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RE: [10GBT-Cabling] RE: [10GBASE-T] channel model





Chris:

I concur with your first paragraph.  Primary reason TIA has requested ICEA
to investigate environmental effects on UTP.

Doug



                                                                                                                                    
                    William Jones                                                                                                   
                    <wjones@solarflare.com>               To:     CDimi80749@aol.com, stds-802-3-10GBT-Modeling@ieee.org            
                    Sent by:                              cc:     stds-802-3-10gbt@ieee.org, stds-802-3-10GBT-Cabling@ieee.org      
                    owner-stds-802-3-10gbt@majordom       Subject:     RE: [10GBT-Cabling] RE: [10GBASE-T] channel model            
                    o.ieee.org                                                                                                      
                                                                                                                                    
                                                                                                                                    
                    01/30/2003 04:41 PM                                                                                             
                                                                                                                                    
                                                                                                                                    





Chris,

Accounting for temperature dependencies by a simple extension of length may
be reasonable for some frequency ranges as established in those forums.
But, we must be very careful to make sure that a similar extension is valid
over the wider frequency ranges we are considering here.

For the benefit of the study group, can you give us just the highlights of
the "hot" debate?  Even a pointer to some of the key technical
contributions in this debate would be helpful.  While we don't want to
re-enter into a messy discussion, we do want to benefit from what has gone
before.

Bill

Chair Modeling Ad Hoc


Director of Systems Engineering
SolarFlare Communications, Inc.
949-581-6830, ext. 2550
mobile: 619-405-2445
fax: 949-581-4695
wjones@solarflare

-----Original Message-----
From: CDimi80749@aol.com [mailto:CDimi80749@aol.com]
Sent: Thursday, January 30, 2003 8:22 AM
To: CDimi80749@aol.com; William Jones;
stds-802-3-10GBT-Modeling@ieee.org
Cc: stds-802-3-10gbt@ieee.org; stds-802-3-10GBT-Cabling@ieee.org
Subject: Re: [10GBT-Cabling] RE: [10GBASE-T] channel model


Bill,

 Frequency range of channel characterization:
 Based on the modeling ad hoc input I'll recommend to the cabling ad hoc
that
they provide
 channel characterization (measurement data) from DC to 500 MHz (min) and
that we
 consider measurements to 1 GHz.

 The use of temperature dependent transmission models:
 The ISO/IEC 11801 implementations (channel models) are based on component
performance at 20 C.
 For operating temperatures above 20 C a calculation is provided to adjust
the horizontal link length.

 The use of temperature dependent channel models was "hotly" debated over a
long period of time in both
  ISO and TIA. Let's avoid revisiting the fun and excitement and base our
channel models on
 component performance consistent with ISO/IEC 11801.


 Regards,

  Chris DiMinico
  Chair Cabling Ad Hoc
  MC Communications
  e-mail: cdiminico@ieee.org
  phone:978-441-1051


 In a message dated 1/29/03 6:43:18 PM Eastern Standard Time,
wjones@solarflare.com writes:

 << Chris

  The issues that I see in determining the frequency range of the channel
characterization are:

  1) The ability to make accurate high frequency measurements and to
validate
the results among multiple independent cable vendors.  This suggests a
lower
frequency range.

  2) The frequency range must be the same for all types of measurements
(line
as well as crosstalk measurements).  So, although accurate higher frequency
channel measurements may be possible, our experience has been that FEXT is
the most challenging.  This can limit the frequency range more.

  3) Flexibility to perform system tradeoffs suggests a higher frequency
range.

  Based on these considerations, I propose the characterization of all
measurements (line and crosstalk) be
  from DC to 500 MHz.

  Bill

  Chair Modeling Ad Hoc

  William W. Jones, Ph.D.
  Director of Systems Engineering
  SolarFlare Communications, Inc.
  949-581-6830, ext. 2550
  mobile: 619-405-2445
  fax: 949-581-4695
  wjones@solarflare.com


  -----Original Message-----
  From: CDimi80749@aol.com [mailto:CDimi80749@aol.com]
  Sent: Wednesday, January 29, 2003 9:32 AM
  To: Larry Cohen; William Jones; stds-802-3-10gbt@ieee.org;
  stds-802-3-10GBT-Cabling@ieee.org
  Subject: Re: [10GBASE-T] channel model


  Larry,

  Thanks for getting this started.

  Your contribution addresses (at least) three significant elements of the
  channel model development:

  1. frequency range of channel characterization
  2. the use of temperature dependent transmission models
  3.proposed model limits (with supporting measurement data)

  We should try to reach consensus on the elements.

  1. The modeling ad hoc should reach a consensus on the frequency range of
  channel characterization.
  Note:We should limit the channel characterization to account for relevant
  signal spectrum and
  minimize excess bandwidth characterization.

  2. The 10GBASE-T study group should reach consensus on temperature
  dependencies (in the objectives?).

  3. I'm in the process of developing a straw proposal for the cabling ad
hoc
  to address
  the generation of measurement  data.  Note: We need the resolution of the
  frequency range of channel
  charcterization (1).

  Regards,

  Chris DiMinico
  Chair Cabling Ad Hoc
  MC Communications
  e-mail: cdiminico@ieee.org
  phone:978-441-1051

  In a message dated 1/29/03 1:33:04 AM Eastern Standard Time,
  lcohen@solarflare.com writes:

  << Attached is a proposed 100 meter Cat 5e channel model for 10GBaseT
study
  (CHANMOD.TXT).  This model is defined by complex-valued (X + jY format)
  insertion gain in the at 500 kHz intervals from DC to 1 GHz.

   The proposed model is derived from measurement (at 20 C) of a 100 meter
  channel (with Cat 5e patch cords and 4 Cat 5e RJ45 connector interfaces).
  The baseline 100 meter channel model was temperature corrected to 50 C.
(122
  F.) using the procedure defined in ASTM D4566 Section 26.4.  The above
  mentioned temperature correction method modifies the magnitude but not
the
  phase of the insertion loss.  Experimental measurements confirm that
  temperature effects on the phase are minimal so the approximation is
  sufficiently accurate.

   The most recent proposed model is an extrapolation of the ISO 11801
Class
D
  channel loss limit.  The ISO 11801 Class D limit is designed to
accommodate
  expected worst-case measurements below 100 MHz and consequently includes
some
  additional margin to meet this requirement.  Since this limit is only
  specified below 100 MHz, extrapolation of the limit through smooth curve
  fitting becomes less accurate as it is extended farther beyond its
defined
  boundaries.  The new proposed model is based upon measurements beyond 500
MHz
  and thus validated to at least 500 MHz (and somewhat beyond 500 MHz).  As
  shown in the attached graphs (CHANMOD.DOC), the insertion loss for the
  proposed model differs from the ISO 11801 Class D 2002 channel limit by
less
  than 0.2 dB from DC to 50 MHz and less than 0.5 dB from 50 to 100 MHz.
While
  it does not represent an absolute worst-case channel, it represents a
  reasonable model for a feasibility study simulating a maximum length
channel
  under worst-case temperature conditions.