DOCSIS 3.1 and the path to
1GB/s and beyond
Robert J. Flask
April 2015
[email protected]
Advertised speeds are driving the speed growth
How does DOCSIS 3.1 help?
 Adding bandwidth through two different ways
• Increasing Capacity by adding Megahertz – plant extensions
• Increasing efficiency by more bits/Hz – OFDM & LDPC
• OR BOTH
Source: Jeff Finklestein, CED webinar 11/2013
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Increasing Efficiency - More Bits/Hz
OFDM modulation and LDPC Error
Correction
New Carriers – OFDM & OFDM-A
OFDM
Legacy DOCSIS SC-QAM
• Orthogonal Frequency
Division Multiplexing
• Multi-Carrier Technology
• Composed of “Subcarriers”
• FFT-Based Implementation
6MHz
Source: Arris, CED DOCSIS 3.1 webinar 11/2013
192MHz
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Multi-Carrier vs. Single-Carrier systems
SC-QAM (6MHz)
OFDM (192MHz)
Adjacent subcarriers are
packed so tightly that they
overlap in the frequency
domain BUT they do not
interfere with each other
Source: Arris, CED DOCSIS 3.1 webinar 11/2013
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LDPC Error Coding
Source: Arris, CED DOCSIS 3.1 webinar 11/2013
Low Density Parity Check
(LDPC) Forward Error
Correction:
LDPC provides
3-6dB of gain
Previously too complex to
implement
Gets more bits/Hz
Source: Cable Congress 2013: HFC Readiness for DOCSIS 3.1 Kabel
Deutschland
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Effectively can get
1024 QAM where
256 QAM with RS
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OFDM – The power of individual subcarriers
 Subcarrier spacing can be 25kHz or 50kHz
• Each subcarrier can be turned ON/OFF
• Each subcarrier can have its own modulation order (variable bitloading)
OFDM channel
with Excluded
subcarriers to
accommodate
legacy carriers
Individual subcarriers
Source: Arris, CED DOCSIS 3.1 webinar 11/2013
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Variable Bit-Loading: Another benefit from managing
individual subcarriers
Individual subcarriers
experience different
SNR Values
Spectral view of
noise
• OFDM’s variable bitloading permits the
selection of
appropriate
modulation for each
subcarrier
Narrow Band Interferer
SNR
Subcarrier flexibility
allows for tweaking to
get the maximum
capacity out of the plant
Source: Arris, CED DOCSIS 3.1 webinar 11/2013
25kHz
FREQ
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DOCSIS 3.1 Downstream Profiles
Tailor profiles to account for
SNR differences in the plant
Worst – (mostly 256 QAM)
Avg. – (mostly 1024 QAM)
Better (mostly 2048 QAM)
Best (mostly 4096 QAM)
Worst
Avg.
Better
Some CM’s can do
better than others – so
let them
Best
Net capacity is
higher than the
“least common
denominator”
Source: Robert Howald, Arris, SCTE Seminar 10/13
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Higher speed through multiple carrier bonding and DOCSIS 3.1
1.2 Gb/s (6.3 b/s/Hz)
192 MHz
32 SC QAM DOCSIS Channels
2.0 Gb/s MAX(10.5 b/s/Hz max)
1.6 Gb/s typ (8.3 b/s/Hz)
1.2 Gb/s (6.3 b/s/Hz)
192 MHz
32 SC QAM DOCSIS Channels
192 MHz
DOCSIS 3.1 OFDM Carrier
1.2 Gb/s
192 MHz
32 SC QAM DOCSIS Channels
2.0 Gb/s MAX
1.6 Gb/s typ
192 MHz
192 MHz
DOCSIS 3.1 OFDM Carrier
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2.0 Gb/s
1.6 Gb/s typ
DOCSIS 3.1 OFDM Carrier
