Ildana to get Nobel Prize

jwt

johnmu wrote:

At this stage, you can or should have, depending on the transport mechanism, have a reliable link. Now the throughput should only be at the mercy of the round-trip-time or RTT which will not vary. It takes approximately 113ms for a request to get to the satellite and approximately the same to come back to Earth, and then then the same again in reverse. This is your starting point, the absolute minimum for the RTT will be approximately 452milliseconds.

Firstly John, welcome to the forum.

We do welcome input from ISPs and providers in here, so feel free to get stuck in.

And for the record, although many posters here will happily argue/debate with you/your company anybody taking that onto a personal level gets banned. So feel free to PM the moderators if that happens.

Before i get to the quote above, just to clear up Enfield (GBS II)

Both Gareth (Viking) and I were there (I was the git stood up telling people not to use Sat. for GBSs)

Gareth was the one asked to view the tech in action and was presented with a powerpoint show but tbh I thought that was a different sat provider, not yourselves? I may be wrong, I'll let Gareth comment more on that.

Re the quote above, a reasonable assumption is that sat has a minimum latency of 500ms under the very best possible circumstances. On top of that add in operator error/misconfiguration which I'm sure you'll agree some sat providers have done, and latency from 800ms to several seconds have been the norm.

I appreciate that you offer a system using a highly optimized protocol, but if memory serves me correctly you were also quoting 6000-7000 Euro for an install offering this level of service? (I may be wrong)

And while I can see this being economically viable in a GBS scenario, it still means that a minimum latency of 500ms is being offered, plus whatever latency is introduced on the wireless distribution at the GBS end plus latency on the far side of the sat link and then the normal day to day latency experienced by everyone on the internet as your packets hop around the world.

My final comment on sat is one I have asked everyone from Comreg to minister Dempsey and not received a straight answer.

If Sat provided all the benefits of Broadband and is in fact a form of broadband, why do we not have the OECD, the EU, Forfas, Comreg and in fact any official body in the world classing Sat as broadband when presenting reports on broadband availability, penetration and usage.

To my mind if Sat was truly broadband, then OECD reports etc. would show everyone including the Outer Hebrides as having 100% broadband availability.


Regards


John

P.S.

Re the original post, whatever justification a company has when doing a PR piece to "embellish", the reporter and magazine that took or in this case mistook what you said as gospel should be ashamed of themselves.

watty

jwt wrote:

My final comment on sat is one I have asked everyone from Comreg to minister Dempsey and not received a straight answer.

If Sat provided all the benefits of Broadband and is in fact a form of broadband, why do we not have the OECD, the EU, Forfas, Comreg and in fact any official body in the world classing Sat as broadband when presenting reports on broadband availability, penetration and usage.

To my mind if Sat was truly broadband, then OECD reports etc. would show everyone including the Outer Hebrides as having 100% broadband availability.

They won't answer because they would have to take action against Eircom (which the State & Comreg seem reluctant to do) and also the State would have to fork out 60m to 200m to fix the problem.

Which as we all know in the bigger scheme of things to spend 200m to fix BB access would be a bargain.

bminish

jwt wrote:

Re the quote above, a reasonable assumption is that sat has a minimum latency of 500ms under the very best possible circumstances. On top of that add in operator error/misconfiguration which I'm sure you'll agree some sat providers have done, and latency from 800ms to several seconds have been the norm.

the speed of light dictates that from the Equator it will take 120 msec for the signal to reach from ground to the satellite. so the minimum RTT from a user AT the Equator using a geostationary satellite overhead for connect to a destination also at the equator is 120x4 = 480 Msec.

As some of you may have noticed we are somewhat north of the equator. I'll use 52 degrees north as an average for Ireland considering Ildana claim to have an Irish ground station.
using the formulae given at
http://members.aol.com/meersalz/CelestialNavigation.html#Calculations%20of%20a%20Geostationary%20Orbit
I work out that the distance to the satellite, assuming it was due south of Ireland is 38700 Km.
It takes 129 msec for light to do that trip
129x4 = 516 msec

The RTT can never ever be less than 516 msec.
Now factor in TDMA (or whatever other scheme of multiplexing is used) FEC error correction as well as Internet and processing overheads and 600msec is probably a more reasonable absolute minimum RTT time. Any attempts at jitter smoothing will add further to the latency since prefeching is pretty much out of the question (the sat bandwidth costs too much for that.)

This does not make for good VoIP, especially between VSAT locations nor does it make for playable Gaming unless chess is your game. Querying a remote database over a VPN is not going to work well either, regardless of what tricks are used.

