RF Amplifiers in HFC Architectures

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RF Amplifiersin HFC Architectures

• SCTE, Chattahoochee Chapter
• Museum of Aviation
• June 3, 2009

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SCTE Value

• Professional Development
• Training Materials
• Reference Papers
• ANSI standards, NCTA custodian
• Statistically a SCTE trained tech has more value

3
Welcome

• We in the Telecom industry work with very unique
  technologies
• Technologies ranging from DC to Daylight
• We are in the business of BW and S/N

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What is HFC?
Headend Or Hub
Home or business
Outside Plant
Coaxial Cable Network
CPE
Coaxial Cable
Drop
Drop Cable
Trunk Amplifiers
Distribution Amplifiers
Feeder Amps taps
HFC Network
Hybrid-Fiber / Coax
Node 5-8 amps, 1000HP
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How our HFC Networks are Built

• Homes and businesses
• Base maps
• Drop codes
• Signal levels
• Performance

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Base Mapping
4.7 COMMERCIAL AND INSTITUIONAL UNITS
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Drop Level Calculations
FCC Rules
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FCC Rules Part 7676.605 Technical Standards

• (4) The visual signal level on each channel, as
  measured at the end of a 30 meter cable drop that
  is connected to the subscriber tap, shall not
  vary more than 8 decibels within any six-month
  interval, which must include four tests performed
  in six-hour increments during a 24-hour period in
  July or August and during a 24-hour period in
  January or February, and shall be maintained
  within
• (i) 3 decibels (dB) of the visual signal level of
  any visual carrier within a 6 MHz nominal
  frequency separation
• (ii) 10 dB of the visual signal level on any
  other channel on a cable television system of up
  to 300 MHz of cable distribution system upper
  frequency limit, with a 1 dB increase for each
  additional 100 MHz of cable distribution system
  upper frequency limit (e.g., 11 dB for a system
  at 301-400 MHz 12 dB for a system at 401-500
  MHz, etc.) and
• (iii) A maximum level such that signal
  degradation due to overload in the subscriber's
  receiver or terminal does not occur.

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HFC Performance

• Goal is to provide a reliable, noise and
  distortion free path for RF signals
• And to provide the performance necessary for all
  services

NTSC Video today going to ALL DIGITAL 256 QAM to
1024 QAM Downstream 16 to 64 to 256 QAM
Upstream Change in Spectrum Splits Options open
to other Architectures
Call out the System Design Specification 17.4
SYSTEM PREPARATION
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FCC Rules Part 7676.605 System Performance

• (6) The amplitude characteristic shall be within
  a range of ltplus-minusgt2 decibels from 0.75 MHz
  to 5.0 MHz above the lower boundary frequency of
  the cable television channel, referenced to the
  average of the highest and lowest amplitudes
  within these frequency boundaries.
• (i) Prior to December 30, 1999, the amplitude
  characteristic may be measured after a subscriber
  tap and before a converter that is provided and
  maintained by the cable operator.
• (ii) As of December 30, 1999, the amplitude
  characteristic shall be measured at the
  subscriber terminal.
• (7) The ratio of RF visual signal level to system
  noise shall be as follows
• (i) From June 30, 1992, to June 30, 1993, shall
  not be less than 36 decibels.
• (ii) From June 30, 1993 to June 30, 1995, shall
  not be less than 40 decibels.
• (iii) As of June 30, 1995, shall not be less then
  43 decibels.
• (8) The ratio of visual signal level to the rms
  amplitude of any coherent disturbances such as
  intermodulation products, second and third order
  distortions or discrete-frequency interfering
  signals not operating on proper offset
  assignments shall be as follows
• (i) The ratio of visual signal level to coherent
  disturbances shall not be less than 51 decibels
  for noncoherent channel cable television systems,
  when measured with modulated carriers and time
  averaged and
• (ii) The ratio of visual signal level to coherent
  disturbances which are frequency-coincident with
  the visual carrier shall not be less than 47
  decibels for coherent channel cable systems, when
  measured with modulated carriers and time
  averaged.
• (9) The terminal isolation provided to each
  subscriber terminal
• (i) Shall not be less than 18 decibels. In lieu
  of periodic testing, the cable operator may use
  specifications provided by the manufacturer for
  the terminal isolation equipment to meet this
  standard and
• (ii) Shall be sufficient to prevent reflections
  caused by open- circuited or short-circuited
  subscriber terminals from producing visible
  picture impairments at any other subscriber
  terminal.
• (10) The peak-to-peak variation in visual signal
  level caused by undesired low frequency
  disturbances (hum or repetitive transients)
  generated within the system, or by inadequate low
  frequency response, shall not exceed 3 percent of
  the visual signal level. Measurements made on a
  single channel using a single unmodulated carrier
  may be used to demonstrate compliance with this
  parameter at each test location.