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Maximizing the Downstream potential with DOCSIS 3.1
2.4Gb/s of Linear Video + 4.8 Gb/s of
Data or IP Video
Maximum capacity on 1 GHz plant
192 MHz
61 SC QAM Video Channels
192 MHz
192 MHz
32 SC QAM DOCSIS Channels
DOCSIS 3.1 OFDM
Carrier
DOCSIS 3.1 OFDM Carrier
54 MHz
1000 MHz
Frequency extensions add additional capacity
Maximum capacity on 1.2 GHz plant
95 SC QAM Video Channels
3.7 Gb/s of Linear Video + 4.8 Gb/s
of Data or IP Video
32 SC QAM DOCSIS Channels
DOCSIS 3.1 OFDM Carrier
54 MHz
DOCSIS 3.1 OFDM Carrier
1200 MHz
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OFDM Flexibility allows it to overlay and work between
carriers
192 MHz
192 MHz
D3.1
OFDM
D3.1 OFDM
192 MHz
DOCSIS 3.1 OFDM
Carrier
54 MHz
1000 MHz
95 SC QAM Video Channels
32 SC QAM DOCSIS Channels
DOCSIS 3.1 OFDM Carrier
54 MHz
DOCSIS 3.1 OFDM Carrier
1200 MHz
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UPSTREAM Efficiency options
Higher Bonding counts ( and frequency extension)
123 Mb/s (4.8 b/s/hz @ 64 QAM )
4 DOCSIS Channels
OOB
Carriers
QAM
QAM
QAM
5 MHz
QAM
42 MHz
4 Channels Bonded
246 Mb/s (4.8 b/s/hz @ 64 QAM )
8 DOCSIS Channels
OOB
Carriers
SC
QAM
SC
QAM
SC
QAM
SC
QAM
SC
QAM
SC
QAM
SC
QAM
SC
QAM
85 MHz
5 MHz
8 Channels Bonded
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OFDM-A overlay in upstream
Source: Cisco, John Chapman, CED DOCSIS 3.1 webinar 11/2013
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Upstream Efficiency options
Bonding and adding OFDM-A
123 Mb/s (4.8 b/s/hz @ 64 QAM )
98.7 Mb/s MAX(10.5 b/s/hz @ 4096 QAM)
78 Mb/s Typs (8.3 b/s/Hz typ)
4 DOCSIS Channels
OOB
Carriers
D3.1 OFDM
SC
QAM
SC
QAM
SC
QAM
5 MHz
212 Mb/s MAX
200 Mb/s Typ
shared 42 MHz/ system
SC
QAM
42 MHz
4 Channels Bonded
571.2 Mb/s MAX (10.5 b/s/hz @ 4096 QAM ) –
451.5 Mb/s typ (8.3 b/s/Hz)
80 MHz
694 Mb/s max in shared
85 MHz/ system
4 DOCSIS Channels
OOB
Carriers
123 Mb/s (4.8 b/s/hz @ 64 QAM )
D3.1 OFDM
SC
QAM
SC
QAM
SC
QAM
SC
QAM
85 MHz
5 MHz
4 Channels Bonded
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Upstream Migration and bonding options
98.7 Mb/s MAX(10.5 b/s/hz @ 4096 QAM
123 Mb/s (4.8 b/s/hz @ 64 QAM )
78 Mb/s Typs (8.3 b/s/Hz typ)
4 SC DOCSIS Channels
OOB
Carriers
SC
QAM
D3.1
OFDMA
SC
QAM
5 MHz
SC
QAM
SC
QAM
42 MHz
793Mb/s MAX = 670 Mb/s (10.5 b/s/hz @ 4096 QAM) + 123 Mb/s (4.8 b/s/Hz @64 QAM)
674Mb/s TYP= 551 Mb/s (8.3. b/s/hz ) + 123 Mb/s (4.8 b/s/Hz @64 QAM)
92 MHz
212 Mb/s MAX
200 Mb/s Typ
shared 42 MHz/ system
Reality is that the max effective rate
will be lower due to modulation
profiles and variable bit loading
1.7 Gb/s Max
1.3Gb/s Typ
970 Mb/s MAX (10.5 b/s/hz)
760Mb/s Typ (8.3 b/s/Hz)
92 MHz
OOB
Carriers
D3.1
OFDMA
S
C
Q
A
M
S
C
Q
A
M
S
C
Q
A
M
S
C
Q
A
M
D3.1 OFDMA
5 MHz
204 MHz
970 Mb/s (10.5 b/s/hz @ 4096 QAM)
760 Mb/s Typ (8.3 b/s/Hz)
92 MHz
970 Mb/s (10.5 b/s/hz)
760 Mb/s Typ (8.3 b/s/Hz)
92 MHz
D3.1 OFDMA
1.94 Gb/s Max
1.4 Gb/s Typ.
D3.1 OFDMA
5 MHz
204 MHz
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Frequency Extensions
DS
Extensions
• 1.2GHZ
• DOCSIS 3.1 supports plant expansions to 1.2GHz. The
D3.1 CM & CMTS must support 1.2GHz
• 1.794 GHz
• DOCSIS 3.1 support for 1.7GHz is optional for the CM &
CMTS. be supported in a later version.
