I do networking generally, i have recently been using 802.11AC devices (Ubiquiti, Mikrotik) to transfer data over short Distances like 3KM. They generally provided good throughputs, i was reading about 802.16 Wimax Standards. I always thought the kind of connections i was doing with 802.11n and 802.11ac are wimax.. I guess my main question is , with the relatively new 802.11AC , how should i choose between the two? Especially for long distance transmitions, lets say 10KM
WiMax operates in spectra that needs to be licensed from the FCC (or the corresponding body if you're not in the US). Depending on the frequency in use the licensing process may- or may not- be an issue, but it's not a situation where you can simply buy the gear and start using it the same day.
In contrast, the 802.11 standards operate in unlicensed frequencies and don't require a special license.
There are plenty of Wifi links operating at- and well beyond- the 10KM mark, with the caveat that the link needs to be properly surveyed and engineered and appropriate antennae (read: high gain / highly directional) employed.
In general I would say that there's a lot more activity happening with 802.11 than 802.16. This means that there's more (and cheaper) solutions and a lot more innovation and development happening in the industry.