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Re: [802.3_EPOC] EPoC Bandwidth Discussion

Marek-
In the brief look I had (by searching on the term "bandwidth) at the 1st 20 years worth of the standard the usages were fairly obvious in their context. We should certainly make sure do that in new work.
While reading it really became obvious to me that it would be appropriate to do a wholesale search and replace of the digital version (to bit rate or data rate as appropriate). But it would be a significant change and only appropriate to do in a revision. That isn't going to happen until AT LEAST the next revision, so it will be awhile.
We do use "bit rate" and "data rate" quite a bit in the standard but the following text would seem to indicate that we should use "data rate: 

   *1.2.3 Physical Layer and media notation*
   Users of this standard need to reference which particular
   implementation is being used or identified. Therefore,
   a means of identifying each implementation is given by a simple,
   three-field, type notation that is
   explicitly stated at the beginning of each relevant clause. In
   general, the Physical Layer type is specified by
   these fields:
   <data rate in Mb/s> <medium type> <maximum segment length (× 100 m)>

Best regards,
Geoff


On 208//12 5:27 PM, Marek Hajduczenia wrote:


Jorge,
In EPON, we used term "bandwidth" in the meaning of "data rate" / "channel capacity", which in the retrospect perhaps was not the best idea. For example, we had statements like "Flexible architecture allowing dynamic allocation of *_bandwidth_*", which does not speak of spectrum allocation, but rather channel capacity allocation. I could produce more examples where it is used in this context, but I think you get the idea where it is going.
In general, EPON we only spoke of wavelength / wavelength band allocation in Clause 75/60, which is effectively spectrum allocation. However, the term used was "wavelength" and "wavelength band/range". 

Does this help ?

Marek

*From:* Salinger, Jorge [mailto:Jorge_Salinger@xxxxxxxxxxxxxxxxx]
*Sent:* Tuesday, August 21, 2012 01:15
*To:* Marek Hajduczenia; stds-802-3-epoc@xxxxxxxxxxxxxxxxx
*Subject:* Re: [802.3_EPOC] EPoC Bandwidth Discussion

Marek,

I understand.
So, how is the term bandwidth used in EPON parlance? I looked down in the thread and can't see an example, but maybe I missed it. 

Thanks!

Jorge
*From: *Marek Hajduczenia <marek.hajduczenia@xxxxxxxxx <mailto:marek.hajduczenia@xxxxxxxxx>> 
*Date: *Monday, August 20, 2012 8:08 PM
*To: *"Salinger, Jorge" <Jorge_Salinger@xxxxxxxxxxxxxxxxx <mailto:Jorge_Salinger@xxxxxxxxxxxxxxxxx>>, EPoC Study Group <STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx <mailto:STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx>> 
*Subject: *RE: [802.3_EPOC] EPoC Bandwidth Discussion

Jorge,
The only concern that I have with this is that multiple times we speak of "bandwidth" without other denominators, leaving it open to interpretation.
While I can certainly understand where Geoff would like us to go, if we set different terminology from what was used in EPON before, we will create a rift and people who understand EPON, will have to get used to a different terminology for EPoC, something that I'd rather (personally) avoid. 

Marek

*From:* Salinger, Jorge [mailto:Jorge_Salinger@xxxxxxxxxxxxxxxxx]
*Sent:* Tuesday, August 21, 2012 01:04
*To:* STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx <mailto:STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx> 
*Subject:* Re: [802.3_EPOC] EPoC Bandwidth Discussion

All,
No quite being an RF guy, but having worked in the cable industry for over 20 years... (for those thinking that I am old... I started when I was 19 years old ;-) 

My 2 cents...
I would propose that when speaking of RF capacity we refer to it as spectrum. So, in the case of the discussion referenced by this Email thread, we say "spectrum for EPoC" or "EPoC spectrum".
I think that the term bandwidth can be ambiguous unless it is used in a specific context, such as "the bandwidth of an analog cable channel is 6 MHz" and I also hear "the bandwidth of the highest HSD tier is 300 Mbps". 

Jorge
*From: *Duane Remein <Duane.Remein@xxxxxxxxxx <mailto:Duane.Remein@xxxxxxxxxx>> *Reply-To: *Duane Remein <Duane.Remein@xxxxxxxxxx <mailto:Duane.Remein@xxxxxxxxxx>> 
*Date: *Monday, August 20, 2012 1:15 PM
*To: *EPoC Study Group <STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx <mailto:STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx>> 
*Subject: *Re: [802.3_EPOC] EPoC Bandwidth Discussion

Geoff,
I see your point, could we at least agree to preface there term with "Spectra" when referring to RF (old habits, the only kind I have at this point, die hard)? 

