It has been approved that there is no significant
difference (<0.3dB) between the continuous mode sensitivity
and burst mode sensitivity for a good designed burst mode receiver
in the GEPON and GPON application. Theoretically, there is no any deference
between the BM sensitivity and CM sensitivity, if the discharging time for the
large signal and charging time for the small signal is fast enough in the
amplification circuit in the burst mode receiver.
There are several factors that affect the
burst mode receiver sensitivity in the real application.
1. Receiver settling time defined by the standard
and application.
a. In the 802.3ae, the receiver settling time is
defined as 400ns.
b. In the GEPON application in Asia, most
customers tighten the receiver settling time to 64ns or 32ns.
c. In the ITU-T G.984.2 GPON application,
the receiver settling time is not defined clearly, but 984.2 defined the guide
time as 32bits, preamble as 44 bits, delimiter as 20bits. Normally, the
received upstream signal needs to be recovered in the first 30 bits of the
preamble, and the CDR needs at least 14bits to lock the signal.
Generally, the longer the receiver settling time
allowed, the better the BM receiver sensitivity (less difference with the
continuous mode senstivity) and BM dynamic range.
2. The coding scheme of the data
a. In the 802.3ae and GEPON application in Asia,
the coding is 8B/10B. Therefore, a low time constant signal path without
RESET is good enough to pass the 8B/10B code and meet the RX settling
time without extra RESET circuit.
b. In the ITU-T G.984.2 GPON application, the
coding is PRBS2^7-1 scramble, and the BM receiver needs to pass the 72bits
CID. There is no simple circuitry to pass the scramble signal without error
and meet the short RX recovering time at the same time.
3. RESET vs. no RESET design
a. In the GEPON application, RESET for the
receiver is not needed in the burst mode receiver, due to the 8B/10B coding
scheme and the longer RX Settling time requirement.
b. To handle the scramble signal with longer CID
in the GPON application, (maybe the same case for the 10GEPON application with
either 64B/66B or 32B/33B coding as proposed), It seems that a RESET is
necessary for the industrial temperature application (-40ºC
to +85ºC).
Even for the comercial temperature application, the OLT receiver without RESET
will generate problems when the temperature and dynamic range
varies.
c.
There are several GPON 1.25G OLT receiver design without RESET. As commented
by Maurice, all the OLT receivers without RESET need to get the optical signal
from the ONU TX with very high extinction ration (normally higher than
15dBm). The high ER is very difficult to keep through the operating
temperature range. It is noticed that in the 10G XFP or XENPAK application,
the ER is defined only as 6dB or 4dB (or the optical modulation amplitude is
used to replace the ER in order to avoid a higher ER
value).
4.
BM dynamic range
For
the GEPON and GPON application, the burst mode dynamic range (difference
between two consecutive signal) is either 15dB, 21dB or 25dB, depending on the
requirements in the applications.
The
BM receiver sensitivity (or the sensitivity differnce between the BM
receiver and CM receiver) is a function of the coding scheme, the RX settling
time allowed in the standard, the BM dynamic range defined in the standard,
and certainly the BM receiver design approach (with or w/o
RESET).
Best
regrds,
David
David
Li
Ligent
Photonics, Inc.
2701 Dukane Dr., Suite 102
St. Charles, IL
60174
Phone 630-513-7226 ext 15
----- Original Message -----
Sent: Tuesday, February 06, 2007 4:32
AM
Subject: Re: [8023-10GEPON]
[POWER_BUDGET] ad hoc group 2nd meeting
Maurice,
if I understand well, we will end up with a public
auction this way :-) What do You think is a reasonable value to assume (the
one which does not cause too significant technical challenges for TX and Rx
designers) ?
Best wishes
From: Maurice Reintjes
[mailto:maurice.reintjes@MINDSPEED.COM]
Sent: terça-feira, 6 de
Fevereiro de 2007 3:26
To:
STDS-802-3-10GEPON@listserv.ieee.org
Subject: Re: [8023-10GEPON]
[POWER_BUDGET] ad hoc group 2nd meeting
...ooohh stepped in that
one... It depends greatly on the extinction ratio The higher
the ER, the easier a time of it the OLT receiver has from one
burst to the next. The OLT designer
would like to have 30db of ER, the Burst mode TX designer, 3db. From
there we start negotiating.
Best
Regards
Maurice
Reintjes
MindspeedTM
Hillsboro, Oregon,USA
Office Phone
(503)-914-5370
Mobile (503)-701-0797
In
reviewing past contributions on ways to meet the power budgets, I
notice
that people often use -18 dBm as a max Rx sensitivity for PIN and
-24 as max
Rx sensitivity for an APD. I presume that this is for
continuous mode
operation.
What do we know about how that number
will change for burst mode operation
in the
upstream?
Robert
-----Original Message-----
From: Lingle,
Jr, Robert (Robert) [mailto:rlingle@OFSOPTICS.COM]
Sent: Friday, February
02, 2007 4:37 PM
To: STDS-802-3-10GEPON@listserv.ieee.org
Subject: Re:
[8023-10GEPON] [POWER_BUDGET] ad hoc group 2nd meeting
Please
find attached the notes for the first Power Budget Ad Hoc
meeting.
Please direct any corrections to
me.
Robert
-----Original Message-----
From: Lingle, Jr,
Robert (Robert) [mailto:rlingle@OFSOPTICS.COM]
Sent: Thursday, February
01, 2007 3:09 PM
To: STDS-802-3-10GEPON@LISTSERV.IEEE.ORG
Subject:
[8023-10GEPON] [POWER_BUDGET] ad hoc group 2nd
meeting
All,
I will send the notes from this week's
meeting tomorrow 2/2.
As discussed in the previous call, the next
call(s) will occur on Tuesday
Feb 6 at 7PM EST and Wednesday Feb 7 at 9AM
EST.
Notes from this week's call as well as agenda for next week will
be sent
Friday.
Toll-free in US
866-263-8899
Outside US
816-249-6061
Conf. Code
7707985015
Robert
Robert Lingle, Jr.
Fiber Design and
Transmission Simulation
OFS Corporate R&D, Atlanta
404-886-3581
(cell)
770-798-5015
(office)