logo EDITE Anastasios GIOVANIDIS
État académique
Thèse soutenue le 2010-04-12
Laboratoire: personnel permanent
Encadrement de thèses (depuis 2007)
Ellipse bleue: doctorant, ellipse jaune: docteur, rectangle vert: permanent, rectangle jaune: HDR. Trait vert: encadrant de thèse, trait bleu: directeur de thèse, pointillé: jury d'évaluation à mi-parcours ou jury de thèse.
Productions scientifiques
A Stochastic Geometry Framework for Analyzing Pairwise-Cooperative Cellular Networks
Cooperation in cellular networks has been recently suggested as a promising scheme to improve system performance, especially for cell-edge users. In this work, we use stochastic geometry to analyze cooperation models where the positions of Base Stations (BSs) follow a Poisson point process distribution and where Voronoi cells define the planar areas associated with them. For the service of each user, either one or two BSs are involved. If two, these cooperate by exchange of user data and channel related information with conferencing over some backhaul link. Our framework generally allows variable levels of channel information at the transmitters. In this paper we investigate the case of limited channel state information for cooperation (channel phase, second neighbour interference), but not the fully adaptive case which would require considerable feedback. The total per-user transmission power is further split between the two transmitters and a common message is encoded. The decision for a user to choose service with or without cooperation is directed by a family of geometric policies depending on its relative position to its two closest base stations. An exact expression of the network coverage probability is derived. Numerical evaluation allows one to analyze significant coverage benefits compared to the non-cooperative case. As a conclusion, cooperation schemes can improve system performance without exploitation of extra network resources.
research report 2013-05-28
Measurement-Adaptive Cellular Random Access Protocols
This work considers a single-cell random access channel (RACH) in cellular wireless networks. Communications over RACH take place when users try to connect to a base station during a handover or when establishing a new connection. We approach the problem of optimal coordination of user actions, taking into account a dynamic environment (channel fading, mobility, etc.). Within the framework of Self-Organizing Networks (SONs), the system should self-adapt to such environments without human intervention. To do so certain information should be gathered at the base station. Control actions of the users are the transmission power and the access (back-off) probability. For the performance improvement of the RACH procedure, we propose protocols which exploit information from measurements and user reports in order to estimate current values of the system unknowns and broadcast global action-related values to all users. The protocols suggest an optimal pair of user actions (transmission power and back-off probability) found by minimizing the drift of a certain function. Numerical results illustrate the great performance benefits at a very low or even zero cost in power expenditure and delay, as well as the fast adaptability of the protocols to envoronment changes.
research report 2013-06-03
Analyzing Interference from Static Cellular Cooperation using the Nearest Neighbour Model
Invited paper at the WIOPT-SPASWIN conference 2015, Mumbai, India
International audience
The problem of base station cooperation has recently been set within the framework of Stochastic Geometry. Existing works consider that a user dynamically chooses the set of stations that cooperate for his/her service. However, this assumption often does not hold. Cooperation groups could be pre-defined and static, with nodes connected by fixed infrastructure. To analyse such a potential network, in this work we propose a grouping method based on proximity. It is a variation of the so called Nearest Neighbour Model. We restrict ourselves to the simplest case where only singles and pairs of base stations are allowed to be formed. For this, two new point processes are defined from the dependent thinning of a Poisson Point Process, one for the singles and one for the pairs. Structural characteristics for the two are provided, including their density, Voronoi surface, nearest neighbour, empty space and J-function. We further make use of these results to analyse their interference fields and give explicit formulas to their expected value and their Laplace transform. The results constitute a novel toolbox towards the performance evaluation of networks with static cooperation.
13th International Symposium on Modeling and Optimization in Mobile, Ad Hoc and Wireless Networks (WIOPT-SPASWIN) https://hal.archives-ouvertes.fr/hal-01112704 13th International Symposium on Modeling and Optimization in Mobile, Ad Hoc and Wireless Networks (WIOPT-SPASWIN), May 2015, Mumbai, India. 2015, Proceedings WIOPT 2015. <10.1109/WIOPT.2015.7151121>ARRAY(0x7f03ff38b248) 2015-05-25
Analysis of Static Cellular Cooperation between Mutually Nearest Neighboring Nodes
https://hal.archives-ouvertes.fr/hal-01394181 2016ARRAY(0x7f03ff38a930) 2016-11-08
Coverage Gains from the Static Cooperation of Mutually Nearest Neighbours
International audience
Cooperation in cellular networks has been recently suggested as a promising scheme to improve system performance. In this work, clusters are formed based on the Mutually Nearest Neighbour relation, which defines which stations cooperate in pair and which do not. When node positions follow a Poisson Point Process (PPP) the performance of the original clustering model can be approximated by another one, formed by the superposition of two PPPs (one for the singles and one for the pairs) equipped with adequate marks. This allows to derive exact expressions for the network coverage probability under two user-cluster association rules. Numerical evaluation shows coverage gains from different signal cooperation schemes that can reach up to 15% compared to the standard non-cooperative network coverage. The analysis is general and can be applied to any type of cooperation or coordination between pairs of transmitting nodes.
Proceedings GLOBECOM'16 https://hal.archives-ouvertes.fr/hal-01304176 Proceedings GLOBECOM'16, Dec 2016, Washington, United States. 2016, <10.1109/GLOCOM.2016.7841705>ARRAY(0x7f03fed77950) 2016-12-04
Wireless Node Cooperation with Resource Availability Constraints
International audience
—Base station cooperation is a promising scheme to improve network performance for next generation cellular networks. Up to this point research has focused on station grouping criteria based solely on geographic proximity. However, for the cooperation to be meaningful, each station participating in a group should have sufficient available resources to share with others. In this work we consider an alternative grouping criterion based on a distance that considers both geographic proximity and available resources of the stations. When the network is modelled by a Poisson Point Process, we derive analytical formulas on the proportion of cooperative pairs or single stations, and the expected sum interference from each of the groups. The results illustrate that cooperation gains strongly depend on the distribution of available resources over the network.
Proceedings of the 15th International Symposium on Modeling and Optimization in Mobile, Ad Hoc, and Wireless Networks, Telecom ParisTech, Paris, France, 15th - 19th May, 2017 WIOPT'17 - Workshop on Spatial Stochastic Models 
for Wireless Networks (SpaSWiN) https://hal.archives-ouvertes.fr/hal-01481627 WIOPT'17 - Workshop on Spatial Stochastic Models 
for Wireless Networks (SpaSWiN), May 2017, Paris, France. Proceedings of the 15th International Symposium on Modeling and Optimization in Mobile, Ad Hoc, and Wireless Networks, Telecom ParisTech, Paris, France, 15th - 19th May, 2017, 2017ARRAY(0x7f03ff384ba8) 2017-05-15