New long distance record with wifi connection : 382 Km via : http://www.eslared.org.ve/articulos/Long%20Distance%20WiFi%20Trial.pdf

1. Long Distance WiFi Trial
Long Ermanno Pietrosemoli
Distance WiFi Trial
EsLaRed-ULA
www.eslared.org.ve
Ermanno Pietrosemoli
Venezuela
International Summit for
EsLaRed-ULA
Community Wireless Networks
Venezuela
Columbia, Md. May 18, 2007
Pico del Aguila

2. 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

3. 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

4. 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

5. 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

6. 279 km path
Pietrosemoli 6

7. 279 km path
Pietrosemoli 7

8. Aerial view of El Aguila site
Pietrosemoli 8

9. View from El Aguila site
Pietrosemoli 9

10. El Baul Site
Accounting for the declination, we aimed the antenna
to a bearing of 277 degrees
Pietrosemoli 10

11. TIER Wireless routers at Baul
Pietrosemoli 11

12. We were able to establish a video and audio
communication over the 279 km path:
Iperf showed a
solid throughput
greater than 3
Mbps in both
directions
Pietrosemoli 12

13. With the Linksys WRT54
Pietrosemoli 13

14. With the Linksys WRT54
The measured
throughput
was above 65
kbps, enough
to sustain an
audio and
video session:
Pietrosemoli 14

15. Can we do better?
Pietrosemoli 15

16. From Platillon:
Pietrosemoli 16

17. Aguila-Platillon (382 km)
• We tried at different power • The Iperf results for the 382 km
settings and there was a link with TIER routers and
considerable variation on the TDMA:merida2:~# ping
results, 10.0.200.12PING 10.0.200.12
(10.0.200.12) from 10.0.200.12 :
• So we concluded that although
56(84) bytes of data.64 bytes from
communication over this path
10.0.200.12: icmp_seq=1 ttl=64
is feasible, further testing are
time=0.745 ms64 bytes from
required to ascertain the
10.0.200.12: icmp_seq=2 ttl=64
stability of this kind of links.
time=0.399 ms64 bytes from
10.0.200.12: icmp_seq=3 ttl=64
time=0.399 ms--- 10.0.200.12
ping statistics ---3 packets
transmitted, 3 received, 0% loss,
time 2003msrtt min/avg/max/mdev
= 0.399/0.514/0.745/0.164
Pietrosemoli 17

18. We then repeated the experiment
over the 382 km path using two
Linksys boxes, obtaining the following results:
• --10.0.1.1 ping statistics ---58 packets
transmitted, 57 received, 1% packet loss,
time 57569 ms rtt
• min/avg/max/mdev =
6.165/11.990/40.591/8.011 ms
Pietrosemoli 18

19. Acknowledgements
• This work was funded by ICA-IDRC
• Dr. Eric Brewer from Berkeley University
provided the wireless routers with the modified
MAC for long distance, as well as enthusiastic
support through his collaborator, Sonesh Surana
• RedULA, CPTM, Dirección de Servicios ULA
and Fundacite Mérida contributed to this trial
• Roger Coudé, author of the free Radio Mobile
Software, which has been so useful to the
international wireless community
Pietrosemoli 19

20. Members of the Team
El Aguila Baúl and Platillón sites
• Javier Triviño, EsLaRed • Leonardo González V.,
Dirección de Servicios –
• José Torres M., CPTM-
ULA
ULA
• Alejandro González,
• Francisco Torres N.,
RedULA
RedULA
• Leonardo González G.,
EsLaRed
• Ermanno Pietrosemoli,
EsLaRed
Pietrosemoli 20

21. Conclusions
• WiFi is a viable and economic means for
wireless links at distances of hundreds of
kilometers when a good LOS is available.
• TDMA over WiFi as implemented by the
TIER group of UC Berkeley has shown a
remarkable throughput greater than 3
Mbps over a 300 km on a Pt- to- Pt link.
Pietrosemoli 21