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Designing A Free Space Optical/Wireless Link

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2005 Annual Conference


Portland, Oregon

Publication Date

June 12, 2005

Start Date

June 12, 2005

End Date

June 15, 2005



Conference Session

Curriculum Development in Computer/Communications ET

Page Count


Page Numbers

10.416.1 - 10.416.13



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Paper Authors

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Chandra Sekhar

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Jai Agrawal

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Omer Farook

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NOTE: The first page of text has been automatically extracted and included below in lieu of an abstract

Session: 2247 Designing A Free-Space Optical/Wireless Link

Jai P. Agrawal, Omer Farook and C.R. Sekhar

Department of Electrical and Computer Engineering Technology Purdue University Calumet


This paper presents the design of a very high-speed data link between two buildings in a University campus that will operate at gigabit rates. The project uses a cutting edge technology of eye-safe laser communication through free space. This is an all-optical design is future-proof in regards to technological advancement in the rate of data transmission and introduction of newer protocols. The two buildings are approximately 500 meters apart. The free-space optical link uses 1550 nm wavelength in normal usage but has a wireless link operating at 2.4 GHz as the back-up. The line of site alignment will be achieved using telescopes initially but will have automatic tracking alignment system. The wireless back-up link is used only in very dense fog conditions. This paper presents the design of only the free-space optical connection, some parts of which are implemented in laboratory setup.

I. Introduction

The technology of establishing a high-speed networking between two buildings or campuses is one of the three: 1) copper wire, 2) wireless and 2) optical fiber technology. The copper technology is low-speed, labor-intensive and requires a regime of permissions. The advantages are high reliability and full availability. The wireless technology uses a few GHz carrier, is medium speed (up to few Gigabits per second), has small link span and requires a regime of licenses. Advantage is the ease of deployment. The disadvantages are low reliability (high bit error rate) and severe fading in rain.

Fiber optic technology poses no foreseeable limit in speed, enables large link span, and has high reliability (very low reliability) and full availability. Laying optical fiber in the ground requires huge expenses and a considerable time and efforts go in obtaining permissions from various agencies[1]. Once laid, the fiber cannot be re-deployed easily. Capital expenditure (CapEx) is tied directly to the off –network customer. If the customer is lost, so is the CapEx. Furthermore, trenching may run into physical obstructions.

Proceedings of the 2004 American Society for Engineering Education Annual Conference & Exposition Copyright © 2004, American Society for Engineering Education

Sekhar, C., & Agrawal, J., & Farook, O. (2005, June), Designing A Free Space Optical/Wireless Link Paper presented at 2005 Annual Conference, Portland, Oregon. 10.18260/1-2--14283

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