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The study aims to identify, analyse, simulate, optimise and demonstrate resource management (RM) schemes for adaptive fade mitigation techniques with the necessary corresponding algorithms, functionalities, protocols, signalling information and formats for future broadband, DVB-based satellite systems leading to a higher efficiency with respect to current systems.
The study will propose solutions and recommend RRM schemes for modifications of the current DVB-S2/RCS air interface standards allowing an evolutionary development of the current standards. Also cost of terminals and gateway will be considered in the evaluation of different RRM schemes to support the competition of satellite systems with low cost mass market products of the competing terrestrial networks.
Appropriate RM techniques will include CAC and scheduling algorithms, MAC protocols and signalling resource allocation algorithms. In order to optimise the resource management for FMT under realistic conditions, the considerations will take into account physical layer impairments, such as channel estimation errors, synchronisation performance and interference.
The study will investigate the performance of the RM solutions through detailed simulations. A sophisticated simulator will be developed that allows in-depth modelling of the satellite system, and will implement the pre-selected RRM architecture, algorithms and protocols. End-to-end service simulation will derive system performance measures for efficiency and quality.
A sophisticated simulation tool for radio resource management (RRM) in DVB-S2/RCS systems using fade mitigation techniques will be developed to assess the performance of possible RRM algorithms and protocols.
Profound research on potential RRM schemes will be performed and advanced algorithms and protocols will be developed and assessed.
Efficient radio resource management is key for the service cost of satellite systems. The competition with terrestrial networks forces satellite services to come down in cost. Fade mitigation techniques offer enormous potential on spectrum saving or on the increase in bit rate. This study will enable
Simulator for DVB-RCS adaptive fade mitigation techniques:
A simulator was developed to investigate DVB-S2/RCS systems in detail. The simulator is based on OMNET++ libraries. This library features:
The simulator architecture implements a full DVB-RCS system architecture including gateway, satellite and terminal nodes. Pre-processing of traffic and rain scenarios allow faster and repeatable simulations. Using Matlab post-processing routines, a variety of measurements can be analysed:
The following figure gives an impression of the simulator GUI:
A functional architecture of radio resource management (RRM) in DVB-S2/RCS systems supporting ACM and other FM techniques is depicted in the figure below.
Basically, two entities are performing the RRM: the gateway and the terminals. The gateway may perform:
i) layer 1 functions such as power control channel estimation, and frequency allocation, and mode selection,
ii) layer 2 functions such as MAC fragmentation, encapsulation, scheduling and congestion control, and finally
iii) layer 3 functions such as call admission control. The terminal may have similar functions.
click for larger image
In the case of the regenerative scenarios, there is a similar central entity "Network control center" (NCC) for the central control of RM. In addition, functionalities of the RM can also be performed in the satellite depending on the level of processing that the satellite is able to do. Such satellite function may include: scheduling of downlink traffic, and channel estimation/power control.
Basically, one should distinct between data plane and signalling plane. Application data are forwarded over the DVB-S2/RCS data transport network with appropriate interworking functions at layer 3 (routing, NAT, etc.). Layer 2 adopts the data for the physical layer transmission between gateway and terminal, or between terminal and gateway, respectively. In the signalling plane interaction at each layer can take place between the data and signalling plane, e.g., for monitoring of buffers in the data plane and requesting new resources via the signalling plane.
Adaptive return link structures have been proposed for future versions of the RCS return link with use of ACM. The structures could have fixed information per slot however at different symbol rate and varying burst length. Thus, the slot durations will vary in a frame organisation. The organisation and assignment of the frame structure may vary from frame to frame. One central point of the RRM management is the continuous management of the frame structure and the adoption to changing physical layer constraints by assigning new slots and physical layer modes to terminals. A superframe structure with consecutive frames can be assumed furthermore.
The study has five tasks:
In detail the following sub-tasks are included:
For the simulator development the following work plan is envisaged:
The simulator serves for extensive system simulations towards
The project investigated DVB-S2/RCS with adaptive fading mitigation techniques using the simulator tool. The simulation confirmed impressive improvements of adaptives systems in throughput and efficiency compared with non-adaptive systems. However, it could be also shown that the system improvements depend on many factors that need to be optimized in a joint way. Such factors are radio resource segmentation, scheduling behavior, encapsulation protocol, and the resource allocation scheme.
The following key findings have been found: