Re: [802.3_EPOC] Exclusion bandwidth question
Charaf,
Subcarrier spacing is important, I agree. I don't think we have heard from the channel model people yet but it will depend in part on the level and duration of multipath echo, which will in turn determine the duration of the cyclic prefix, which will in turn determine the OFDMA symbol period (loosely but I don't think the CP can be much more than 10% of the symbol period), which will in turn determine the subcarrier spacing.
Hal
From: Charaf HANNA [mailto:charaf.hanna@xxxxxx]
Sent: Tuesday, September 11, 2012 9:37 AM
To: STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_EPOC] Exclusion bandwidth question
Subcarrier spacing is an important parameter to consider, if it is too small and the full RF-bandwidth is too wide then a big number of bits would be required to access every single subcarrier (still doable). Grouping subcarriers could be an interesting option (2, 4, 6 or more).
Regards,
Charaf
From: Dai, Eugene (CCI-Atlanta) [mailto:Eugene.Dai@xxxxxxx]<mailto:[mailto:Eugene.Dai@xxxxxxx]>
Sent: Tuesday, September 11, 2012 9:28 AM
To: STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx<mailto:STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx>
Subject: Re: [802.3_EPOC] Exclusion bandwidth question
Kevin: If we open a 6MHz or multiple 6MHz window in the OFDM range, depends on the spectra location of that window and relative location to the rest of OFDM subcarriers, beats could be generated in that window that could make some channel unusable. Since the leading order beats could be calculated we can mitigate this effect by muting a few relevant subcarriers to guarantee coexistence. To do this we need to have accessibility to individual subcarriers.
Thanks,
Eugene
From: Noll, Kevin [mailto:kevin.noll@xxxxxxxxxxx]<mailto:[mailto:kevin.noll@xxxxxxxxxxx]>
Sent: Monday, September 10, 2012 5:21 PM
To: Dai, Eugene (CCI-Atlanta); STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx<mailto:STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx>
Subject: Re: [802.3_EPOC] Exclusion bandwidth question
Eugene,
Forgive my ignorance in this subject matter, I certainly understand the need to mute portions of the spectrum so that DOCSIS and other users aren't impacted. However, I don't see why co-existence with DOCSIS requires the ability to mute individual sub-carriers.
Please explain.
--kan--
--
Kevin A. Noll
Principal Engineer
Time Warner Cable
13820 Sunrise Valley Dr
Herndon, Va 20175
o: +1-703-345-3666
m: +1-717-579-4738
AIM: knollpoi
From: <Dai>, "Eugene (CCI-Atlanta)" <Eugene.Dai@xxxxxxx<mailto:Eugene.Dai@xxxxxxx>>
Reply-To: "Dai, Eugene (CCI-Atlanta)" <Eugene.Dai@xxxxxxx<mailto:Eugene.Dai@xxxxxxx>>
Date: Monday, September 10, 2012 5:02 PM
To: "STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx<mailto:STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx>" <STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx<mailto:STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx>>
Subject: Re: [802.3_EPOC] Exclusion bandwidth question
I wonder without bandwidth granularity down to subcarrier level in OFDM(A) for EPOC PHY, how can we have interoperability? Ability to mute individual subcarriers is a way to have coexistence of EPOC with DOCSCIS, why not?
Thanks,
Eugene
From: Matthew Schmitt [mailto:m.schmitt@xxxxxxxxxxxxx]
Sent: Monday, September 10, 2012 4:40 PM
To: STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx<mailto: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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