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99.99998
99.9965
Mean Down Time 65.7 min/year
Reliability
Cost of operation
1
2
4
Time (Years)
3
5
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And that our ability to maintain our Availability
goal, A(t), gets harder over time and cascade
depth
99.9902
99.9872
99.9965
99.9818
99.9807
99.9797
A(t) 99.9797
Estimated down time 420.5 min/year
Reliability
Cost of operation
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A Closer Look at Coxs HFC Architecture

• Detailed design picture

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A Closer Look at Coxs HFC Architecture
1000 HP/1000 HP
950 MHz
37 MHz
2 x 500 HP/ 2 x 500 HP
1000 HP/ 2 x 500 HP
950 MHz
950 MHz
37 MHz
37 MHz
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1451
1451
HP/active 1451/84 HP/active 17.3
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1517
313
1204
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Effect of Upstream SplittingReduced Contention
for Upstream Bandwidth
54 MHz
860MHz
42 MHz
5 MHz
Return
330 Homes passed
330 Homes passed
600
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2nd Splits
1st Splits
Segmentation (xWDM)
Segmentation (dark fiber)
Virtual Splits 9k/
1000/250
1000/500
500/250 POR
1000/1000
Todays Position
Split / Bandwidth
Node 5-7 Amps
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Goal 500 HP Down/250 HP Up
N
N
N
N
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We could light up dark fibers Or construct new
fiber back to the headend
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Or we can leverage emerging technologies to
multiplex many wavelengths onto existing fibers
These approaches have limitations on power, reach
and distortion and must be used carefully
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Effect of Downstream SplittingReduced Contention
for Downstream Narrowcast Bandwidth
X/2 Homes passed
X/2 Homes passed
Net effect is more Narrowcast Bandwidth
availability, If we install the added service
ports.
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1st Splits
2nd Splits
Node 5-7 Amps
Node 3-5 Amps
Segmentation (xWDM) 47.7k/
Segmentation (dark fiber) 68.5k/
Virtual Splits 9k/
1000/250
1000/500
1000/500
500/250 POR
Fiber Deep Node 1 Drop-In
Fiber Deep Node 1 Re-work Coax
Whats Next? 250/125 ???
1000/1000
1000/1000
Is this enough?
Todays Position
Split / Bandwidth
Are we done?
Are we positioned for something else?
Node 5-7 Amps
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Upgrade to Node 1 by Drop-In
62 Amps 18.5 HP/amp
5 Power Supplys 2896 Watts
10 New Nodes 10,576 Aerial Overlash 7,949 New
Underground 18,525 New Fiber
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Re-Designed to Node 1 Amp, RF Drop-In (SA
method)
27 Amps 43.4 HP/amp
5 Power Supplys 2286 Watts
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Re-Designed to Node 1 Amp, RF Drop-In (SA
method)
2 Fibers
22 Fibers
This requires new fiber Or very expensive optics
We think there is a better way.
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Re-Designed to Node 1 Amp, RF Re-worked (Cox
method)
28 Amps 48.0 HP/amp
3 Power Supplys 1957 Watts
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Re-Designed to Node 1 Amp, RF Re-worked (Cox
method)
2 Fibers
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Comparison of N1 Designs to Existing
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Cost of Ownership ComparisonYearly
Based on Planned and Demand Maintenance only No
service call reduction estimated
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1st Splits
2nd Splits
Node 5-7 Amps
Node 3-5 Amps
Segmentation (xWDM) 50k/
Segmentation (dark fiber) 70k/
Virtual Splits 9k/
1000/250
1000/500
500/250
Fiber Deep Node 1 Drop-In 110k/
Fiber Deep Node 1 Re-work Coax 100k/
110/55
325/162
(HP dn/HP up)
1000/1000
FTTC Node 0 4,600M
FTTH 9,000M
Todays Position
Split / Bandwidth
Node 5-7 Amps
New Split 1,200M
Frequency split or Bandwidth
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Change Frequency SplitIncrease Upstream Spectrum
54 MHz
1000MHz
42 MHz
5 MHz
Downstream Spectrum 950 MHz
Return 37 MHz
85 MHz
1000MHz
65 MHz
5 MHz
Return 60 MHz
Downstream Spectrum 915 MHz
Euro-Split
108 MHz
1000MHz
85 MHz
5 MHz
Return 80 MHz
Downstream Spectrum 892 MHz
NGNA Split
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Change All Frequency Limited Devices
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Changing the Split

