long distance wifi trial.pdf

Long Distance WiFi Trial Ermanno Pietrosemoli Long Distance WiFi Trial EsLaRed-ULA .ve Ermanno Pietrosemoli Venezuela International Summit for EsLaRed-ULA Community Wireless Networks Venezuela Columbia, Md. May 18, 2007 Pico del Aguila Motivation • For rural area, Wireless is the only economically feasible solution for achieving digital inclusion • WiFi is by far the less expensive technology available, and can provide voice and data • Interference is less severe in sparsely populated areas Pietrosemoli 2 WiFi LD Background • 70 km link operational in Merida since 2001 • Swedish space agency 300 km transmission towards a stratospheric balloon • Defcon contest in 2004 achieved 125 miles w/o amplifiers Pietrosemoli 3 WiFi LD Background • EHAS program for health maintenance support in rural areas • Berkeley’s TIER group activities in several countries • EsLaRed 279 km link with 100 mW transmitters and repurposed antennas in 2006 Pietrosemoli 4 Issues • MAC of WiFi designed for up to 100 m, extending the range two orders of magnitude requires modifications • CSMA/CA not well suited for Pt-Pt links • Established Telecom operators vested interests Pietrosemoli 5 279 km path Pietrosemoli 6 279 km path