& cplSiteName &
Comments
Newest First  |  Oldest First  |  Threaded View        ADD A COMMENT
<<   <   Page 2 / 3   >   >>
paolo.franzoi
paolo.franzoi
12/5/2012 | 4:04:31 AM
re: Optical Solutions Wins FTTP Contract

fg,

Are the BPON offerings you have looked at the same as the EPON from Wave 7 (3 wavelengths, Outside the House ONT, Black Phones on the ONT, etc.)?

seven
Balet
Balet
12/5/2012 | 4:04:30 AM
re: Optical Solutions Wins FTTP Contract
...they looked so Calix today at the MTA show, including the mentioned in the article CEO, who is not a CEO anymore.
A good news,they seem to be happy with this transition.
fgoldstein
fgoldstein
12/5/2012 | 4:04:25 AM
re: Optical Solutions Wins FTTP Contract
stephencooke,

I'm well aware of the motivation for scrambling; that's why a lot of media scramble. But it is not without risk. In the ATM world, where bits were not broken up into "columns", there was a real risk that somebody could send a cell payload with the scramble pattern in it, resulting in a 384-bit string of no transitions. This could cause a loss of clock under marginal circumstances. So the self-synchronous scrambler (1+x^43) was added. It fixed that problem but caused error doubling, thus impeding some error recovery options and making error detection a bit more difficult.

Frequent transitions are most important when the signal is marginal. But a group code line 8/10 both guarantees a transition density and bounds the on/off time of the light, since only 25% (plus a few special values) of bit combinations are needed. So perhaps it can be recovered even with 25% more skew (from the higher raw bit rate) than a merely-scrambled pattern, if there is a chance that the scramble pattern could result in longer transition-free gaps. In other words, maximum raw bit rate for the medium may not be constant, if the nature of the bitstream is tightly bounded.
stephencooke
stephencooke
12/5/2012 | 4:04:25 AM
re: Optical Solutions Wins FTTP Contract
fgoldstein,

"The 8/10 coding is perhaps not so bad -- I wonder (has this been studied?) if the physical media can be less critical if that coding is used instead of a more bit-efficient scheme. It's not obvious, and SONET had a problem trying to use scrambling for transparency. Maybe it's easier to send 1.2 Mbps of 8/10 than 1 Mbps of 8/8? I honestly don't know."

Fred,

The reason SONET uses scrambling and Ethernet uses 8B/10B is to increase the rate of data transitions (ie: '1' to '0' and '0' to '1') for clock recovery purposes on the receivers. If a long string of '1's or '0's hits a clock recovery it gets confused due to the low frequency content of the apparent data. This, of course, yields data interpretation errors due to sampling at some point other than the middle of the data eye.

The Ethernet OH totals 28% of the general data stream (including Inter-Frame Gap - IFG and Preamble). By comparison, SONET's OH is less than 10% (including Section, Line and Path OH).

Steve.
fiber_r_us
fiber_r_us
12/5/2012 | 4:04:23 AM
re: Optical Solutions Wins FTTP Contract
Not that PONs currently use it, but 10GE uses a 64/66b encoding (3.125% overhead) , thus providing better efficiency than SONET.

Unfortunately, it still has the near useless IFG and pre-amble. How much these contribute to overhead is variable dependent on packet size:

Worst case (for minimum 64-byte packets):

(64 + 8 + 12) / 64 = 31.25%

Best case (for maximum standard, not jumbo, 1518-byte packets):

(1518 + 8 + 12) / 1518 = 1.32%
Pete Baldwin
Pete Baldwin
12/5/2012 | 4:04:22 AM
re: Optical Solutions Wins FTTP Contract
nwave sez:
If both technologies [10GE PON and WDM-PON] begin to emerge in the next 2-3 years the early adopters and mfgs of GPON could end up in a classic technological cul-de-sac.

The WDM case I could see but ... shouldn't GPON be able to counter with a 10GE option of its own?

I haven't heard anybody speak of such a thing, but given that GPON is Ethernet-friendly, it seems like a 10GE version would be possible. (Well, using pointy-haired-boss logic, anyway.)
nwave
nwave
12/5/2012 | 4:04:22 AM
re: Optical Solutions Wins FTTP Contract
"Not that PONs currently use it, but 10GE uses a 64/66b encoding (3.125% overhead) , thus providing better efficiency than SONET."

10GE PONs? Not yet at least but there is much action going on in the 10GE PON and WDM arena. Teknovus has made announcements about 10GE and Novera Optics in WDM PON. In lab testing 10GE PON prototypes have proven to be feasible. WDM based PONs are in use in Korea. If both technologies begin to emerge in the next 2-3 years the early adopters and mfgs of GPON could end up in a classic technological cul-de-sac.

Most of the efficiency claims in GPON vendors white papers seem to only consider small packets fiber_r_us noted the efficiency does suffer when small packets voice packets are sent. Since Ethernet was purposed designed as data transport a more reasonable approach would be to compare data
efficiency and in particular IPTV multicast efficiencies of the particular PON approaches.
Pete Baldwin
Pete Baldwin
12/5/2012 | 4:04:21 AM
re: Optical Solutions Wins FTTP Contract
A good news,they seem to be happy with this transition.

Good to hear.

Regarding the CEO being changed ... Balet, you realize this ("Optical Soutions Wins FTTP Contract") is a press release from a year-and-a-half ago, right?
stephencooke
stephencooke
12/5/2012 | 4:04:21 AM
re: Optical Solutions Wins FTTP Contract
OK, so the carriers are looking for a technology that will get them to a point that is beyond current cable offerings (in terms of bandwidth). Fiber makes sense as a transport medium. Carriers need assurances that, once they spend the billions of dollars needed to upgrade their networks to support PONs (of whatever flavour), that they will not need to upgrade the CPE again in the next 2 years.

I would say that this is a major roadblock to moving forward in volume for any carrier. Unless a downloadable software upgrade can transform CPE from BPON - GPON - GEPON - WPON, etc. why would I risk putting a stake in the sand with any of these current or potential technologies? This is the classic access edge vs. core debate (ie: access edge needs to be cheap with long projected lifetime as implementation times are very long and costs are incredibly high vs. core where equipment can be more expensive as there are fewer NEs to upgrade, implementation times are relatively short and costs are relatively low).

Steve.
optical Mike
optical Mike
12/5/2012 | 4:04:13 AM
re: Optical Solutions Wins FTTP Contract
"Unless a downloadable software upgrade can transform CPE from BPON - GPON"
The latest ONT's from Calix do just what you asked for...
Auto-detect optics allow interoperability with 622 Mbps BPON and 1.2 Gbps or 2.4 Gbps GPON OLTs

http://www.calix.com/spotlight...
<<   <   Page 2 / 3   >   >>


Featured Video
Upcoming Live Events
November 5, 2019, London, England
November 7, 2019, London, UK
November 14, 2019, Maritim Hotel, Berlin
December 3-5, 2019, Vienna, Austria
December 3, 2019, New York, New York
March 16-18, 2020, Embassy Suites, Denver, Colorado
May 18-20, 2020, Irving Convention Center, Dallas, TX
All Upcoming Live Events