Hello to the tcp-over-satellite community.
My name is Burt Liebowitz. I am Vice President of Technology at Orion
Network Systems in Rockville Maryland. We are a satellite operator,
selling both space segment and networks. We have an Internet service
called
WorldCast, which provides access to the US Internet for European ISPs.
We have an uplink in Virginia connected via a US ISP to the US Internet.
We transmit to dishes at European ISP sites. The ISP redistributes via
terrestrial circuits to its customers. We provide asymmetric satellite
links, and in some cases one way satellite links with terrestrial return
( a hybrid system).
We have done some work on analyzing TCP performance based on file size,
bit error rate and window size utilizing somewhat idealized models of
efficient TCP transfers. I am particularly interested in any work done
in the field that shows the impact of BER on throughput. I have seen
some articles in the literature but very few that show actual test
results.
I have heard some talk that BER is not an issue on satellites, because
the circuits can be designed to meet any stated requirement. However, my
experience is that we need in the order of 1 db of power for each decade
improvement in BER (after coding). This relates to dollars because power
costs money.
We typically design our link budgets for better than 10 <6> BER, 99.5%
of the time. We figure that another 1 to 2% of the time, we operate
between 10 <6> and 10<10>, depending up the degree of moisture, and the
rest of the time better than 10<10>. We know that if we increase window
size we can get better throughput but we must also improve BER. I am
extremely interested in references to studies that indicate what type of
improvements are needed i.e. what BER is required to support throughput
going up to the megabit range.
I am also interested in spoofers and the use of proxy servers to enhance
performance over the satellite link. References to papers and or
commercial products would be welcomed.
Thanks
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