B Sky B satellite broadband?

I've often wondered why Sky doesn't offer there broadband over there satellite network doing away with BT and getting coverage to most of the UK, can anyone tell me why?

I suspect that the Sky satellites can only transmit data to the consumer, not receive it.

Yes, you'd need some sort of modem to do the uploading, and the latency problems with satellite means that it would be no use for gaming, Skype and other voice calls, or any other time sensitive interactive applications.

Regards,
Steve

In reply to a post by AnotherExPipex:

I suspect that the Sky satellites can only transmit data to the consumer, not receive it.

Satellite BB is poor choice. It rarely supports uploading direct to the satellite so the consumer is still reliant on whatever ground-based BB they have for uploading. This can often cause bottlenecks downstream due to congestion in sending ACKs.

In addition there is lag. Geosync satellites orbit around 36,000km above us. The laws of physics mean that 240ms gets added to your pings (120ms from ground station to sat, then back again).

You are also in effect sharing your downstream connection with everyone else within the satellite footprint. Satellite broadcasting can offer a lot of bandwidth but it isn't unlimited. Sharing it with an entire country-or in the case of Eurobird the entire continent-is not sustainable. A couple of gigabits bandwidth sounds good but when you're sharing it with a couple of million other people it's not so hot.

But the real reason is likely cost. Sky don't own any satellites. They rent space off satellite providers. I doubt that the economics would make sense. In fact a lot of people don't realise that most of what they watch through Sky is not even broadcast by Sky

Personally I detest the idea of satellite BB as a general solution. I accept that it's good if you're stuck in the middle of a desert or a jungle but not for the UK. It's horribly innefficient to send a data stream to 30million homes and businesses when only one of them is actually going to be using it.

Edited by Andrue (Tue 05-May-09 09:58:53)

> It's horribly innefficient to send a data stream to 30million homes and businesses when only one of them is actually going to be using it.

As indeed is the opposite - sending multiple dedicated streams to umpteen different end users (eg iPlayer) when a single broadcast / multiple record system would work virtually as well or better in most instances because the video quality would be better.

In reply to a post by kwikbreaks:

> It's horribly innefficient to send a data stream to 30million homes and businesses when only one of them is actually going to be using it.

As indeed is the opposite - sending multiple dedicated streams to umpteen different end users (eg iPlayer) when a single broadcast / multiple record system would work virtually as well or better in most instances because the video quality would be better.

Agreed.

It'd be cool from a technical POV to have multicast servers in the street cabinets but something of an installation/maintenance headache

Edit:Of course VM don't have that issue but then their local loop doesn't have dedicated end-user feeds. It's surprising how the network topology in the last hundred metres can change things. It occurs to me that VM actually have a potential problem there if VoD takes over from broadcasting. Their network model is more like satellite at the front-door :-/

Edited by Andrue (Tue 05-May-09 10:42:58)

Are Virgin actually supplying digital now or is it just analogue over their coax? Years back a house we bought had cable TV through coax (chan 1-4 and possibly 5 if it was around then). I cancelled it as I couldn't see the point in paying for what came free with an aerial.

In reply to a post by Andrue:

The laws of physics mean that 240ms gets added to your pings (120ms from ground station to sat, then back again).

Shouldn't that be doubled for round-trip time?

Ground to sat => sat to server being pinged => server back to sat => sat back to ground.

Unless you're pinging the satellite

In reply to a post by billford:

In reply to a post by Andrue:

The laws of physics mean that 240ms gets added to your pings (120ms from ground station to sat, then back again).

Shouldn't that be doubled for round-trip time?

Ground to sat => sat to server being pinged => server back to sat => sat back to ground.

Unless you're pinging the satellite

Hmmm.

Entirely ground based route:
EU-ISP->ISP->Target->ISP->ISP->EU

For satellite:
EU->ISP->ISP->Target->ISP->ISP->GS->Satellite->EU.

The final GS->Satellite->EU is 2 lots of 120ms.

You'll only get another 240ms if you are uploading to satellite which I think is unusual unless you're somewhere without access to any other form of telecommunications.

