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Multi-beam satellite systems at Ka Band can provide broadband high capacity access to interactive multimedia services with a good compromise between complexity and cost. It is also well known that the traffic profile tends to be asymmetric from the user point of view, with dynamic behaviour increasing daily and higher levels of QoS being demanded.
For this reason, means to increase system efficiency in support of the demanding dynamic traffic conditions are a key aspect to increasing system competitiveness whilst keeping its quality. On the other hand, the DVB-S2 standard is recognized as providing adaptability to propagation conditions, supporting higher transmission efficiency and dedicating more resources (bandwidth and/or power) to the users able to use them.
In order to cope with this situation, the present project is intended to investigate a solution based on beam hopping techniques, consisting of the illumination of only a subset of the satellite beams through an appropriately designed beam illumination pattern.
The challenge is to satisfy as close as possible the beam traffic requests, maximizing revenues through provision of high capacity in those areas of the coverage region with high demand, and minimizing the amount of resources dedicated to low loaded regions.
As such, the focus of this activity is to fulfil the following objectives:
Assessment of the benefits of beam hopping techniques in order to improve the use of the satellite resources in a more efficient way.
The beam hopping techniques provide the system with greater flexibility in accommodating irregular and time variant traffic requests across the coverage region. To cope with high system efficiency, operators agree in indicating flexibility as the key requirement for a satellite system targeting interactive service provision, as it allows for sustaining the inherent large uncertainty in the broadband communication market evolution.
To evaluate the improvements at system level provided by the use of beam hopping techniques, it is intended to analyse several schemes (referenced as study cases) and compare them in terms of capacity, performance and flexibility. The study cases are:
By defining adequate performance comparison criteria, the gain of the beam hopping system designed will be evaluated and compared with the gain of the flexible system and the conventional one for two different scenarios, both based on DVB-S2 / DVB-RCS air interfaces as the broadband standards:
An appropriate optimization methodology for the complex problem to be solved will be defined. Then such an optimization process will be simulated and results will be iteratively obtained. The optimization methodology consists basically of the following steps:
Finally, the System simulation will use the optimization methodology to end up with an optimised solution as follows:
The results from the optimization process will be the selection of the optimum values for the identified parameters that determine the design of the beam hopping system. The possible impact of such a system on current standards, both at physical layer and MAC layer will be evaluated.
The project is composed of three tasks: