Re: [BP] Additions to Signaling spread sheet
Hi Brian,
If I am interpreting your objection correctly, you are saying that the non-Gaussian ISI will be more "bounded" than a Gaussian pdf, and hence a BER projection based on the SNR will be more pessimistic.
In fact it is safe to say that a BER projection based on SNR will (almost) always be pessimistic.
In that case, let me propose a compromise:
If you think that your favorite signaling scheme will be better served by a BER simulation, then the burden is on you to prove its performance using a BER simulation
If you think that the performance of your favorite signaling scheme is reasonably accurately represented by its SNR, then you can use SNR to project the BER. If anything, you will be hurting your own scheme.
This way the computational burden is placed only on those who choose it.
Regards,
Vivek
________________________________
From: owner-stds-802-3-blade@listserv.ieee.org on behalf of Brian Brunn
Sent: Tue 11/30/2004 7:37 PM
To: STDS-802-3-BLADE@listserv.ieee.org
Subject: Re: [BP] Additions to Signaling spread sheet
Hi Vivek,
ISI is so non-gaussian that I would be very hesisitant to accept that it
treats all signaling techniques equally.
Regards,
Brian
----- Original Message -----
From: "Vivek Telang" <vtelang@broadcom.com>
To: <STDS-802-3-BLADE@listserv.ieee.org>
Sent: Tuesday, November 30, 2004 7:37 PM
Subject: Re: [BP] Additions to Signaling spread sheet
Mike, Mary, and all,
For the purposes of comparing the signaling proposals, it may be
overkill to run long BER simulations. The goal here is to evaluate the
performance of a signaling scheme and verify that the proposed receiver
complexity is adequate to meet the performance requirements.
Fortunately, it is quite straightforward to determine the performance of
finite-length equalizer receivers, without having to run long BER
simulations. Closed form MATLAB analysis can be used to determine the
steady state performance of FFE/DFE based systems. This has a long
history in many of the DSP-based comm. systems, including 1000BASE-T and
now 10GBASE-T. Historically, the steps in determining feasibility have
been (1) Channel Capacity (ideal) (2) Salz Bound (more realistic) (3)
Finite length MMSE analysis (much more realistic, except for transient
behavior) and (4) Finite length, finite precision simulations (the real
deal). While these steps are in the order of approaching real-life
behavior, they also involve increasing computational resources. In
particular, the jump from step 3 to step 4 is huge. I am suggesting that
we use step 3 for the purpose of evaluating the signaling proposals.
There are obvious shortcomings to this method, and I'll be the first to
list them:
1. Transient behavior (e.g., adaptation) is not modeled
2. Finite precision effects are not modeled
3. The performance evaluation is based on SNR and not BER (so there is
an implicit Gaussian assumption for the noise)
But IMHO, the computational simplicity outweighs the flaws. Note, I am
proposing this only for the purpose of solving the problem in front of
us, which is to pick one signaling proposal. I would contend that the
shortcomings do not offer an advantage to one proposal or another.
Regards,
Vivek
Vivek Telang
Broadcom Corp.
-----Original Message-----
From: owner-stds-802-3-blade@listserv.ieee.org
[mailto:owner-stds-802-3-blade@listserv.ieee.org] On Behalf Of Altmann,
Michael W
Sent: Tuesday, November 30, 2004 4:34 PM
To: STDS-802-3-BLADE@listserv.ieee.org
Subject: Re: [BP] Additions to Signaling spread sheet
Mary,
Thanks for your input. I will try to capture this for our discussion on
Friday.
I am concerned about the simulation load for all the data patterns. In
general, longer patterns are tougher than short patterns, but they take
longer to simulate because of the data pattern probabilities. This
causes a problem because, in the strictest terms, a PRBS pattern
requires a simulation of 2^n-1 bits to extract all combinations of data
to find the inside (w/c) eyelids, and/or the transition probability
densities (if BER is to be calculated that way). For PRBS(31), this is
a 4Gbit (about 0.4seconds) simulation.
While it is posible that we may need to do some long sims for final
fine-tuning of things, this is about 4 orders of magnitude more than I
have CPU for. Do you see a way that we can shorten these sims for the
purposes of evaluating the basic signaling comparisons?
