DOCSIS 3.0 US Planning & Bandwidth Management John Downey, Consulting Network Engineer – CMTS BU

© 2010 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 2 Frequency Stacking Levels What is CM max US output with four channels stacked and do channels have to be contiguous? Power/Hz & laser clipping Diplex Filter Expansion to 85 MHz? Amplifier upgrades occurring now; Best to make 1 truck roll Think about diplex filters, line EQs, step attenuators, taps, etc.

© 2010 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 3 Allow more BW for DOCSIS 1.x & 2.0 CMs Limit/reduce more node splits Introduce new HSD service of 50 to 100 Mbps Allow migration of existing customers to higher tier and DOCSIS 3.0 capability Better Stat Muxing

© 2010 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 4 After increasing CW to 6.4 MHz, measure & document unequalized US MER at multiple test points in the plant Use PathTrak Return Path Monitoring System linecard Or Sunrise Telecom Upstream Characterization toolkit 25 dB or higher Unequalized MER is recommended Less than 25 dB reduces operating margin Check US MER as well as per-CM MER Pick freq < 30 MHz away from diplex filter group delay Make sure latest IOS version is running on CMTS Turn on Pre-Equalization

© 2010 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 5 Increasing ch width from 3.2 to 6.4 keeps same average power for single carrier SNR drops by 3 dB or more Keeping same power/Hz could cause max Tx level from CMs and/or laser clipping/overload Equalized vs unequalized MER readings Modulation profile choices QPSK for maintenance, 64-QAM for Data, 16-QAM for VoIP? Max output for 64-QAM is 54 dBmV Cab up n power-adjust continue 6 Pre-EQ affect Great feature in 1.1 & > CMs, but could mask issues

© 2010 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 6 Correctable FEC (US & per-CM) If > 2.5 %: minor alarm If > 5 %: major alarm Uncorrectable FEC (US & per-CM) If > 0.1 %: minor alarm If > 1 %: major alarm Equalized/PRE-EQ MER(SNR) (US & per-CM) If < 27 dB: minor alarm If < 24 dB: major alarm Cable Flap-List D3.0 Modem Diagnostic Log Can utilize IPDR

© 2010 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 7 MER per US with ability to drill-down for per-CM MER Use Return Path monitoring tools Cisco Broadband Troubleshooter (CBT) Need analyzer to read < 5 MHz for AM or ham radio ingress PathTrak to view 5-65 MHz for apparent laser clipping New PathTrak card reads 0.5 MHz - 85 MHz Cable Flap-List monitoring for US or CM issues Uncorrectable /Correctable FEC per US with ability to drill- down for per-CM counters Bottom line is correctable & uncorrectable FEC If correctable FEC is incrementing, then eventually it will lead to uncorrectable FEC, which equals packet drops

© 2010 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 8 CNRMER(SNR)Corr FECUncorr FEC AWGNBad Eventually Bad CW CarrierBadOk Impulse Noise / Laser Clipping BadOk Bad Group Delay / Micro- Reflections OkBad Eventually Bad Ingress cancellation will cancel some CPD CPD resembles AWGN when all DSs are digital

© 2010 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 9 Frequency Stacking Levels What is the max output with multiple channels stacked Is it pwr/Hz & could it cause laser clipping? Diplex Filter Expansion to 85 MHz If amplifier upgrades are planned for 1 GHz, then pluggable diplex filters may be warranted to expand to 85 MHz on the US Still must address existing CPE equipment in the field and potential overload RFoG could be perfect scenario (maybe even 200 MHz split) CM must be w-online (requires 1.1 cm file) for US bonding Monitoring, Testing, & Troubleshooting Just like DOCSIS 2.0, test equipment needs to have D3.0 capabilities

© 2010 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 10 Freq assignments 5 to 42, 55, 65, 85 MHz ? Diplex filters, line EQs, step attenuators, CPE overload Max Tx for D QAM for 1 ch is 54 dBmV D3.0 US ch max power Tx for D3.0 TDMA dBmV (32 & 64-QAM) 58 dBmV (8 & 16-QAM) 61 dBmV (QPSK) Tx for D3.0 S-CDMA dBmV (all modulations) Max Tx per ch for 4 freqs stacked at 64-QAM ATDMA is only 51 dBmV & 53 for S-CDMA

