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Mike Wolf

join:2009-05-24
Beachwood, NJ
kudos:4

1 edit

8 downstream 8 upstream modem?

Anypony know about an 8 downstream 8 upstream modem thats on the market yet?


elkido122

join:2011-02-23
Folsom, CA

Re: Evidence of 8 Downstream Channel Bonding - Post Here

Why do you need one with 8 up? There hardly implementing 4 up


TriForce

join:2008-05-27
Chico, CA
Reviews:
·Comcast
said by elkido122:

Why do you need one with 8 up? There hardly implementing 4 up

Future proofing.


DrDrew
That others may surf
Premium
join:2009-01-28
SoCal
kudos:17
reply to Mike Wolf

Re: 8 downstream 8 upstream modem?

said by Mike Wolf:

Anypony know about an 8 downstream 8 upstream modem thats on the market yet?

Nobody makes one for the U.S. market

Usable upstream in the U.S. is from 5-45 Mhz or about 40 Mhz total.

8 channels at 6.4 Mhz wide = 51.2 Mhz.

That also doesn't take into account other gear using upstream spectrum like cable boxes or unusable spectrum like the 26.5-27.5 Mhz CB band.

Cable ops would have to change out all the diplex filters in their gear to get more upstream spectrum, but then it would impede on the lower broadcast channels (channel 2 starts at 50 Mhz).
--
If it's important, back it up... twice. Even 99.999% availability isn't enough sometimes.


gar187er
I do this for a living

join:2006-06-24
Dover, DE
kudos:4
i wish the cb band was exempt.....we have a 64qam centered at 27.5mhz....
--
I'm better than you!


DrDrew
That others may surf
Premium
join:2009-01-28
SoCal
kudos:17
said by gar187er:

i wish the cb band was exempt.....we have a 64qam centered at 27.5mhz....

Either really good PM, really good CMTS noise avoidance config, or bad engineering decision...

My area just left a 1 Mhz gap.
--
If it's important, back it up... twice. Even 99.999% availability isn't enough sometimes.


telcodad
Premium
join:2011-09-16
Lincroft, NJ
kudos:15
reply to DrDrew
said by DrDrew:

Cable ops would have to change out all the diplex filters in their gear to get more upstream spectrum, but then it would impede on the lower broadcast channels (channel 2 starts at 50 Mhz).

Yes, ARRIS demonstrated a "high-split DOCSIS upstream system" at the 2011 Cable show in Chicago: »www.prnewswire.com/news-releases···744.html

"The demo will also show a proof-of-concept implementation of a 5-200 MHz high-split DOCSIS upstream system with 575 Mbps of DOCSIS upstream bandwidth being transmitted over 24 DOCSIS Upstream channels out of a single Fiber Node. This demo uses a single ARRIS 24U CAM to receive the high-split 5-200 MHz upstream spectrum from a Fiber Node. This record-breaking upstream bandwidth is intended to help the industry explore the future frequency allocations of HFC to protect its value and viability for many years to come."

I also found this item from a year ago on the CED Magazine website:

Cox, Motorola lay claim to new return path speed record
CED Magazine - March 1, 2011
»www.cedmagazine.com/news/2011/03···d-record

"Using a Motorola DOCSIS 3.0 RX48 return path receiver module operating within a Motorola BSR 64000 cable modem termination system (CMTS) edge router, the record of 356 Mbps for a 5-85 MHz return path was set by transmitting across 12 return path channels, of which six channels employed 256 QAM modulation. Motorola said typical HFC networks today have two or three upstream channels delivering an aggregate of 40-70 Mbps.
:
In addition to establishing the world record at 5-85 MHz, a maximum transmission rate of 141 Mbps was also achieved over a 5-42 MHz return path using six return path channels. Three of these channels were able to operate using 256 QAM modulation, as opposed to 64 QAM maximum in use today, which is also believed to be a record.

Motorola said that for the first time, cable operators could use the 5-42 return path to provide 100 Mbps dedicated to business customers, while at the same time providing residential customers with the return path bandwidth necessary to meet their growing needs."


gar187er
I do this for a living

join:2006-06-24
Dover, DE
kudos:4
reply to DrDrew
id like to think its PM


Mike Wolf

join:2009-05-24
Beachwood, NJ
kudos:4
reply to TriForce

Re: Evidence of 8 Downstream Channel Bonding - Post Here

said by TriForce:

said by elkido122:

Why do you need one with 8 up? There hardly implementing 4 up

Future proofing.

