WiMAX Handbook: Building 802.16 Wireless Networks
Describing how WiMAX affects current telecom technologies including Wi-Fi, fiber optics, and VoIP, this book discusses the business and economic implications of this ground-breaking technology.
TABLE OF CONTENTS WiMAX Handbook: Building 802.16 Wireless Networks
Planning
A link budget will tell what is practical given the environment and how to plan cells. With a link budget, one can estimate how many cells will be required for the project. There are trade-offs between more cells and running more power. For an outdoor application, also consider checking the Fresnel zone. For example, the trade-off between working on one long-distance shot versus two back-to-back links can be discovered by working out a few things on paper first.
Fresnel Zone
For a point-to-point shot, it is important to understand the effects of the Fresnel zone. The signal extending from the transmitting antenna forms an ever-expanding cone. Although some of the signal travels directly in the line of sight along the center of the cone, other parts of the signal reradiate off of points along the way. At the receiver, signals from the direct line of sight indirectly cancel and add to each other. The first Fresnel zone is the surface containing every point for which the sum of the distances from that point to the two ends of the path is exactly wavelength longer than the direct end-to-end path. The second Fresnel zone is the surface containing every point for which the sum of the distances from that point to the two ends of the path is exactly one wavelength longer than the direct end-to-end path. Figure A-4 shows the first and second Fresnel zones.
Figure A-4: First and second Fresnel zones
One can calculate the perpendicular distance...
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