Building an Non-Wired Network for Pueblos?

wsxian asks: "We recently received a large grant to install a wireless high speed Internet system for our entire Pueblo here in the State of NM. This would encompass about 150 homes and the range from a central point would be no more than 6 miles, but there are hills, valleys and trees so line of sight is not an option unless we decide to drop homes. I welcome any suggestions for technology to look at, what to avoid, security concerns- and most important for us what companies to avoid. If any of you have had real life experience with doing such a scaled project like this, please give your input!"

Comments

No Non-Line-of-Sight

[Neon Spiral Injector]

No matter what anyone tells you, or tries to sell you: wireless is line-of-sight. Microwaves are electromagnetic radation. They do penetrate a bit better than the visible wavelenghts, but a building or a hill, heck even trees, will put a real cramp on your transmissions.

If all buildings don't have a clear, unobstructed view of a central point; the only way to make this work is to connect the buildings that can see eachother until you reach one that can see your point of origin.

Start by finding the best location that is the most visible, and most central to the most buildings. This is were you will install six radios each with a 60 degree sector antenna on a tower (less if you don't need a full 360 coverage, but don't go any wider then 60 degrees for each sector, or you'll be spreading your power too thin). Then survey each of the other locations to see which have perfect views of this tower. These locations will get an uplink radio with a unidirectional antenna focused on the tower. Plus a second radio operating in a different frequency range with an omnidirectional antenna. Try to use a lower frequency for the omni radios. These secondary radios will operate as a mesh network to pick up the other buildings that don't have line-of-sight to the central point. Finally the non-line-of-sight meshed-in locations can operate on their own omnidirectional antenna if they are close enough so they can pick up tertiary meshes. You really don't want to go any deeper than three into the mesh, speed starts to suffer too much. If the buildings are more than a couple hundred feet from each other the powerloss from transmitting in all directions will be too much and you'll have to go to directionalized antanna at one or both locations to direct the RF in a more focused pattern.

Re:No Non-Line-of-Sight

[VeriTea]

I design wirless networks for a living, so I'd like to add a few words...

Get a good set of topo maps for the entire area you want to cover. Don't let anybody fool you, real paper maps and a good distance calculator like "Topo Companion" are the best way to do wireless design. Next, go to the FCC and download their Antenna Registration Database. You will need the "EN" and "CO" and one other table. Join the tables (useing MS Access would be easiest) using the unique site id and then query out the sites that have coordinates within the boundaries of Pueblo (latitude > y1 and latitude x1 and longitue Now use your "Topo" companion to mark existing towers on the map. Look for ones that are on hills or mountains near the desired coverage area. Some simple trig will tell you if you have line-of-site (LOS). Add the average tree height to your ground elevation when doing calcuations, 802.11x is very low power and high frequency, so you can't afford any pathloss burning through vegetation.

Unlike the parent, I would strongly recommend 30 degree panels for this kind of system, since you are likely to encounter capacity issues, and even log-periodic 60 degree panels have enough overlap between sectors to guarentee a huge interference problem if you use more then one transmitter. Find the equipment you are going to use and use your gains and losses to calculate the ERP / EIRP from your transmit antennas at each site. Now go ahead and use the free-space pathloss equation to figure out the signal strenght at you target locations. If you have adequate signal to meet the needs of the subscriber equipment you plan on using then great (Note: if you plan on supplying subscriber equipment then you can guarentee a minimum quality. If not, your design will need to be especially robust to accomodate low-quality receivers). If not, keep tweeking the design until it will work. Develop a plan for directing the different channels away from each other. Make sure you calculate your expected interference from other sites using the same channel. If you several mountaintop sites this will be a killer.

Once you have it built on paper, the rest is fairly straightforward. Have fun!

Less Networks

[guroove]

These guys created a free wireless network in Austin in less than 6 months, and they recycle old PCs in many of their installations. Definitely worth checking out!

http://www.lessnetworks.com/

Vivato outdoor wireless

[GlL]

Check out http://www.vivato.com/. I have been installing their products, and recently did a baseball stadium. The signal penetrated the concrete construction into the team offices behind the dugout. Good stuff.