jtd wrote:
Throughput deteriorates as the mesh size increases. U have increased latency and reduced per user bandwidth. These are things which are being addressed. Latency is the issue for voip over 802.11.
This is a suggestion. If rural or long distance coverage with good latency and bandwidth is the final goal and cabling is too expensive, then a combination of wireless radio (APs) as well as wireless optical technologies could be tried out. The long link in lieu of the cable can be established using laser tx/rx units mounted high on relaying towers so that maximum LOS distance can be achieved. The last mile connectivity can be provided by the APs.
Optical trancievers will provide almost similar high bandwidth as the optic fibre cables and can be mounted on independent towers that are solar powered during the day and rechargable batt. during the night. A thin long laser beam should be adequete enough to reach a few kms. In order to overcome the wind sway of the tower tops, the optical sensors can be mounted at the focus of parabolic reflectors that are sized as per the maximum deviation of the beam due to the sway. A more sophisticated approach could be to use (if available and not expensive) the military type sensors used in laser guided weapons systems to be able to track moving beams. The entire assembly can be mounted in a sealed all weather box and a water pump positioned to automatically spray water at an off peak hour can be used to clean the optical system everyday, thus eliminating the need for a human touch every day for every tower. Water can be made available once a month from a tanker or from an underground tube well.
The protocol used could be such that a minor interruption caused by bird flights does not disconnect the link, it only pauses till signal is back.
At the final destination, a cluster of towers could optically connect with the final tower and this cluster will mount the APs to give full area coverage. In all this process, no cables are used.
I don't know if this idea may work but an experiment can be carried out in laser based optical connectivity between two tall buildings in Mumbai.
Regards,
Rony. Send instant messages to your online friends http://uk.messenger.yahoo.com