Roberto Ramirez-Iniguez

Optical wireless communications : IR for wireless connectivity

INTRODUCTION Technology Overview System Configurations Evolution of Infrared Communication Systems The Optical Wireless Channel Design Fundamentals Power Budget Considerations Summary and Conclusions ATMOSPHERIC TRANSMISSION LIMITATIONS Introduction to Atmospheric Propagation Important Definitions Atmospheric Transmission Effect of Rain, Fog, and Mist Scintillation Summary and Conclusions DATA TRANSMISSION LIMITATIONS AND EYE SAFETY Data Transmission Limitations Eye Safety Extended vs. Collimated Sources Holographic Diffusers LEDs vs. LDs Special Considerations for Outdoor Systems Summary and Conclusions FUNDAMENTALS OF OPTICAL CONCENTRATION Overview of Optical Concentration Geometrical Optics and Ray Tracing Optical Path Length and Fermats Principle The Etendue or Lagrange Invariant The Edge Ray Principle Concentration Ratio Summary and Conclusions OPTICAL CONCENTRATORS Overview of Optical Concentrators Wireless IR Receiver Requirements Optical Filters Optical Concentrators DTIRC Characteristics Comparison of Concentrators Practical Issues Other Shapes of DTIRCs Summary and Conclusions OPTICAL WIRELESS TRANSMITTER DESIGN Introduction to Optical Wireless Transmitter Design Transmitter Design Considerations Optical Source Characteristics Types of Optical Modulation Driver Circuit Design Concepts Current Steering Output Circuit Back Termination Circuit Predriver Data Retiming Automatic Power Control Transmitters Linearization Techniques OPTICAL WIRELESS RECEIVER DESIGN Receiver Design Considerations Photodetection in Reverse-biased Diodes Choosing the Photodetector Receiver Noise Consideration Bit Error Rate and Sensitivity Bandwidth Signal Amplification Techniques Receiver Main Amplifier (RMA) Transceiver Circuit Implementation Technologies: Hybrid and Monolithic Integration Summary and Conclusions MODULATION, CODING, AND MULTIPLE ACCESS Introduction to Modulation and Multiple Access Techniques Modulation Modulation Techniques Comparison Modulation Schemes in The Presence of Noise Modulation Schemes in the Presence of Multipath Distortion Multiple Access Techniques Summary and Conclusions IrDA PROTOCOLS Wireless Protocol Standards The Infrared Data Association IrDA Standard Overview The Physical Layer Protocol Framer/Driver IrLAP IrLMP Information Access Service and Protocol Tiny Transport Protocol Session and Application Layer Protocols Summary and Conclusions WIRELESS IR NETWORKING Introduction to Wireless IR Networking Network Architecture Optical Wireless Network Specifications The Ad Hoc Network Quality of Service (QoS) Future Infrared Networking REFERENCES

Feed-In Tariff for solar PV in Malaysia: Financial analysis and public perspective

Malaysia is joining the global race for solar photovoltaics (PVs), where the Feed-In Tariff (FIT) mechanism has been introduced recently. This paper presents, first, a chronological overview of solar PV in Malaysia until the present time. Next, a general concept of the FIT Malaysia is explained and a financial analysis is carried out, comparing the return on investment of installing solar PV in different locations in Malaysia, as well as in other countries. The paper also shows a preliminary survey conducted to Malaysians to see their awareness on the national initiatives related to green technologies and their likelihood to invest in the FIT scheme. The financial analysis indicates that installation of PV in Malaysia could potentially generate good investment return during the duration of a contract. The survey on the other hand suggests that Malaysians are not aware of the national initiatives and are not willing to invest in solar PV installation.

Optimised dielectric totally internally reflecting concentrator for the solar photonic optoelectronic transformer system: maximum concentration method

Renewable energies have become a matter of global attention during the last few years, with solar energy being a major focus. Building Integrated Photovoltaic (BIPV) system is an example of solar energy applications. This paper describes the Solar Photonic Optoelectronic Transformer (SPOT) system, one of the components in the SolarBrane, a BIPV system developed by SolarEmpower Ltd. The general design of a dielectric totally internally reflecting concentrator (DTIRC) is described. The process of designing an optimized solar concentrator using the maximum concentration method (MCM) for the SPOT system is also outlined with detailed steps on the simulation setup presented. The paper then compares the performance of the new concentrator with the current concentrator design. The results from the MATLAB simulation shows that the MCM offers a higher geometrical concentration gain, with a slight increase in the concentrator size.

Performance analysis of a DTIRC-LED illumination structure

The Dielectric Total Internal Reflecting Concentrator (DTIRC) is a type of non-imaging optic that has been used in the past to increase the collection efficiency of photovoltaic (PV) cells and photodetectors. It does this by redirecting energy impinging on its largest aperture to a smaller aperture to which the absorber is attached. This paper explores the use of non-imaging optics for light emission control when combined with a Light Emitting Diode (LED). In this case, the smallest aperture of the concentrator acts as its input and the largest aperture as the output. This allows control of the angular characteristics of the emitted light beam and an increase of the illuminance at the target plane, which is of particular relevance in applications such as illumination and optical wireless communications. Its compact size and design characteristics make the DTIRC a more desirable geometry compared to other non-imaging optics when used as a first or secondary optic to control the emission characteristics of a light source. This paper reports the correlation between simulation and experimental results that validate the ability of DTIRCs to collimate the output beam of extended light sources.

