Opportunistic Random Access Scheme Design for OFDMA-based Indoor PLC Networks

International audienceMulti-user systems can benefit from multi-user diversity by assigning channels to users with bestchannel conditions at different time instants. In this paper, we present an opportunistic random accessscheme for OFDMA-based indoor PLC systems, based on time- and frequency-varying channel conditions,to exploit multi-user diversity. The proposed scheme dynamically adjusts the backoff time ofeach user according to its own channel state variations in both time and frequency domains duringthe contention procedure, and thus ’better’ users have higher priority to contend over their favorablesubchannels. Moreover, subchannels are assigned to users with best channel conditions in order tofurther enhance the system throughput. In addition, an analytical throughput model for such a multiuserand multi-channel system is derived to obtain the optimal parameter settings of the proposedaccess scheme. Simulation results show that the proposed scheme provides significant improvement inthe system throughput even in the case where the number of users highly exceeds that of subchannels

An evolutionary controllers' placement algorithm for reliable SDN networks

International audienceSDN controllers placement in TelCo networks are generally multi-objective and multi-constrained problems. The solutions proposed in the literature usually model the placement problem by providing a mixed integer linear program (MILP). Their performances are, however, quickly limited for large sized networks, due to the significant increase in the computational delays. In order to avoid the inherent complexity of optimal approaches and the lack of flexibility of heuristics, we propose in this paper a genetic algorithm designed from the NSGA II framework that aims to deal with the controller placement problem. Genetic algorithms can, indeed, be both multi-objective, multi-constraints and can be designed to be computed in parallel. They constitute a real opportunity to find good solutions to this category of problems. Furthermore, the proposed algorithm can be easily adapted to manage dynamic placements scenarios. The goal chosen, in this work, is to maximize the clusters average connectivity and to balance the control's load between clusters, in a way to improve the networks' reliability. The evaluation results on a set of network topologies demonstrated very good performances, which achieve optimal results for small networks

A Holistic Monitoring Service for Fog/Edge Infrastructures: a Foresight Study

International audienceAlthough academic and industry experts are now advocating for going from large-centralized Cloud Computing infrastructures to smaller ones massively distributed at the edge of the network, management systems to operate and use such infrastructures are still missing. In this paper, we focus on the monitoring service which is a key element to any management system in charge of operating a distributed infrastructure. Several solutions have been proposed in the past for cluster, grid and cloud systems. However, none is well appropriate to the Fog/Edge context. Our goal in this study, is to pave the way towards a holistic monitoring service for a Fog/Edge infrastructure hosting next generation digital services. The contributions of our work are: (i) the problem statement, (ii) a classification and a qualitative analysis of major existing solutions, and (iii) a preliminary discussion on the impact of the deployment strategy of functions composing the monitoring service

A Framework for Edge Infrastructures Monitoring

By relying on small sized and massively distributed infrastructures, the Edge computingparadigm aims at supporting the low latency and high bandwidth requirements of the next generationservices that will leverage IoT devices (e.g., video cameras, sensors). To favor the advent of this paradigm,management services, similar to the ones that made the success of Cloud computing platforms, should beproposed. However, they should be designed in order to cope with the limited capabilities of the resourcesthat are located at the edge. In that sense, they should mitigate as much as possible their footprint. Amongthe different management services that need to be revisited, we investigate in this paper the monitoring one.Monitoring functions tend to become compute-, storage- and network-intensive, in particular because theywill be used by a large part of applications that rely on real-time data. To reduce as much as possible thefootprint of the whole monitoring service, we propose to mutualize identical processing functions amongdifferent tenants while ensuring their quality-of-service (QoS) expectations.We formalize our approach asa constraint satisfaction problem and show through micro-benchmarks its relevance to mitigate computeand network footprints.En s’appuyant sur des infrastructures de petite taille et massivement distribuées, le EdgeComputing cherche à répondre aux besoins en faible latence et grande bande passante des applicationsde nouvelle génération qui favorisent l’utilisation de l’Internet des objets (par exemple, les camérasvidéo, les capteurs). Pour mettre en œuvre ce paradigme, des services de gestion, similaires à ceuxqui ont permis le succès des plates-formes du Cloud Computing, doivent être proposés. Cependant, ilsdoivent être conçus de manière à faire face aux capacités limitées des ressources situées à la périphériedu réseau. Autrement dit, ils doivent réduire autant que possible leur empreinte. Parmi les différentsservices de gestion qui doivent être revisités, nous étudions dans cet article le service de supervision.Les fonctions de supervision ont tendance à nécessiter de grandes capacités de calcul, de stockage et deréseau parce qu’elles sont utilisées par une grande partie d’applications qui nécessite une supervisionen temps réel. Afin de réduire au maximum l’empreinte du service de supervision, nous proposonsde mutualiser des fonctions de traitement identiques entre différents tenants tout en garantissant leursattentes en qualité de service (QoS). Nous formalisons notre approche en tant qu’un problème desatisfaction de contraintes et montrons à l’aide de micro-test sa pertinence pour atténuer l’empreintede calcul et réseau

