[LINK] web: The NBN satellite Malcolm Turnbull never wanted prepares for liftoff

[Karl Auer]

On Sun, 2015-08-30 at 10:29 +1000, Tom Worthington wrote:
> Perhaps someone can answer a question about the current NBN "Interim
> Satellite Service" (ISS): Why is compression OFF by default?
[...]
> Why would compression limit the speed of the service?
 
Probably because compression costs CPU. Like any communications device,
a satellite is fastest when it can just ship stuff in and out. If it has
to process what it ships, it slows down. Also, CPU is energy, and a
satellite has limited energy.

As a general rule, compression should only be used where the time taken
to compress the data is smaller than the difference between the time
taken to send the uncompressed data and the time taken to send the
compressed data AND where the cost of compression is lower than the cost
of that transmission time difference. I suspect it is the second of
those that works against compression in this case.

> compression limits the speed in some cases, would customers benefit overall?

Dunno. I suspect there would be a "tragedy of the commons" effect if
everyone went for compression.

Regards, K.

-- 
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Karl Auer (kauer at biplane.com.au)
http://www.biplane.com.au/kauer
http://twitter.com/kauer389

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