© 2010 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 11

© 2010 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 12 Was only one US channel present, now up to four US chs transmitting at same time Possibly 6.4 MHz each; nearly 26 MHz US channel loading Lots of power hitting return path fiber optic transmitter Probability of laser clipping is increased, especially if using legacy Fabry-Perot (FP) lasers Good idea to upgrade to Distributed Feedback (DFB) lasers, which have significantly more dynamic range Use return path monitoring system capable of looking above 42 MHz to see second and third order harmonics Any burst noise above diplex filter (i.e. 42 MHz) coming out of return path receiver is usually indicative of laser clipping

© 2010 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 13 Blue trace shows case of strong laser clipping Green line represents flat US laser noise floor with no clipping Note that this US has four US bonded channels

© 2010 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 14 Each US channel used for bonding is individual channel Transmitters (channels) are separate Don't have to be contiguous and can have different physical layer attributes like; modulation, channel width, tdma or scdma, etc. Frequencies can be anywhere in US passband and do not need to be contiguous It may be wise to keep relatively close so plant problems like attenuation and tilt don’t cause issues CM will have some dynamic range to allow specific channels to be a few dB different vs. other channels

© 2010 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 15 New conundrum raised when fiber run deeper into network RF over Glass (RFoG) DOCSIS Passive Optical Networks (DPON) May incorporate 32-way optical splitter/combiners. Having a laser Tx in your house combined with 32 other houses feeding 1 Rx in the HE is addressed with lasers timed with the actual traffic from the house; unlike how it is done today where the US laser is on all the time US bonding and/or load balancing presents potential issue where an US laser could be transmitting same time as another US laser May be acceptable with multiple lasers transmitting same instant in time, if they are carrying different frequencies, Will S-CDMA pose same problems? This multiplexing scheme allows multiple CMs to transmit same instant in time

© 2010 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 16 Attempting to “share” one US port across two other US ports Can cause isolation issues Load balance issues (ambiguous grouping) 4-Way CMTS 24 MHz CMTS 24 MHz CMTS 31 MHz Fiber Optic Rx 1 Fiber Optic Rx 2 Filter Amplifier

© 2010 Cisco and/or its affiliates. All rights reserved. Cisco Confidential ’ 500’600’ 1.5 dB Input 43 dBmV PIII.5” cable MHz Reverse transmit the tap A total design variation of ~14 dB! CS(CEQ) tap 17 dB at 5 MHz & 32 dB at 1 GHz Eliminates max transmit CMs Eliminates high DS tilt to TV FEQ w/ US pad Step Attenuator or EQ tap 38 X

© 2010 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 18 Running D3.0 CM in low modulation scheme allows higher power Use D3.0 CM in 2.0 mode Single frequency on D3.0 CM offers 3 dB higher power Using SCDMA with more codes may also allow higher Tx power, but depends on implementation Minimum level of 17 dBmV (24?) could cause issues in lab environment or HE test CM Pmin = +17 dBmV, 1280 ksym/s Pmin = +20 dBmV, 2560 ksym/s Pmin = +23 dBmV, 5120 ksym/s

© 2010 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 19 Cost effective and faster time to market Decrease costs today – deploy DOCSIS 3.0 later with no additional CMTS investment! Targeted insertion of D3.0 Leverage existing US chs while adding more US capacity Load balance 1.x/2.0 and enable D3.0 when needed Minimizes capex & opex Leverage D3.0 bonding for D2.0 tiers & services Better stat-mux efficiency Improved consumer experience

© 2010 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 20 Long term D3.0 service planning Insure optimized frequency allocation Enable seamless upgrade to higher D3.0 tiers Wire once Add QAM chs as tiers or service take-rates go up End-to-end solution minimizes risk CMTS, QAM, and CPE Account for phy connectivity, not just ch capacity Not advantageous to combine noise to satisfy connectivity Fix Max Tx issues now Design for tight “bell-curve” (43-48 dBmV), if possible Good News – ECR to increase US Tx levels 61 dBmV max, with 3 dB typical