Wireless+Networking+in+the+Developing+World_Part19

Wireless+Networking+in+the+Developing+World_Part19 - Figure...

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Unformatted text preview: Figure 11.19: Schematic representing Santiago-2006 FLISOL video streaming transmission, using free software. The wireless transmission speed achieved was 36 Mbps at 1 km. Chapter 11: Case Studies 351 Figure 11.20: Quiani node. This is one of the world’s highest nodes. Its located at an elevation of 4000 m, about 2000 km north of the country’s capital. Figure 11.21: Node in southern Santiago, consisting of a 15 m tower, a Trevor Marshall 16+16 antenna, and 30 clients. The node is connected to a downtown node more than 12 km away. 352 Chapter 11: Case Studies Figure 11.22: Panoramic view of a node from the top of the tower. Figure 11.23: Downtown node connected to the Santiago southern node. Note the parabolic antenna for backhaul and the slotted antenna to connect the clients. Chapter 11: Case Studies 353 Figure 11.24: Implementation of node over a water tower in Batuco, Metropolitan Region, providing backhaul to Cabrati telecenter. Figure 11.25: Workshop on Yagi antennas organized by our community. Participants are building their own antennas. 354 Chapter 11: Case Studies Credits Our community is made up of a group of committed volunteer associates among which are worthy of notice: Felipe Cortez (Pulpo), Felipe Benavides (Colcad), Mario Wagenknecht (Kaneda), Daniel Ortiz (Zaterio), Cesar Urquejo (Xeuron), Oscar Vasquez (Machine), Jose San Martin (Packet), Carlos Campano (Campano), Christian Vasquez (Crossfading), Andres Peralta (Cantenario), Ariel Orellana (Ariel), Miguel Bizama (Picunche), Eric Azua (Mr. Floppy), David Paco (Dpaco), Marcelo Jara (Alaska).--Chilesincables.org Case study: Long Distance 802.11 Thanks to a favorable topography, Venezuela already has some long range WLAN links, like the 70 km long operated by Fundacite Mérida between Pico Espejo and Canagua. To test the limits of this technology, it is necessary to find a path with an unob- structed line of sight and a clearance of at least 60% of the first Fresnel zone. While looking at the terrain in Venezuela, in search of a stretch with high ele- vation at the ends and low ground in between, I f rst focused in the Guayana region. Although plenty of high grounds are to be found, in particular the fa- mous "tepuys" (tall mesas with steep walls), there were always obstacles in the middle ground. My attention shifted to the Andes, whose steep slopes (rising abruptly from the plains) proved adequate to the task. For several years, I have been trav- eling through sparsely populated areas due to my passion for mountain bik- ing. In the back of my head, I kept a record of the suitability of different spots for long distance communications. Pico del Aguila is a very favorable place. It has an altitude of 4200 m and is about a two hour drive from my home town of Mérida. For the other end, I f nally located the town of El Baúl, in Cojedes State. Using the free software Radio Mobile (available at http://www.cplus.org/rmw/english1.html ), I found that there was no obstruction of the f rst Fresnel zone (spanning 280 km) between Pico del Aguila and El Baúl....
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Wireless+Networking+in+the+Developing+World_Part19 - Figure...

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