Over the last few of weeks the networking team has been working hard in getting together a concrete plan, to connect the pilot schools. The network had to be both cost effective as well scalable. So, with all the options available it was decided to connect the schools and the relays over Wireless with cheap point to point Wi-Fi radios from the Kathmandu Valley.
First we conducted field visits to the schools and the Dept of Education (DOE) in the valley and the surrounding area to collect GPS data. Which helped us a great deal with the network design and also chart out the various relay points we could use in places where we didn’t have direct line of sight with other network nodes.
We are using Deliberant brand of radios for the point-to-point connection to the Department of Education. The radio have an effective bandwidth 8 Mbps in the 802.11b standard. The radios from the schools are transmitting at an air distance of 4 km to the DOE located in the valley, which is right next to the international airport, so we’d figured we would be having interferences.
We are using 12 dbi omni-directional antennas from Deliberant Networks, on-site at both schools, powere by a DLB2701 radio. We decided not use the Active Antennas, as they didn’t quite perform upto our expectations. The 250 mw radio is the access point for the XO’s. It costs roughly 150 USD and has a range of 12 km in ideal conditions. We also do not intend to use VSAT for any of Nepal’s pilot schools. Though installation is not terribly expensive but monthly bandwidth charges are prohibitively expensive when compared with the cost of long-range wifi networks, as pioneered by Nepal Wireless Project.
Below is the connectivity diagram between OLE-DOE and the pilot schools. DOE is connected to Ratobangla School in the valley over Canopy radios. And further relays to both schools with a 19dbi Deliberant radio. The radio at DOE is being used as a point to multi-point radio, as it connects to both schools simultaneously. Since both schools do not have a direct line of sight with DOE, we are using relay centres about 100 meters away from the school buildings. OLE is connected to Ratabangla school over a VLAN network installed by Subisu Network, connected at 1/1 Mbps intranet and 256/160 Kbps internet access shared with both schools.
The school servers would be installed on-site at both schools, while we have a proxy and the E-library setup at DOE. We would also be setting a cache server at DOE to save on the bandwidth and plan to monitor usage from OLE across the network while also uploading new educational material as and when ready.
Below are some of the daily notes taken down while setting up the network.
[15th March 08 Update]
We got an 16dbi Deliberant installed at DOE. Being a hazy day, the hills where the schools were located were pretty much next to not being visible. So getting the angles right was all the more challenging, as this relay needs to be broadcasting to both schools simultaneously. And unlike a Canopy a Deliberant radio can broadcast to different relays within an angle of 60-70 degrees. So let’s hope we’ve got it right, which we’d know once at Bashuki.
[19th March 08 Update]
We installed an 19dbi Deliberant at DOE and removed the 16dbi radio. We’re now connected to the school at 70 dbm Rssi and 0% packet loss, which is just what we needed.
Right on the hill-top there is an army base which is about a 100 yards away from the School. The army base has direct line-of-sight with the Department of Education, in a range of 3-4 km air distance.
We plan to mount a Point-to-Point radio for Bashuki School either at the adjacent Military Post or on a tree situated on a high hilltop. The radio located near Bashuki will connect to a multi-point radio located at the Department of Education, 8 km (by road) east of the school and in direct line of sight.
[25th March 08 Update]
We were back to the school to complete this end of the networking. Which required us to fix a relay from DOE at the Army outpost and get it connected to the school and also setup an omni antenna as an AP for the XOs. After half an hour of diplomatic talk with the Army officer in-charge of the barrack, we were finally allowed to setup it up. Since we could not use power from the barrack. We decided to run a cat5 cable across to the school about 100 mtrs away to power up the radio over POE from the switch at the school. For certain reasons the 16di radio refused to power up, and we had to use the 19dbi radio instead as the relay which gave connectivity at 72 dbm rssi 0% packet loss. That was the highlight of the day, as the omni radio too refused to power up, so we didn’t get to install it.
Prior to leaving we did install a battery and an UPS with the XS connected to the switch, though it all needs to be thoroughly tested. Maybe in a couple of days, when I get there next to install the omni radio.
The school itself is a bad location for our long range antenna as it is nestled into the hillside. It does not have line-of-sight with the Department of Education. Instead we are using a house located on the hill opposite the school as a Relay site.
The owner of this house has generously agreed to let us mount our network equipment on his house. We will place the Point-to-Point antenna in the topmost window, which has a line-of-sight view with our Multi-point radio at the Department of Education. We will place our omni-directional antenna on the lower part of the roof facing towards the school. This house is roughly 100 meters from the school. We will have to test the signal strength within the classrooms. If it is too weak, we will run a Cat 6 cable down to the school. We also like putting the antenna in the house because the antenna will less likely be stolen.
[16th March 08 Update]
We headed off to Bishwamitra School, this time we were accompanied by Mahabir Pun, Rabi & Sulochan. Mahabir had been approached by a TV company, who needed some shots of him working on site for an ad campaign. So we decided to to club in and take the crew to Jyamirkot as we needed to install a couple of radios there for the school.
It was an hours ride to the base of the hill and a 15 mins trek up with all the equipment. We were welcomed by the school authorities, who got busy right away arranging for electricity for the house where we’d decided to get the radios installed. Believe this house had not been inhabited in quite a while and was completely empty.
We had a jolly good time unpacking and getting the radios fixed up while the film crew was busy shooting us at it and with our brilliant acting skills, the crew needed no retakes! Once they had their shots we got to some serious work.
The 16dbi radio got fixed at the window looking out to the valley below, where DOE is located. Once installed we were able to connect to the other radio at DOE which had just been fixed the previous day. Though it needed a lot of tweaking to improve the signal and at best we got connectivity at 84 dbm rssi with 10% packet loss. So we decided that the radio at DOE needed a bit more tweaking or we might have to be change it to a 19dbi Deliberant radio. As Kathmandu International Airport happens to be right next to DOE, we’re assuming it might be causing a lot of interference and hence the packet loss.
Rabi and Sulo got the Omni antenna fixed by the side of house facing the school. This 12dbi antenna is attached to a DLB2701 access point, which is a 250 mw radio. Sulo had taken a XO with him to test the AP range and was satisfied with the signal around the school and the village. If required we would also enhance the signal by adding a reflector to the omni facing the school to make it work as a sectoral antenna.
With the omni working out to our expectations, we’re glad that we didn’t have to use the CAT6 cables that we had taken along with us. As it would have been a herculean task having to connect it all the way to the school from the relay.