RE: 1000BASE-T PCS question

["Chang, Edward S" <Edward.Chang@xxxxxxxxxx>]

Dave:

Thanks for inputs.

I am not surprised that some link will keep running for equivalent of seven
years to get one error.  

I agree if you allocate more photons/bit, higher S/N ratio, BER will be
improved.  You mean OC-192 specification sets the receiver minimum input
power at the BER of 10^-12.  Sure it can be done.  We can even assume that
no errors up to O/E conversion just for the sake of discussion.  However,
after O/E conversion, the base-line wander and PLL clock drift caused by
excessive run-length will generate bit errors.  Therefore, just more
photons/bit will not improve over all BER, you may have something more. 

Ed Chang
Unisys Corporation
Edward.Chang@xxxxxxxxxxx         
 

-----Original Message-----
From: David Martin [mailto:dwmartin@xxxxxxxxxxxxxxxxxx]
Sent: Thursday, May 27, 1999 1:09 PM
To: Chang, Edward S
Cc: HSSG_reflector
Subject: RE: 1000BASE-T PCS question



I'd like to clarify the residual BER spec for telecom systems. For OC-48
rate SONET systems, the
end-of-life BER customer requirement is 1E-12 (no FEC). For OC-192 rate the
value is the same, 
1E-12 without FEC (c.f. BCR GR-1377-CORE Section 4.2.1, page 4-3) and 1E-15
with FEC (customer
requirement).

Note that some of our OC-48 customers, who have had systems running for up
to 10 years, are
measuring RBERs in the 1E-16 range (about one error every 7 years on a DS-3
trib). The OC-192
systems out there will need to run awhile longer to acquire similar
performance data.

The point here is that the SONET scrambler is not the limiting issue in
achieving low error rates. The
issue is having enough photons/bit, or optical SNR (eye-Q) to accurately
recover the data. 

...Dave

David W. Martin
Nortel Networks
+1 613 765-2901   
+1 613 763-2388 (fax)
dwmartin@xxxxxxxxxxxxxxxxxx
========================

	-----Original Message-----
	From:	Chang, Edward S [SMTP:Edward.Chang@xxxxxxxxxx]
	Sent:	Thursday, May 27, 1999 9:16 AM
	To:	Jaime Kardontchik; rtaborek@xxxxxxxxxxxxxxxx
	Cc:	HSSG_reflector
	Subject:	RE: 1000BASE-T PCS question


	Jami:

	We have been discussing scramble code versus block code, 8B/10B in
	particular, for a while on the reflector. Many people have the same
feeling
	that scrambled code has run length much longer than desirable to
cause
	base-line wander, and PLL clock drift; as a result, it can not meet
the BER
	of 10^-12

	The SONET using scramble code has BER of 10^-10, which is not
recommended
	for the datacom file transfer.  I believe the BER of 1000BASE-T is
10^-10,
	again, which is not recommended for file transfer.

	You can prove the BER is 10^-12 for the 4D symbol code to enable it
to be
	used for all purposes, or stay at 10^-10 BER to be used, as 802.3ab,
for
	less critical data handling. 

	Please clarify.

	Ed Chang
	Unisys Corporation
	Edward.Chang@xxxxxxxxxx