second gesture is also determined, and the electronic device is controlled in response to the determined parameter of the second gesture according to a second mode of operation.

Electronic device with sensing assembly and method for interpreting offset gestures

We discuss two modifications to the design of wireless infrared links that can yield significant performance improvements, albeit at the price of increased complexity. In line-of-sight and non-line-of-sight links, replacement of a single-element receiver by one employing an imaging light concentrator and a segmented photodetector can reduce received ambient light noise and multipath distortion. For a fixed receiver entrance area, such an imaging receiver can reduce transmit power requirements by as much as about 14 dB, depending on the link design and the number of photodetector segments. Imaging receivers also reduce co-channel interference, and may therefore enable infrared wireless networks to employ space-division multiplexing, wherein several transmitters located in close proximity can transmit simultaneously at the same wavelength. In nondirected non-line-of-sight links, replacement of the diffuse transmitter by one that projects multiple narrow beams can reduce the path loss, further reducing the transmit power requirement by several decibels. We describe the design of an experimental 100 Mb/s infrared wireless link employing a multibeam transmitter and a 37-pixel imaging receiver.

Beh Kian Teik

Papers

Imaging diversity receivers for high-speed infrared wireless communication