Efficient Resource Allocation for Multi-tenant Monitoring of Edge Infrastructures

International audienceBy relying on small sized and massively distributed infrastructures, the Edge computing paradigm aims at supporting the low latency and high bandwidth requirements of the next generation services that will leverage IoT devices (e.g., video cameras, sensors). To favor the advent of this paradigm, management services, similar to the ones that made the success of Cloud computing platforms, should be proposed. However, they should be designed in order to cope with the limited capabilities of the resources that are located at the edge. In that sense, they should mitigate as much as possible their footprint. Among the different management services that need to be revisited, we investigate in this paper the monitoring one. Monitoring functions tend to become compute-, storage-and network-intensive, in particular because they will be used by a large part of applications that rely on real-time data. To reduce as much as possible the footprint of the whole monitoring service, we propose to mutualize identical processing functions among different tenants while ensuring their quality-of-service (QoS) expectations. We formalize our approach as a constraint satisfaction problem and show through micro-benchmarks its relevance to mitigate compute and network footprints

Utility-based joint resource allocation and scheduling for indoor power line communications

International audienc

A two-dimension opportunistic CSMA/CA protocol for OFDMA-based in-home PLC networks

International audienceMultichannel systems can benefit from multiuser diversity by assigning channels to users with best channel conditions in different time instants. In this paper, a two-dimension opportunistic scheme for OFDMA-based in-home PLC systems with random access is presented in order to exploit multiuser diversity over different subchannels and time diversity across different time slots. The proposed scheme adjusts the backoff time for each user based on the knowledge of instantaneous channel information in both frequency and time domains, and thus assigns users with better channel quality higher priority to channel accessing. Moreover, users are scheduled to transmit over their favorable subchannels in order to further improve the system throughput. The analysis shows that the collision probability of the proposed scheme is extremely small. Additionally, simulation results demonstrate that the saturated throughput is significantly augmented even in the case that the number of users is highly exceeds that of subchannels

A cognitive cross-layer resource allocation scheme for in-home power line communications

International audienc

A cognitive cross-layer resource allocation scheme for in-home power line communications

International audienc

An opportunistic random access MAC protocol for indoor PLC networks with short-term fairness

International audienceWe consider a random scheduling problem for OFDMA-based indoor PLC systems with time- and frequencyvarying channel conditions in a multiuser context. In multichannel systems, opportunistic scheduling can exploit multiuser diversity in both time and frequency domains to improve the system performance. On the other hand, designing a scheduling scheme that simultaneously attains high performance and coordinates different users to share the channel fairly, especially over short time scales, is a challenging problem. In this paper, we propose an efficient opportunistic random access MAC protocol with short-term fairness constraint for OFDMA-based indoor PLC networks. Contrary to the conventional CSMA/CA, the proposed MAC protocol opportunistically adjusts the backoff time of each user based on the knowledge of channel state variations, and thus better users are more likely to access the channel. In addition, users that are involved in collisions and fail to contend during backoff process because there is no available subchannels are assigned higher priority in the following contention period to achieve a tradeoff between high throughput and shortterm fairness. Simulation results demonstrate that the proposed protocol provides significant improvement in system throughput and short-term fairness