Mécanismes de contrôle de qualité de service dans l'UMTS pour les applications sur IP

Racunica, Illia

The UMTS (Universal Mobile Telecommunications System) networks, third-generation mobile networks, will support high-speed multimedia services.

This thesis concerns the UMTS-TDD with a radio access sub-system (UTRAN) directly connected to IPv6. The whole QoS is managed by the DiffServ protocol mechanisms.

First, we propose a mechanism to map the DiffServ QoS to a UMTS QoS. Then, from this UMTS QoS, we propose a parameter tuning method with respect to the QoS (delays and loss criteria) required by the applications. When several parameters combinations were possible, we selected the parameter that maximizes the system efficiency.

Knowing that the most efficient parameter combination changes with the radio channel conditions, we have proposed and evaluated an adaptive tuning scheme that maximizes this efficiency.

Then, we have considered a system combining Real-Time (RT) and Non Real-Time applications (NRT). The real-time applications use dedicated resources (DCH), conversely the non real-time applications use shared resources (DSCH).

In order to maintain the current applications QoS, we have applied an access control and radio resource allocation mechanism to the RT applications. The access control does not accept an application if there is not enough available resources or if the use of necessary resources for the new application will exceed a power threshold (in this case, the new application will decrease the current applications performances)

The resource allocation mechanism allows by an appropriate (codes, power) combination, to decrease the amount of rejected real-time applications.

Concerning the NRT applications, we propose a scheduling mechanism. This scheduling is called ‘opportunistic’. It takes into account the channel state to select a flow. This will decrease the amount of rejected real-time packets. A credit mechanism allows this scheduling to be fair. Furthermore, the scheduling algorithm is linked to the access control. A DSCH can only be used when it does not degrade the current RT applications (threshold power control).

We have proposed thereby a set of coherent mechanisms for the QoS control of multimedia applications in a UMTS-TDD network in a “all IPv6” architecture.

Systèmes de Communication
Eurecom Ref:
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