[e2e] Satellite networks latency and data corruption

[alok]

Hi,

What I want to know is:

(a)
If the retransmission/ARQ is entirely offloaded to the end transmitter 
and receiver (say my PC and your PC if we are doing a peer to peer),

versus

(b)
each transmitter and receiver pair on intermediate hop does the same,

How is (a) different from (b) in terms of effective utilization? 
Obviously it is true if an end point A is talking to B and C :

A----hop1---hop2--hop3---C
|
B

so if the loss is seen in hop2--hop3, incase of (b) we have hop1 and 
hop2 being utilised again for the same data that A has to send to C.

but are there any numbers/simple experiments illustrating (a) and (b) 
and the corresponding results on the utilization of A--hop1 and hop1--hop2?

My other question is as to how the "buffer sizes" on each hop are 
estimated in case of (a).

-thanks
Alok

Christian Huitema wrote:

>>It would also help to understand the typical errors seen, does the
>>    
>>
>noise
>  
>
>>tend to impact just one "end to end to end association", is it evenly
>>distributed etc?
>>    
>>
>
>Well, last time I checked that was about 20 years ago, but conditions
>probably have not changed too much.
>
>The error rate depends on the propagation conditions. In the band where
>most satellites operate (12/14 GHz), these conditions are affected
>mostly by the weather, and more precisely by the presence of
>hydrometeors. A large cumulonimbus between antenna and satellite can
>drop the transmission balance by 3 to 5 db. Cumulonimbus can be a few
>kilometer wide, so a typical event can last a few minutes, depending of
>the size of the wind.
>
>The effect on the error rate depends of the engineering of the system.
>If the system is "simple" (no FEC), users may see a very low error rate
>when the sky is clear, and a rate 1000 times higher during a weather
>event. If the system uses FEC, the effect can be amplified, i.e. quasi
>no error in clear sky, and a high error rate during the event.
>
>-- Christian Huitema
>
>  
>