Network coding meets multimedia: a review

While every network node only relays messages in a traditional communication system, the recent network coding (NC) paradigm proposes to implement simple in-network processing with packet combinations in the nodes. NC extends the concept of "encoding" a message beyond source coding (for compression) and channel coding (for protection against errors and losses). It has been shown to increase network throughput compared to traditional networks implementation, to reduce delay and to provide robustness to transmission errors and network dynamics. These features are so appealing for multimedia applications that they have spurred a large research effort towards the development of multimedia-specific NC techniques. This paper reviews the recent work in NC for multimedia applications and focuses on the techniques that fill the gap between NC theory and practical applications. It outlines the benefits of NC and presents the open challenges in this area. The paper initially focuses on multimedia-specific aspects of network coding, in particular delay, in-network error control, and mediaspecific error control. These aspects permit to handle varying network conditions as well as client heterogeneity, which are critical to the design and deployment of multimedia systems. After introducing these general concepts, the paper reviews in detail two applications that lend themselves naturally to NC via the cooperation and broadcast models, namely peer-to-peer multimedia streaming and wireless networkin

On feedback-based rateless codes for data collection in vehicular networks

The ability to transfer data reliably and with low delay over an unreliable service is intrinsic to a number of emerging technologies, including digital video broadcasting, over-the-air software updates, public/private cloud storage, and, recently, wireless vehicular networks. In particular, modern vehicles incorporate tens of sensors to provide vital sensor information to electronic control units (ECUs). In the current architecture, vehicle sensors are connected to ECUs via physical wires, which increase the cost, weight and maintenance effort of the car, especially as the number of electronic components keeps increasing. To mitigate the issues with physical wires, wireless sensor networks (WSN) have been contemplated for replacing the current wires with wireless links, making modern cars cheaper, lighter, and more efficient. However, the ability to reliably communicate with the ECUs is complicated by the dynamic channel properties that the car experiences as it travels through areas with different radio interference patterns, such as urban versus highway driving, or even different road quality, which may physically perturb the wireless sensors. This thesis develops a suite of reliable and efficient communication schemes built upon feedback-based rateless codes, and with a target application of vehicular networks. In particular, we first investigate the feasibility of multi-hop networking for intra-car WSN, and illustrate the potential gains of using the Collection Tree Protocol (CTP), the current state of the art in multi-hop data aggregation. Our results demonstrate, for example, that the packet delivery rate of a node using a single-hop topology protocol can be below 80% in practical scenarios, whereas CTP improves reliability performance beyond 95% across all nodes while simultaneously reducing radio energy consumption. Next, in order to migrate from a wired intra-car network to a wireless system, we consider an intermediate step to deploy a hybrid communication structure, wherein wired and wireless networks coexist. Towards this goal, we design a hybrid link scheduling algorithm that guarantees reliability and robustness under harsh vehicular environments. We further enhance the hybrid link scheduler with the rateless codes such that information leakage to an eavesdropper is almost zero for finite block lengths. In addition to reliability, one key requirement for coded communication schemes is to achieve a fast decoding rate. This feature is vital in a wide spectrum of communication systems, including multimedia and streaming applications (possibly inside vehicles) with real-time playback requirements, and delay-sensitive services, where the receiver needs to recover some data symbols before the recovery of entire frame. To address this issue, we develop feedback-based rateless codes with dynamically-adjusted nonuniform symbol selection distributions. Our simulation results, backed by analysis, show that feedback information paired with a nonuniform distribution significantly improves the decoding rate compared with the state of the art algorithms. We further demonstrate that amount of feedback sent can be tuned to the specific transmission properties of a given feedback channel

Techniques for improving predictability and message efficiency of gossip protocols

Ph.DDOCTOR OF PHILOSOPH

Fundamental limits of wireless ad hoc networks: lower MO bounds

Fundamental performance limits of multi-hop wireless transmissions are currently being investigated from a multiobjective perspective where transmission decisions (i.e. relay selection, scheduling or routing decision) modify the trade-off between capacity, reliability, end-to-end delay or network-wide energy consumption. In our previous work presented in the Inria research report RR-7799, Pareto-optimal performance bounds and network parameters have been derived for a 1-relay and 2-relay network within a MultiObjective(MO) performance evaluation framework. We show in this report that these bounds are tight since they can be reached by simple practical coding strategies performed by the source and the relays. Such strategies constitute achievable lower MO performance bounds on the real MO performance limits. More precisely, we adopt a coding strategy where the source transmits a random linear fountain code which is coupled to a network coding strategy performed by the relays. Two different network coding strategies are investigated. Practical performance bounds for both strategies are compared to the theoretical bound. We show that the theoretical bound is tight: generational distance between the practical and theoretical bound for the best strategy is only of 0.0042Ce rapport s'intéresse à la caractérisation des performances en limite d'un point de vue multiobjectif des transmissions dans un réseau sans fil ad hoc multi-saut. Les critères de performance considérés sont la capacité ou la robustesse de la transmission, le délai de bout en bout et la consommation énergétique. L'objet de cette étude est de déterminer les meilleurs compromis possibles entre ces critères en ajustant les décisions de transmission (sélection des canaux de transmissions et des relais). Dans nos précédents travaux présentés dans le rapport de recherche Inria RR-7799, nous avons proposé un modèle de réseau et une modélisation du problème d'optimisation multicritère qui nous a permis de dériver les limites de performance Pareto-optimales et les paramètres réseau pour un réseau 1- et 2-relais. Ces limites en performance Pareto-optimales sont des bornes supérieures. L'objectif de ce rapport est de que ces bornes supérieures sont serrés, car elles peuvent être atteintes à l'aide de simples stratégies de codage effectuées par la source et les relais. Ces stratégies constituent des bornes inférieures réalisables. Nous présentons des résultats où la source émet un code source linéaire aléatoire couplé à une stratégie de codage réseau effectuée par des relais. Deux différentes stratégies de codage réseau sont étudiées et comparées à la borne supérieure théorique obtenue par le modèle d'évaluation de performances multicritère. Nous montrons que la borne théorique est serrée : la distance générationnelle entre la borne théorique et pratique pour la meilleure stratégie est seulement de 0,0042

Network streaming and compression for mixed reality tele-immersion

Bulterman, D.C.A. [Promotor]Cesar, P.S. [Copromotor

Maximizing Routing Throughput with Applications to Delay Tolerant Networks

abstract: Many applications require efficient data routing and dissemination in Delay Tolerant Networks (DTNs) in order to maximize the throughput of data in the network, such as providing healthcare to remote communities, and spreading related information in Mobile Social Networks (MSNs). In this thesis, the feasibility of using boats in the Amazon Delta Riverine region as data mule nodes is investigated and a robust data routing algorithm based on a fountain code approach is designed to ensure fast and timely data delivery considering unpredictable boat delays, break-downs, and high transmission failures. Then, the scenario of providing healthcare in Amazon Delta Region is extended to a general All-or-Nothing (Splittable) Multicommodity Flow (ANF) problem and a polynomial time constant approximation algorithm is designed for the maximum throughput routing problem based on a randomized rounding scheme with applications to DTNs. In an MSN, message content is closely related to users’ preferences, and can be used to significantly impact the performance of data dissemination. An interest- and content-based algorithm is developed where the contents of the messages, along with the network structural information are taken into consideration when making message relay decisions in order to maximize data throughput in an MSN. Extensive experiments show the effectiveness of the above proposed data dissemination algorithm by comparing it with state-of-the-art techniques.Dissertation/ThesisDoctoral Dissertation Computer Science 201