[ILUG] Help needed about Broadband Ratio?

[Michael Watterson]

Thomas Bridge wrote:
> On 25/02/2008, Kevin Chen <kevin2600 at gmail.com> wrote:
>
>   
>> Hi all,
>>     one of my friend try to have a broadband connection from Digiweb.
>>  And he quite interesting the DSL option for Download speed up to 2MB,
>>  but there is also said Ratio would be 48:1? I'm confused about this
>>  Ratio thing. Could anyone point out more info about it and if there is
>>  any formular to work it out? Thanks!
>>     
>
> Contention Ratios are better described as planning ratios.
>
> I'm sure things have changed since I left Ireland, but in the last
> conversation I had with Eircom about their wholesale broadband product
> that's exactly what it was.
>
> It is true that it would be practically unusable if everyone tried to
> use their bandwidth at once, but that rarely happens,
>
> Thomas
>
>   
It's not 24 or 48 people using one thing either, but 240 to 480  people 
(approx)  sharing something 10 x the size  of one  thing.  Because of 
statistics & Probability and all that stuff, averages are more average 
the larger the group. HSDPA really is up to 24 max sharing one sector of 
3.6Mbps max. Except as it is CDMA, the efficiency drops  when  even only 
10 connected and  you may only  get  150Kbps, not  360kbps.

On DSL, Cable or Metro Wireless because of how it works, you don't get 
10th of say 3Mbps (cake is more like 25MBps to 50Mbps), but it can fill 
others traffic in the gaps of your traffic etc, which HSDPA can't, so 
contention is not a meaningful measure of user experience of any system. 
HSDPA with 24 users can easily go to less than 70kbps.  You'd never see 
that sort of performance hit on Digiweb Metro, DSL or Cable.

On my 10Mbps system with 48:1 "contention", the worst ever speed was 
about 4.5Mbps.

UK users on DSL typically only see 1/3rd to 1/2th of their sold speed.

On some systems you will experience less contention on a slower package! 
I.e. 10Mbps will vary more than a 1Mbps Irish package, which may almost 
always be near 1Mbps.

Some Wireless users (A company maybe with a Merkian Way, or a chilly 
provider) seem to rarely get more than 1/2 or 1/3rd their package speed, 
but that is well within the Comreg 48:1 limit.

48:1 is simply Comreg's planning limit for  Broadband  licence.  You are 
doing  bad if  you  see 3:1 and  typically  better than 1.5:1 on decent 
providers.


-- 
Michael Watterson

EI 9 FEB