Re: [802.3_EPOC] Questions on varanese_01_0912.pdf
Victor,
To elaborate my comments a bit further, we are defining a PHY for something in between an optical network (well defined physical attributes) and a wireless network (variable attributes between networks and time varying within an network). With the optical network there are a small number of parameters, optical power, dispersion, etc that define the PHY. These can have rigid physical layer minimums where it is therefore easy to define the minimum service level.
With wireless it would be ludicrous to suggest that the MCS is not be dynamically adjusted. Without this our smart phones would not work the way we have come to expect. With optical networks, there is little or no benefit to "downshifting" for an impaired network. Instead, the network should simply be repaired to the minimum requirements.
With coax we have something in between. Should it be adaptive or fixed?
I think it is better to not have a fixed position on adaptive MCS but to be cognizant of how wireless networks function and take what is useful and leave what is not. By specifying a range of MCS (and other PHY parameters) this can be left to the implementation. The channel model should reflect this philosophy and provide guidance on how we can select the MCS choices to handle the variables in the model.
Make sense?
Hal
From: Victor Blake [mailto:victorblake@xxxxxxxxxxxxxxx]
Sent: Monday, October 08, 2012 6:41 PM
To: Hal Roberts; STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx
Subject: RE: [802.3_EPOC] Questions on varanese_01_0912.pdf
Great. Guess that was my pessimistic assumption, not yours!
From: Hal Roberts [mailto:Hal.Roberts@xxxxxxxxx]<mailto:[mailto:Hal.Roberts@xxxxxxxxx]>
Sent: Monday, October 08, 2012 6:50 PM
To: STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx<mailto:STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx>
Subject: Re: [802.3_EPOC] Questions on varanese_01_0912.pdf
No assumption at all on automatic vs provisioned (on my part). Only assumption is the MCS not be fixed and the channel model acknowledge a range of conditions. As in DOCSIS there would be multiple knobs to turn. However operators may desire to set a certain mode of operation that assumes a certain plant condition and defines the knob settings.
Sent from my Verizon Wireless 4G LTE DROID
Victor Blake <victorblake@xxxxxxxxxxxxxxx<mailto:victorblake@xxxxxxxxxxxxxxx>> wrote:
Hal,
Is there an assumption being made here that "impairments" will be automatically identified and some algorithm will be followed to determine the mcs(MCSes ?) that will be used ? Might it not be the case that these would be determined in advance by operator's administrative settings (aka configurations).
Just want to ask because it sounds like an assumption to me (because it may be the case - I'm begging the question here, that an operator may want to elect a specific subset of supported MCSes and then presumably have some level of automation from there.
-Victor
From: Hal Roberts [mailto:Hal.Roberts@xxxxxxxxx]<mailto:[mailto:Hal.Roberts@xxxxxxxxx]>
Sent: Monday, October 08, 2012 1:54 PM
To: STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx<mailto:STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx>
Subject: Re: [802.3_EPOC] Questions on varanese_01_0912.pdf
Matt,
I agree that a number of MCSs should be defined and that a specific set of MCS attributes could consist of a profile, as you propose. The Channel Model should inform the choice of MCSs. To do this, the Channel Model should not be a single set of parameters/impairments but identify a range of values for each impairment, where necessary.
Hal
From: Matthew Schmitt [mailto:m.schmitt@xxxxxxxxxxxxx]<mailto:[mailto:m.schmitt@xxxxxxxxxxxxx]>
Sent: Monday, October 08, 2012 12:24 PM
To: STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx<mailto:STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx>
Subject: Re: [802.3_EPOC] Questions on varanese_01_0912.pdf
As an FYI, if deployed for residential services, especially early on I think that you might have numbers of devices per OLT port on the order of what might be done for a DOCSIS service group, achieved by aggregating a number of OCUs onto a single OLT port. That could easily be on order of 250-500 CNUs per OLT port. Probably less in actuality, but I think we should be prepared for those types of numbers.
Over time, I agree with Jorge and Ed that it will likely get smaller (by disaggregating those OCUs onto different OLT ports), probably on order of 64 CNUs for a single OLT port (give or take). The key, though, is that we need to design the system to handle more than that.
Business services might be closer to the 64-128 number to start, ramping down to smaller numbers over time.
Note that the above is my personal opinion; I have not talked to my members to generate a specific consensus position on that topic.