• Requires channels 2-6 be removed from carriage
• All devices in the headend and network that are
  specific to 5-42 MHz operation are replaced
• Some headend combiners, upstream receivers
• Amplifiers, In-line Equalizers, Upstream lasers,
  some taps
• Potential Interference
• Legacy CPE, such as VCR, STB, TVs
• White spaces concerns

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1st Splits
2nd Splits
Node 5-7 Amps
Node 3-5 Amps
Segmentation (xWDM) 50k/
Segmentation (dark fiber) 70k/
Virtual Splits 9k/
1000/250
1000/500
500/250 POR
Fiber Deep Node 1 Drop-In 110k/
Fiber Deep Node 1 Re-work Coax 100k/
110/55
325/162
1000/1000
FTTC Node 0 4,600M
FTTH 9,000M
Todays Position
Split / Bandwidth
Node 5-7 Amps
New Split 1,200M
RF Overlay 1,400M
Frequency split or Bandwidth
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Bandwidth of Cable

• How many know what the bandwidth of coaxial cable
  is?
• 6-10 GHz versus what we are using today

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3GHz OverlayIncrease Downstream and Upstream
Spectrum
54 MHz
1000MHz
42 MHz
5 MHz
Downstream Spectrum 950 MHz
Return 37 MHz
Downstream Spectrum 650 MHz
Upstream Spectrum 300 MHz
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3GHz Overlay
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3GHz Overlay

• Dual cable bandwidth over single cable
• New optical path required to node
• All passive devices changed to 3GHz capability
• Dual amplifiers required (integrated amp coming)
• STB like device required to access second network
• Not practical for widespread deployment with
  current RF inefficiencies (N1/0 required)
• Currently proposed as a high capacity business
  services solution

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• End of Presentation

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Annual Cost of Ownership Comparison
Based on Design, Routine and Demand Maintenance
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Bandwidth of Competing Providers
Best Case
Avg. BW/HP

• Cable
• Satellite
• Telco U-Verse
• Telco FIOS

7.6 Gbps / 500 HP
15.2 Mbps/HP
6.0 Gbps /120 MHP
50 bps/ HP
6 to 45 Mbps/ HP
6 to 45 Mbps/ HP
10 Gbps / 32 HP
312 Mbps/ HP
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Spectrum Bandwidth
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Vocabulary of Reliability Engineering
(Adhere to MIL-STD 338 Standard and Telcordia)
Availability and Reliability
Availability is the probability the system is
ready to go when needed to perform its intended
service (Is the cable modem ready when the
customer want to connect to the internet?).
Reliability is the probability that an item will
perform its intended functions without failure
for a specified interval under stated conditions.

• Pf Probability of failure
• Mean time between failure
• ? Failure rate

Mean Time Between Failure (MTBF) is the average
number of service hours between failure events
from a state of operation (manual or automatic).
Failure Rate, ?, is the probability that the
product being monitored will fail, and is usually
expressed as events per million service hours.
(Note Failure Rate equals 1/MTBF)

• Relationship Availability is determined by
  Reliability failures and the speed of repair or
  Maintainability
• Combinations of Reliability and Maintainability
  can yield the same result
• One long duration outage could yield the same
  availability as frequent short outages.

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The Bathtub Curve

• The three life cycle phases in reliability can be
  described by the bathtub curve which is derived
  from statistical distributions that describe the
  failure behavior of systems/parts
• Infant mortality
• Useful life
• Wear-out