I could be wrong of course. I think that general advice is that satellite BB adds 300ms to ping times which suggests I might not be far of the mark

Edited by Andrue (Tue 05-May-09 11:03:52)

I nearly replied to your pre-edit post

And it could be a lot worse than I said- if the server is too far around the planet you might have to go via two satellites... not sure if that would mean an extra ground station or if the satellites can talk to each other directly?

In reply to a post by kwikbreaks:

Are Virgin actually supplying digital now or is it just analogue over their coax? Years back a house we bought had cable TV through coax (chan 1-4 and possibly 5 if it was around then). I cancelled it as I couldn't see the point in paying for what came free with an aerial.

They seem to be offering digital these days but still not very many channels. I also believe that they don't carry those channels that are available through DTT. I'm not sure how that works. It'd be a sensible idea to conserve bandwidth but if I was designing it I'd have the VM STB take a feed from the aerial and present those channels through the STB. Perhaps they do.

I think what I'd be most interested to know is what is the bandwidth available around the 'street loop' for IP traffic. ITSM that that's the area of concern moving forward. BT's FTTC can remove contention from the local loop quite easily. VM's, not so much. If a street/neighbourhood becomes congested you're pretty much stuffed.

I would imagine that a BB satellite would communicate directly with a ground-based router (one appropriate for it's position), so it would just be up - down - normal Internet route to server.

In reply to a post by AnotherExPipex:

I would imagine that a BB satellite would communicate directly with a ground-based router (one appropriate for it's position), so it would just be up - down - normal Internet route to server.

That would make more sense... but implies some semi-dedicated kit. Depends whether the money is there I suppose.

In reply to a post by billford:

I nearly replied to your pre-edit post

And it could be a lot worse than I said- if the server is too far around the planet you might have to go via two satellites... not sure if that would mean an extra ground station or if the satellites can talk to each other directly?

Heh, well that depends on the network itself. I'm assuming using satellite in-place of BB. If you're considering a full-on satellite network then I have no idea. It doesn't sound too clever though. I don't know if you can guarantee line-of sight between geo-sync satellites. Presumably there's also an issue of frequency allocation if you're going to start broadcasting between themselves?

I must admit that I've never really looked into satellite communications in-depth. In recent years I've learned a lot about how Sky/Freesat 'do their thing' but that's mostly about politics.

I don't know if you can guarantee line-of sight between geo-sync satellites.

Depends how many you've got, but if they can cover the whole planet then each will be able to see at least one other.

Incidentally, if you remove the square brackets from your sig, the youtube link will work

In reply to a post by AnotherExPipex:

I would imagine that a BB satellite would communicate directly with a ground-based router (one appropriate for it's position), so it would just be up - down - normal Internet route to server.

I don't quite understand what you're saying there.

Until recently I think all traffic for Europe went through Goonhilly in Cornwall (a brilliant name for such a high-tech site ).

Although not all that significant it implies an extra hop from ISP to Goonhilly to me.

http://en.wikipedia.org/wiki/Goonhilly_Satellite_Ear...

"On 12 September 2006, BT announced it would shut down satellite operations at Goonhilly in 2008, and move them to Madley Communications Centre in Herefordshire, which will become BT's only earth station and the biggest in the world."

Edit:I think I see what you're implying. Yeah, it could just go ISP->GS rather than ISP->ISP->GS.

Edited by Andrue (Tue 05-May-09 11:23:40)

In reply to a post by billford:

Incidentally, if you remove the square brackets from your sig, the youtube link will work

Hmmm.

What I was trying to say (not very clearly) is that the satellite doesn't talk directly to the end server, it communicates with a ground station.

I'm not sure what's happening at Goonhilly. Although it was announced that it was closing in 2008, it seems to be still going. In any case, "Arthur" is now a listed building!

In reply to a post by AnotherExPipex:

What I was trying to say (not very clearly) is that the satellite doesn't talk directly to the end server, it communicates with a ground station.

Analogy- the ground station acts as an industrial grade wireless router?

