On Tuesday 18 April 2006 09:20 pm, Rony Bill wrote:
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.
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,
This is the problem. Not just wind but ground vibirations from passing vehicles, causes the link to loose connection all the time. Beside scattering due to rain and dust storms.
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.
You need a very expensive servo head at both ends.
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.
Bore well water is full of calcium and residues will make the lens opaque faster than dust.
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.
Not cost effective at all. Wireless PtP links are far better. But from an academic point it would be very interesting.