Advanced PHY Performance - cisco.com

Advanced PHY Performance - cisco.com

ADVANCED PHY PERFORMANCE RON HRANAC Note: This presentation is intended for Cisco internal audiences and customers under NDA only. This presentation contains confidential intellectual property information that is proprietary to Broadcom Corporation and Texas Instruments. Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved. 1 DOCSIS Background Data Over Cable Service Interface Specification DOCSIS 1.0 gave us standards-based interoperability, which means certified cable modems from multiple vendors work with qualified cable modem termination systems (CMTSs) from multiple vendors. DOCSIS 1.1 added a number of features, including quality of service (QoS), more robust scheduling, packet classification and other enhancements that facilitate voice services.

Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved. 2 DOCSIS Background DOCSIS 1.0 and 1.1collectively known as DOCSIS 1.x support two downstream modulation formats: 64-QAM (quadrature amplitude modulation) and 256-QAM. Modulation format Advanced PHY Performance Channel bandwidth, MHz Symbol rate, Msym/sec Raw data

rate, Mbps Nominal data rate, Mbps 64-QAM (DOCSIS) 6 5.056941 30.34 ~27 256-QAM (DOCSIS) 6 5.360537 42.88

~38 64-QAM (Euro-DOCSIS) 8 6.952 41.71 ~37 256-QAM (Euro-DOCSIS) 8 6.952 55.62 ~50 2003 Cisco Systems, Inc. All rights reserved. 3

DOCSIS Background DOCSIS 1.x supports several upstream data rates, ranging from a low of 320 kbps to a high of 10.24 Mbps. It also supports two modulation formats quadrature phase shift keying (QPSK) and 16-QAM as well as five upstream RF channel bandwidths. Channel bandwidth, MHz Symbol rate, QPSK raw ksym/sec data rate, Mbps QPSK nominal data rate, Mbps 16-QAM raw data rate, Mbps 16-QAM nominal

data rate, Mbps 0.200 160 0.32 ~0.3 0.64 ~0.6 0.400 320 0.64 ~0.6 1.28 ~1.2

0.800 640 1.28 ~1.2 2.56 ~2.4 1.60 1,280 2.56 ~2.3 5.12 ~4.8 3.20

2,560 5.12 ~4.6 10.24 ~9.0 Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved. 4 DOCSIS Background DOCSIS 1.1 added some enhancement to upstream transmission robustness, using 8-tap adaptive equalization. DOCSIS 2.0: Higher upstream data throughput per RF channel, up to 30.72 Mbps DOCSIS 2.0 supports 64-QAM in the upstreamplus 8-QAM and 32QAMand optionally supports 128-QAM trellis coded modulation (TCM) encoded modulations for S-CDMA channels.

Higher orders of modulation require more robust data transmission To facilitate more robust upstream data transmission, DOCSIS 2.0 introduced advanced PHY Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved. 5 What is Advanced PHY? PHY: Physical Layer Advanced PHY 2nd Generation Burst Mode RX Direct sampled RF front end Ingress cancellation Frequency stacking Spectrum management Improved adaptive equalizer from 2.0 Spec Improved burst mode RX preamble Improves 1.x as well as 2.0 cable modems Advanced PHY Performance

2003 Cisco Systems, Inc. All rights reserved. 6 What is Advanced PHY? Symbol (T)-spaced adaptive equalizer with 24 taps compared to 8 taps in DOCSIS 1.x Allows operation in the presence of more severe multipath and microreflections, and should accommodate signals near the band edge where group delay is more prevalent Improved burst acquisition Carrier and timing lock, power estimates, equalizer training and constellation phase lock are all done simultaneously. This allows shorter preambles, and reduces implementation loss. Better forward error correction (FEC) DOCSIS 1.x provides for the correction of up to 10 errored bytes per Reed Solomon block (T=10) with no interleaving, while DOCSIS 2.0 allows correction of up to 16 bytes per Reed Solomon block (T=16) with programmable interleaving. Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved. 7

What is Advanced PHY? Advanced PHY silicon incorporates ingress cancellation technology in the upstream receiver chip, which further enhances upstream data transmission robustness. Think of ingress cancellation as a way to digitally remove in-channel impairments such as ingress and common path distortion. Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved. 8 Performance Concepts Implementation Margin Closeness to theoretical in an additive white Gaussian noise (AWGN) environment Example If the theoretical bit error rate (BER) at 21 dB carrier-tonoise ratio (CNR) is 1x10-6 but a CMTS actually needs 23 dB CNR to achieve a 1x10-6 BER, the implementation margin is 2 dB.