Marek, as to your point about SNR variance... The problem is that even if there are only 2 devices, while statistically the odds are lower that there's a significant spread in SNR, there's still a chance that they will be spread quite a bit. Additionally, if you're looking at multiple OCUs aggregated to a single OLT port, the odds of significant SNR spread between devices sharing that single OLT port (because they're on different OCUs) is actually quite high.
I believe very strongly that we need to adopt some sort of mechanism in EPoC that allows for different CNUs to operate with different Modulation and Coding Schemes (MCSs). I believe you can get the majority of the benefit with a limited number of "profiles" that CNUs could be grouped into, but I think you will need at least on order of 3-4 of these.
Thanks.
Matt
From: <Salinger>, Jorge Salinger <Jorge_Salinger@xxxxxxxxxxxxxxxxx<mailto:Jorge_Salinger@xxxxxxxxxxxxxxxxx>>
Reply-To: Jorge Salinger <Jorge_Salinger@xxxxxxxxxxxxxxxxx<mailto:Jorge_Salinger@xxxxxxxxxxxxxxxxx>>
Date: Sunday, October 7, 2012 4:07 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] Questions on varanese_01_0912.pdf
Right, I meant to describe things in the longer term.
Maybe in a nutshell, on could say that networks will be designed in such a way that the number of CNUs/OLT port will be to be similar to the number of ONUs/OLT port, by aggregating several OCUs/OLT port initially as CNU penetration is low, and by splitting OCUs into more OLT ports as the number of CNUs grows. I think his would apply to both resi and business services.
Does that make sense?
Jorge
From: Edwin Mallette <edwin.mallette@xxxxxxxxx<mailto:edwin.mallette@xxxxxxxxx>>
Date: Saturday, October 6, 2012 3:02 PM
To: "Salinger, Jorge" <Jorge_Salinger@xxxxxxxxxxxxxxxxx<mailto:Jorge_Salinger@xxxxxxxxxxxxxxxxx>>, EPoC Task Force <STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx<mailto:STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx>>
Subject: Re: [802.3_EPOC] Questions on varanese_01_0912.pdf
In general it makes sense, I think what Jorge describes might be true in time - not sure that's true "day-1." In fact I can easily see a case where we might dabble with aggregating as many CCDNs together to a single 10G-EPON port to efficiently utilize the bidirectional capacity (and efficiently utilize our Capex and Opex spend). In the early days where we have 120MHz or less of downstream bandwidth, I can see attempting to aggregating 10 CCDNs together, as an example, for mostly residential services. As a result you might see a pretty high number of scheduled services (LLIDs.)
Eventually I think we'll trend to having the number of CNUs in a CCDN roughly equivalent to what we could see with ONUs per OLT port (32 or 64) and accordingly we'd see the OCUs per OLT port trend to one or two if that makes sense.
Ed
From: Jorge Salinger <jorge_salinger@xxxxxxxxxxxxxxxxx<mailto:jorge_salinger@xxxxxxxxxxxxxxxxx>>
Reply-To: Jorge Salinger <jorge_salinger@xxxxxxxxxxxxxxxxx<mailto:jorge_salinger@xxxxxxxxxxxxxxxxx>>
Date: Saturday, October 6, 2012 12:24 AM
To: <STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx<mailto:STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx>>
Subject: Re: [802.3_EPOC] Questions on varanese_01_0912.pdf
Personally, I think that for the use case of residential services, there would be few OCUs/OLT port, yielding an effective number of CNUs/OLT port that is similar as the number of ONUs/OLT port. For business services, since the subscriber density is lower, there would be multiple OCUs/OLT port, and even in that case the number of CNUs/OLT port would be lower than for residential services. Does this make sense?
JD,
Ed,
Does what I describe make sense to you?
Thanks!
Jorge
From: Marek Hajduczenia <marek.hajduczenia@xxxxxxxxx<mailto:marek.hajduczenia@xxxxxxxxx>>
Date: Friday, October 5, 2012 6:12 PM
To: "Salinger, Jorge" <Jorge_Salinger@xxxxxxxxxxxxxxxxx<mailto:Jorge_Salinger@xxxxxxxxxxxxxxxxx>>, EPoC Task Force <STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx<mailto:STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx>>
Subject: RE: [802.3_EPOC] Questions on varanese_01_0912.pdf
Jorge,
Makes sense. Have you given a thought to bandwidth available per CNU in the case of "hundreds of CNUs per ONU" ? That seems that a single 10G OLT port might be shared by several thousands CNUs, leaving bandwidth per CNU less than attractive.
