Wireless Infrared Communications

Front Cover
Springer Science & Business Media, Aug 31, 1994 - Technology & Engineering - 181 pages
The demand for wireless access to network services is growing in virtually all communications and computing applications. Once accustomed to unteathered opera tion, users resent being tied to a desk or a fixed location, but will endure it when there is some substantial benefit, such as higher resolution or bandwidth. Recent technolog ical advances, however, such as the scaling of VLSI, the development of low-power circuit design techniques and architectures, increasing battery energy capacity, and advanced displays, are rapidly improving the capabilities of wireless devices. Many of the technological advances contributing to this revolution pertain to the wireless medium itself. There are two viable media: radio and optical. In radio, spread-spectrum techniques allow different users and services to coexist in the same bandwidth, and new microwave frequencies with plentiful bandwidth become viable as the speed of the supporting low-cost electronics increases. Radio has the advantage of being available ubiquitously indoors and outdoors, with the possibility of a seam less system infrastructure that allows users to move between the two. There are unan swered (but likely to be benign) biological effects of microwave radiation at higher power densities. Optical communications is enhanced by advances in photonic devices, such as semiconductor lasers and detectors. Optical is primarily an indoor technology - where it need not compete with sunlight - and offers advantages such as the immediate availability of a broad bandwidth without the need for regulatory approval.
 

Contents

Introduction
1
11 Comparison of Infrared and Radio Communications
2
12 The Wireless Infrared Communications
3
13 History of Wireless Infrared Communications
6
14 A HighSpeed Wireless LAN
10
15 Optoelectronic Components
11
16 Outline
12
Link Analysis and Optics Design
15
43 MultipleBounce Impulse Response
84
44 Simulation and Experimental Results
87
45 MultipathInduced Power Penalty
102
46 Summary
107
Modulation and Equalization
109
52 Binary Modulation
112
53 MultiLevel Modulation
120
54 Discussion
133

22 ThinFilm Optical Filters
17
23 Truncated Spherical Concentrators
24
24 Joint Optimization of Transmitter and Filter
37
25 Summary and Conclusions
46
Receiver Design
49
32 Limitations on Photodetector Bandwidth
51
33 Analysis of CurrentFeedback Pair
52
34 Optimal Filtering for Quadratic Noise Spectrum
57
35 Choosing the Right Transistor and Filter
59
36 Design Procedures
60
37 Optional Design Embellishments
68
38 Summary and Conclusions
77
Modeling Multipath Dispersion
79
42 Models for Diffuse Reflectors and Transmitters
81
55 ML Sequence Detection and Equalization for PPM
135
56 Coherent Optical Communication
146
57 Summary
147
SystemLevel Issues
149
62 SingleCell Architectures
150
63 Overlapping Cells
153
64 Summary
158
Conclusions and Future Work
161
72 Future Work
162
References
167
Power Efficiency on the Linear Gaussian Noise Channel
175
Index
179
Copyright

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