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StatusOngoing
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Status date2009-05-26
The main goal of this project is to provide an overall network performance characterization for different configurations of a DiffServ/DVB-RCS integration architecture in function of different architectural configurations, network loads, traffic profiles, etc.
The subsequent critical analysis of the obtained characterisation should allow:
- to validate the proposed architecture itself as an adequate solution to support end-to-end QoS;
- to identify the most adequate mappings between DiffServ traffic classes and DVB-RCS MAC capacity types;
- to identify tuning criteria for DiffServ and DVB-RCS configuration parameters to optimise overall performances;
- to enable subsequent design of appropriate Admission Control functions to maximize system utilization (thus overall revenues) while maintaining the committed service quality as perceived by end users.
This study shall allow a better understanding of the trade-off between DVB-RCS system utilization and committed service quality as perceived by end users, thus enabling subsequent design of appropriate Admission Control functions.
The study shall share with satellite telecom community the knowledge and conclusions obtained from the study and foster the definition of adequate solutions for QoS integration and control in DVB-RCS systems.
The object of the study is a transparent satellite system, using DVB-RCS in the return and DVB-S in the forward link.
The DiffServ architecture proposed for the return channel (shown in Figure 1) contains standard DiffServ building blocks like classifiers, token buckets, queues and schedulers. A Resource Mapper module monitors queue occupation and, when needed, issues capacity requests to the Network Control Centre (NCC), which dynamically assigns bandwidth resources according to the demand and the user's SLA parameters through the system's TBTP table.
Figure 2 depicts the proposed DiffServ architecture for the DVB-S forward link. Inbound flows are separated and classified per satellite terminal in order to enable further DiffServ handling according to specific SLA parameters per terminal. Once terminal flows have been metered, marked and shaped according to these SLA parameters, they enter into a PHB queue shared with the rest of terminals. There they are served following a strict priority discipline and finally transmitted over the forward link.
The project focuses on the different mappings between DiffServ classes (EF, AF and BE) and combinations of DVB-RCS capacity types (CRA, RBDC, VBDC, FCA), analysing the trade-off between resource utilization efficiency and quality of service perceived by end users. Four mappings, providing different levels of service guarantees, are studied (two for consumer and two for prosumer type terminals).
A key element for the proposed study is the development of an advanced DVB-RCS/DVB-S system emulator
The project is structured as follows:
- QoS Architecture Refinement In this phase, the Diffserv architecture of both the teminal and Hub side is specified in detail based on current practices and a thorough documentation review.
- Detailed Specification Using as input the previous analysis, the required Test Bed (including traffic generation tools and emulator) is specified and designed. In parallel, a Characterisation Test Plan is produced, specifying the tests to be performed using the Test Bed.
- Platform Implementation
- Test Campaign and Analysis Tests are performed using the developed Test Bed. Measurements are analysed in order to derive useful conclusions.
- Dissemination Results shall be presented in the relevant forums.
After an extensive test campaign and critical results analysis, the project has now reached its final stage, which includes results presentation and dissemination at relevant forums. In compliance with its initial objectives, project results show performance of a representative DVB-RCS system with DiffServ support for different PHBs, under a broad set of load conditions and with different user traffic patterns. Besides of analysing DAMA impact on QoS from a more qualitative point of view, it provides quantitative QoS and resource utilization efficiency measurements for different test conditions and even for real applications.