I agree, futureproofing is always awesome

medbuyer

join:2003-11-20
kudos:4

1 recommendation

said by Mike Wolf:

said by TriForce:

said by elkido122:

Why do you need one with 8 up? There hardly implementing 4 up

Future proofing.

I agree, futureproofing is always awesome

not quite...by the time you have a supposedly "future proof" modem and the time they implement such technology, your "future proofed" modem might be un-useful, not compatible, not to mention getting old etc...


NetFixer
Bah Humbug
Premium
join:2004-06-24
The Boro
Reviews:
·Cingular Wireless
·Comcast Business..
·Vonage
said by medbuyer:

not quite...by the time you have a supposedly "future proof" modem and the time they implement such technology, your "future proofed" modem might be un-useful, not compatible, not to mention getting old etc...

Yep, a number of years ago I bought a DOCSIS 2 modem for my initial testing of Comcast HSI (at that time Comcast was still DOCSIS 1.x). That modem never got the chance to work on a DOCSIS 2 system because Comcast just bypassed DOCSIS 2. Yes I know that in some areas Comcast did take over some DOCSIS 2 plants, but that did not happen here.
--
We can never have enough of nature.
We need to witness our own limits transgressed, and some life pasturing freely where we never wander.


telcodad
Premium
join:2011-09-16
Lincroft, NJ
kudos:15
reply to telcodad

Re: 8 downstream 8 upstream modem?

said by telcodad:

said by DrDrew:

Cable ops would have to change out all the diplex filters in their gear to get more upstream spectrum, but then it would impede on the lower broadcast channels (channel 2 starts at 50 Mhz).

I also found this item from a year ago on the CED Magazine website:

Cox, Motorola lay claim to new return path speed record
CED Magazine - March 1, 2011
»www.cedmagazine.com/news/2011/03···d-record

:
In addition to establishing the world record at 5-85 MHz, a maximum transmission rate of 141 Mbps was also achieved over a 5-42 MHz return path using six return path channels. Three of these channels were able to operate using 256 QAM modulation, as opposed to 64 QAM maximum in use today, which is also believed to be a record.

Motorola said that for the first time, cable operators could use the 5-42 return path to provide 100 Mbps dedicated to business customers, while at the same time providing residential customers with the return path bandwidth necessary to meet their growing needs."

BTW - I found this thread from April 2011 on the possible use of (and problems with) higher-order QAM carriers (256-QAM on the upstream, 512-QAM and 1024-QAM on the downstream) to increase DOCSIS transmission rates:

Forums>US Cable Support>Cable users>QAM 512/1024
»QAM 512/1024

"Well Ron Hranac said:

1024-QAM requires a very clean and tight plant, and about 6 dB higher carrier-to-noise ratio to achieve the same bit error rate as 256-QAM (for instance, 1.0E-08 BER requires approx. 34~35 dB CNR for 256-QAM; the same BER with 1024-QAM needs around 40~41 dB). As well, 1024-QAM is very susceptible to even small amounts of phase noise, requiring new tuner designs in set-tops, cable modems, and the like. Depending upon the plant's performance, it likely will require increasing the digital channel power of 1024-QAM signals to overcome the CNR requirements, risking downstream laser clipping."

andyross
Premium,MVM
join:2003-05-04
Schaumburg, IL
reply to DrDrew
said by DrDrew:

said by Mike Wolf:

Anypony know about an 8 downstream 8 upstream modem thats on the market yet?

Nobody makes one for the U.S. market

Usable upstream in the U.S. is from 5-45 Mhz or about 40 Mhz total.

8 channels at 6.4 Mhz wide = 51.2 Mhz.

Upstream channels can also be 3.2MHz wide down to 200KHz.
From Wikipedia:
quote:
In the upstream, DOCSIS 1.0/1.1 specifies channel widths between 200 kHz and 3.2 MHz. DOCSIS 2.0 also specifies 6.4 MHz, but can use the earlier, narrower channel widths for backward compatibility.


DrDrew
That others may surf
Premium
join:2009-01-28
SoCal
kudos:17

1 edit
Click for full size
said by andyross:

said by DrDrew:

said by Mike Wolf:

Anypony know about an 8 downstream 8 upstream modem thats on the market yet?

Nobody makes one for the U.S. market

Usable upstream in the U.S. is from 5-45 Mhz or about 40 Mhz total.

8 channels at 6.4 Mhz wide = 51.2 Mhz.

