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Dear Andrea et al., Slide number would be welcome, for starters J On slide 3, I think the question “Is 1 Gb/s PAR objective to individual CNU or on coax segment?” is poorly stated. When you think of EPoC and EPoC bandwidth, it is bandwidth provided by the CLT port, and not per CNU. For example, if CLT supports the baseline conditions, it will provide 1 Gbit/s to be shared by any number of connected CNUs. It is the same as in EPON, really, where 1G-EPON OLT provides 1 Gbit/s link to connected ONUs. If there is 1 ONU, it will get full 1 Gbit/s, if there are more ONU connected, the bandwidth is shared. So really, the bandwidth in EPoC is not per coax segment (what is that, really?) but rather than CLT port. Then all discussions on how much bandwidth per CNU is available are moot, since it depends on distance, scheduling efficiency and number of connected CNUs. Operators have known this trade-off for quite some time, since it is the same in DOCSIS, EPON and any other multi-access technology. So I do not understand why we are making such a fuzz about it and trying to impose a new meaning / interpretation of available bandwidth in case of EPoC. Regarding the performance model. I fear that the level of detail you try to go into in the slide deck cannot be really simulated (or even approximated reliably) using Excel model. Given the self-similar nature of user traffic, combined with scheduling model and QoS enforcement, to reliably evaluate the system performance one would have to build at least a cure simulator tool, accounting for queuing delay, through-stack delay and scheduling delays, something that cannot be estimated using limited tools that Excel provides. My fear is that we will spend a lot of time on this model, have discussions on something that will eventually turn out to be of very limited use to progress EPoC process forward. Yes, we can consider line efficiency, to compare transmission efficiency with various FEC, encoding or interleaving solutions, but the effect of scheduling and queuing on overall system performance is very hard to estimate in such a simplified model. Just FYI, some more comprehensive analysis of EPON delay were done by Glen and myself for both 1G-EPON and 10G-EPON systems, and the obtained results cannot be accounted for using simple Excel models. There are stochastic effects in play in shared media systems which you cannot really capture in formulas. Further, on slide 5 you show various reference architectures. I would like to remind you (and others) that the scope of this project is quite strictly limited and examining OCU delay, EPON delay etc., is not within our work scope at this time. I would certainly like to see option c) removed. If you want to model some sort of optical backhaul, remember that it can be also P2P fiber, or any other P2P technology for that matter. EPON that you show in option c) is just one of possible options. In either case, it does not matter, since it is just a fixed delay component for EPoC, nothing more. Slide 7 contains some interesting new terms, like E_bits and I_bits – are these intended to be defined anywhere? Slide 14 – the assumptions about the scheduling model you have there allow you to simplify the model with a non-scheduled, dedicated link with 1/N capacity of overall EPoC link. The average delay will be exactly the same. No need to account for scheduling in such a situation, unless you want to model a real scheduling model, which shares bandwidth among CNUs in a non-equal fashion, depending on report and gate mechanism. But in that case, Excel model is not sufficient and simulations should be employed. Marek From: Garavaglia, Andrea [mailto:andreag@xxxxxxxxxxxx] Resending as PDF (size was too large). Andrea From: Garavaglia, Andrea Hi all, Please find attached the status report slides for today’s call. I hope last week we got sorted out most questions on scope and so we can keep it shorter this week, here my proposal for discussion: - Briefly confirm on the scope (added a disclaimer on slide 2 and included new slide 5 – there were comments to remove the last case) - Slides 8-10 are new for completing FDD upstream modeling (on the same line as downstream) – can briefly touch on that if needed - Slide 11 includes formulas for FDD PHY and some related considerations/notes – this is the main one to review - The rest is ongoing work – we will not discuss it today Thanks, Andrea |