Nicolas Courville

Non-Linear Interference Mitigation for Broadband Multimedia Satellite Systems

This contribution explores the use of interference mitigation techniques applied to broadband satellite systems with co-channel interference. In particular, our focus is on nonlinear precoding techniques, borrowing ideas from the theory of broadcast MIMO channels. A number of schemes are compared, including several implementations of Tomlinson-Harashima precoding and their linear precoding counterparts. Simulations on realistic scenarios show potential improvements of non-linear precoding with respect to linear interference mitigation and classical countermeasures based on frequency division among beams. Also, we identify several practical issues related to the implementation of Tomlinson-Harashima Precoding in satellite communication systems.

WISECOM: A rapidly deployable satellite backhauling system for emergency situations

This paper presents the detailed architecture of the WISECOM system, which can quickly re-establish and provide telecommunication services after a disaster by integrating terrestrial mobile radio networks, such as GSM, WiFi, WiMAX and TETRA, with satellite technologies. The system aims to be a useful tool to be deployed in the early hours after a disaster event, for both the victims and the rescue services who will be able to communicate in a reliable and robust way, improving the coordination of the different teams and reducing the time needed to provide victims with the proper treatment. The paper presents in detail the different services provided by the system taking into account its two different versions, based on two different satellite technologies, Inmarsat BGAN and DVB-RCS. Together with the presentation of the system capabilities, a business model is also proposed. Thereafter, the architecture of the general system and the demonstrators that have been developed are detailed, according to the two versions of the system. The work also presents the outcomes of the tests conducted with a prototype of the system, and of the final project demonstration, which was held in Germany in May 2008 with the involvement of real end-users (fire brigades and civil protection authorities).

Emergency Communications over Satellite: the WISECOM Approach

This paper presents the overall architecture of the WISECOM system, which can quickly re-establish and provide telecommunication services after a disaster. The architecture is explained and it is described together with a role model, which adapts to the system. The work tries to map the existing complex interactions taking place nowadays in an emergency situation to a sensible architecture, which can accommodate all needed actors and roles, and which can exploit, at the same time, the newest wireless technologies.

Integrated GSM/WiFi Backhauling over Satellite: Flexible Solution for Emergency Communications

This paper presents the development of a compact, ruggedized satellite terminal, to be used for communications in emergency situation. The terminal provides GSM coverage in disaster area, where existing communication infrastructure is destroyed or overloaded. It uses GSM backhauling over satellite to transport GSM signalling and data traffic to the core GSM network infrastructure in the disaster-safe area. Additionally, basic data services such as HTTP Web browsing and email are also provided via WiFi access. Issues related to the terminal design and the tests that have been undertaken are presented in the paper.

Integrating satellite and terrestrial technologies for emergency communications: the WISECOM project

In this paper, the main concepts of the Wireless Infrastructure over Satellite for Emergency COMmunications project (WISECOM) are presented. These concepts rely upon the idea of a light and rapidly deployable system that can be autonomously used in remote areas where telecommunication networks have broken down to provide access to emergency telecommunication services using a large set of wide-spread telecommunication technologies such as GSM, UMTS, WiFi, WiMAX, and TETRA and a satellite back-hauling link. In the paper, a detailed description of the whole WISECOM system is provided, with emphasis on the WISECOM Access Terminal, the unit deployed on the disaster area and interfacing the selected satellite system to different wireless local access technologies. Then, three relevant and realistic examples of configuration of the WISECOM system (GSM, UMTS and TETRA over satellite) are detailed.

Internet by satellite: a flexible processor with Radio Burst Switching

This article introduces a new switching approach, offering to satellite operators a wide flexibility for bandwidth, waveform, quality of service and service assignment, even during flight. Inherited from the optical domain, the prime mission of radio burst switching (RBS) is to provide efficiently circuit and packet switching solutions between a high number of spot beams. Uncertain market direction and speed of adaptation will also favor such agile technologies. RBS idea intrinsically minimizes the processing section dedicated to the regeneration of header, while the bulk of traffic bursts travels transparently without on-board processing. This concept also widely simplifies the terminal characteristics. The related techniques have been studied and simulated in the frame of the ULISS project. At the horizon 2010, the on board processor feasibility will be enabled thanks to ASIC technology improvements, to integrated multi gigabit transceivers and to system on chip processing architecture

Optical high-capacity satellite downlinks via high-altitude platform relays

Earth-observation (EO) satellite missions produce a large amount of data using high-resolution optical or radar sensors. During the last decades the amount of data has steadily increased due to improved sensor technologies with increased temporal resolution, sensor resolution, and pixel count. As a consequence EO satellite missions have become limited by the downlink data rates of microwave communication systems, which are inhibited by spectrum restrictions, manageable antenna sizes, and available transmit power. Optical downlinks from EO satellites with data rates of several Gbps mitigate the limiting effects of microwave communication systems; however optical links do not provide the necessary link availability through the atmosphere due to cloud blockage above the ground station. Apart from diversity concepts with several ground stations or satellite networks, a stratospheric High Altitude Platform (HAP) could act as a relay station to forward the optical communication beam over the last 20km through the atmosphere to the ground station, where short-range, high data-rate microwave systems are feasible. This paper will discuss the capabilities of HAP and GEO relay stations to increase the downlink capacities of LEO satellites. Environmental aspects for the deployment of HAP relays and regulatory/technology issues for a microwave downlink on the last 20km to the ground will be discussed.

QoS-oriented traffic management in multimedia satellite systems

The next generation of satellite systems will likely use some on-board switching techniques enabling the direct transmission of data from any up-link spot-beam to any down-link spot-beam. If the switch used in the payload of the system is an ATM-based shared buffer switch, some losses and delays can occur. Fortunately, these drawbacks can be fought thanks to some buffer management policies (HSPO, SMXQ, EPD) that either ensure low delay or low loss ratio. Real-time (voice or MPEG video streams) and non-real-time applications (file transfer, email, web browsing using TCP/IP protocols) should be carried over these satellite systems with different quality of service (QoS) requirements. Different combinations of buffer management policies are presented to guaranty the QoS required by the user. Especially, special emphasis is put on the way to transmit efficiently layer 3 messages (IP datagrams) within a mix of traffic in order to avoid some high layer retransmission techniques (provided in TCP for instance) wasting both time and bandwidth.

A Survey and Perspective on NVoD Systems for Satellite Networks

In this paper, we review different architectures for near video-on-demand (NVoD) systems on satellite networks. In many scenarios, satellites are the only available option for content distribution. On the other hand, video-on-demand (VoD) has been a topic of intense research in the past. The main problem of VoD systems is that their bandwidth requirements do not scale well with user requests. For this reason, VoD is only feasible under some constraints. In general, NVoD systems are an approximation of VoD ones. In them, downloads do not necessarily start when the request arrives, but some time later. By doing so, it is possible to bound the total required bandwidth at the cost of introducing some delay in content download.

Development of Integrated and Transportable Communication Terminal Using GSM and WiFi over Satellite for Emergency Communications

This paper presents the development of a compact, ruggedized satellite terminal, to be used for communications in emergency situation. The terminal provides GSM coverage in disaster area, where existing communication infrastructure is destroyed or overloaded. It uses GSM backhauling over satellite to transport GSM signalling and data traffic to the core GSM network infrastructure in the disaster-safe area. Additionally, basic data services such as HTTP web browsing and email are also provided via WiFi access.