Cable  Network  Overview  Presented  by:    Ma1  Schmi1  (CableLabs)  

 

Contributors  &  Supporters  Alphabe?cal  by  First  Name  

•  Alberto  Campos,  CableLabs  •  Edwin  Malle1e,  Bright  House  

Networks  •  Eugene  Dai,  Cox  

Communica?ons  •  George  Hart,  Rogers  

Communica?ons  •  Jack  S.  Burton,  Cablevision  •  Jeff  Finkelstein,  Cox  

Communica?ons  •  Joe  Solomon,  Comcast  •  John  Bevilacqua,  Comcast  

•  John  Dickinson,  Bright  House  Networks  

•  Jorge  Salinger,  Comcast  •  Kevin  Noll,  Time  Warner  Cable  •  Kirk  Erichsen,  Time  Warner  

Cable  •  Ma1  Schmi1,  CableLabs  •  Michel  Allard,  Cogeco  Cable  •  Mike  Darling,  Shaw  

Communica?ons  •  Saif  Raman,  Comcast  •  Volker  Leisse,  Cable  Europe  

Labs  

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Introduc?on  •  This  slide  deck  is  intended  to  provide  an  overview  of  the  following:  – How  cable  networks  have  evolved  over  ?me  –  The  components  of  an  HFC  network  – Main  sources  of  impairments  in  HFC  networks  and  their  impact  on  opera?ons  

– How  the  cable  network’s  spectrum  is  divided  up  into  different  services,  and  how  that  may  change  over  ?me  

•  Please  note  that  these  slides  are  merely  representa?ve,  and  do  not  necessarily  depict  actual  cable  systems  

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United States Cable Statistics

•  114 million households, 131.7 million housing units •  129.3* million homes passed by cable video service

(~98%) •  124.3* million homes passed by cable high speed

data service (~93%)

•  Ubiquitous coverage of high speed data services

4

*  Sta?s?cs  by  NCTA  June  2011  

Headend    Tap  

Drop  Cable  

Coax  Feeder  Cable  

Cable Networks: Then and Now

Node  

Master  Headend/    Data  Center  

Node   Node  

Hub  

Hub  Node   Node   Node  

Hub  Node  

Coax  Trunk  Node  

Node  

50-­‐500  Homes  

Regional HUB

Coax  Feeder  

Fiber  

Redundant    Fiber  Ring  

Home Architecture

From  

Tap  

Coax  Trunk  Cable  

Amplifier  

Drop  Cable  

Amplifier  

Tree  and  Branch  

Ring-­‐Star-­‐Bus  

To  

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Node + N Generic Implementation

FiberNode

Fiber

Taps

Taps

RigidCoax

Fiber

Fiber

DropCable

Home Network

Opt. Tx/Rx

Headend

RigidCoax

CPECPE

CPE

CPE CPE

CPE

CPE

CPE

CPE

Multi-port Amplifier

Amplifier

Trunk Amp.

Line ExtenderAmplifier

Bridger Amplifier

Analog  Tx  over    

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Op?cal  Node  

Downstream  Blue  Upstream  Red  

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Mul?port  and  Line  Extender  Amplifier  Structure  

MulJport                Amplifier  

Line  Extender        Amplifier  

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Distribu?on  Tap  

Downstream  DirecJon  

Drop  Ports  

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Plant Impairments

FiberNode

4- 6 TapsRigidCoax

Fiber Fiber

Drop

Cable

Home Wiring

CMTS

Provisioning andManagement

. /

Headend

RigidCoax

CM

Micro-reflection

Impulses

End-of-Line Issues

Isolation

Narrow-band interferers

In home issues

Cascading Amplifiers (GDD & roll-off)

Corroded connector

(CPD)

Primary SignalReflected Signal

In-Line Equalizer

(GDD & Tilt)

Opt Tx Rx

Coaxial Cable Tilt

CTB & CSO

Laser Clipping

5 50 550 870-100242

DIGITAL

RETURN DOWNSTREAM

ANALOG

Diplexer

Cable Modem Upstream Cable Modem Downstream

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Impulse  /Burst  Noise  

•  Generated    mostly  from  external  sources  entering  via  ingress  

•  Arise  through  cable  defects  in  proximity  of  noise  sources  such  as  electric  motors,  appliances,  thermostats,  arc  welders,  light  fixtures,  power  lines,  sta?c  from  lightning  etc.  

