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back to article Cellular architectures not great for TV: study

A study by the KTH Royal Institute of Technology in Sweden has found that cell-based distribution of broadcast TV content can be a glutton for spectrum. Around the world, mobile network owners have their eyes on spectrum being vacated by the move to digital TV, and the received wisdom is that video is going to keep driving huge …

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Bronze badge

Belongs in the catagory...

Duh!

You only need ONE broadcast channel for a widely distributed program (say, Royal Wedding), and if you distribute it on cellular data channels, you have zillions of channels with the same content. Not very efficient!

To repeat: Duh!

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Anonymous Coward

Re: Indeed. It's called broadcasting for a reason

When you watch Dr Who on Netflix (via IP over DSL, cable or 4G), that's a form just narrow-casting on steroids. It's impressive (at least for me, bearing in mind my first modem was 4800), and great if we don't all do it at once :-).

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Silver badge

Re: Indeed. It's called broadcasting for a reason

The whole point of broadcast is the huge number who are happy to watch an event simultaneously, either because it is convenient or it is a special "live" event.

But don't knock the study too much, I bet they knew the result all along but needed to have the technical evidence so those who make the license decisions could see the downside to handing over all of the spectrum to broadband companies when then promis to deliver TV-like service as part of it.

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Silver badge
Alert

Re: Indeed. It's called broadcasting for a reason

Yes, it needs to be said. It may be stating the obvious but Governments and Regulators are ignoring the Obvious.

Mobile, Satellite, Fibre, IP etc is all wonderful but complementary to Radio & TV Broadcast.

It was greedy short-sighted stupidity to sell off part of the TV spectrum to Mobile. That part of spectrum is only good for larger cells and isn't enough channels big enough for decent 4G any better than 3G. A total waste.

Terrestrial TV needs the spectrum to compete with cable & satellite TV, which never can be portable or instantly available at a new location. Satellite is very vulnerable and cable only viable for Urban areas, both are tethered so though "Broadcast" are not replacements for Terrestrial TV, despite Ofcom's and Comreg's agenda to abolish Terrestrial TV entirely.

As we read this, Ofcom and Comreg are planning to reduce DTT further to sell off a 2nd block (even poorer mobile capacity and larger cells).

Mobile to give decent 4G coverage and speed needs MORE cells than 3G. This isn't possible on UHF.

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Silver badge

Re: Indeed. It's called broadcasting for a reason

Well 4G in it's later incarnations can do beamforming. So you could split up your cells into many different sectors.

However for dense areas, simple 5GHz WLAN would be the far better solution.

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Silver badge

Re: Indeed. It's called broadcasting for a reason

Beamforming works best on higher frequencies and smaller cells. Planning permissions and cost mitigate against any useful "Beamforming" on UHF. You need huge aerial arrays and much more electronics.

MIMO and Beamforming is way hyped and available on WiFi, 2G and 3G also but rarely deployed on Mobile.

When you have small cells (= higher capacity per area) then 2.1 to 2.6GHz bands are fine. There should be nearly 200MHz at 2.6Hz. Since the aerial size is less than 1/3rd size of 800MHz, MIMO and Beamforming is more practical. Also BECAUSE the 2.6 GHZ signal can't travel as far as 800MHz, frequency reuse to have higher capacity is 10 to 20 times more capacity.

But operators are more interested in maximizing revenue than performance and the Licence conditions let them. The most efficient use of any band is a SINGLE wholesale RAN, not Ofcom's and Comreg's pack in as many operators on separate channels (more licence revenue). On average a single RAN gives about x4 capacity or speed compared to splitting up the band the way Ofcom and Comreg do.

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Silver badge

And meanwhile, in the department of the bleedin' obvious

This has been wishful thinking since day one. While the bandwidth to broadcast dtt or satellite remains constant irrespective of the number of viewers, if each and every one of them wants their own personalised TV then you either need a hell of a lot of distribution, or you, er, broadcast...

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They did assume broadcast on LTE

Reading the paper, it looks like they did assume broadcast on LTE for broadcast-type networks, thus using some of the LTE bandwidth stolen from traditional TV for that. Even so, the numbers don't look good. A DTT network is now extremely well optimised for its purpose, so it's not too surprising that a network optimised for more general-purpose communication, including mostly single station to single station communication, would not compare favourably on spectrum utilisation.

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ZPO

How much did they pay the department of obvious studies for this?

This is a study that might as well have said that fire is hot and ice is cold. A single stream broadcast at the multi-KW level is going to cover a much larger area with a single transmission. This iisn't rocket science. It is how the networks are built with different goals in mind.

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Gold badge
Thumb Up

Had to be done to *demonstrate* the idea is stupid, not just believe it is.

It's proving a negative and (very occasionally) it produces counter intuitive results.

But not in this case. Which is good.

Now will Ofcom take a blind bit of notice?

Thumbs up for proving the idea is b***ocks, not just thinking it is.

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Silver badge

So...

A network designed for broadcast is better suited for broadcast than a network designed for unicast. Wow.

Also the much bigger problem is that cellular networks tend to include brain dead DRM which tends to be incompatible with the way people use TV since the advent of widespread digitalisation. (ca 2000)

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