It has been fun to watch the MFN SFN debate. As an "unbiased" observer, I must say I am not convinced by any of the arguments. But there have been more than a few cannards in the discussion that should be addressed...
Bert Wrote
You can't conflate all issues into one simplistic notion, John. Cretainly, you cannot deny that a big stick to cover a single market is more spectrally efficent than a SFN *to cover a single market*. Right? That was the original trade.
This is ONLY true if we are talking about a market that exists in isolation - that is, it is sufficiently distant from any other market that one does not need to consider the loss of white space channels in adjacent markets. But the reality, especially in the areas where spectrum is in the greatest demand, is that big sticks DO require LARGE non-interference areas in surrounding markets. The only way to mitigate this is to reduce the HAAT and power levels so that the areas of interference are reduced.
In the case of using SFNs in dense urban areas, there is NO way that big sticks or MFNs can provide the spectral efficiency of properly designed SFNs. And I would add that we demonstrated solid mobile reception using now legacy tech COFDM at NAB in 2000. THe ATSC has since managed to equal this feat, but only with a kludge that eats up spectrum (payload) to enable mobile reception.
Now, let's look at a single scenario of distributed antennas that perhaps can cover of the multi-transmitter discussions in one fell swoop.You want to create a regional broadcast to include the Wash DC to NYC markets, and everything inbetween.
Nobody wants to do this Bert. Qualcomm did this because they were offering a subscription service with almost no local content. In case you failed to notice Bert, this offer was widely rejected by prospective customers, just as USDTV failed to generate a viable subscription service in the OTA spectrum.
Broadcasters WANT localism. This is the backbone of their existence. Without localism we could all use DBS for fixed receivers, and the networks could dump affiliates and keep every dime of the subscriber fees that would be generated. The reality is that broadcasters are not close enough to their customers, especially in larger markets with dozens or even hundreds of local communities. In these markets cable has a huge advantage because they can target viewers to the neighborhood, and in some case individual homes.
What is really important here is what consumers are looking for in a mobile TV service. The real buzz today is "location based services," that is, the ability to deliver useful information relative to the location of the mobile device.
Somehow, regional based services just don't have the same cachet. Hey they have the popular widget I want in Philadelphia, but I am currently in D.C.
It should be obvious by now that consumers have shown little interest in paying for mobile TV, at least beyond the portion of their wireless bills that pay for data services. And then there's the little game that the MVPDs are playing - if you pay for our content for the fixed receivers in your home, you can access this content via your mobile devices as well.
So the real question here is what is the business model for this next generation broadcast infrastructure?
John wrote.
> The point being completely lost here is that cell phones use a MFN matrixof towers not for increased coverage or ease of reception, but for overall system capacity. Cell phones are by their nature two way, so the smaller you can make the cells, the more you can reuse frequencies and thereby increase overall system call capacity.
And Bert replied:
True. That's whay the mere term "cellular TV," to describe SFNs, is so profoundly annoying in its cluelessness.
Near as I can remember, Bert is the only person calling SFNs Cellular TV. They are Single Frequency Networks that cover a market and limit interference into adjacent markets. And in many cases a portion of the content will be different in the sub markets covered by the broadcast infrastructure; that is, some frequencies will be used across the entire market, while a few frequencies will be used to provide hyper-local coverage for the sub-markets.
Whagt we are talking about here Bert is improved spectral re-use, which is exactly what the telcos get from their networks.
This is called spectral efficiency Bert. And guess what? It works for broadcast signals too.But the size of the cells does not need to be as small as for a phone network since most of the bits will reach many people, not just two phones.
This has already been tested in markets like New York City, where a handful of transmitters (5-6) can easily cover the entire market.
.Television is a broadcast medium, so the only reason for either an SFN or an MFN is for ease of reception.Can't have it both ways, John. But if ease of reception is the goal, then MFNs win hands down.
John is correct. Broadcasters have all but lost the war for fixed receivers. The future is service to mobile devices (and a small percentage of fixed receivers that do not subscribe to a MVPD or use Over-the-top services). The goals are:
1. Improved spectral efficiency - more content in less spectrum2. Ease of reception by low complexity mobile devices (no power hungry chips here). 3. Improved compatibilty with the radios that are going to be deployed in mobile devices - if you can use some of the same hardware for both data and TV you may have a better chance of getting receivers built into mobile devices.
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