Optical Wireless Communications: IR for Wireless Connectivity
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Summary
Over the last three decades, interest in Infrared (IR) technology as a medium to convey information has grown considerably. This is reflected by the increasing number of devices such as laptops, PDAs, and mobile phones that incorporate optical wireless transceivers and also by the increasing number of optical wireless links available for indoor and outdoor use. The popularity of IR is based on the advantages it has over radio including unregulated bandwidth, immunity to radio interference, and inherent security.
Optical Wireless Communications examines some of the most important features of optical wireless communication systems. It considers the benefits and limitations of IR as a medium conveying information wirelessly and compares the advantages and disadvantages of infrared to microwave and other radio systems. It also details the evolution of IR communication systems and describes atmospheric and other types of data transmission limitations.
The book presents design fundamentals of optical concentrators, as well as a review of some of the most important receiver optical front-ends (containing imaging or non-imaging concentrators and optical filters), including an explanation of the different sources of infrared noise and an introduction to eye safety. It also describes optical wireless transmitter and receiver design issues, typical modulation, coding, and multiple access techniques, and introduces IrDA protocols and wireless IR networking.
Table of Contents
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 Fermat's 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
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