Dynamic Topology Estimation and Resource Allocation for Power Line Communication

Power line communication (PLC), which uses existing infrastructure of power delivery for data transfer, is regarded as an economical, pervasive and extensive communication solution for smart grid and home broadband applications. One of the challenges of applying communication technologies to power line network lies in acquirement of channel state information (CSI), which is dependent on network topology. Moreover, the knowledge of topology provides a basis for the design of routing protocols and power flow optimization. Therefore, efficient approaches for dynamic topology estimation are highly demanded. While dynamic routing and resource allocation enable high-speed and multi-tasking communication services over power lines. In this thesis, a dynamic topology estimation scheme for PLC is investigated, and a cross-layer routing and resource allocation scheme assisted by dynamic topology estimation is developed to improve the system performance. In the first contribution, a high-resolution and low-complexity dynamic topology estimation scheme for time-varying indoor PLC networks is proposed. The scheme consists of three parts: a) a time-frequency domain reflectometry (TFDR) based path length estimation method, which requires measurement at a single PLC modem and achieves a much higher resolution than the frequency domain reflectometry (FDR) based method; b) a node-by-node greedy algorithm for topology reconstruction, which is much more computationally efficient than the existing peak-by-peak searching algorithm; c) an impulsive noise assisted dynamic topology re-estimation method, which results in a significant complexity reduction over fixed-frequency re-estimation. In the second contribution, a cross-layer routing and resource allocation (RA) scheme assisted by dynamic topology estimation is proposed to optimize the system throughput of indoor PLC network with heterogeneous delay requirements. The proposed scheme provides a multi-layer solution, which conducts the network layer routing based on the result of PHY layer resource allocation which is constrained by the MAC layer queuing delay. With the dynamic topology estimation proposed in the first contribution, the routing can be solved centrally at the source, which is more robust against topology changes compared to distributed solutions. The proposed cross-layer RA scheme consists of subcarrier allocation (SA) to multiple users and power allocation (PA) to subcarriers satisfying heterogeneous delay requirements. It is demonstrated that the proposed centralized routing strategy achieves a much lower packet loss rate (PLR) than a distributed routing scheme; while with optimal RA, the system throughput is significantly improved compared to the routing schemes without considering RA

Underwater acoustic communications in warm shallow water channels

Ph.DDOCTOR OF PHILOSOPH

Contributions à l'étude des communications numériques sur le réseau électrique à l'intérieur des bâtiments : modélisation du canal et optimisation du débit

In recent years, the electrical network has become an essential candidate for high-speed data transmission inside buildings. Many solutions are currently underway in order to optimize these technologies known under the name of in-home Power-Line Communications (PLC). Multiple-Input Multiple-Output (MIMO) technique has recently been transposed into power-line networks for which different signal feeding possibilities can be considered between phase, neutral and earth wires. In this thesis, we propose two original contributions to indoor broadband PLC. The first contribution concerns the MIMO-PLC channel modeling. Based on a Single-Input Single-Output (SISO) parametric channel model presented in the literature, we propose a MIMO one by considering a new parameter which characterizes the spatial correlation. The proposed model enables an accurate description of the spatial correlation of European MIMO PLC field measurements. The second contribution is related to the impulsive noise present in power-line networks which constitutes a major problem in communications systems. We propose an outage capacity approach in order to optimize the average data rate in Orthogonal Frequency Division Multiplexing (OFDM) systems affected by impulsive noise. First, we study the channel capacity as a function of a noise margin provided to the transmitted symbols. Then we determine the analytical expression of the outage probability of an OFDM symbol in terms of the noise margin, by studying in detail the interaction between the noise impulse and the symbol. Based on the two aforementioned relations, we deduce the outage capacity. Then we propose an approach that enables to maximize the average system data rate. Finally, we present the results in the particular case of indoor broadband PLC in the presence of impulsive noise.Au cours de ces dernières années, le réseau électrique est devenu un candidat incontournable pour la transmission de données à haut débit à l’intérieur des bâtiments. De nombreuses solutions sont actuellement à l’étude afin d’optimiser ces technologies connues sous le nom Courants Porteurs en Ligne (CPL) ou PLC (Power-Line Communications). La technique MIMO (Multiple-Input Multiple-Output) a été tout récemment transposée au réseau filaire électrique pour lequel différents modes d’alimentation peuvent être envisagés entre la phase, le neutre et la terre. Dans le cadre de cette thèse, nous proposons deux contributions originales à l’étude des communications numériques sur le réseau électrique à l’intérieur des bâtiments. La première contribution concerne la modélisation du canal MIMO-PLC. En repartant d’un modèle du canal paramétrique SISO (Single-Input Single-Output) connu dans la littérature, nous proposons un modèle du canal MIMO en considérant un nouveau paramètre caractérisant la corrélation spatiale. Le modèle proposé permet de représenter fidèlement la corrélation spatiale des mesures effectuées à l’échelle européenne. La deuxième contribution concerne le bruit impulsif présent sur le réseau électrique domestique qui constitue un problème majeur dans les systèmes de communications. Nous proposons une méthode basée sur la notion de capacité de coupure afin d’optimiser le débit moyen dans les systèmes OFDM (Orthogonal Frequency Division Multiplexing) soumis aux bruits impulsifs. D’abord, nous étudions la capacité du système en fonction d’une marge de bruit fournie aux symboles transmis. Ensuite, nous déterminons l’expression analytique de la probabilité de coupure (outage) d’un symbole OFDM en fonction de cette marge, en étudiant de manière détaillée l’interaction entre l’impulsion de bruit et le symbole. A partir de ces deux calculs, nous déduisons la capacité de coupure. Puis, nous proposons une approche qui maximise l’espérance mathématique du débit reçu. Finalement, nous présentons les résultats obtenus dans le cas particulier d’une transmission à haut débit sur PLC en présence de bruits impulsifs