The VSAT system I was on (not Ildana) for a couple of years could manage RTT times averaging about 750 msec to Irish sites and jitter was mostly not too bad. it was still crap for anything interactive and the usage caps were tiny

.brendan

watty

Good analysis. Now why is RTT to a user on IBB 200 meters from its base to me 1780ms? My pings to other non-IBB users are "normal". Do IBB use TWO Satellite links for back haul from Limerick Clarion? Can you figure that one, bminish?

Capt'n Midnight

watty wrote:

Even Antartica has an optic fibre Backhaul...

No Fair.
They can't see a geo sync satellite from the south pole

Betcha they don't use pair gains down there either.

Ildana�s Murphy acknowledged that up until now satellite broadband had been given a bad name due to latency issues but mostly due to the unpredictability of satellite coverage.

you mean wind & rain ??

He continued: �It�s like the difference between a well ordered meeting where everybody gets a chance to speak and a student�s union meeting where no one gets a word in edgeways. Whether Ireland likes it or not, in terms of satellite coverage we are the Outer Hebrides of Europe and most satellites are designed for the most populated areas of Europe.

Does he just mean you need a bigger dish ? Or is he talking about some wonderful new collision avoidance system for the uplink. Although he's raised a very interesting question. Can you get broadband in the Outer Hebridies or do they just rely on a fixed price dial up that lots of people in the west would kill for ?

[edit] Western Isles already have ADSL and Plan B is wireless, but they have already been awarded £2,575,000 towards the cost. - so he must mean that you need a bigger dish as you go West in the same way you need one if you go North.
http://www.hie.co.uk/wie-BB.html
http://www.connectedcommunities.co.uk/

bminish

watty wrote:

Good analysis. Now why is RTT to a user on IBB 200 meters from its base to me 1780ms? My pings to other non-IBB users are "normal". Do IBB use TWO Satellite links for back haul from Limerick Clarion? Can you figure that one, bminish?

VBG. My guess it has 'something' to do with IBB's 'core' network being in ****e but I'll say no more on that...

Even Antartica has an optic fibre Backhaul...

Hmm.. any references for that?

I was almost sure that all datacomms was still done via a number of satellites owned by NOAA that are in inclined orbits , each providing a number of hours of coverage a day. There was a good article in QST a couple of years ago about this and a quick google finds the following links. Nothing directly giving the true bandwidth available though
http://www.tgdaily.com/2005/09/01/running_wi/index.html
http://www.aad.gov.au/default.asp?casid=14189
http://antarcticsun.usap.gov/oldissues2001-2002/2002_0127/it.html
http://www.smh.com.au/news/Management-Focus/Cool-runnings/2005/04/11/1113071897708.html

It would be tricky in the extreme to lay fibre in the antarctic Continent since you could only lay it into ice most places and that's all moving.
HF radio still plays a pretty important role in Antarctica and of course iridum works pretty well too.

.brendan

watty

Even Antartica has an optic fibre Backhaul...

Well not exactly... more a fibre "local loop"

http://news.bbc.co.uk/1/hi/sci/tech/2207259.stm

BBC News: 21 August, 2002
The South Pole is the only permanently inhabited place on Earth that cannot see geosynchronous communication satellites, a fact that severely restricts communication with the base.

The American National Science Foundation has just issued a request for industry to bid to build the trans-Antarctic fibre optic link. It is planned to be in use in 2009.

Yes you are quite right about aging inclinded orbit Sats.

bminish

watty wrote:

Well not exactly... more a fibre "local loop"

http://news.bbc.co.uk/1/hi/sci/tech/2207259.stm

Ahh, a MAN with VSAT backhaul then

.Brendan

kazoo106

He's back !!!
http://www.siliconrepublic.com/comms/item/25084-dublin-tech-firm-brings/

jbkenn

kazoo106 wrote: »

He's back !!!
http://www.siliconrepublic.com/comms/item/25084-dublin-tech-firm-brings/

Proof positive, you can't keep a good man down, bejaysus, if it's good enough for Cahirciveen then shur they will be only flying it out in Africa, I am sure all his "fans" in West Kerry will have nothing but kind thoughts for him, and wish him all the best in this venture.

watty

That article is misleading.

Many in Africa are getting rid of Satellite. Combination of Fixed Microwave links and extensive fibre.

Only very remote locations will use Satellite and only very few people.

Capt'n Midnight

All I can think is that satellite must have dropped in price since the submarine fibre cables landed in Kenya a few years back.

In Kenya facebook is huge.


http://www.safaricom.co.ke/index.php?id=244
entry level 3G bundle 250MB per month €4.58


and there are usually some special sign up offers too.


110.00 KES = 1.00834 EUR
11 Ksh = 10c

watty

Not that expensive to get fibre installed to door if you in Urban Kenya.