DOCSIS 3 0 US Planning Bandwidth Management John
DOCSIS 3. 0 US Planning & Bandwidth Management John Downey, Consulting Network Engineer – CMTS BU Presentation_ID © 2009 Cisco Systems, Inc. All rights reserved. Cisco Confidential 1
Co-Sponsor – CCI Systems § Cisco Gold Partner § End-to-end network services – – – Presentation_ID Network and headend engineering Network mapping Network construction (cable/fiber) Network maintenance NOC services © 2009 Cisco Systems, Inc. All rights reserved. Cisco Confidential 2
Co-Sponsor – Todd Gingrass, CCI Systems § Vice President of Network Technology § 14 years at CCI Systems. § Bachelor of Electrical Engineering degree from Michigan Technical University § Certifications include Cisco Certified Network Associate Routing & Switching (CCNA), Cisco Certified Design Associate (CCDA), and Cisco Certified Internetwork Professional (CCIP) § A member of the Society of Cable and Television Engineers (SCTE) and Institute of Electrical and Electronics Engineers (IEEE) Presentation_ID © 2009 Cisco Systems, Inc. All rights reserved. Cisco Confidential 3
Presenter – John Downey, Cisco § 20 years in the data/telecommunications/ networking industry § BS in Electrical Engineering from Penn State University. § Nine years with Cisco as a Broadband Network Engineer presently with the Cable Modem Termination System (CMTS) Business Unit. § Certifications include CCNA and CCCS. § An SCTE member since ’ 96. Presentation_ID © 2009 Cisco Systems, Inc. All rights reserved. Cisco Confidential 4
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. Presentation_ID © 2009 Cisco Systems, Inc. All rights reserved. Cisco Confidential 5
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 Presentation_ID © 2009 Cisco Systems, Inc. All rights reserved. Cisco Confidential 6
ATDMA General Deployment Recommendations § After increasing CW to 6. 4 MHz, measure & document unequalized US MER at multiple test points in the plant – Use Path. Trak Return Path Monitoring System linecard – Or Sunrise Telecom Upstream Characterization toolkit § 25 d. B or higher Unequalized MER is recommended – Less than 25 d. B 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 Presentation_ID © 2009 Cisco Systems, Inc. All rights reserved. Cisco Confidential 7
US MER(SNR) Issues § Increasing ch width from 3. 2 to 6. 4 keeps same average power for single carrier – SNR drops by 3 d. B 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 Vo. IP? – Max output for 64 -QAM is 54 d. Bm. V • Cab up n power-adjust continue 6 § Pre-EQ affect – Great feature in 1. 1 & > CMs, but could mask issues Presentation_ID © 2009 Cisco Systems, Inc. All rights reserved. Cisco Confidential 8
D 3. 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 – RFo. G 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, now test equipment needs to have D 3. 0 capabilities Presentation_ID © 2009 Cisco Systems, Inc. All rights reserved. Cisco Confidential 11
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 D 2. 0 64 -QAM for 1 ch is 54 d. Bm. V § D 3. 0 US ch max power – Tx for D 3. 0 TDMA • 17 - 57 d. Bm. V (32 & 64 -QAM) • 58 d. Bm. V (8 & 16 -QAM) • 61 d. Bm. V (QPSK) – Tx for D 3. 0 S-CDMA • 17 - 56 d. Bm. V (all modulations) § Max Tx per ch for 4 freqs stacked at 64 -QAM ATDMA is only 51 d. Bm. V & 53 for S-CDMA Presentation_ID © 2009 Cisco Systems, Inc. All rights reserved. Cisco Confidential 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 Presentation_ID © 2009 Cisco Systems, Inc. All rights reserved. Cisco Confidential 14
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 Presentation_ID © 2009 Cisco Systems, Inc. All rights reserved. Cisco Confidential 15
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 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 d. B different vs. other channels Presentation_ID © 2009 Cisco Systems, Inc. All rights reserved. Cisco Confidential 16
New Architectures § New conundrum raised when fiber run deeper into network – RF over Glass (RFo. G) – 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 Presentation_ID © 2009 Cisco Systems, Inc. All rights reserved. Cisco Confidential 17
US Load Balance & Isolation Example CMTS US 0 @ 24 MHz 4 -Way Fiber Optic Rx 1 Filter CMTS US 2 @ 31 MHz Amplifier 4 -Way Fiber Optic Rx 2 CMTS US 1 @ 24 MHz § Attempting to “share” one US port across two other US ports – Can cause isolation issues – Load balance issues (ambiguous grouping) Presentation_ID © 2009 Cisco Systems, Inc. All rights reserved. Cisco Confidential 18
System Levels Reverse • 17 d. B at 5 MHz & 32 d. B at 1 GHz • Eliminates max transmit CMs CS(CEQ) tap • Eliminates high DS tilt to TV 26 350’ 1. 5 d. B 23 500’ 2 17 FEQ w/ US pad 600’ 2. 5 Input 17 Reverse 43 d. Bm. V transmit level @ the tap 42 39. 5 4 Step Attenuator or EQ tap 29 X 38 PIII. 5” cable. 40 d. B @ 30 MHz A total design variation of ~14 d. B! Presentation_ID © 2009 Cisco Systems, Inc. All rights reserved. Cisco Confidential 19
Transmit Level Possibilities § Running D 3. 0 CM in low modulation scheme allows higher power § Use D 3. 0 CM in 2. 0 mode – Single frequency on D 3. 0 CM offers 3 d. B higher power § Using SCDMA with more codes may also allow higher Tx power, but depends on implementation § Minimum level of 17 d. Bm. V (24? ) could cause issues in lab environment or HE test CM – Pmin = +17 d. Bm. V, 1280 ksym/s – Pmin = +20 d. Bm. V, 2560 ksym/s – Pmin = +23 d. Bm. V, 5120 ksym/s Presentation_ID © 2009 Cisco Systems, Inc. All rights reserved. Cisco Confidential 20
Summary § Cost effective and faster time to market – Decrease costs today – deploy DOCSIS 3. 0 later with no additional CMTS investment! § Targeted insertion of D 3. 0 – Leverage existing US chs while adding more US capacity – Load balance 1. x/2. 0 and enable D 3. 0 when needed – Minimizes capex & opex § Leverage D 3. 0 bonding for D 2. 0 tiers & services – Better stat-mux efficiency – Improved consumer experience Presentation_ID © 2009 Cisco Systems, Inc. All rights reserved. Cisco Confidential 21
Summary (cont) § Long term D 3. 0 service planning – – Insure optimized frequency allocation Enable seamless upgrade to higher D 3. 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 physical connectivity, not just channel capacity – May not be advantageous to combine noise to satisfy connectivity Presentation_ID © 2009 Cisco Systems, Inc. All rights reserved. Cisco Confidential 22
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