[LINK] 3G RF Latency - was- Latency across Australia

Tom Koltai tomk at unwired.com.au
Thu Apr 28 20:39:56 AEST 2011



> -----Original Message-----
> From: link-bounces at mailman.anu.edu.au 
> [mailto:link-bounces at mailman.anu.edu.au] On Behalf Of Richard Chirgwin
> Sent: Thursday, 28 April 2011 3:42 PM
> To: link at mailman.anu.edu.au
> Subject: Re: [LINK] Latency across Australia
> 
> 
> My bet would be the extra routing between Perth and Sydney (where the 
> Internet gateway probably is).
> 
> Cheers,
> RC
> 
> On 28/04/11 11:56 AM, Marghanita da Cruz wrote:
> > Many years ago, on a visit to Perth, I noticed the
> > difference in response times of a Sydney based corporate 
> application.
> >
> > Now, it seems that response times via the Internet are also much 
> > poorer than Sydney. The 3G Internet dongle connects in 
> Perth as well 
> > as it does in Sydney. But the usual sites I access, in Sydney, are 
> > performing very noticeably worse.
> >
> > Anyone care to comment/speculate on whether thehough the local poor 
> > performance is due to capacity, route (via singapore/satellite), 
> > distance related latency or something else.
> >
> > Marghanita


Hmmm

I think it might have a lot more to do with the choice of 3G carrier.
RF contention issues in Perth. 

The Map in [1] shows 181 sites loaded of which 11 are possibly in
Contention (during heavy broadband usage periods.)
For example, if you were a Telstra user, according to [2] there are over
5,000 registrations of Telstra Lower Band 800 MHz in the Perth area. 
That would obviously cause some serious contention and timing
(reflective) issues creating enormous latency...
(I'm joking of course - there aren't that many radio towers in Perth so
the Telstra Registrations for the area must be an ACME database hiccup.)

Latency could also be caused by unfavourable RF conditions like Solar
Flare activity on the day or rain squalls [if any].

If on the other hand you are an Optus user, then I would hazard a guess
that someone left some Newbridge [circa 1993] switches in the Perth to
Sydney segment and they just can't handle bursty TCP packet traffic.

Lastly, most (pre LTE) 3GPP or EDGE RF would appear to have 10 ms+
latency.
I don't believe any of the carriers have rolled out LTE in Perth yet
whereas in Sydney, it would have been applied to most of the CBD towers.
[Vivid excepted].

[1]
http://maps.spench.net/rf/#pos=-31.9534826,115.8483839&zoom=14&type=hybr
id&auto_fetch=true&clustering=true&cluster_level=17&filter=[{%22site_des
c%22%3A%22mobile%20spectrum%20licensing%22}%2C{%22client_name%22%3A%22op
tus%22}%2C{%22client_name%22%3A%22telstra%22}%2C{%22client_name%22%3A%22
vodafone%22}%2C{%22client_name%22%3A%22hutchison%22}]&q=s%20%22mobile%20
spectrum%20licensing%22%2C%20c%20optus%2C%20c%20telstra%2C%20c%20vodafon
e%2C%20c%20hutchison&tiles=[{%22t%22%3A%22u%2Fblack%22%2C%22v%22%3Afalse
}%2C{%22t%22%3A%22s%2Fall%22%2C%22v%22%3Afalse}%2C{%22t%22%3A%22s%2Fmobi
le%22%2C%22v%22%3Afalse}%2C{%22t%22%3A%22s%2Fmobile-spectrum%22%2C%22v%2
2%3Afalse}]

[2]
http://web.acma.gov.au/pls/radcom/licence_search.licence_lookup?pLICENCE
_NO=1136524

/body




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