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Quality of Service

Network Services are considered end-to-end, this means from a Terminal Equipment (TE) to another TE. An End-to-End Service may have a certain Quality of Service (QoS) which is provided for the user of a network service. It is the user that decides whether he is satisfied with the provided QoS or not.

To realise a certain network QoS a Bearer Service with clearly defined characteristics and functionality is to be set up from the source to the destination of a service.

A bearer service includes all aspects to enable the provision of a contracted QoS. These aspects are among others the control signalling, user plane transport and QoS management functionality. A UMTS bearer service layered architecture is depicted below, each bearer service on a specific layer offers it's individual services using services provided by the layers below.


QoS

QoS Architecture


There are four different QoS classes:
  • conversational class
  • streaming class
  • interactive class
  • background class


    Traffic class

    Conversational class

    Real Time

    Streaming class


    Real Time

    Interactive class


    Best Effort

    Background class


    Best Effort

    Fundamental characteristics

    - Preserve time relation (variation) between information entities of the stream

    - Conversational pattern (stringent and low delay )

    - Preserve time relation (variation) between information entities of the stream

    - Request response pattern


    -Preserve payload content

    -Destination is not expecting the data within a certain time

    -Preserve payload content

    Example of the application

      voice

      streaming video

    		   web browsing

      telemetry, emails

    UMTS QoS classes



    List of UMTS Bearer Service Attributes:

  • Traffic class ('conversational', 'streaming', 'interactive', 'background')
  • Maximum bit rate (kbps)
  • Guaranteed bit rate (kbps)
  • Delivery order (y/n)
  • Maximum SDU size (octets)
  • SDU format information (bits)
  • SDU error ratio
  • Residual bit error ratio
  • Delivery of erroneous SDUs (y/n/-)
  • Transfer delay (ms)
  • Traffic handling priority
  • Allocation/Retention Priority
  • Source statistics descriptor ('speech'/'unknown')

    SDU = Service Data Unit


    Further reading: 3GPP 23.107


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