US
Extensions
• 85MHz QAM or OFDM
• DOCSIS 3.1 supports 85 MHz upstream just like D3.0
• 117MHz – for OFDM
• DOCSIS 3.1 adds additional support for 117 MHz return
• 204MHz – for OFDM
• DOCSIS 3.1 adds optional support for a 204MHz return
Source: Cable Labs, DOCSIS 3.1 specification
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Frequency Extensions in DOWNSTREAM add Capacity
61 SC QAM Video Channels
32 SC QAM DOCSIS Channels
DOCSIS 3.1
OFDM Carrier
54 MHz
1GHz available now
for SC QAM
DOCSIS 3.1
OFDM Carrier
1000 MHz
95 SC QAM Video Channels
32 SC QAM DOCSIS Channels
DOCSIS 3.1 OFDM
Carrier
DOCSIS 3.1 OFDM
Carrier
54 MHz
SC QAM Video Channels
1.2 GHz available
now for DOCSIS 3.1
and OFDM above
1GHz
1200 MHz
32 SC QAM DOCSIS Channels
DOCSIS 3.1 OFDM
Carrier
DOCSIS 3.1 OFDM
Carrier
DOCSIS 3.1 OFDM
Carrier
DOCSIS 3.1 OFDM
Carrier
54 MHz
> 10 GB/s capacity for an all 3.1 system
1700 MHz
1.7 GHz OPTIONALY available now
for DOCSIS 3.1 and OFDM above
1GHz
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Upstream Frequency Extensionoptions
Bonding and adding OFDM-A
SC
QAM
D3.1 OFDM
SC
QAM
SC
QAM
5 MHz
SC
QAM
42 MHz
SC
QAM
D3.1 OFDM
SC
QAM
SC
QAM
SC
QAM
85 MHz
5 MHz
D3.1
OFDMA
S
C
Q
A
M
S
C
Q
A
M
S
C
Q
A
M
S
C
Q
A
M
D3.1 OFDMA
5 MHz
> 1 GB/s capacity for all 3.1 system
85 MHz available now
for DOCSIS 3.0 and
up to 8 bonded
carriers
204 MHz
D3.1 allows for mid split up to 204
MHz. OFDM-A only above 85 MHz
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Expansion Summary
D3.1
OFDM-A
5 MHz
S
C
S
C
S
C
S
C
Q
A
M
Q
A
M
Q
A
M
Q
A
M
42 MHz
DOCSIS 3.1
OFDM Carrier
D3.1 OFDM-A
Upstream
Expansion
85 MHz 117 MHz
DOCSIS 3.1
OFDM Carrier
1000 MHz
1200 MHz
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DOCSIS 3.1
OFDM Carrier
Optional
Downstream
Expansion
Downstream
Expansion
204 MHz
DOCSIS 3.1
OFDM Carrier
|
1700 MHz
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Traditional problems still affect OFDM
LTE and noise interferences
If QAM Leaks
out
LTE can get in
Source: Robert Howald, Arris, SCTE Seminar 10/13
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Things to do in preparation for 3.1
 Upstream noise mitigation
• Cleaning up return spectrum for the best possible S/N will allow
highest overall bits/Hz in OFDM-A profiles
• Impulse noise elimination
- LDPC is resilient but it still can be impacted by repetitive impulse
noise
 Upstream Sweep and alignment
 Downstream noise mitigation
• Identify and eliminate QAM leakage out and LTE or Off-Air
leakage in to plant to provide best possible performance
 Downstream Sweep and Balance
 Plant Characterization
• Identify how QAM and OFDM carriers will perform in new
spectrum
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The path to DOCSIS 3.1
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Questions?