Pose calibrations for inertial sensors in rehabilitation applications

Inertial motion capture systems are now used across a broad range of applications where optical motion capture systems would traditionally be used. The decreasing cost of building inertial sensors has prompted many researchers to build inertial motion capture systems for use in rehabilitation applications where they are used to track body movement. Pose calibrations are the standard method used to estimate and correct for body-sensor alignment when using inertial sensors but they have the potential to introduce a systematic error that is carried through the whole usage session. Pose calibrations are the only suitable method for inexpert users and interactive applications. Validation of the pose calibration methods is carried out using an optical motion capture system. The accuracy of the pose calibration is tested under several practical variations of the technique, we quantify the approximate errors that can be introduced by variations of the implementation and on the choice of pose used. Finally we make recommendations on how an improved pose calibration scheme should be implemented.

Analysis of uniformity of illumination of a freeform lens when combined with different optical sources

This paper presents the performance analysis of a freeform lens that can be used as a first or secondary optic when combined with a point or an extended light source. The light source can be an LED. The purpose of the optic is to increase uniformity of illumination within the footprint. The analysis is performed on the freeform lens when combined with: (i) an isotopic or a Lambertian point light source (ii) an isotropic or a Lambertian extended light source. This paper shows that through a design based on energy mapping between a light source and a target plane it is possible to achieve uniform illumination. The ZEMAX ray tracing simulation shows that the uniformity reduces gradually when the size of the light source increases. The results indicate that a freeform lens combined with a point source can generate over 95% uniformity.

Novel non-imaging optic design for uniform illumination

The Dielectric Totally Internally Reflecting Concentrator (DTIRC) has been developed in the past for wireless infrared communications and solar energy applications. This paper proposes a novel non-imaging optic design based on the DTIRC family of concentrators for use in illumination applications. The novel optic can be integrated with a light emitting diode (LED) and can be tailored to meet specific requirements. The proposed optic can be used as a first or secondary optic to provide uniform illumination within a circular footprint with a desired radius. The results from this work show that, with the optimised DTIRC, it is possible to achieve a uniformity of illuminance of over 95%.

Indoor localization based on multiple LEDs position estimation

This paper describes the simulation results and hardware implementation of an inexpensive, low-complexity LED based indoor positioning system. Localization by multiple LEDs estimation model (MLEM) approximates position of a mobile receiver by the acquisition of positional information from LED transmitters. Multiple LED orientation can either be with or without overlap. Receivers in a no-overlap LED orientation experience only single access while multiple access receivers are designed for orientations with overlaps. Single and multiple access systems were developed and implemented by the use of low cost ATMEG 328 microcontroller. Since multiple LEDs transmit data at the same wavelength and are asynchronous, overlap in multiple access system causes interference. The possibility of this interference is reduced by packet based pulse duration multiplexing (PDM) and a low duty cycle transmission protocol. By the use of MLEM, root mean square error in position estimation is reduced to about 1 percent of the length an indoor location. Experimental results show that overlap increases positional accuracy over a wider coverage region and that the multiple access system allows for a more reliable positioning.

Rotationally asymmetric optical concentrators for solar PV and BIPV systems

Building Integrated Concentrated Photovoltaic (BICPV) systems are one of the options to reduce the dependency on fossil fuels and minimise energy consumption in buildings. These systems not only contribute to the generation of electricity, but also to the reduction of energy consumption by allowing the passage of ambient light and by making use of the cogenerated heat for indoor heating and/or cooling. This paper presents a novel optical concentrator called Rotationally Asymmetric Dielectric Totally Internally Reflecting Concentrator (RADTIRC) for use in BICPV systems. The RADTIRC-PV structure is capable of providing a maximum power concentration of 4.2x. Key benefits of this technology include: reduction of cost of BICPV systems, flexibility of design, and higher electrical power outputs.

Soft loan for domestic installation of solar photovoltaic in Malaysia: Is it the best option?

Malaysia has passed the Renewable Energy Act in April 2011, in which the Feed-In Tariff (FiT) mechanism is introduced. The FiT gives much emphasis on the solar photovoltaic (PV). This paper presents, first, an overview of solar PV in Malaysia until the present time. Next, a general concept of the FIT Malaysia is explained and finally the loan financing option for solar PV is presented. It also analyses the impact of the proposed interest rate to household consumers in Malaysia, in terms of the total profit, the net present value and the internal rate of return. It is found that the FiT scheme could potentially help in increasing renewable energy penetration, particularly for solar PV. To provide upfront capital for domestic solar PV installation, the soft loan facility from banking institutions is a feasible source if the interest rate is 5% or less.