Just trying to see what the target scenario might be and what number of CNUs to expected subtended to a single OLT port
Marek
From: Salinger, Jorge [mailto:Jorge_Salinger@xxxxxxxxxxxxxxxxx]
Sent: Friday, October 05, 2012 22:57
To: STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx<mailto:STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx>
Subject: Re: [802.3_EPOC] Questions on varanese_01_0912.pdf
I wanted to share some thoughts on this...
I think that there are two deployment scenarios and two use cases that MSOs are considering. One of the deployment scenarios is where the OCU is deployed close/next to the node and the EPoC signals traverse amplifiers, and the second where the OCU is deployed past the amplifier. The two use cases are business and residential services.
For the use case of residential services, in the first deployment scenario there could be hundreds of CNUs per ONU, and in the second there would be far fewer CNUs/OCU. For the use case of business services, in either of the deployment scenarios there would be far fewer CNUs per ONU.
Does this make sense?
Thanks!
Jorge
From: Marek Hajduczenia <marek.hajduczenia@xxxxxx<mailto:marek.hajduczenia@xxxxxx>>
Reply-To: Marek Hajduczenia <marek.hajduczenia@xxxxxx<mailto:marek.hajduczenia@xxxxxx>>
Date: Friday, September 28, 2012 5:47 AM
To: EPoC Task Force <STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx<mailto:STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx>>
Subject: Re: [802.3_EPOC] Questions on varanese_01_0912.pdf
Thank you Andrea,
Please see inline
Marek
From: Marek Hajduczenia [mailto:marek.hajduczenia@xxxxxx]<mailto:[mailto:marek.hajduczenia@xxxxxx]>
Sent: Friday, September 28, 2012 10:29
To: STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx<mailto:STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx>
Subject: [802.3_EPOC] Questions on varanese_01_0912.pdf
Dear colleagues,
Here are some questions on the varanese_01_0912.pdf presentation which did not get sufficient time for discussion. I'd appreciate if they were answered via reflector so that everybody benefits from these clarifications:
- How many taps have been examined in total in this study? I do not care much about names, types but rather to see what the sample size we are looking at and whether it is representative of a large network as a whole rather than a single CMT port or not.
[AG] I think it is mentioned in the slides, we have 140 subscriber (CNU) ports for the model, we considered all of them in the analysis. As you can see from the curves, since this is a model and small variability have not been included, SNR curves overlap when users are attached to same last splitter - in reality, the CDF is more continuous like shown in the measured valued, rather than step-wise. Does that answer your question?
[mh0928] This begs a question then. Is this a number of CNUs that you'd consider typical? What I am trying to understand whether the scenario that was presented is the worst-case, best case or average (what can be expected in majority of deployments)? Would it be possible for an operator to use more tailored service groups to optimize them for SNR performance and to avoid complicating the design of devices, allowing for more optimized performance, rather than complicating the design of active devices?
- What is the most probably SNR distribution for a much smaller population of CNUs connects to a single CLT port? I assume that you will see some difference in SNR but it is not very likely to be as high as it was presented at the meeting for the whole measured population of taps and ports.
[AG] That may be the case, depends on how the few users are distributed in the plant. However, the question is whether this would be representative of a realistic plant - measurements are over population of ~240 modems, so it seemed to us that 140 (already smaller) was in the correct ballpark. Do you see any use case for much smaller plants, we could include in the analysis?
[mh0928] This is something that operators should speak to. However, when I look at the OLT driven deployment model with several CLTs deployed in field, I'd not expect each CLT to be connected to 150+ CNUs. That would easily reach thousands of CNUs visible to a single OLT, which brings the available bandwidth down drastically, while burning a lot of bandwidth on scheduling overhead. I'd like to understand the trade-off here, that is all.
Please consider presenting more focused study for the next meeting, focusing on a number of drop sections to show what is expected to be seen on a single CLT port. While I am not against adaptive loading on per CLT port, I do not believe that this contribution has sufficient footing to justify adaptive loading on per CNU basis.
[AG] What we shown is one CLT port and 140 CNU ports attached for the modeled plant - for measured values, each plant is one node and ~240 CM all attached to the same coax distribution tree (Comcast may provide more clarifications in case) - we can make it more clear and improve in the next steps.
Regards
Marek Hajduczenia, PhD
ZTE Portugal
Technology Strategy Department
Edifício Amoreiras Plaza,
Rua Carlos Alberto da Mota Pinto, nr. 9 - 6 A,
1070-374 Lisbon, Portugal
Office: +351 213 700 090
Fax: + 351 213 813 349
Mobile: +351 961 121 851 (Portugal)
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