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Implementation Issues: SI & CA

Martin GoldNDS

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Overview of SI Discussion

SI Implementation issues for•Tuning to Transport Streams

•Selection of Services

•Event Information

•Use of IDs

Common issues are•Choosing from optional DVB data

•System guidelines - more complex approaches require more rules for transmission and receiver

•“Private” extensions and local interpretations

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SI: Tuning to Transport Streams

Scan tune•Ensures coverage of all services at time

of scan

•Simple algorithm

•SI used to identify signals

•Additional frequency list not required

•User intervention needed for new transmissions

•May be slow if many modulation parameter variables

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SI: Tuning to Transport Streams

SI directed search•Need to start somewhere - pre-determined,

keyed in, or scanned

•NIT data needs to describe “other” transmissions in consistent manner

•Alternative frequencies for Terrestrial transmission makes algorithm complicated

Issues:•Scope of particular Network (Network_id)

•Rules for completeness of NIT transmission

•Rules for transmission parameter options

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SI: Service Selection

Receiver needs to form a list of services to offer user

•Require consistent results otherwise user is confused

Issues:•Rules for transmission of SDT other

•Use of BAT

•Use of Mosaic Services

•“Logical” Channel Numbers

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SI: Event Information

Event data dominates SI bit-rate•One or more Services per Transport Stream

•Many events per Service

Memory-bandwidth trade-off:•Trade-off: Not enough memory, not enough

bandwidth!

•Potential for optimisation of transmission with knowledge of storage capability of receiver

•Data repetition rate determined by access-time or memory loading time.

•Data could be mainly on one transport stream

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SI: Event Information

EIT other (“cross-carriage”)•Becomes more desirable with lower

repetition rates

•Requires co-operation and sharing of data between broadcasters

•Central collation of schedules and central SI generation easier than “mixing”data in SI format.

•Complexity may not justify the benefits.

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SI: Event Information

Example Data Size•10 services

•8 days schedule

•45 minute average event length

•100 bytes average text name & description

Data ~350kbytesBit-rate: 280kbit/s for 10 second repetition rate

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SI: Local Adaptation

Choice of language(s) Interpretation of parental rating

•match to FACTS/ABA TV PG Classifications

Interpretation of country_region_id for time zones

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SI: Use of IDs

Values to be assigned by ETSI:•Network_ids

•Original_Network_ids

•Bouquet_ids

Unique combinations:•Original_network_id & transport_stream_id

•Original_network_id & service_id

•Original_network_id & service_id & event_id (during period of EIT schedule depth)

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Example - “Grid” from EIT Schedule

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Example: Event Details

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Example: Selection by Genre

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Example: Selection by Genre

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Overview of CA Discussion

CA capabilities Scope of DVB Standards Multicrypt & Simulcrypt

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CA Capabilities

Charging for Services (subscriptions and PPV)

Addressing particular users/receivers

•By any characteristic of user/receiver known by SMS

Authentication•Transmitted data

•User identity

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CA Capabilities

Supports Software Download•Addressing particular receivers

– Particular make/model– Trial downloads

•Secure authentication to avoid receiver “hacking”

•Can encrypt software and charge users for it

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DVB Standardisation of CA

DVB scrambling Data transport of ECMs and EMMs Multicrypt model

Common Interface specification for receiver CA module

Simulcrypt modelSpecification for interfaces between CA and

compression systems

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Simulcrypt

Allows service to be accessible to receivers with different CA Systems

•Most existing DVB CA systems implemented prior to Simulcrypt specification

•Part 1 now coming into operational use

•Part 2 close to ETSI standard. Introduces standard interfaces for “custom” PSI and SI insertion from CA system to compression system

•Part 2 implementations not yet available from CA and compression system vendors

•CA functions of different CA systems not identical

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Multicrypt

Allows Receiver to support multiple CA systems via plug-in module

•Module has PCMCIA format– Usually smart card also

•Higher cost than embedded CA system

•Expensive for consumer, particularly if multiple modules needed

•Limited support for PPV through Common Interface

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Conclusions

SI•Choices of which optional data will be transmitted

•Use of national interpretations and extensions

•System Rules of Operation needed– specify transmission against assumed receiver model(s)

CA•Introduction of CA services likely to drive

implementation

•Useful also for addressing capability and for software download