Processing Gain Processing to improve performance (e.g., FEC or ingress cancellation) Example When ingress cancellation is turned off and a carrier-tointerference ratio (C/I) of 10 dB yields 1x10-6 BER, then turning on ingress cancellation allows C/I = 0 dB for 1x10-6 BER, processing gain is 10 dB. Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved. 9 MC16C/S, MC28C/E Burst Mode Receivers - 1st Generation Burst Error Rate vs. Frequency Offset 2.56 Msym/sec, 16-QAM 10-Byte Preamble, RS(236,220) Burst Error Rate Broadcoms BCM3137 is within 2 dB of theory @16-QAM AND

1.00E+00 1.00E-01 14 16 18 1.00E-02 20 22 0 kHz RS(236,220) Theory 1.00E-03 1.00E-04 1.00E-05 1.00E-06 CNR (dB) Implementation margin of analog receiver (VCO, SAW) adds another 2-3 dB

Advanced PHY Performance Broadcom Confidential 2003 Cisco Systems, Inc. All rights reserved. 10 MC28U/X 2nd Generation Direct Sampled Burst Mode Digital Receiver Gmax = 32 dB F-connector A/D LPF PGA Amplifier LPF ToPHY G=1

To FFT Subsystem (AWACs) FromAGC All frequency conversion and selectivity in PHY ASIC Total implementation margin < 0.5 dB of theory Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved. 11 Ciscos Advanced PHY MC28U/X MC16U/X Annex A/B Upstream Broadcom BCM3138 (same as BCM3140 2.0 chip, but without S-CDMA) 5-65 MHz dual A-TDMA, adaptive ingress cancellation, integrated FFT Downstream Broadcom BCM3034 Annex A/B Modulator No SAW filter required with downstream chip MC5x20U Annex A/B Upstream Texas Instruments TI4522 series 5-65 MHz A-TDMA, advanced PHY including ingress

cancellation Downstream Broadcom BCM3034 Annex A/B modulator No SAW filter required with downstream chip Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved. 12 Ciscos Advanced PHY Advanced RF front end and Cisco MAC hardware, allow Ciscos MC5x20U and MC28U Broadband Processing Engines (BPE) to offer improved capacity, performance and reliability. Operates within 0.5 dB of theory Advanced PHY with ingress cancellation Greater than 17 Mbps single modem upstream throughput Line rate DOCSIS 1.1 and 2.0 processing using the advanced Cisco DOCSIS MAC technology

Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved. 13 Ciscos Line Card RF Front End High density2 downstreams, 8 upstreams (MC28U) or 5 downstreams, 20 upstreams (MC5x20U) per line card Enhanced RF robustness Embedded upstream ingress cancellation Direct sampling Integrated upconverters ATDMA-capable Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved. 14

RF Performance: BER vs. AWGN Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved. 15 MC28U Packet Error Rate Versus AWGN QPSK 1.00E+00 1.00E-01 9.24E-02 7.81E-02 3.51E-02 1.53E-02 1.00E-02 PER Frequency: 30

MHz Mod: QPSK Symbol Rate: 1,280 ksym/sec Power: 0 dBmv Packet Size: 64 Bytes Packet Rate: 100 Packets: 1000000 RS_N=84 RS_T=3 1.00E-03 6.44E-04 1.71E-04 1.00E-04 1.00E-05 2.00E-06 1.00E-06 4.04E-07

MC28U Theoretical 1.00E-07 8 8.5 9 9.5 10 10.5 11 11.5 12 CNR (dB) Advanced PHY Performance

2003 Cisco Systems, Inc. All rights reserved. 16 MC28U Packet Error Rate Versus AWGN 16-QAM 1.00E+00 2.25E-01 9.08E-02 1.00E-01 PER 1.00E-02 Frequency: 30 MHz Mod: 16QAM Symbol Rate: 1,280 ksym/sec Power: 0 dBmv Packet Size: 64 Bytes Packet Rate: 100 Packets: 1000000 RS_N=88

