Vincent Deslandes

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.

Ultra Narrow Band Technique for Low Power Wide Area Communications

Ultra Narrow Band (UNB) transmission technique makes a powerful comeback in the frame of Machine-To-Machine (M2M) communications thanks to advances in signal processing. After explaining why, among others, it is one of the best candidate for Low Power Wide Area (LPWA) communications, we present its specificities and associated constraints. In particular UNB is inseparable from random access so we introduce Time/Frequency Aloha, a random access scheme adapted for UNB. Then, we propose an analytical model to evaluate its performance in terms of packet loss ratio and normalized throughput in both terrestrial and satellite context. Several axes of improvement based on advanced signal processing techniques are proposed to enhance the capacity of a system using UNB signals.

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.

Modeling and performance analysis of ultra narrow band system for M2M

Ultra Narrow Band (UNB) has been shown to be one of the best candidate technologies for Machine-To-Machine and Low Power Wide Area communications. Its properties - long range with small RF power - make it naturally attractive for satellite communications, but also draw new challenges compared to terrestrial systems where this technology is already deployed. In this paper we propose a general semi-analytical model to evaluate the performance of a terrestrial or satellite system using UNB technology, taking into account the multiuser interference. This model is then used to assess the packet loss ratio and the throughput of a representative LEO satellite system for which Doppler effect introduces a frequency drift that has a significant impact on the UNB performances. With our model, we analyze the effect of frequency drift on the system performance.

Modelling discontinuous LEO satellite constellations: impact on the machine-to-machine traffic and performance evaluation

Discontinuous LEO satellite constellations (DisLEO) are expected to be more and more exploited in future satellite telecommunication systems especially in the context of delay-tolerant networks such as messaging and Machine-To-Machine (M2M) communications. No modelling for this type of constellation has been proposed yet. We highlight two different studies points of view: satellite and ground. In this paper, we analyse widely the satellite point of view and we define a new traffic modelling for M2M communications at the satellite point of view. Because of the satellite discontinuity, classical traffic modelling for terrestrial or satellite networks are inadequate. This paper explains the generation of new terminals (who has new message to transmit) under the satellite coverage. To illustrate how works the new traffic model, we perform an example of protocols performance evaluation.

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.