[CUWiN-Dev] degradation between hops, antennas, etc.

[Quantum Scientific]

On Sunday 06 March 2005 10:51, Stephen Ronan wrote:
> They mention approximately 15% degradation and say the access points 
> could support two radios but they're only using one. I wonder whether 
> the 15% is what's theoretically achievable with two radios rather than 
> what they're getting in practice.

Yes, I'd posted and discussed Mesh Dynamics' research here previously.  
They've actually been around for a while.

Throughput degradation depends entirely on node density.  In a completely 
linear topology and single radios you should lose 50% per hop, because of the 
half-duplex nature, and with dual radios about 18% per hop.  Both approaches 
get considerably worse when nodes can see multiple neighbors, again, because 
of half-duplex packet propagation...  and this doesn't take into account 
multipath.

I love the idea of capacious nodes, all seeing one another and aggregating 
their bandwidth, but it can't happen when a frequency is shared.  So other 
measures must be taken.

I'm sufficiently freaked out about this to plan two-radio nodes, and probably 
directional antennae on designated nodes.  I also believe that there must be 
some measure of software distinction for gateways, but I think I'm too 
enthusiastic to be listened to or something.

Carl Cook