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Convergence manager

In order to manage the simultaneous use of standards, a convergence manager (CM) is introduced as a functional entity to manage the inter-working between multiple standards and the mapping between different services.

Several proposals on the possible locations of CM and the flexibility and optimisation of systems were studied. Every proposed location, such as either in the terminal or at the network side or both including location with the protocol stack has pros and cons, given the different aspects that can be taken into consideration, e.g. architecture, complexity of implementation, end user’s and network operator’s point of view.

There are two main issues related to the CM assessed in FLOWS:
- The location of the CM
- The functionality of the CM

Regarding the location of the CM, several options are viable. The CM functionality may be distributed over several elements. As potential hosting entities, the terminal, access network components, core network components, backbone network components and server entities have been investigated, each including significant pros and cons. To make the resulting architecture applicable to real world networks, it is furthermore of importance to consider also the migration path from existing standards towards a CM enabled architecture.

An analysis of the convergence manager location was done taking into account the simultaneous use concepts and their mapping into services and standards. It was concluded that:
- In order to deal with simultaneity, it is imperative that the MT has a CM.

- The location of CMs in the terminal and in the core network is the case that provides the most flexible management of all the simultaneous use concepts.

- For the case where, at both ends of the communication, two compatible terminals exist, each with a CM, simultaneous use concepts can easily be used on an end-to-end perspective. In the case where one of the extremes is a server with a CM, the same approach can be considered.

For the case where different simultaneous use concepts are being used by each extreme of the communication, a CM is needed in the core-network to allow the concepts adaptation.

FLOWS has defined scenarios and performed simulations in order to evaluate the CM options related to the issues above, i.e. its location and its functionality. The evaluation criteria may be split into benefits for users, operators and service providers. This is documented in FLOWS D12.

The functionality of the CM is dependent upon the location in the network and the level of converged operation required. It is seen that the mapping of services to standards may be performed based on different policies, each having pros and cons for the parties involved (the customer, the network operator, the service provider, etc). A unique CM perspective/strategy was considered, based on a highest throughput / best system approach. The highest throughput concept means that for data and video applications, the highest available/possible transmission bitrate is selected based on the current networks loads. In respect to the best system approach, priority is given to the most appropriate application-oriented access technology (e.g., data applications first priority WLAN; Voice Calls first priority GSM).

Two approaches to CM have been studied: one is a dynamic mapping of services in response to time variations in the channel and traffic. The other is a static mapping based on average channel and traffic. Two scenarios have been concentrated on: isolated cell for HL/2 and UMTS and multiple cells for UMTS and GSM. Several CM scheduling policies were discussed, and the quantitative results of simulation are produced to illustrate the comparison of different scheduling policies and the benefit of CM. The CM is also used to optimise link adaptation. Results from the evaluation based on simulations can be found in FLOWS D19.

Additional investigations on the possible location and functionality of the convergence manager have been made with focus on easy integration into existing networks [Stad04a].

Two approaches have been studied:
- An integration of the UMTS and WLAN core network components by combining the GGSN (Gateway GPRS Support Node) and PDG (Packet Data Gateway).
- The use of session layer mechanisms, based on SIP signalling.

Both concepts have been evaluated with respect to:
- Signalling delay and overhead.
- Flexibility in terms of service categories and mobility scenarios.

Related information

Reported by

Technische Universitaet Hamburg-Harburg
Eissendorfer Strasse 40
21073 Hamburg
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