DOCSIS 3.0 US Planning & Bandwidth Management

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

2. Agenda • 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.

3. Business Objectives • 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

4. ATDMA General Deployment Recommendations • 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

5. US MER(SNR) Issues • 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

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 Post-Deployment Monitoring Metrics

7. Post-Deployment Troubleshooting • 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

8. Impairment Increase vs Reporting • Ingress cancellation will cancel some CPD • CPD resembles AWGN when all DSs are digital

9. D3.0 US Issues • 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

10. US Frequency and Level Issues • Freq assignments • 5 to 42, 55, 65, 85 MHz ? • Diplex filters, line EQs, step attenuators, CPE overload • Max Tx for D2.0 64-QAM for 1 ch is 54 dBmV • D3.0 US ch max power • Tx for D3.0 TDMA • 17 - 57 dBmV (32 & 64-QAM) • 58 dBmV (8 & 16-QAM) • 61 dBmV (QPSK) • Tx for D3.0 S-CDMA • 17 - 56 dBmV (all modulations) • Max Tx per ch for 4 freqs stacked at 64-QAM ATDMA is only 51 dBmV & 53 for S-CDMA

11. US Input Spec

12. Total Power • 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

13. Laser Clipping • 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

14. Channel Placement • 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

15. New Architectures • 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

16. Fiber Optic Rx 1 Amplifier CMTS US0 @ 24 MHz 4-Way CMTS US2 @ 31 MHz Fiber Optic Rx 2 4-Way CMTS US1 @ 24 MHz Filter US Load Balance & Isolation Example • Attempting to “share” one US port across two other US ports • Can cause isolation issues • Load balance issues (ambiguous grouping)

17. 17 dB at 5 MHz & 32 dB at 1 GHz • Eliminates max transmit CMs • Eliminates high DS tilt to TV CS(CEQ) tap FEQ w/ US pad 4 26 17 23 500’ 600’ 350’ 2.5 2 1.5 dB Step Attenuator or EQ tap 17 Input 38 43 dBmV X 42 29 39.5 Reverse transmit level @ the tap PIII .5” cable .40 dB @ 30 MHz System Levels Reverse A total design variation of ~14 dB!

18. Transmit Level Possibilities • 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

19. Summary • 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

20. Summary (cont) • 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