RS_T=5 3.94E-02 1.61E-02 1.00E-03 4.48E-04 1.04E-04 1.00E-04 1.00E-05 1.00E-06 1.00E-06 1.00E-07 15 15.5 16 16.5 17

8.55E-08 17.5 18 MC28U Theoretical CNR (dB) Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved. 17 MC28U Packet Error Rate Versus AWGN 64-QAM 1.00E+00 3.99E-01 2.64E-01 Frequency: 30 MHz Mod: 64QAM Symbol Rate:

5,120 ksym/sec Power: 0 dBmv Packet Size: 64 Bytes Packet Rate: 100 Packets: 1000000 RS_N=96 RS_T=9 1.00E-01 2.64E-02 9.63E-03 PER 1.00E-02 1.00E-03 1.84E-04 1.00E-04 2.46E-05 1.00E-05

2.00E-06 1.00E-06 4.31E-07 1.00E-07 19 19.5 20 20.5 21 21.5 22 MC28U Theoretical 22.5

CNR (dB) Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved. 18 MC28U/MC28C Comparison Cisco MC28C/U AWGN Impairment Performance: QPSK 1.00E+00 1.00E-01 9 7.81E-02 9.5 1.53E-02 PER 1.00E-02 Frequency: 30 MHz Mod: QPSK Symbol Rate: 1,280 ksym/sec

Power: 0 dBmv Packet Size: 64 Bytes Packet Rate: 100 Packets: 1000000 RS_N=84 RS_T=3 5.50E-02 5.79E-03 1.00E-03 10.5 2.35E-04 1.71E-04 1.00E-04 2.80E-05 1.00E-05 4.00E-06 11.5

1.00E-06 MC28U Theoretical 4.04E-07 1.00E-07 8.5 9.5 10.5 11.5 12.5 MC28C 13.5 14.5 15.5

CNR (dB) Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved. 19 MC28U/MC28C Comparison Cisco MC28C/U AWGN Impairment Performance: 16-QAM 1.00E+00 2.25E-01 9.08E-02 3.94E-02 1.61E-02 1.00E-01 PER 1.00E-02 Frequency: 30 MHz Mod: 16-QAM Symbol Rate: 1,280 ksym/sec

Power: 0 dBmv Packet Size: 64 Bytes Packet Rate: 100 Packets: 1000000 RS_N=88 RS_T=5 1.86E-02 8.56E-03 2.03E-03 1.00E-03 4.59E-04 4.48E-04 1.04E-04 1.00E-04 9.40E-05 1.80E-05 1.00E-05 4.00E-06

1.00E-06 1.00E-06 1.00E-07 14.5 8.55E-08 18.5 16.5 MC28C MC28U Theoretical 20.5 22.5 CNR (dB) Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved.

20 MC520S/U BER Versus AWGN Within Measurement Uncertainty of Theory QPSK Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved. 21 MC520S/U BER Versus AWGN Within Measurement Uncertainty of Theory 16-QAM Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved. 22

MC520S/U BER Versus AWGN Within Measurement Uncertainty of Theory 64-QAM Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved. 23 Lower Implementation Margin Advantages Can operate at lower CNR for a given BER than earlier generation CMTSs Provides improved operating headroom Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved. 24 RF Performance:

Ingress Cancellation Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved. 25 Ingress Cancellation Opens previously unusable spectrum Enables reliable operation in the presence of ingress Narrowband and wideband Works with all DOCSIS 1.0, 1.1, & 2.0 cable modems Advanced PHY Performance 16-QAM 10-8 BER Texas Instruments Confidential 2003 Cisco Systems, Inc. All rights reserved.

26 MC28/16 U/X w/ Broadcom BCM3138 Adaptive Ingress Cancellation RX AFE Advanced PHY Performance Demod Ingress Cancel & Equalizer Broadcom Confidential 2003 Cisco Systems, Inc. All rights reserved. 27 Broadcom BCM3138 Ingress Performance Static CW Ingress (64-QAM, SIR = 0 dB) Symbol Rate = 5.12 MHz

Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved. Cluster SNR = 28.83 dB Broadcom Confidential 28 Broadcom BCM3138 Ingress Performance Wideband Ingressors 20 kHz and 100 kHz (16-QAM, SIR = 9 dB) Symbol Rate = 5.12 MHz Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved. Cluster SNR = 20.96 dB Broadcom Confidential 29