•  Typically  last  a  few  microseconds  and  covers  a  good  por?on  of  spectrum  

•  Burst  noise  related  to  laser  clipping  and  overdriving  amplifiers  can  have  dura?ons  a  long  as  a  data  burst.    

56 10 14 18 22 26 30 34 38 42

Frequency in MHz

Carrier Level

Noise

256QAM

16QAM64QAM

CNR

Narrowband Interferers in Upstream Spectrum

•  Narrowband interferers and wideband noise determines possible modulation efficiencies

Loss  Comparison  

“N” Feet Tap to Tap Spacing

23 20 17 11 814

Tap Coupling Loss

Drop Cable Loss

Fiber Node

ES1

Amplifier

ES2

Coax Loss Tap Insertion Loss

ES  =  End  Sta?on  or  CPE  

0

5

10

15

20

25

30

0 300 600 900 1200 1500

Atte

nuat

ion

(dB

)

Frequency - MHz

1000’ Feet 0.500”

150’ Feet RG6

300’ Feet RG6

1000’ Feet 0.625”

Decreasing  tap  values  give  each  ES  approximately  same  performance    3/6/12   13  

Example Channel Spacing

54 MHz 60 MHz 66 MHz 72 MHz

Channel Tuned

Upper Adjacent Channel

Lower Adjacent Channel

6MHz

54  MHz  5  MHz  

Analog  Channels  

Digital  Channels  

STB  OOB  

42  MHz   550  MHz   -­‐  1  GHz  

           One  256  QAM  Downstream    6  MHz  Digital  Channel    

carries  ~40  Mbps  

1  GHz  System  contains  ~  158    6  MHz  Downstream  channels    

           One  64  QAM  Upstream    6.4  MHz  Digital  Channel    

carries  ~30  Mbps  

VOD,  SDV  

Data,  Voice  

Data,  Voice  

750  MHz  

Noisy  (unused)  

STB  OOB  

Analog  Channels  

130  MHz  

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2008  Example  Frequency  Alloca?on  

Example  frequency  alloca?on  circa  2008;  free  channels  typically  do  not  exist  today  

Equivalent  channel  capacity  

1  Analog  channel  

10-­‐12  SD    Digital    channels  

2-­‐3  HD    Digital    channels  

10  SD  VOD    streams  

1  DOCSIS  Channel    

1  Telephony  Channel  

1  Control  channel  

2-­‐3  HD    VOD    

= or or or or or or 1  SDV  channel  

or

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2008  Example  Channel  Alloca?on  

Figures  rounded  up  3/6/12   16  

Spectrum  Usage  Over  Time    (not  to  scale)  

Where  are  we  going  with  spectrum?  B

road

cast

Nar

row

cast

750 MHz System

Example

HSD/Voice  

VOD  

ADS  

HD  

SD  

Analog  

Past

HSD Voice

HSD/Voice

VOD  

SDV  SO  

ADS  

HD

SD

Analog

Today

VOD  nDVR  

SDV SO

ADS  

HD

SD

Analog

Soon

IP Video

HSD Voice

VOD  SDV  SO  

nDVR  

ADS  

HD

SD  

Future

Some IP Video

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Addi?onal  Notes/Informa?on  •  STBs  receive  informa?on  and  communicate  to  the  network  in  one  of  two  ways  –  Older  STBs  transmit  on  a  proprietary  channel,  and  receive  guide  data  on  a  Forward  Data  Channel  tunable  up  to  130  MHz  (see  SCTE  55  for  details)  

–  Newer  STBs  support  both  SCTE  55  and  the  use  of  DOCSIS  channels  for  signaling  

•  Most  receivers  (in  STBs,  TVs  with  QAM  tuners,  etc.)  use  wideband  Automa?c  Gain  Control  equipment  –  As  a  result,  they  receive  signals  across  the  en?re  spectrum,  and  may  be  sensi?ve  to  nearby  high  power  transmissions  

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Ques?ons?  

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Background  Material  

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Node  Topology  Example  

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