Upstream channels can also be 3.2MHz wide down to 200KHz.
From Wikipedia:
quote:
In the upstream, DOCSIS 1.0/1.1 specifies channel widths between 200 kHz and 3.2 MHz. DOCSIS 2.0 also specifies 6.4 MHz, but can use the earlier, narrower channel widths for backward compatibility.

DOCSIS 3 removes the use of 200khz-1.6 Mhz 800 khz channnels, if I remember right.

If it's a DOCSIS 3 modem, all the upstream channels it CAN produce have to be able to be run at 6.4 Mhz so an 8 upstream channel modem has to be able to use 51.2 mhz of spectrum. It just doesn't have to be configured that way.
--
If it's important, back it up... twice. Even 99.999% availability isn't enough sometimes.


EG
The wings of love
Premium
join:2006-11-18
Union, NJ
kudos:10
What would be the bandwidth carrying capacity advantage of having such narrow carriers anyway ???


DrDrew
That others may surf
Premium
join:2009-01-28
SoCal
kudos:17
said by EG:

What would be the bandwidth carrying capacity advantage of having such narrow carriers anyway ???

Less susceptible to noise.


netcool
Premium,VIP
join:2008-11-05
Englewood, CO
kudos:109

1 recommendation

said by DrDrew:

said by EG:

What would be the bandwidth carrying capacity advantage of having such narrow carriers anyway ???

Less susceptible to noise.

Also gives you an option to keep a legacy TDMA channel around for D1.0/1.1 modems/DOCSIS transponders without consuming extra spectrum.


EG
The wings of love
Premium
join:2006-11-18
Union, NJ
kudos:10
Agreed to both but these don't really directly address the question.


DrDrew
That others may surf
Premium
join:2009-01-28
SoCal
kudos:17
The bandwidth carrying capacity advantagse would be the ability to use bandwidth otherwise unusable by wider carriers (rare), usable by older modems (but they can use up to 3.2 mhz carriers), or to offload low bandwidth devices to a separate carrier (not much of an advantage).

Really, the narrow carriers are a throwback to gear or systems from 10 or more years ago. I've never seen a good use for them, other than as a bandaid to make up for something else that should be really done, i.e. phase out old gear, clean up noise, reconfig CMTSs settings, etc.
--
If it's important, back it up... twice. Even 99.999% availability isn't enough sometimes.


EG
The wings of love
Premium
join:2006-11-18
Union, NJ
kudos:10
I hear you Doc !!


telcodad
Premium
join:2011-09-16
Lincroft, NJ
kudos:15

1 edit
reply to telcodad
said by telcodad:

BTW - I found this thread from April 2011 on the possible use of (and problems with) higher-order QAM carriers (256-QAM on the upstream, 512-QAM and 1024-QAM on the downstream) to increase DOCSIS transmission rates:

Forums>US Cable Support>Cable users>QAM 512/1024
»QAM 512/1024

"Well Ron Hranac said:

1024-QAM requires a very clean and tight plant, and about 6 dB higher carrier-to-noise ratio to achieve the same bit error rate as 256-QAM (for instance, 1.0E-08 BER requires approx. 34~35 dB CNR for 256-QAM; the same BER with 1024-QAM needs around 40~41 dB). As well, 1024-QAM is very susceptible to even small amounts of phase noise, requiring new tuner designs in set-tops, cable modems, and the like. Depending upon the plant's performance, it likely will require increasing the digital channel power of 1024-QAM signals to overcome the CNR requirements, risking downstream laser clipping."

For those of you who can handle the more "technical stuff," I found this excellent presentation by Cisco's Ron Hranac on return path (upstream) design, characteristics and troubleshooting:
»www.ciscoknowledgenetwork.com/ca···ting.pdf

andyross
Premium,MVM
join:2003-05-04
Schaumburg, IL
reply to EG
said by EG:

What would be the bandwidth carrying capacity advantage of having such narrow carriers anyway ???

It seems like one advantage might be to work around a known noise issue. You may not be able to fit a full 6.4MHz channel in, but maybe a smaller one would fit just above or below the problem.


DrDrew
That others may surf
Premium
join:2009-01-28
SoCal
kudos:17
said by andyross:

said by EG:

What would be the bandwidth carrying capacity advantage of having such narrow carriers anyway ???

It seems like one advantage might be to work around a known noise issue. You may not be able to fit a full 6.4MHz channel in, but maybe a smaller one would fit just above or below the problem.

It's usually just easier to fix the noise issue or move the wider carrier over.

