[opendtv] Re: Doug Lung series on OFDM

  • From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
  • To: "opendtv@xxxxxxxxxxxxx" <opendtv@xxxxxxxxxxxxx>
  • Date: Wed, 14 Nov 2012 15:14:30 -0600

Craig Birkmaier wrote:

> Yes, as I described above, you can use A-91 to cache ads in a receiver,

(Actually I meant A/90. Sorry. The data broadcast standard.)

No need to even cache anything. The way this can work is, a user stores his 
preferences in the receiver. When the ad breaks occur, the broadcaster 
transmits a "baseline" ad with the main program stream, and then a small number 
of additional ads, each one with its identifying IP multicast destination 
address. During ad breaks (i.e. when the IP multicast is seen by the receiver), 
if a user has stated preferences, the receiver will replace the "baseline" ad 
with the targeted ad. This is doable, and it is doable with full backward 

The app in the receiver is used to "tune" the receiver to the IP multicast 
address related to the user's preferences, for that particular station. In 
principle, the IP multicast addresses can be reused from one multiplex to the 
next, unless you worry about possible future ramifications, if you really want 
to get fancy.

> And who said anything about interactive ads?

I did! That is how the OTT service discovers what you want to see. They present 
you with, say, three possible ads to watch, and have you pick one. From that, 
theoretically they can figure you out. Or another option is that they ask, with 
each ad, whether it is of interest to you. Becomes a nuisance fast, is my point.

> The way Bert frames this argument, broadcasters should give back ALL of their
> spectrum and let the telcos handle their wireless distribution.

It's a super risky game to be playing, to change the one-way broadcast standard 
at this point, IMO. Reason being, there aren't a whole lot of programs that 
really benefit from a one-way pipe, now that 2-way pipes are already deployed. 
For instance, all local broadcasters could share, say, a single multiplex in 
any given market, for that content that really must be live and one-way, and 
that a huge segment of the population of the market really wants to see. 
Political maneuvering can change this, however IMO this is the technical 
reality of today. So changing the OTA broadcast standard will force the FCC to 
go through all of this, all over again.

> Moving to a network of COFDM (and LTE?) transmitters ads the ability to
> zone advertising by default.

No, actually it doesn't. If you use SFNs, the signal has to be identical from 
each tower, Otherwise, you will create dead interference zones during ad 
breaks. That's unavoidable.

With LTE, same thing exactly, unless you mean that you're using unicast vs 
broadcast. Unicast requires a 2-way pipe.


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