In reply to a post by billford:

In reply to a post by AnotherExPipex:

What I was trying to say (not very clearly) is that the satellite doesn't talk directly to the end server, it communicates with a ground station.

Analogy- the ground station acts as an industrial grade wireless router?

Heh, that didn't help me

I would have said that the satellite is a wireless router. It takes a stream sent up from the ground station and broadcasts it to all the End Users. I'll try and improve my routing diagram for a ping. I'll leave out the outward bound part because that is entirely ground-based for satellite BB as proposed for the UK:

Target->Target's ISP->EU's ISP->Ground station->Satellite->EU

The only improvement I can currently see is:

Target->Target's ISP->Ground station->Satellite->Client

..and I'm not entirely sure whether it would be practical to remove the EU's ISP on the return trip like that or whether it would have much of an impact if they did.

Edited by Andrue (Tue 05-May-09 11:46:42)

I would have said that the satellite is a wireless router. It takes a stream sent up from the ground station and broadcasts it to all the End Users.

I think we're a bit at cross-purposes- I was including the end user as a ground station, I'll separate the two terms from now on .

The satellite isn't a router, it's just part of a radio link. It can handle multiple inputs from end users and squirt them to a "proper" ground station connected to the internet, but stuff coming the other way is only routed to the satellite if it's addressed to an end user, and then it's broadcast to all of them within its footprint. Bit of a security/privacy risk, actually.

The sat is acting more like a multiplexer in one direction and a simple repeater in the other, all the routing is done in the ground station.

In reply to a post by billford:

I would have said that the satellite is a wireless router. It takes a stream sent up from the ground station and broadcasts it to all the End Users.

I think we're a bit at cross-purposes- I was including the end user as a ground station, I'll separate the two terms from now on .

The satellite isn't a router, it's just part of a radio link. It can handle multiple inputs from end users and squirt them to a "proper" ground station connected to the internet, but stuff coming the other way is only routed to the satellite if it's addressed to an end user, and then it's broadcast to all of them within its footprint. Bit of a security/privacy risk, actually.

The sat is acting more like a multiplexer in one direction and a simple repeater in the other, all the routing is done in the ground station.

Fair enough. Actually I wonder how it handles inputs for 2-way BB? Does it rely on collision detection (seems unlikely with 120ms latency) or assigned frequencies? Seems like another potential bottleneck with large numbers of users.

Edited by Andrue (Tue 05-May-09 13:30:09)

In essence the whole satelite link replaces a single cable - that from you to your nearest point of presence (pop). Just with satelite the pop may be hundreds of miles away rather than the nearest exchange.

Everything else in the network is just the same.

In reply to a post by Andrue:

I wonder how it handles inputs for 2-way BB?

I have absolutely no idea .

With modern clocks it could be done with TDM, but it's getting complicated...

In reply to a post by billford:

In reply to a post by Andrue:

I wonder how it handles inputs for 2-way BB?

I have absolutely no idea .

With modern clocks it could be done with TDM, but it's getting complicated...

No kidding.

http://en.wikipedia.org/wiki/Time-division_multiplexing

And today's new word is:

http://en.wikipedia.org/wiki/Plesiochronous

brought to you by the letter 'P'

Edited by Andrue (Tue 05-May-09 14:11:26)

The laws of physics mean that 240ms gets added to your pings

and again. Two way satellite adds 480ms

you - sat - ground station - sat - you

on top of standard network latency.

On commercial data sat providers. Your looking at 500ms round trip. This is usually over come back wan/bandwidth mangement device i.e. PacketShapers Riverbeds etc etc.

Therefore the ammount of data on demand would not be small beer.

Also, the Hotbird/Eurobird does not provide data service on 19o East transponder.

In reply to a post by Anonymous:

The laws of physics mean that 240ms gets added to your pings

and again. Two way satellite adds 480ms

you - sat - ground station - sat - you

on top of standard network latency.

Yes but I'm assuming it'll be one-way. I believe that's what's most likely in the UK. Two way seems like rather a specialised option.

In reply to a post by Anonymous:

I've often wondered why Sky doesn't offer there broadband over there satellite network doing away with BT and getting coverage to most of the UK, can anyone tell me why?

