On Mon, 24 May 2010 08:48:29 +0200, Marts <marts@ymail.com> wrote:
> Just ran a speed test on my phone which is allegedly capable of 7
> mbits/sec
> download speeds.
>
> Speedtest.net reports a download speed of 2.92 mbit/sec and an upload
> speed of
> 0.44 mbit/sec and a ping of 343 m/s.
>
> I know that various factors can affect these tests, but that's the case
> for any
> network performance. But, when they claim a max. performance figure then
> something like this should give you an idea as to how your equipment is
> performing.
>
> And this is especially so if say, Optus and Vodaphone users compare their
> results if they're testing from the same site (in this case, it was one
> in
> Adelaide).
>
> Anyway, just wondering what others are seeing, and are there any phones
> out
> there that can run at Telstra's claimed max (20 mbps?).
>
>
>
I think that the best performing devices can reach 10Mbits/s, to get
better speeds that that you'll need a purpose made modem.
To answer your speed question in an unnecessary complicated way:
The problem with W-CDMA (used for Next-G) is that with two devices
communicating at the same time and with an equal load the maximum speed of
the devices will be shared. If both are 10Mbit/s then it will be 5 for
each, if one is 10 and the other is 20 one will get 5 and the other 10
(always half the maximum). If more are connected it will be slowed down
linear to the load. Ten devices with an equal load on the net will then
reach 1/10 of the maximum speed their capable of. Now there is almost
never loads that are equal, you might be watching Youtube, I might be
surfing news.com.au and Joe is downloading the latest DVD ISO of Ubuntu
Linux from a high performance FTP (or Usenet's alt.bin.*). Then I will get
the slowest speeds and Joe the highest, you should get somewhere close to
Joe.
Then how does this work? Why doesn't we all share the cells maximum speed?
Well, we do! The problem lies in that UMTS (and all other packet access
connections) doesn't share the Mbits, but the available slots. GSM uses
time slots (easier to describe and understand), if we have 100 slots over
1 second and can reach 10Mbits per second (100 slots) sharing it will make
half the speed. The cell itself can reach 20Mbit/s (100 slots) only if the
device can. So knowing this, we can balance the load in slots or speed,
anyway someone will suffer from an unfair system.
With W-CDMA we also have spread-spectrum and a special coding to maximize
the available slots (adding the possibility to communicate with more than
one device at the same time on the same frequency). This makes it harder
to calculate the speeds, but the theory is the same.
Cable and DSL is also affected by the load of the network, but in a
different way. The interference between signal will slow down your speed
somewhat, on an old cable/line or a very long one it will have a bigger
effect. Then when the node is reaching the maximum speed it can
communicate to the internet in the speed will also decrease, but now more.
Here you all share the speed, so if the node can handle 100Mbit per cable,
but max lets say 500Mbit total, and only you has it, all the rest of the
10 connected has 10Mbit you will be the first one to notice as the others
still can have their speeds until we reach way closer to them in speed.
This also happens to mobile cells reaching their maximum speed towards the
node (they're usually connected via cable of fibre to a node). But they
rarely do reach their maximum speeds as the mobile network is so much
slower (remember the cell can handle 20Mbit max and the cable 100Mbits and
fibre over 1Tbit - 1,000,000Mbits).
Fibre will not be affected by interference as the cable, but the rest
works the same.
And now I'm not even sure I actually answered your question.
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