Outdoor WiFi Equipment
For dedicated outdoors and long distance installation, we need to consider outdoor WiFi equipments. Most of these equipments would be more expensive than indoor equipement.
These outdoor WiFi equipments are normally produced in environmental protection enclosure for outdoor installation.
It normally has power over Ethernet build-in. Thus, the equipment can be place on top of the tower powered through a shielded Ethernet cable. Consequently, coaxial cable between the outdoor WiFi equipment and the external antenna can be kept very short, in some cases, shorter than one (1) meter. It will significantly reduce the signal loss by placing the WiFi equipment close to the antenna.
The significant different between indoor and outdoor equipment is not only in its external packaging enclosure, but also its internal firmware and radio equipments design for a more robust outdoor operation.
Inside the firmware, outdoor WiFi equipments may have some sort of proprietary protocol to increase data transfer reliability. For example, some may use polling mechanism on the Access Point to all the nodes on the frequency to reduce packet collisions.
Some equipment may have latest state of the art radio equipment to fight with multipath and signal reflection. Orthogonal Frequency Division Modulation (OFDM) radios might be a good example to serve in NLOS (Near Line Of Sight) links.
Choosing the correct outdoor equipment would be a headache, some equipment gear for urban / city crowded environment with high concentration of nodes with multipath problem. Some vendors more concentrate on long distance backbone transmission in rural areas where less nodes and interference.
Some example of outdoors WiFi manufactures is,
http://www.cirronet.com
http://www.cisco.com
http://www.orthogonsystems.com
http://www.smartbridges.com
http://www.wavelan.com
http://www.waverider.com
We are looking at US$1000-2000 investment per outdoor node excluding the tower. It is very expensive for most installation. We may modify indoor equipment for outdoor usage to start a simple WiFi infrastructure.