Because it's not their satellite network.

</thread>

In reply to a post by billford:

In reply to a post by Andrue:

I wonder how it handles inputs for 2-way BB?

I have absolutely no idea .

With modern clocks it could be done with TDM, but it's getting complicated...

Here you go: http://www.satsig.net/vsat-equipment/tdma-explanatio...

EDIT: Could also use a flavour of CDMA, all depends on the implementation.

Edited by deleted (Tue 05-May-09 16:13:39)

Thank you everybody, now I know..

I believe that's what's most likely in the UK.

I believe you are incorrect. The satellite services in the news are all two way ( HYLAS from Avanti, Tooway from Eutelsat etc).

In reply to a post by Anonymous:

I believe that's what's most likely in the UK.

I believe you are incorrect. The satellite services in the news are all two way ( HYLAS from Avanti, Tooway from Eutelsat etc).

Hmmm. Well in that case latency is going to be double my original comment.

http://www.tooway.com/tooway-faq.html#q12

£29.99 a month for 2Mbps, and apparently buys you 1.2GB of data, with speeds slowing down beyond that.
£100 gets you 6GB at the highest priorty.

So hardly meeting the requirements of affordable access to services like iPlayer. If no other solution it would be useful, or for people who travel and set-up for a number of days in different locations.

If subsidies are available to cover setup fees they may stand a chance, but its deja-vu as back in 2002/2003 we had a rash of satellite propositions.

In reply to a post by MrSaffron:

http://www.tooway.com/tooway-faq.html#q12

£29.99 a month for 2Mbps, and apparently buys you 1.2GB of data, with speeds slowing down beyond that.
£100 gets you 6GB at the highest priorty.

So hardly meeting the requirements of affordable access to services like iPlayer. If no other solution it would be useful, or for people who travel and set-up for a number of days in different locations.

If subsidies are available to cover setup fees they may stand a chance, but its deja-vu as back in 2002/2003 we had a rash of satellite propositions.

Yeah, the Tooway specs don't sound all that fantastic for speeds.

http://www.tooway.com/tooway-packages.html

So basically it's meeting Lord Carter's proposed USO albeit with a half second latency and horrible usage restrictions.

Not really surprising I suppose. Satellite is heavily contended in the 'local loop' (can't really call it the last mile, lol) so speed and usage are going to be restricted accordingly. All in all it sounds like a good solution if you're stuck half way up a mountain or in the wildnerness but in the UK at least you'd have to be pretty unfortunate to need to rely on satellite and pretty desperate to want to pay those kind of prices.

But it would allow virtually everyone to have access who does not now - ie. satisifies political statements.
Virtually as satellite's can be blocked by mountains, gorges

For a farm miles from any other property it may make sense, but those small villages of 200 homes suffering due to line length to an already enabled exchange are a different matter.

It has been mentioned that I-Player from BBC could be watched via satellite broadband. This is not the case, as your IP add will be based in Italy or Luxembourg and Iplayer is only available in the UK!!
Rubbish!!

I fiind satellite broadband very good for online gaming ,I play World of war craft and Lord of the rings online also use voice for in game play no problem.I would say it is expensive £26.00 a month this allows me 25 mb a month and a good speed for all I need.I live remote so land based broadband not an option at moment.
I also found out you can play online games very well on dial up speed,but you will not update easily, that does require a good speed,but not imposible.

In reply to a post by Anonymous:

I fiind satellite broadband very good for online gaming

Really? Don't you find the long ping times off-putting?
Many people on these forums whine when their pings (to the game servers) go above something like 30ms, so I can't imagine how many complaints there'd be when the return path (from www to the satellite subscriber) takes at least 240ms (approximately the time taken for a round trip of 44,000 miles - about that from the satellite base station, up to the satellite, then back down to Earth).
And this 240ms doesn't include time to get from the user, over a dial-up modem, out to the internet, to the game server, then back from the game server to the satellite base station.

I'm amazed on-line gaming is possible with such high pings (like I said; given how much people complain when their normal pings go up by a few tens of ms).