Wireless:LongLinks

From TIER

Wireless Group at ICTP, Trieste

Marco, Ermanno, Steve and others setup a long distance link from the Galileo to Piancavallo (about 101 km long) using TIER routers and 28 dBi fixed dish antennas in February 2007.

Details are here with pictures.

EsLaRed in Venezuela

Ermanno and his group tried a 279 km link El Baul to Aguila and a 382 km link from Platillon to Aguila using TIER routers in April 2007.

Report on the trial is here.

Some pictures: http://www.cs.berkeley.edu/~sonesh/venezuela/

Details from Ermanno:

We have finally been able to perform the test on 279 km path previously used last year, using the link you provided and a couple of commercial 30 dBi antennas (sold by Hyperlink).

The experiment confirmed the feasability of links of this length. We got an asymmetrical thruput of up to 1 Mbps with CSMA and an astonishing symmetrical thruput of 3 Mbps (both directions) with TDMA. We were able to pass video and audio on the link with good quality.

We were also able to establish a link on the same path using Linksys routers and the same antennas. The throughput was only 65 kbps with the Linksys but we managed to run video as well.

Next we moved one end of the link to a new path that I had identified at a distance of 382.6 km (237,8 Miles) (2.6 F1 clearance, 4200 m at one end, 1540 m at the other end). Again we were able to establish a link with the TIER routers, both with CDMA and TDMA. This link proved to lack stability, and we would loose connection from time to time, but we were still able to attain 2 Mbps with TDMA in one instance.

Again, we also tried with the Linksys and were able to transmit video and audio and attained a 65 kbps thruput, but would loose the signal occasionally. We had to use a 500 mW, 17 dB bidirectional amplifier at one end with the Linksys. Ping times were around 20 ms although there was a strong variation.

The coordinates for the Aguila Site are 8 deg 49'47" N, 70 deg 50'07"W, h=4200 mm, El Baul, 8 deg 57'27.6"N, 68 deg 17'51.1 " W (279 km to Aguila), Platillon: 9 deg 51' 33"N, 67 deg 31' 19.1"W, h= 1540 m, 382 km to Aguila with 264 magnetic bearing.

In conclusion, the routers that you provided attained 3Mbps in both directions at a distance of 279 km with the TIER MAC, and were able to establish a link at 382 km although in the latter there was a lot of fading in the signal and the connection was not stable.

Report about the 279 km link testing in 2006 is here.