Jérôme Tronc

Analysis of interference issues in Integrated Satellite and Terrestrial Mobile Systems

The recent emergence of satellite and terrestrial integrated mobile systems raises new challenges for interference coordination between satellite and terrestrial users. The terrestrial component aims at improving the satellite coverage in highly populated areas where satellite communications often suffer from a high blocking factor caused by the buildings. The term “integrated system” refers to a system composed of a multi-beam Satellite Based Network (SBN) and a Complementary Ground Component (CGC) network that re-uses the same frequency band than the satellites one. This principle is of major interest to improve the spectral efficiency of the overall system and spatially optimize the usage of scarce spectrum resource available at low frequency bands such as L or S-band. Satellite and CGCs are assumed to be controlled by the same resource management entity which allows the coordination of frequency allocation between both components. The understanding of mutual interferences between both components is a key element for the design of such a system taking into account the forecasted balance between the number of terrestrial and satellite users in the system. This paper presents a model of an integrated mobile network composed of a multi-beam satellite, terrestrial base stations and hybrid satellite/terrestrial user terminals. This model is then used for statistical simulations of a continental scale network over Europe in order to analyze interferences between satellite and terrestrial users. The influence of several parameters such as the satellite frequency reuse pattern and the exclusion zone size between terrestrial and satellite cells is then presented.

Frequency Sharing Implementation in LTE-based Integrated Satellite-Terrestrial System

In order to be implemented, frequency sharing in integrated systems must be efficient and c ost effective. Usual static frequency reuse planning sc hemes are not sufficient to deal with inter-compone nt interferences issue as they cannot deal with them w hen the terrestrial user density becomes too high. In this paper, we propose a scheme based on opportunistic spectrum access techniques and cooperation between systems, which guarantees that the interferences be tween systems will always be limited. We also provi de the procedures to implement it effectively. In addition , as LTE promises to be the next 4G standard and of fers many features that can be used for interference coo rdination between systems, we studied how they could be adapted to integrated systems.

Inter-Component Interference Reduction through Flexible Frequency Reuse in Integrated Mobile Satellite-Terrestrial System

The recent evolution of European and North American telecoms regulation allows the deployment of low frequency bands (L or S) integrated mobile satellite-terrestrial system, composed of a Satellite Based Network (SBN) and, for urban areas, a Complementary Ground Component (CGC) network. The system targets broadcast or two-way broadband services for handset, nomadic or vehicular terminals. We consider here the two-way broadband mission with handset terminals. One way to improve the overall system spectral efficiency is to share the frequency between the SBN and the CGC network, considering terrestrial users as secondary users of the radio resource. This therefore requires dealing with the resulting inter-component interference problem, particularly on the uplink. Recently, the terrestrial cellular network community has proposed a number of flexible frequency reuse schemes for reducing inter-cell interferences in OFDMA based networks. Such schemes can be combined with interference reduction principles in order to reduce the inter-component interference. Assuming that both satellite and terrestrial radio access methods are OFDMA based, a fixed number of Physical Resource Blocks (PRB) are allocated to satellite spotbeams according to a simple reuse pattern. Then, terrestrial cells can allocate PRBs in a fashion that do not create harmful interferences with surrounding satellite spotbeams. In this paper, the performance of several reuse schemes are evaluated and compared in terms of interference generated towards the satellite and capacity of the terrestrial network.