Stefan Erl

DVB-S2X-enabled precoding for high throughput satellite systems

Multi-user multiple-input multiple-output MU-MIMO has allowed recent releases of terrestrial long-term evolution LTE standards to achieve significant improvements in terms of offered system capacity. The publication of the DVB-S2X standard and particularly of its novel superframe structure is a key enabler for applying similar interference management techniques -such as precoding- to multibeam high throughput satellite HTS systems. This paper presents results from the European Space Agency-funded R&D activities concerning the practical issues that arise when precoding is applied over an aggressive frequency re-use HTS network. In addressing these issues, the paper also proposes pragmatic solutions that have been developed in order to overcome these limitations. Through the application of a comprehensive system simulator, it is demonstrated that important capacity gains beyond 40% are to be expected from applying precoding even after introducing a number of significant practical impairments. Copyright

Radio resource management techniques for high throughput satellite communication systems

In this paper, interference-aware radio resource management (RRM) algorithms are presented for the forward and return links of geostationary orbit (GEO) high throughput satellite (HTS) communication system. For the feeder link, satellite-switched smart gateway diversity is combined with two scheduling methods to improve the feeder link availability in rain conditions. For the user link, interference-aware scheduling (IAS) for the forward link and scheduling based on multi-partite graph matching for the return link are shown to enable full frequency reuse (FR) multi-beam satellite systems. The performance assessment of scheduling algorithms is carried out in a system-level simulator with realistic channel models and system assumptions. The improvements of the system capacity and user rates are evaluated.

Capacity Enhancing Techniques for High Throughput Satellite Communications

In this paper, we present physical layer and system level techniques that can increase the capacity of a multi-beam high throughput satellite (HTS) communication system. These include advanced predistortion and equalization techniques for the forward link, synchronization and non-linear distortion minimization techniques for the return link waveforms. Interference management techniques such as precoding, multi-user detection (MUD), interference cancellation and coordination are evaluated under realistic co-channel interference (CCI) conditions. Interference-aware radio resource management (RRM) algorithms are presented for the forward and return links with full frequency reuse. These include satellite-switched smart gateway diversity, interference-aware scheduling (IAS) for the forward link and scheduling based on multi-partite graph matching for the return link. The capacity enhancing techniques are evaluated in the Broadband Access via Integrated Terrestrial and Satellite Systems (BATS) framework.

Radio Resource Management Optimization of Flexible Satellite Payloads for DVB-S2 Systems

The increasing demand for high-rate broadcast and multicast services over satellite networks has pushed for the development of high throughput satellites characterized by a large number of beams (e.g., more than 100). This, together with the variable distribution of data traffic request across beams and over time, has called for the design of a new generation of satellite payloads, able to flexibly allocate bandwidth and power. In this context, this paper studies the problem of radio resource allocation in the forward link of multibeam satellite networks adopting the digital video broadcasting-satellite-second generation standard. We propose a novel objective function with the aim to meet as close as possible the requested traffic across the beams while taking fairness into account. The resulting non-convex optimization problem is solved using a modified version of the simulated annealing algorithm, for which a detailed complexity analysis is presented. Simulation results obtained under realistic conditions confirm the effectiveness of the proposed approach and shed some light on possible payload design implications.

Implementation and experimentation of network coding in DVB-S2/RCS2 systems.

Summary Applicability of network coding (NC) to satellite networks and related advantages has been long addressed and thoroughly analyzed by the scientific community in the last years, through theoretical approaches and simulations campaigns. Despite the great effort devoted to such analysis, few insights have been actually given to the NC implementation in real satellite systems and to the related validation. In particular, no recommendations on how to implement exemplary NC solutions in the widespread DVB-S2/RCS2 system architecture have been given. In the attempt to bridge this gap, the present paper extends the DVB-S2/RCS2 architecture so as to implement NC functions, operating between network and datalink layers. The study is corroborated by the implementation of the proposed protocol stack in a testbed closely reproducing a real system architecture. Finally, performance analysis results demonstrate the effectiveness of the proposed integrated architecture.

DVB-RCS2/S2 testbed: A distributed testbed for next-generation satellite system design and validation

DVB-RCS2 is the second generation of DVB standards for the return link in interactive satellite systems, which is combined with the well consolidated DVB-S2 standard, applicable to forward links. This paper presents a DVB-S2/RCS2 testbed, able to reproduce all functionalities specified for higher and lower layers (HL and LL) of the protocol stack, down to the physical layer characteristics, which are instead accounted by means of a channel emulator for both return and forward links. The presented testbed turns out to be a formidable tool for research investigation and overall system design thanks to the implemented features and the flexible architecture, allowing easy reconfiguration and extensions of functionalities according to specific purposes. Some merit figures shown at the end of the paper also prove the possibility to plug the testbed to external systems and carry out performance monitoring/tracking tasks through regular Simple Network Management Protocol (SNMP) agents.

Efficient Synchronization of Multiple Databases over Broadcast Networks

This work deals with the problem of synchronizing multiple distributed databases over a broadcast network, such as satellite networks. The proposed method is based on introducing network coding techniques besides extending the well-known database reconciliation algorithm, the (CPISync). One key element is to elect a master node that manages the operations in a central manner. Performance is shown in terms of completion time for full synchronization, and average number of packets exchange. Compared to point-to-point and traditional broadcasting synchronization methods, the algorithm implementing network coding allows reaching the lower-bound for the number of packets exchange.