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Re: RE: [EFM] EFM Active Architectures

[Second attempt at getting this message out... ]

Frank Effenberger, 

Yes, as with Dave's half-PON concept which I also like very 
much, the TDM and slicing options are also of interest and 
certainly deserving of further investigation.

The thing that occurs to me, at least in the two optical 
tracks of EFM (p2p and pt-mpt), is this: 

How do either of these proposed designs, or _any_ of the 
others, for that matter, lend themselves to extensibility 
to higher speeds down the road? Stated another way, should an
approach that "locks in" an upper bound on throughput be of 
concern? As in, being able to deliver the next two powers 
of 10 beyond 100Mb/s (since 100 is often cited as the target 
delivery rate at this time), at least, without a major forklift
when they arrive. What happens to be friendly at 100 Mb/s 
between the OLT and/or the field "thingie" and the ONU at 
this time may not be as friendly at 10Gb/s or higher. 

Or, is this even something that should concern EFM at this time? 


> All, 
> We have considered this topology to some degree ourselves.  
> The variant we considered is to use TDM in the downstream, 
> and WDM in the upstream.  The advantages of doing this are 
> that you avoid the TDMA protocol issues, and you save N lasers. 
> over doing it point-to-point.  You also reduce your spectrum 
> requirement by a factor of 2 (half as many wavelengths), and 
> this can be key if you are using coarse WDM.  Since cost is 
> key, CWDM would be a good direction.  Spectral slicing is 
> also an interesting option.   
> Versus a TDMA PON, you must add N receivers at the CO; however, 
> an array of receivers is *much* more tractable than an array 
> of WDM lasers.  
> Lastly, the use of WDM in the upstream retains the all passive 
> outside plant advantage of PON.  No field electronics. 
> Any interest? 
> Frank Effenberger.