Best Regards,

Duane

FutureWei Technologies Inc.

duane.remein@xxxxxxxxxx <mailto:duane.remein@xxxxxxxxxx>

Director, Access R&D

919 418 4741

Raleigh, NC

*From:* Geoff Thompson [mailto:thompson@xxxxxxxx]
*Sent:* Monday, August 20, 2012 1:04 PM
*To:* STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx <mailto:STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx> 
*Subject:* Re: [802.3_EPOC] EPoC Bandwidth Discussion

Colleagues-
Just goes to show the extent to which Wikipedia is not an authoritative source. The answer to this question is obvious within the word itself. Bandwidth is the width of the spectral band, i.e. it is an analog measurement.
The so called "digital bandwidth" is not a bandwidth it is "channel capacity" or "data rate" or "bit rate".
To illustrate how silly it is to use the spectral term for the digital term just think of it in concrete terms. You would never use the term "pavement width" when you mean "cars per hour".
I took a brief tour of older clauses of 802.3 and the term is mostly used correctly. There are several instances (which are unfortunately duplicated in several places) where "bit rate" would have been more accurate.
I would strongly prefer that we preserve its analog meaning and use other appropriate terminology for digital rate measurement (even if it means bucking current common terminology). 

Geoff Thompson

On 208//12 9:22 AM, Hesham ElBakoury wrote:

Jim,

Wikipedia defines bandwidth as follows:

*Bandwidth* has several related meanings:

    * Bandwidth (signal processing)
      <http://en.wikipedia.org/wiki/Bandwidth_%28signal_processing%29>
      or /analog bandwidth/, /frequency bandwidth/ or /radio
      bandwidth/: a measure of the width of a range of frequencies,
      measured in hertz
    * Bandwidth (computing)
      <http://en.wikipedia.org/wiki/Bandwidth_%28computing%29> or
      /digital bandwidth/: a rate of data transfer, bit rate or
      throughput, measured in bits per second (bps

Hesham

*From:* Jim Farmer [mailto:jfarmer@xxxxxxxxxx]
*Sent:* Monday, August 20, 2012 8:50 AM
*To:* STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx <mailto:STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx> 
*Subject:* Re: [802.3_EPOC] EPoC Bandwidth Discussion
Unfortunately, as if often the case, we have multiple different definitions for the same term -- as an RF nerd myself, I had difficulty getting used to "bandwidth" referring to data. But the data usage certainly is a common use of the term. If we need to differentiate the two, I'd suggest the shorter term "RF bandwidth" when we need to differentiate the two. 

Thanks,

jim

Jim Farmer, K4BSE

Chief System Architect,

FTTP Solutions

Aurora Networks

1220 Old Alpharetta Rd.

Ste. 370

Alpharetta, GA 30005 USA

678-339-1045 (office)

678-640-0860 (mobile)

jfarmer@xxxxxxxxxx <mailto:jfarmer@xxxxxxxxxx>

*From:* Duane Remein [mailto:Duane.Remein@xxxxxxxxxx]
*Sent:* Monday, August 20, 2012 11:32 AM
*To:* STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx <mailto:STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx> 
*Subject:* Re: [802.3_EPOC] EPoC Bandwidth Discussion

Steve,
Your use ot the term "bandwidth" completely threw me, I've always associated this term with data bandwidth.
Can I suggest we use something like Spectrum Channel Width -- defined as a portion of RF spectrum dedicated to a transmission channel or sub-channel.
Once we agree on such a term Marek can then add this to the definitions list. 

Best Regards,

Duane

FutureWei Technologies Inc.

duane.remein@xxxxxxxxxx <mailto:duane.remein@xxxxxxxxxx>

Director, Access R&D

919 418 4741

Raleigh, NC

*From:* Shellhammer, Steve [mailto:sshellha@xxxxxxxxxxxx]
*Sent:* Friday, August 17, 2012 6:42 PM
*To:* STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx <mailto:STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx> 
*Subject:* [802.3_EPOC] EPoC Bandwidth Discussion

EPoC Group,
Several of us had a good discussion on EPoC bandwidth this morning. I would like to see if there are other who would like to join us for future calls on Friday mornings (10 AM Pacific Time).
If anyone else would like to join us, please send me an email and I will add you to the meeting invite.
Once we have some slides put together we will review them on the Monday AM calls, hosted by Comcast. 

Steve

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