UMTS Services and Service Aspects

Zahid Ghadialy

Date: 16/04/2004

Introduction:

Services are communication capabilities that are made available to the users by the Home Environment (HE) and the Serving Network(SN). The services are divided into four main classes:

  1. Bearer Services
  2. Teleservices
  3. Supplementary Services
  4. Service Capabilities

Lets discuss each of them below

Bearer Services:

Bearer services in UMTS are negotiable (unlike GSM where they are not) and can be used flexibly by applications. Bearer services provide the capability for information transfer between access points and only lower layer functions. PS (see [4]) and CS (see [3]) domains provide a specific set of bearer capabilities.

Bearer services are charachterised by a set of end-to-end charachteristics with requirements on QoS. QoS (or Quality of Service) is the quality of the service that has been requested. The service charachteristics includes things like traffic type, supported bit rates and the quality of information. These parameters are negotiated when a connection is being established. If the network is unable to provide the required QoS, it will re-negotiate the QoS depending on what is available. After the connection has been established, if there is a need then these parameters can be re-negotiated again. The following are the brief description of the bearer services.

Information transfer:

Connection oriented / connectionless services

Both Connection oriented and connectionless services shall be supported.

Traffic type:

It is required that the bearer service provides one of the following:

  • guaranteed/constant bit rate,
  • non-guaranteed/dynamically variable bit rate, and
  • real time dynamically variable bit rate with a minimum guaranteed bit rate..

Real time and non real time applications shall be supported.

  • Real time video, audio and speech shall be supported. This implies the:
  • ability to provide a real time stream of guaranteed bit rate, end to end delay and delay variation.
  • ability to provide a real time conversational service of guaranteed bit rate, end to end delay and delay variation.
  • Non real time interactive and file transfer service shall be supported. This implies the:
  • ability to support message transport with differentiation as regards QoS between different users.
  • Multimedia applications shall be supported. This implies the:
  • ability to support several user flows to/from one user having different traffic types (e.g. real time, non real time)

Traffic characteristics

It shall be possible for an application to specify its traffic requirements to the network by requesting a bearer service with one of the following configurations

  1. Point-to-Point
    • Uni-Directional
    • Bi-Directional
    • Symmetric
    • Asymmetric
  2. Uni-Directional Point-to-Multipoint
    • Multicast
    • Broadcast

Information Quality

Information quality characterises the bit integrity and delay requirements of the applications.

Maximum transfer delay

Transfer delay is the time between the request to transfer the information at one access point to its delivery at the other access point.

Delay variation

The delay variation of the information received information over the bearer has to be controlled to support real-time services.

Bit error ratio

The ratio between incorrect and total transferred information bits.

Data rate

The data rate is the amount of data transferred between the two access points in a given period of time.

Supported bit rates

It shall be possible for one application to specify its traffic requirements to the network by requesting a bearer service with any of the specified traffic type, traffic characteristics, maximum transfer delay, delay variation, bit error ratios & data rates. It shall be possible for the network to satisfy these requirements without wasting resources on the radio and network interfaces due to granularity limitations in bit rates. It shall be possible for one mobile termination to have several active bearer services simultaneously, each of which could be connection oriented or connectionless. The only limiting factor for satisfying application requirements shall be the cumulative bit rate per mobile termination at a given instant (i.e. when summing the bit rates of one mobile terminationís simultaneous connection oriented and connectionless traffic, irrespective of the traffic being real time or non real time) in each radio environment:

  • At least 144 kbits/s in satellite radio environment.
  • At least 144 kbits/s in rural outdoor radio environment.
  • At least 384 kbits/s in urban/suburban outdoor radio environments.
  • Greater than 2 Mbits/s in urban/suburban outdoor radio environments.
  • At least 2048 kbits/s in indoor/low range outdoor radio environment.
  • Greater than 2 Mbits/s in indoor/low range outdoor radio environment.

Teleservices

Teleservices provide the full capabilities for communications by means of terminal equipment, network functions and possibly functions provided by dedicated centres. Basically it is a service that provides complete end-to-end capability for communication between mobile users according to standards. Teleservices contain both single media and miultimedia services. Some of the teleservices are listed below

  • Speech/Telephony
  • Emergency Calls
  • Short Message Service - Point to Point (SMS-PP)
  • Short Message Service - Cell Broadcast (SMS-CB)
  • Internet Access

Teleservices utilises the bearer services provided by lower layers. The Bearer Services and the Teleservices are not coupled to each other so as to aid independent development and changes to one may not necessarily mean changes to other.

Supplementary Services (SS)

A supplementary service modifies or supplements a basic telecommunication service. Consequently, it cannot be offered to a user as a stand alone service. A stand alone service can be either Bearer Service or Teleservice but cannot be Supplementary service. It shall be offered together or in association with a basic telecommunication service. The same supplementary service may be applicable to a number of basic telecommunication services. Also, one basic telecommunication service may use several SS simultaneously.

The following is list of some of the supplementary services (see [5] for more details)

  • Call Forwarding
  • Call Deflection
  • Call Waiting
  • Call Hold
  • Call Restriction and Call barring
  • Number Identification

Service Capabilities

Services Capability Features are open, technology independent building blocks accessible via a standardised application interface. This interface shall be applicable for a number of different business and applications domains (including besides the telecommunication network operators also service provider, third party service providers acting as HE-VASPs, etc.). All of these businesses have different requirements, ranging from simple telephony and call routing, virtual private networks, fully interactive multimedia to using UE based applications. Since the API is standardised but not the services, Mobile operators can utilise the API to build unique value-added services.

Two different types of service capability features can be distinguished (see [8] for details:

  • Framework service capability features: these shall provide commonly used utilities, necessary for the non-framework service capability features to be accessible, secure, resilient and manageable.
  • Non-Framework service capability features: these shall enable the applications to make use of the functionality of the underlying network capabilities (e.g. User Location service capability features).

Examples of Framework Service Capability features are

  • Authentication
  • User-Network Authentication
  • Application-Network Authentication
  • User-Application Authentication
  • Authorisation
  • Application-Network Authorisation
  • User-Application Authorisation
  • Registration
  • Discovery
  • Notification.

Examples of Non-Framework service capability features are

  • Session Control
  • Security/Privacy
  • Address Translation
  • Location
  • User Status
  • Terminal Capabilities
  • Messaging
  • Data Download
  • User Profile Management
  • Charging


References:

[1] 3GPP TS 22.105: Service Aspects; Services and Service capabilities

[2] 3GPP TS 23.107: Quality of Service (QoS) concept and architecture

[3] 3GPP TS 22.002: Circuit switched Bearer Services supported by PLMN

[4] 3GPP TS 22.060: General Packet Radio Service; Service Description; Stage 1

[5] 3GPP TS 22.004: General on Suplementary Services

[6] 3GPP TS 22.001: Principles of circuit telecommunication services supported by a Public Land Mobile Network

[7] 3GPP TS 22.003: Circuit Teleservices supported by a Public Land Mobile Network

[8] 3GPP TR 22.121: The Virtual Home Environment

[9] 3GPP TS 22.038: SIM Toolkit; Stage 1

[10] 3GPP TS 22.057: Mobile Execution Environment (MExE); Service Description; Stage 1

[11] 3GPP TS 22.078: Customised Applications for Mobile network Enhanced Logic (CAMEL); Service Definition - Stage 1





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