[opendtv] Re: Qualcom OFDM networks with MediaFlo

Manfredi, Albert E wrote:

>Craig Birkmaier wrote:
>
>  
>
>>here we go again...
>>    
>>
>
>Sorry, Craig. You ain't no Ronald Reagan "great
>communicator."
>
>  
>
>>So I take it Bert was involved in the development
>>of this system
>>    
>>
>
>No, I merely read what is written with the intention
>of understanding, rather than reading with the
>intention on twisting my previous political
>platforms to try to prove that I was right before,
>as you seem to enjoy doing (but fail).
>
>  
>
>>however they are just what you would expect for a
>>COFDM-based Single Frequency Network.
>>    
>>
>
>You mean, like the 200 KW big sticks (for *one* of
>the nine DTT channels) in Berlin. Sure. That is in
>line with many big sticks the TV transmitters use now,
>even here.
>
>Remember that a 3 dB difference (doubling power) does
>not amount to much difference in range. You have to
>think in orders of magnitude. A 200 or 500 KW
>transmitter and 600' tower *is* a big stick, by any
>definition.
>
>Big sticks in the US now, depending on frequency,
>range from the single or tens of KW to 1 MW. Many
>big sticks are in the 100s of KW. In line with
>the Berlin SFN approach.
>
>  
>
>>You obviously did not read the links I provided.
>>These networks have been designed to work
>>together to maximize the potential for both.
>>    
>>
>
>When we talked about this infrastructure, I
>explained that you could mix and match any
>modulation scheme and different transmitters
>entirely. Remember? You were instead pushing this
>imprecise concept of an all-COFDM mesh of small
>sticks. Need I remind you? Was it 10-30 KW per
>stick? Or less? It made no sense then, and it
>doesn't make sense now either.
>
>Well, what I described is what they are proposing.
>They are talking separate transmitters for the two
>services, with a cell approach for the unicast
>2-way service.
>
>The IP (or other) encapsulation is purely optional
>with *any* infrastructure you care to build. Don't
>make more of a big deal out of it than it deserves.
>IP over 8-VSB or over QAM works too.
>
>  
>
>>COFDM is simply a more efficient way to deliver
>>this data to CDMA enabled appliances, especially as
>>it relates to power consumption.
>>    
>>
>
>This is jibberish. What does "CDMA-enabled
>appliances" mean? The truth is that COFDM is
>more spectrally efficient, at 16-QAM or 64-QAM,
>than CDMA is. So they use COFDM for the TV
>broadcast, potentially, instead of cdma2000.
>They propose either scheme, though.
>
>And if the COFDM transmissions are high enough in
>power, the greater spectral efficiency will still
>provide enough robustness.
>
>The appliance would simply incorporate both
>tuners. This is a CDMA *and* COFDM enabled
>appliance, if that terminology makes you happy.=20
>
>  
>
>>You missed it again Bert.
>>
>>The channels are 1.25 MHz. They can be used to
>>deliver any kind of packet data including audio
>>and video.  But this has nothing to do with what I
>>wrote.
>>    
>>
>
>Narrowband CDMA was always specified for 1.25 MHz
>channels. cdma2000 was always specified to fit in 5
>MHz bands or in separate 1.25 MHz bands, for backward
>compatibility with narrowband CDMA. The COFDM they
>would introduce, unlike the COFDM used in DVB-T,
>would also be made to fit in something less than 6
>MHz. Guess what? You can do the same thing with any
>modulation scheme. It's simply a different
>modulation technique used in the same 6 MHz band.
>Which is exactly what you were *not* proposing back
>when, in your spectrum utility.
>
>I explained to you (i.e. to deaf ears) back then
>that although your notion of small sticks and all
>COFDM was essentially unworkable, a viable utility
>was still possible, and by the way, 8-VSB could be
>in there as well. You just can't be too dogmatic
>about these things.
>
>  
>
>>This approach moves most of the IP Multicast
>>traffic OFF of the CDMA network, freeing up
>>bandwidth for more unicast and phone transactions.
>>    
>>
>
>It moves the high bit rate TV channel traffic off
>the 2-way infrastructure. Wow. Isn't that how
>DOCSIS and cable TV works?
>
>In fact, you need use no IP overhead at all. The
>broadcast TV traffic can use MPEG-2 TS without IP
>overhead, and the two-way traffic can use normal
>circuits as defined in CDMA. Or IP overhead can be
>added to the data circuits of the CDMA 2-way
>unicast service. And/or IP overhead can be added
>to the MPEG-2 TS in the broadcast service. This
>is all very interesting, but let's not over-hype.
>
>  
>
>>I did provided two references that verified the
>>notion that these would be COFDM SFNs.
>>    
>>
>
>Your references said high power towers. They did
>not even hint at 10-30 KW towers you had mentioned
>previously. The arithmetic never did work for
>those small sticks, Craig, and no amount of
>obfuscation can change that fact.
>
>As far as I can tell, none of the above is
>remotely similar to your previous utility
>concepts. But I am gratified that maybe you're
>starting to get it?
>
>Bert
>
First this is an overlay network that works with current carrier CDMA 
networks. They are not proposing to build both a COFDM and CDMA network.

Second they are limited to 50 kW so if that is big stick it is but I 
would think big stick high power starts at 200 kW and over. LPTV is 
definitely 15 kW and lower. I would expect most of the transmitters that 
Qualcomm uses to be in the 1 to 30 kW especially in cities. That is if 
they use towers at all. If not the power levels could fall to a kW or 
even less.

Bob Miller



 
 
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