That way you don't lose bandwidth, since a 1.6 Mhz wide carrier has 1/4 the bandwidth of a 6.4 Mhz carrier using the same modulation rate.
--
If it's important, back it up... twice. Even 99.999% availability isn't enough sometimes.


telcodad
Premium
join:2011-09-16
Lincroft, NJ
kudos:15

1 edit
A blog item on the Multichannel News site this morning about what comes next after DOCSIS 3.0 and the possibility of widening the upstream bandwidth:

DPoE, EPoC: What's It All About?
By Leslie Ellis, Technology Analyst
Multichannel News - March 5, 2012
»www.multichannel.com/blog/Transl···out_.php

"DOCSIS, the cable-modem specification, is a teenager this month (turning 13 on March 20), which made us wonder about the road map for the industry's most successful interoperability maneuver.

Namely: We're up to version 3.0. Is there a DOCSIS 4.0?

Answer: Maybe not by that name, but one just-as-sexy (ahem) acronym is making steady inroads. It goes by "EPoC" (pronounced "ee-pock"), and stands for Ethernet PON over Coax. So, another nested acronym; PON stands for "passive optical network."

That nested PON is what links EPoC as a cousin to "DPoE" (DOCSIS Provisioning over EPON, where the "E" in "EPON" is Ethernet).
:
EPoC, as a variation, supplants the fiber necessity of PON with coax. It says, “I don’t need fiber to the anything (basement, building, house). Instead, I’ll convert that optical signal into a bidirectional electrical signal, then send it over coax to multiple end points.”

Think of it in an apartment sense. Fiber to the building, coax in the walls. Something was needed to adjoin what came in over glass, to coax. In a cable sense, that’s DPoE - a way to spoof the DOCSIS back-office components into thinking that an optical transmitter (a PON term) is a CMTS, and an optical receiver is a cable modem.
:
... welcome back to the oldie-but-goodie about widening the upstream signal path. All such discussions trigger decisions about the fielded base of amplifiers and “passives” - gear that passes signal without needing electricity. Like like taps and splitters. As little futzing as possible is always a design goal there.

One school of EPOC thought moves the upper boundary of the upstream band to 200 MHz from 42 MHz. Including spectral padding to prevent cross-modulation, that lands the downstream signal path at 250 MHz to 1 GHz.

Then, attention must be paid to what’s already sitting in the spectral areas within the change zone - 42-200 MHz, in this scenario. Lots of digital set-tops are wired to receive command-and-control signals (guide data, etc.) at a specific location within that region, for instance (122 MHz)."

medbuyer

join:2003-11-20
kudos:4

1 recommendation

said by telcodad:

A blog item on the Multichannel News site this morning about what comes next after DOCSIS 3.0 and the possibility of widening the upstream bandwidth:

DPoE, EPoC: What's It All About?
By Leslie Ellis, Technology Analyst
Multichannel News - March 5, 2012
»www.multichannel.com/blog/Transl···out_.php

can you tell us what do you do exactly? your username sounds intriguing...

you always post quotes from the internet...not that it matters..but I think people here would like your personal opinion / experience rather than copy and pasting a quote from an online article which everybody might have read already.


telcodad
Premium
join:2011-09-16
Lincroft, NJ
kudos:15
said by medbuyer:

can you tell us what do you do exactly? your username sounds intriguing...

you always post quotes from the internet...not that it matters..but I think people here would like your personal opinion / experience rather than copy and pasting a quote from an online article which everybody might have read already.

Well, as my username implies, I currently work in the telecom industry and I'm a father.

I lurked on the Comcast Cable TV forum for quite a while, until I recently signed up for Comcast HSI service and had a few questions about things. So I signed up for DSLR membership.

While, agreed, posting news items is probably more Karl Bode's job, when I do come across an interesting news item on one of the websites that I normally visit, I like to share that with others who may not have seen it (yet).

Anyway, I have been posting more about my own experiences and opinions lately, so hopefully that may be more helpful to fellow forum readers.


SpottedCat

join:2004-06-27
Miami, FL
reply to Mike Wolf
>Anypony know about an
~~~~~~

All I have to say is *brohoof*


Mike Wolf

join:2009-05-24
Beachwood, NJ
kudos:4
lol.

bgoodbody
Bill G

join:2002-05-08
North Truro, MA

1 recommendation

reply to TriForce

Re: Evidence of 8 Downstream Channel Bonding - Post Here

IPV6 before 8x8.

Even the latest Gateway distributed by Comcast: Arris TG852G is 8x4
--
- Bill


Mike Wolf

join:2009-05-24
Beachwood, NJ
kudos:4

1 edit

2 recommendations

I agree, I want to start seeing some true native IPv6.