Re: [802.3_EPOC] another argument for MCS
For George…
From: "George Hart @ Rogers" <George.Hart@xxxxxxxxxxxxxx<mailto:George.Hart@xxxxxxxxxxxxxx>>
Date: Thursday, October 11, 2012 12:04 PM
To: Victor Blake <victorblake@xxxxxxxxxxxxxxx<mailto:victorblake@xxxxxxxxxxxxxxx>>, "STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx<mailto:STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx>" <STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx<mailto:STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx>>
Cc: Matthew Schmitt <m.schmitt@xxxxxxxxxxxxx<mailto:m.schmitt@xxxxxxxxxxxxx>>
Subject: RE: [802.3_EPOC] another argument for MCS
Our recent real world experience with LTE interference has prompted us to become much more concerned about this interference source. We can expect this challenge to only grow in future as wireless carriers increasingly overlap with cable spectrum and also increase channel widths through carrier aggregation. Femtocells may become particularly problematic for their downlink transmissions. This field experience and expectations on future developments will need to be incorporated into the channel model, but in the meantime, having an adaptive mechanism for dealing with the intermittent nature of these interference sources (mobile handsets have a habit of moving around) seems highly desirable.
While we do our best to clear up defects in our network to clear up ingress, this takes time and service outage in the meantime is not an option. So as we push the envelope on spectral efficiency for EPoC, the requirement for autonomously adapting to degraded plant performance becomes essential.
Thanks,
George
From: Victor Blake [mailto:victorblake@xxxxxxxxxxxxxxx]
Sent: Thursday, October 11, 2012 1:35 PM
To: STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx<mailto:STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx>
Subject: Re: [802.3_EPOC] another argument for MCS
Identify well known ingressors. There are a lot of them besides cellular and satellite (unlicensed wran, wireless microphones, etc.).
-Victor
From: Marek Hajduczenia [mailto:marek.hajduczenia@xxxxxx]
Sent: Thursday, October 11, 2012 1:16 PM
To: STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx<mailto:STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx>
Subject: Re: [802.3_EPOC] another argument for MCS
I was going to ask whether the next step would be also protecting against GPS signaling as well as satellite radio and such … it seems to me that it is the problem which has been solved in the past, as Rich points out.
Marek
From: Rich Prodan [mailto:rprodan@xxxxxxxxxxxx]
Sent: Thursday, October 11, 2012 13:12
To: STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx<mailto:STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx>
Subject: Re: [802.3_EPOC] another argument for MCS
On the other hand, it is easier to avoid LTE interference by carrier nulling the small amount of spectrum impacted. This is also why premium services today are not placed in the 88 to 108 MHz FM band on many systems.
From: Tom Williams [mailto:T.Williams@xxxxxxxxxxxxx]<mailto:[mailto:T.Williams@xxxxxxxxxxxxx]>
Sent: Thursday, October 11, 2012 10:58 AM
To: STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx<mailto:STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx>
Subject: Re: [802.3_EPOC] another argument for MCS
All-
Here is a another good reason to use different MCS’es: some homes will have LTE interference and will need a more powerful (and less efficient) FEC to overcome the ingressing interference.
Again, it makes little sense to force everybody to the lowest common denominator when the lowest comment denominator is low and the spread is high.
I personally think a big value of multiple MCS’es may be 1-1.8GHz downstream band. At these frequencies, the attenuation differences will be huge due to different cable lengths between the subscriber right off the node and subscriber at the end of the line. Once attenuation gets too high, S/N falls.
Tom Williams
Cablelabs
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