Originally Posted by BiggAW
I get that, and how an SFN would co-located on cell towers, but where this goes off the deep end is where it's somehow combined with a 5G network, as opposed to just sharing physical tower infrastructure with 5G providers, which may make sense in some markets and applications. Since you can't split the 6mhz of spectrum, that whole scenario makes no sense.
You can definitely split all 6 MHz by time, not by spectrum, within the 3.0 spec. See below reply.
Originally Posted by Tschmidt
I'm confused by the discussion of SFN. My understanding is one of the benefits of ATSC 3.0 is it allows stations that use low power repeaters to extend coverage, such as WENH here in NH, to operate all transmitters on the same frequency.
What I'm missing is how this plays with 5G cellular? Sounds like the discussion is that ATSC 3.0 allows the 6MHz of TV channel bandwidth to be split into a TV portion and 5G cellular portion.
It can do both of what you're describing. Basically the main tower and repeaters can operate what are known as "physical layer pipes", which are, under the 3.0 spec, sent by time slices. So PLP 1 can have TV signals, and a few milliseconds later, there can be a second PLP which can have 5G content. All of this is coordinated from the bootstrap. Then from there, the cell companies can use their 5G towers as low power repeaters that will rebroadcast the PLP 1 TV signal, timed up with the main tower, while the 5G content goes on PLP 2. Alternately, the TV stations can set up low-power repeaters on their own. In theory, both cell companies and TV stations can set up their own repeaters, but that's not usually going to happen because a cell company's repeaters would usually be enough to provide solid TV coverage. My theoretical scenario of "set 5 MHz aside for exclusive 5G use", still allows for these repeaters to be used, and TV signals timed up, just the 5G signal does what it does without need for a 3.0 decoder chip, and hopefully TV signals on the remaining 1 MHz can still be decoded by 3.0 tuners.
Originally Posted by dr1394
You can't split the spectrum. The minimum size of an ATSC 3.0 signal is 6 MHz. That's cast in concrete in the bootstrap specification.
I mean yes, the 3.0 spec claims a 6 MHz minimum spectrum, but if the overall signal being received by a tuner is 6 MHz wide, I can't help but think the tuner could, and should, decode what it can understand within a given PLP time slice, even if most of what it sees is nonsense. Or what if one is using an antenna whose gain falls off the map past a certain point? If a tuner picks up enough data, including the bootstrap, to theoretically decode a TV station's signal, but can't see all 6 MHZ of the signal, it's not supposed to decode the usable signal it can see? That sounds like a bad decoder to my opinion, especially in the latter situation.
Offering a few MHz of spectrum in a low-frequency band won't magically get 3.0 OTA TV tuners into phones. Verizon and AT&T simply will not agree to putting a Trojan horse into their phones. It's not going to happen, because they own cable companies that have to negotiate with Sinclair for retrans deals, and if your cell/cable company makes it easier for people to get TV through an end-around, it's going to increase Sinclair's leverage in retrans negotiations. So VZ and ATT simply will not swallow a poison pill from their perspective. Sprint is cash-strapped and in the process of being purchased by T-Mobile. T-Mobile might want to do an arrangement of some kind, because they're not in the cable TV business for now, but I'm not sure they'd want to have the tuners in there, because they'd want to have an ability to control the pipes used to receive content on phones, so to speak. So they'd probably want to do some sort of deal, but if their tech boffins can find a way to make a 3.0 tuner tune a TV signal on a net 1 MHz of spectrum, they'd force Sinclair's hand. Who else would negotiate with them?
, T-Mobile would agree to a deal to include 3.0 chips if all phones included with tuners didn't have hardware or software support for the HEVC and AC-4 codecs, or at least AC-4. To allow for HEVC decoding of content it would control pipe access to (Netflix, YouTube, etc.), would T-Mobile be OK with video decoding, but not audio decoding, of TV signals?