.../Mike
-----Original Message-----
From: Mary Mandich [mailto:mandich@lucent.com]
Sent: Tuesday, November 30, 2004 1:43 PM
To: Altmann, Michael W; STDS-802-3-BLADE@listserv.ieee.org
Subject: Additions to Signaling spread sheet
Hi:
Here are our suggestions for input to the Signaling spreadsheet V3.2:
1) On the coding summary worksheet:
Split rows for Power (32-34) into additional entries as
follows (all under power subheading):
Power (typical) Total, Tx, Rx, other (backchannel, FEC, extra clocks,
etc.)
Power (best) Total, Tx, Rx, other (backchannel, FEC, extra clocks,
etc.)
Power (worst) Total, Tx, Rx, other (backchannel, FEC, extra clocks,
etc.)
A note should be added that best/worst/typical refers to powers required
for all of the channels on the V&T worksheet.
2) On the V&T worksheet:
Need to specify data patterns that must be exercised in reporting the
BER and report the worst case. I suggest we choose the following BER
patterns for simulations:
- PRBS 7 or 9
- PRBS 15 -- or the longest the group believes is reasonable for
simulations
Also, if it is expected that actual measurement data will be reported,
should specify that BER be reported for
- PRBS 17
- PRBS 23
- PRBS 31
- a CID (consecutive identical digit) pattern containing one string
each of zeros
and ones with have zero timing content separated by a PRBS31
pattern.
The length of this string is given by the worst case longest
such sequence
in data, autonegotiation, etc. sequences.
Regards,
Mary
__________________________________________
Mary Mandich
Technical Manager
Network Hardware Integration Research
Bell Labs, Lucent Technologies
600 Mountain Avenue
Murray Hill, NJ 07974
Tel: (908) 582-3396
FAX: (908) 582-6228
email: mandich@lucent.com __________________________________________
-----Original Message-----
From: owner-stds-802-3-blade@listserv.ieee.org
[mailto:owner-stds-802-3-blade@listserv.ieee.org]On Behalf Of Altmann,
Michael W
Sent: Monday, November 29, 2004 6:55 AM
To: STDS-802-3-BLADE@listserv.ieee.org
Subject: [BP] Upcoming Signaling ad hoc conference calls
802.3ap Task Force Members (Signaling ad hoc),
Below are the schedule, bridge details and dial-in numbers for the
remainder of the .3ap Signaling ad hoc conference calls for 2004.
All material for discussion in these meetings should be posted to the
reflector or web-site at least two days before the conference calls
(i.e. EOD on the Wednesday before each call). Per our recent interim mtg
discusions, please observe the deadlines discussed in the interim
meeting for updating submissions for the signaling spreadsheet. The
deadlines and ad hoc topics are below:
Spreadsheet input deadlines to Signal Ad Hoc via reflector
Nov. 30 - Specific parameters for extension to spreadsheet
Dec. 10 - Specific values for all parameters in spreadsheet
Signaling ad hoc Conference Call Topics
Dec. 3 - Define specific parameter changes, TP4 - TP5 link details and
packaging effects Dec. 17 - Define specific simulation parameter values
Dec. 10 - Provide complete test case channel data - all data means
through and crosstalk Jan. 19 - Submit simulation results for entry
into spreadsheet
Regards.
.../Mike
Signaling ad hoc Conference Call Schedule
N.B.: The dial-in number for all meetings is the same. Local dial-in
numbers are provided below.
Date: Friday, December 3, 2004
Time: 10:00 US Pacific Time
Duration: 2 Hours
Chairperson: Michael Altmann
Bridge: 2 Passcode: 6297476
Date: Friday, December 17, 2004
Time: 10:00 US Pacific Time
Duration: 2 Hours
Chairperson: Michael Altmann
Bridge: 4 Passcode: 0666263
Bridge Dial-In Numbers
Arizona
480-552-2663
480-715-2663
California
949-567-4666
916-356-2663
858-391-1711
408-765-2663
Colorado
719-273-2663
Massachusetts
978-553-2663
NewJersey
973-967-6770
NewMexico
505-794-2663
Oregon
503-696-2663
503-264-2663
South Carolina
803-216-2246
Texas
512-314-3030
Utah
801-445-2663
Washington
253-371-2663
.../Mike