“Infrastructure for Transport
of Multimedia Applications to
the End User”
Access Network Architectures and
High Speed Access Technologies
Summary
• What are access network options that would be
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used by different multimedia services providers
to carry the multimedia applications to the end
users?
Where we stand regarding deployment of
numerous DSL and cable modem technologies?
What are the most suitable DSL technologies
and why?
How these technologies are deployed in
practice?
Summary Contd..
• How much the current infrastructure is ready for
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them
What are the considerations for the success and
acceptance of the end user for delivery of
multimedia services over the these technologies.
Few questions to gain
perspective??
• What is a multimedia application?
• What is meant by triple play?
• How much you know about access
networks and their capabilities?
• What is a DSL network?
• What is a Cable network?
• What is the difference between an ATM
and IP network?
Application Characteristics from
Physical Transport Perspective
• Three main features for Physical Transport from
an application’s perspective.
– Bandwidth required
– Delay or Latency accepted
– Bit Error Ratio
• A suitable access network to provide multimedia
application needs to provide sufficient
bandwidth, necessary BER and data transport
delay
Access Networks
• Traditional networks are copper loop networks providing
POTS telephone service and then Coaxial Cable networks
providing broadcast video service
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Both of these were analog
Multiplexing different applications was difficult if not impossible
Access networks need to be digital to multiplex applications
Next generation Access networks were digital but lacked
sufficient bandwidth for Video applications.
– Latest Access Networks provide for the bandwidth but are costly
to deploy
Dilemma for Access Network
Upgradation
• Who pays for it? Why a service provider should invest?
– Given
• multimedia services are not necessarily yet a need in society, &
• Subscription is a function of economic development of the society
– Societies being economically developed should be able to deploy
and subscribe
– But
• What to do with the existing infrastructure
– Societies less economically developed are making green field
deployments and can start with Triple play support. But there
are not many who have extra money to enjoy the service
DSL System Model
DSLAM/ATM Switch
DSLAM/ATM Switch
USB
DSL Modem
Ethernet
DSL Modem
Access Network
LAN
mini
port
I/F
ATM Network
Access Network
TCP/IP DHCP etc. (rout. fun.)
ATM
mini
port
I/F
App. Sp. AL/
PPP-o-ATM
RFC
1483
AAL5
ATM
AAL5
ATM
ATM
ATM-TC
ATM
CDC1.1
ADSL PHY
ATM
USBD
CDC 1.1
ATM-TC
USB
USB
ADSL PHY
Access Network
USB Cable
UTOPIA
PHY
PHY
TCP/IP
Ethernet
PHY
Ethernet
PHY
UTOPIA
ATM-TC
ATM-TC
ADSL PHY
ADSL PHY
ATM Network
IEEE
802.3
MAC
Access Network
Centillium
CO Chip
Centillium
CPE Chip
IEEE
802.3
MAC
HFC Network
Headend
CATV Network
Cable Modem
ATM Network
Headend
CATV Network
Cable Modem
Observations on HFC Networks
• Shared medium like LAN so bandwidth
guarantee issue
• Return path bandwidth Issue for legacy
reasons
• Point-to-multipoint signaling issue if using
ATM transport over HFC networks
Full Rate ADSL
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ADSL - Asymmetric Digital Subscriber Line
Supports asymmetric rates on medium loops
Application focus is both business and residential
Typical rates:
– 6 Mbps Down /0.5 Mbps Up @ 9 kft
• Issues with Full Rate ADSL
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Late deployment
dual latency
power consumption
POTS Splitter
coverage
Splitterless ADSL Lite
• Supports asymmetric rates on long loops
• Addresses the main Issues with Full Rate ADSL
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single latency
reduced complexity, hence low power consumption
no home rewiring
extended coverage
no POTS splitter
• fast retrain procedure
SHDSL Technology
• SHDSL - Single-pair High-Speed Digital Subscriber Line
• Supports symmetric rates; 192, 256, 384, 512 768, 1544 2048 and
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2304 kbps on moderate to long loops
Application focus is on business, residential office and
telecommuters
Uses Trellis coded PAM line code
Echo cancellation is required as both directions use the same
frequency band
Spectrally compatible with other DSL systems with some reach
restrictions at different rates
Low symmetric rate may compete with ADSL service
Initially SHDSL service is expected to be costlier than ADSL
Draws from ANSI HDSL2 and ETSI SDSL standards
VDSL Technology
• VDSL - Very-high-speed Digital Subscriber Line
• Supports both symmetric and asymmetric rates on much shorter
loops
• Application focus is both business and residential
• Keyword is “Video Delivery”
• Typical rates:
– Asymmetric;
• 52 Mbps Down /6.4 Mbps Up @ 1 kft
• 26 Mbps Down /3.2 Mbps Up @ 3 kft
• 13 Mbps Down /1.6 Mbps Up @ 4.5 kft
– Symmetric;
• 26 Mbps @ 1 kft
• 13 Mbps @ 3 kft
• 6.5 Mbps @ 4.5 kft
VDSL Technology - Access
Network Growth
DSLAM/ATM Switch
DSL Modem
Access Network
DSLAM/ATM Switch
DSL Modem
Copper
Access Network
FTTN - Fiber to the Neighborhood
DSLAM/ATM Switch
DSL Modem
Copper
Access Network
DSLAM/ATM Switch
FTTC
Fiber to the Curb
Fiber Modem
FTTH
Fiber to the Home
Conclusions
Conclusions
• Quality multimedia applications would only
be possible with VDSL type technologies
with new deployments
• Issues to be resolved are everywhere in
the protocol stack