Application Level Adaptations for Multimedia Applications

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Application Level Adaptations for Multimedia
Applications
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Aim

• Enable multimedia applications in a heterogeneous
  network environment using application level
  adaptations.

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Background

• Internet Protocol
• routes datagrams independently (using
  hierarchically structured unique addressing).
• provides seamless delivery over heterogeneous
  networks (using fragmentation and reassembly).
• depends on higher layers to satisfy real time
  data transfer constraints such as loss, delay
  jitter.

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QoS Where to apply?

• User level
• specifying user perceivable service parameters.
• Network level
• traffic models, service classification, and
  resource reservation on a per-flow or flow
  aggregate basis.
• Application level (ALA)
• adapting the application according to network and
  system resource availability.
• Others
• Intelligent routers,

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Motivation for ALA

• Leave complexity at the edges and keep the
  network core simple.
• QoS achieved - degree of satisfaction of
  applications resource requirements.
• Can handle applications dynamic resource
  requirements better.
• Works on IP and can readily leverage the QoS
  support available at the network level.

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Requirements

• Sensitive to the dynamic needs of the
  application.
• Knowledge about the network system resource
  availability.
• Maintain end-to-end QoS significance for the
  application.

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Design

• Distributed policy based framework.
• Each client is guided by a resource management
  policy that captures degree of QoS adaptation
  tolerated by application.
• Policy defines adaptations to be done in
  application in response to variations in resource
  availability.
• Policy should be configurable to support
  deployment in a heterogeneous environment.

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Design (Contd..)

• Active coordination between otherwise
  independently operating clients may be required
  for non trivial adaptations.
• Can be achieved by an agent based event
  delegation model.
• SNMP based network monitor for local statistics.
• RTP RTCP for real time data transfer.

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Design (Contd..)
User Interface
Application Interface
Policy Enforcement
Policy configuration
Application data
Manager
RTP / RTCP interface
Remote Client information
Local state information
Data Control Information
End-system / Network Monitor
Multicast channel (UDP/ IP)
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RTP

• Primarily designed to satisfy the needs of
  multi-participant multimedia conferences.
• Deliberately not complete, supposed to be
  integrated into application processing rather
  than being implemented as separate layer.
• Doesnt assume that all clients want to receive
  media data in the same format.
• Independent of network and transport protocol.
• Can be used over both unicast and multicast if
  supported in lower layers.
• Internet standard for transfer of real-time data.

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RTP (Contd..)

• Provides support to
• user as sender, receiver or both.
• identify type of data.
• determine order of data packets.
• synchronize media streams.
• different media types handled in diff. sessions.
• association of related sessions using canonical
  names of participants.

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RTCP

• Periodic updates through sender and receiver
  reports.
• Identify source of media.
• Info about amount of data transferred.
• Supports application specific packets.
• Allows for third party monitors implementation.

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Implementation

• Receiver side adaptation
• Classify application data (layered, progressive
  encoding).
• Define corresponding states for clients such as
  Normal, Congested, Loaded.
• Client places itself, based on current state,
  into appropriate class.
• Client transitions into higher class if it
  performs within threshold performance parameters
  in a lower class for a specified period of time.

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Implementation (Contd..)

• Receiver side adaptation (contd..)
• Client transitions into lower class if threshold
  parameter limits are exceeded.
• Time for which client stays in a particular state
  can be altered linearly/exponentially.
• State of sender can be maintained at each client.
• Sender side adaptation
• State of clients maintained at sender using RTCP
  receiver reports.
• determine transmission adaptations such as
  modifying the rate of transmission if all clients
  of a particular class are suffering high losses.

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Implementation (Contd..)

• Media Transformation
• Enhanced application level processing of data in
  transit from the sender to receiver.
• Service localized low capability group of clients
  using a transcoder to change the data format to a
  more suitable encoding.

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Status

• Java RTP API
• Video/Audio streaming performed.
• Monitoring of transmission statistics possible.
• Problem in API for Control Interface.
• Adaptable multimedia application with control
  interface the need of the hour.