Whitepaper defining how superior video performance assurance is engineered into the IP protocol stack for Cupria's unique DSL transport chipset

1. Innovation at the network edge APPLICATION NOTE
for enhanced service delivery
and carrier competitiveness . . .
QOS & Quality of
User Experience
for IPTV Services
Pure IP Triple Play
High-Fidelity IP using
Internet Protocol Subscriber Line
TM
QoS Challenge for
The Cupria Advantage Cable-Competitive Triple-Play
Rim Semiconductor - a fabless IC manufacturing
firm – is building “System on a Chip” ICs that QoE – Quality of User Experience
deliver networking solutions instead of component
designs. As such, we are delivering industry-
leading innovations in DSP architecture focused © Copyright 2006 (rev1.1b)
Rim Semiconductor Company
explicitly on xDSL applications for the wireline all rights reserved - www.rimsemi.com
503 . 257 . 6700
carrier.

2. xDSL INNOVATION USING CUPRIA
Pure IP Triple Play
The importance of making a robust, reliable access transport technology available
cannot be overstated. The VP in charge of network planning at one of the largest
US telcos expressed concern about delivering premium services over xDSL
because they were continuously challenged in making their 5Mbps DSL work
reliably. Their business plan for 3-tiered DSL service was working fine for the
bronze and silver subscribers at 1.5 and 3 Megs respectively, but that service
interruptions at 5 Megs was intolerable. So if today’s DSL transport at 5Mbps
and higher is not reliable, how could they realistically expect to extend their access
network to serve an IPTV strategy?
IPTV Work-Arounds
Another way to describe our thinking on
Cupria is to ask the question, “If you
were going to design a new video-over-
copper solution for the access network,
would it end up looking like toady’s
VDSL2?” Repeatedly we have been told
by carriers that no, VDSL2 is merely a
patched-up VDSL that still cannot
deliver the fundamental advances in
bandwidth payload, copper reach, and
quality of service that a cable-competitive
IPTV deployment will require. In 2006,
the dominant IPTV installations in actual
deployment are using ADSL2+ serving
Fig 1 – VDSL2 cobbled as a work-around solution vs. Cupria
18Mbps out to only 3Kfeet and similar
numbers are being used for VDSL2
planning. We believe a robust IPTV access network must be planned for 26Mbps serving 6Kfeet.
IP-only environment using “Internet Protocol Subscriber Line”
One of our objectives in designing a broadband over copper solution form the ground up was to provide an
IP-only environment free of the complexities of ATM. We believe that the clearly emerging trend for an all-
IP access network makes the most sense for both carriers and equipment makers – and provides the quickest
path to making broadband over copper as reliable as POTS.
However reliability alone is useless if the payload bandwidth capacity is not large enough to accommodate the
multimedia traffic that carriers need to become cable-competitive. Our target service capacity is 26Mbps of
Ethernet payload. We believe this is adequate to support the next 20 years of domestic household
requirements for voice, video, and data.
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3. xDSL INNOVATION USING CUPRIA
Internet Protocol Subscriber Line - IPSL
The optimized performance of the Cupria family of transport processors is achieved using a next-generation
xDSl protocol we call “Internet Protocol Subscriber Line”, or IPSLTM. The unique qualities of IPSL enhance
the ability of the telco to deliver Triple Play Services over existing copper lines by using these features:
• Time Division Duplexing - TDD
• Rapid Bi-Directional Switching
• Adjustable Downstream / Upstream Data Rates
• PSD Masks adjustable across the copper spectrum
• Adjustable Power Boost within each spectrum
band to auto-adapt to NEXT / FEXT
• Shorter xDSL frame size
• -150 dBm/Hz noise floor (auto-adaptive)
• Higher processing efficiency
• Reed / Soloman forward error correction
• Trellis Coding equalization
• Adaptive Equalization
• Optimized IP Link & SAR providing four levels of traffic prioritization
• Triple-Play grooming of the voice, video, and data streams at the Phy layer
The Network QOS Challenge for Triple-Play
Originally the copper access network was engineered to support the voice intolerance for audible delay, and
to compromise bandwidth requirements with an acceptable level of noise in the circuit. Emerging data
requirements flipped this priority in QOS for the copper loop – and ATM provided an ideal method for
assuring both data and voice QOS. However today’s emergence of IPTV brings a third – and most
demanding – intolerance of both noise and delay. Ethernet data packets will easily re-transmit and re-
assemble to make up for noise-induced packet loss. But streaming video cannot tolerate IP delay, which
results in picture break-up and/or MPEG artifacts.
Delivering a cable-competitive grade of
digital video service will mandate that
the access loop be engineered to deliver a
Bit Error Rate of at least 10 -9 (which
delivers an annoying picture artifact
every 6 minutes for a 3Mbps SDTV
stream). Cupria’s adoption of a Pure-IP
transport approach helps bridge the gap Fig 2 – Unique QOS constraints for the video access network in
today’s network performance to make
cable-competitive IPTV both
technically and financially feasible for
the copper carrier
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4. xDSL INNOVATION USING CUPRIA
QoE – Quality of User Experience
The fate of IPTV will hinge on the quality of digital
video picture and sound that can be extended across
the copper plant. For subscribers to endorse IPTV
and switch form cable, the carrier cannot afford to
invest in a less than cable-competitive level of image
quality.
For HDTV, the
MPEG4 payload
must be 8 to 10
Mbps per channel
Fig 3 – MPEG artifacts resulting from packet-loss
– with up to three
can jeopardize carriers’ ability to effectively compete channels simul-
with cable television service taneously served
per home, each
with a bit-error rate lower than 10 -9. And this performance must be
maintained when two VoIP lines are in use and the kids are also
downloading music at 1.5Mbps via the internet.
Once MPEG artifacts – induced by jitter, latency, and packet errors – are
introduced at the Phy layer of the protocol stack, they are uncorrectable Fig 4 - IP Artifacts Irretrievably
all the way up the stack. Thus the impact of the xDSL transport device is Embedded in the Protocol Stack
of utmost importance in delivering cable-competitive services.
Dynamic Bandwidth Management (DBM)
Essential to preserving image quality is the adaptive DBM
built into Cupria’s DSP. We achieve this by integrating
routing functionality to groom the voice, video, and data
streams. Rather than leave the control of these streams to
the random intelligence of the modem or STB maker, the
Cupria phy will assure preservation of video integrity with a
minimum Bit Error Rate, accommodate VoIP traffic
accordingly, and prioritize internet traffic to not interfere
with either the voice or video streams. The QOS
functionality provided by IPSL at the CPE within the DSP Fig 5 – “System-on-a-Chip” feature integration
consists of:
• DiffServ tagging
• Dynamic Bandwidth Management for each voice, video, and data channel
• Outbound grooming of each discrete channel using an integral routing capability
• Optimized IP SAR for reduced latency and jitter to minimize BER in the video stream
Meeting the Challenge
The access network engineer has never faced such daunting performance requirements. ADSL is at best, a
best-effort service while T1 is a constant struggle to preserve with 30% of T1 lines requiring a truck-roll every
year. Cupria is anticipating and solving the video access challenge to make IPTV a quality user experience for
both the subscriber and the wireline network engineer.
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