Re: [802.3_EPOC] Exclusion bandwidth question
Matt,
One of the issues we need to keep in mind that some of the subcarriers are likely going to be pilot signals used for channel estimation, frequency offset estimation, etc. When we exclude portions of spectrum we will likely lose some of those pilot tones. So we need to make sure we do it in such a way that we still have sufficient number and placement of the pilot tones. An extreme example showing what we could not do, would be to exclude just the pilot tones. That is not something that would come up in practice, but if all the pilots were excluded they would not be available for channel estimation, etc.
There are several motivations for excluding sub-bands. If it is to make room for a legacy system then we should be able to identify the systems in advance and account for them. For narrowband noise we need to figure out how much flexibility is needed. We may want to exclude a smaller sub-band.
Steve
From: Matthew Schmitt [mailto:m.schmitt@xxxxxxxxxxxxx]
Sent: Monday, September 10, 2012 1:40 PM
To: STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx
Subject: [802.3_EPOC] Exclusion bandwidth question
With apologies for missing the first part of the call, I wanted to follow up on the discussion of exclusion bandwidth in the presentation materials that were reviewed on the call.
In particular, I wanted to ask the following question: is there any reason why we can't have granularity down to the level of a sub-carrier? Why does it need to be 6 or 8 MHz in the downstream, or 6.4 or 3.2 or 1.6 MHz in the upstream? Is there a reason we can't just mute individual sub-carriers? Does it really impact the complexity of the solution that much? Or is it more a concern regarding how deeply an individual sub-carrier can be muted? I'd like to better understand the implications and the tradeoffs here before I jump to one conclusion or another.
Thanks!
Matt
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