> Let us take the most common situation, i.e. rain fade. Can someone
> explain to me its quantitative impact on BER. Is the satellite link
> completely out of order when it rains or can we still find rescue in
> methods like ARQ or some TCP which is able to distinguish corruption
> from congestion ? Is there information available on the noise
> characteristics on modern satellite links ? (BER, distribution of bit
> errors, ...)
You need to look at the link power budget and know the rain conditions
locally. Both an outage (if the fade is deep) or a period of
increased BER may result. Depends upon where you are, how bad the
rain is (act of god), and how you designed the system. The latter
part is up to the engineers building the link. If they choose to
use lots of FEC, then that is one approach which sacrifices bandwidth
for higher availability. ARQ sacrifices complexity and delay for
better maintained throughput. TCP enhancements may also help somewhat
mitigate the effect.
There is no single answer, which keeps engineers busy. Things are
certainly worse at Ka-Band and even more so in certain locations.
Gorry Fairhurst.
This archive was generated by hypermail 2b29 : Mon Feb 14 2000 - 16:14:47 EST