1 edit | 8 downstream 8 upstream modem? Anypony know about an 8 downstream 8 upstream modem thats on the market yet? |
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| Re: Evidence of 8 Downstream Channel Bonding - Post Here Why do you need one with 8 up? There hardly implementing 4 up |
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Reviews:
 ·Comcast
| said by elkido122:Why do you need one with 8 up? There hardly implementing 4 up
Future proofing. |
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 DrDrewSo that others may surf.
join:2009-01-28
SoCal
kudos:8 | 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).
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If it's important, back it up... twice. Even 99.999% availability isn't enough sometimes. |
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 gar187erI 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....
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I'm better than you! |
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DrDrewSo that others may surf.
join:2009-01-28
SoCal
kudos:8 | 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.
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If it's important, back it up... twice. Even 99.999% availability isn't enough sometimes. |
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 telcodad
join:2011-09-16
Lincroft, NJ
kudos:2 | 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.
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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." |
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gar187erI do this for a living
join:2006-06-24
Dover, DE
kudos:4 | reply to DrDrew
id like to think its PM  |
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Reviews:
·Comcast
| 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 |
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| 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... |
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 NetFixerFrom my cold dead handsPremium
join:2004-06-24
The Boro
·Comcast Business..
 ·Vonage
 ·Cingular Wireless
·Comcast
| 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.
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We can never have enough of nature.
We need to witness our own limits transgressed, and some life pasturing freely where we never wander. |
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telcodad
join:2011-09-16
Lincroft, NJ
kudos:2 | 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." |
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andyrossPremium,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.
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DrDrewSo that others may surf.
join:2009-01-28
SoCal
kudos:8
1 edit | 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.
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If it's important, back it up... twice. Even 99.999% availability isn't enough sometimes. |
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 EGThe wings of lovePremium
join:2006-11-18
Union, NJ
kudos:9 | What would be the bandwidth carrying capacity advantage of having such narrow carriers anyway ??? |
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DrDrewSo that others may surf.
join:2009-01-28
SoCal
kudos:8 | said by EG:What would be the bandwidth carrying capacity advantage of having such narrow carriers anyway ???
Less susceptible to noise. |
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netcoolPremium
join:2008-11-05
Englewood, CO
kudos:11 | 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. |
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EGThe wings of lovePremium
join:2006-11-18
Union, NJ
kudos:9 | Agreed to both but these don't really directly address the question. |
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DrDrewSo that others may surf.
join:2009-01-28
SoCal
kudos:8 | 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.
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If it's important, back it up... twice. Even 99.999% availability isn't enough sometimes. |
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EGThe wings of lovePremium
join:2006-11-18
Union, NJ
kudos:9 | I hear you Doc !!  |
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