Broadcom BCM3138 Ingress Performance Four CW Ingressors (64 QAM, SIR = 6 dB) Symbol Rate = 5.12 MHz Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved. Cluster SNR = 26.94 dB Broadcom Confidential 30 Broadcom BCM3138 Ingress Performance Four CW Ingressors (16-QAM, SIR = 0 dB) Cluster SNR = 22.79 dB Advanced PHY Performance Broadcom Confidential

2003 Cisco Systems, Inc. All rights reserved. 31 CableLabs PHY22B Ingress Cancellation CableLabs optional PHY test Packet error rate in presence of single CW interferer & AWGN PER <0.5%, 64-byte packets Note: Negative C/I indicates interferer is larger than desired signal C/I QPSK 16QAM 64QAM Single CW Ingress 1.28MBaud 2.56MBaud

5.12Mbaud AWGN = -20 dB AWGN = -25dB AWGN = -30dB -20.2 dB -18.2 dB -10.7 dB MC28/16U/X Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved. 32 RF Performance: Receive Equalizer

Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved. 33 DOCSIS 2.0 ADTMA Equalizer DOCSIS 1.1 specifies an 8-tap T-Spaced Pre-Equalizer which can mitigate microreflections of 10dB (at .5 micro-sec delay) with 27 dB MSE DOCSIS 1.1 Pre-Equalizer enables reliable operation at 16-QAM in channels that could only support QPSK in DOCSIS 1.0 DOCSIS 2.0 specifies a 24-tap T-Spaced Pre-Equalizer which can mitigate microreflections of 10dB (at .5 micro-sec delay) with 33 dB MSE DOCSIS 2.0 Pre-Equalizer can enable reliable operation at 64-QAM even in channels that can only support QPSK in DOCSIS 1.0 24-tap adaptive equalizer can operate in DOCSIS 1.0 Mode to compensate linear plant errors (slope, group delay, microreflections) increasing DOCSIS 1.0 modem channel capacity Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved. Cisco Systems Confidential 34

24-Tap Adaptive Equalizer Operate 1.0 cable modems at band edge 16-QAM 2.56 Msym/sec over 3.4dB slope and 125 nsec group delay Impaired 39 42 MHz Band BER < 1x10-8 : Reed Solomon T=0 (Off) DOCSIS 1.0 8-tap equalizer could only support QPSK or 1.28 Msym/sec Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved. 35 RF Performance: Downstream MER Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved. 36

RF Downstream Path MC16C/S BCM3033 High Speed D/A Modulator SAW UPX DSx MC28U/16U No SAW Filter !! BCM3034 Modulator Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved.

High Speed D/A UPX DSx 37 Downstream Constellation 256-QAM @ 857 MHz Total EVM = 1.18% ! Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved. 38 Does Advanced PHY Work? Advanced PHY

Performance 2003 Cisco Systems, Inc. All rights reserved. 39 SCTE Cable-Tec Expo Advanced PHY Demo AM carriers from comb generator No packet loss! Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved. 40 SCTE Cable-Tec Expo Advanced PHY Demo CPD from downstream feed and diode circuit No packet loss! Advanced PHY Performance

2003 Cisco Systems, Inc. All rights reserved. 41 SCTE Cable-Tec Expo Advanced PHY Demo Noise from HP signal generator No packet loss! Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved. 42 SCTE Cable-Tec Expo Advanced PHY Demo CBT screen shot showing all three impairments Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved. 43

24-Tap Adaptive Equalization Lab Test 6.4 MHz bandwidth 64-QAM signal Before adaptive equalization: Correctable FEC errors were incrementing about 7000 codewords per second (232 bytes per codeword). The CMTSs upstream SNR (MER) estimate was 23 dB After adaptive equalization: No correctable FEC errors and the CMTSs upstream SNR estimate increased to 36+ dB Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved. 44 Customer Field Test 16-QAM signal riding on top of S-CDMA signal, with CW carrier in-channel

No packet loss! Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved. 45 Customer Field Test Spectrum analyzer screen shot showing 16-QAM signal at ~12 MHz center frequency No packet loss! Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved. 46 Advanced PHY: The Bottom Line Improves upstream data transmission robustness Allows use of spectrum that was previously unusable

Facilitates higher orders of modulation Provides additional operating headroom Many advanced PHY features work with DOCSIS 1.x cable modems Cost-effective way to kick-start the deployment of new services Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved. 47 Q and A Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved. 48 Advanced PHY Performance 2003 Cisco Systems, Inc. All rights reserved.

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