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Software Defined Networking (SDN) allows new approaches to provide Quality of Service (QoS). In legacy networks, strict QoS guarantees often result in bandwidth over-provisioning. Then, QoS enforcement either consumes too many resources, or is not flexible enough. We present a solution to provide QoS based on the creation of on-demand MPLS tunnels with guaranteed bandwidths across an SDN network. We introduce an SDN Traffic Engineering Management (STEM) module that interacts with the northbound applications to satisfy their requests to forward QoS-guaranteed traffic flows. STEM delegates the path selection to a Path Computation Element (PCE), and the path enforcement to an SDN controller. We rely on a stateful PCE to record the attributed resources and estimate the remaining network capacity, avoiding overloading the network with monitoring traffic. Upon STEM requests, the SDN controller enforces the QoS policy in the data plane. User flows are aggregated into MPLS tunnels and packets are labeled with a priority depending on the flow effective bandwidth. We highlight the shortfalls of several material and software OpenFlow compatible switches and detail an implementation based on a pica8 switch to overcome them. The experimental results demonstrate that this solution efficiently enforces bandwidth sharing in SDN networks.

International audience; For audiovisual network operators, end-users satisfaction is a major issue. This is the case for TDF who operates a nationwide network in France whose main purpose is to carry Digital Terrestrial Television streams. Such audiovisual content is forwarded through multicast real-time streams which require continuity of service. Therefore, the main goal of this work is to define a new architecture to prevent impact during network healing time. The proposed architecture aims to use a pair of redundant multicast trees, and ensure their seamless resiliency. This architecture called “Seamless Multicast” takes advantage of the network-end equipment’s ability to receive and combine two identical streams, complete or not. The main contribution of this paper is the development and evaluation of an algorithm for the computation of a pair of multicast trees and the associated hitless deployment scheme. Implementation requires an Software-Defined Networking architecture, in which performance knowledge and bandwidth management are centralized in a controller. A proof of concept controller has been used for validation of the architecture’s global behaviour using a virtualized environment in multiple scenarios.

The latest video coding standard, called versatile video coding (VVC), includes several novel and refined coding tools at different levels of the coding chain. These tools bring significant coding gains with respect to the previous standard, high efficiency video coding (HEVC). However, the encoder may still introduce visible coding artifacts, mainly caused by coding decisions applied to adjust the bitrate to the available bandwidth. Hence, pre and post-processing techniques are generally added to the coding pipeline to improve the quality of the decoded video. These methods have recently shown outstanding results compared to traditional approaches, thanks to the recent advances in deep learning. Generally, multiple neural networks are trained independently to perform different tasks, thus omitting to benefit from the redundancy that exists between the models. In this paper, we investigate a learning-based solution as a post-processing step to enhance the decoded VVC video quality. Our method relies on multitask learning to perform both quality enhancement and super-resolution using a single shared network optimized for multiple degradation levels. The proposed solution enables a good performance in both mitigating coding artifacts and super-resolution with fewer network parameters compared to traditional specialized architectures., Comment: accepted as a conference paper to Picture Coding Symposium (PCS) 2021

The Internet of Things (IoT) is currently one of the most trending research topic. Many wireless network technologies, called LPWAN (low power wide area network), have been developed with low-power, long-range and low-throughput in mind. It is estimated that there will be over 50 billion connected devices in these LPWAN networks. This paper focuses on Medium Access Control (MAC) protocol of LPWAN networks to evaluate the scalability and energy consumption performances. More precisely, we compare the two well-known MAC protocols, namely pure Aloha and slotted Aloha. First, we define two performances indicators such as the Data Extraction Rate (DER) and the Network Energy Consumption (NEC). Then we simulate a typical LoRaWAN networks based on the LoRaSim simulator. The results show that the slotted Aloha protocol is more efficient than the pure Aloha protocol in terms of energy consumption.

International audience; Recently, the coding and transmission of immersive 360 • video has been intensely studied. The technologies provided by standards developing organizations mainly address requirements coming from over-the-top services. The terrestrial broadcast remains in many countries the mainstream medium to deliver high quality contents to a wide audience. To enable seamless introduction of immersive 360 • video services over terrestrial broadcast, the deployed technologies shall fulfill requirements such as backward compatibility to legacy receivers and high bandwidth efficiency. While bandwidth efficiency is addressed by existing techniques, none of them enables legacy video services decoding. In this paper, a novel scalable coding scheme is proposed to enable immersive 360 • video services introduction over broadcast networks. The experiments show that the proposed scalable coding scheme provides substantial coding gains of 14.99% compared to simulcast coding and introduces a limited coding overhead of 5.15% compared to 360 • single-layer coding. A real-time decoding implementation is proposed, highlighting the relevance of the proposed design. Eventually, an end-to-end demonstrator illustrates how the proposed solution could be integrated in a real terrestrial broadcast environment.

International audience; In this paper, we propose, through an objective study, to compare and evaluate the performance of different coding approaches allowing the delivery of an 8K video signal with 4K backward-compatibility on broadcast networks. Presented approaches include simulcast of 8K and 4K single-layer signals encoded using High-Efficiency Video Coding (HEVC) and Versatile Video Coding (VVC) standards, spatial scalability using SHVC with 4K base layer (BL) and 8K enhancement-layer (EL), and super-resolution applied on 4K VVC signal after decoding to reach 8K resolution. For up-scaling, we selected the deep-learning-based super-resolution method called Super-Resolution with Feedback Network (SRFBN) and the Lanczos interpolation filter. We show that the deep-learning-based approach achieves visual quality gain over simulcast, especially on bit-rates lower than 30Mb/s with average gain of 0.77dB, 0.015, and 7.97 for PSNR, SSIM, and VMAF, respectively and out-performs the Lanczos filter in average by 29% of BD-rate savings.

International audience; The number of connected devices is increasing with the emergence of new services and trends. This phenomenon is leading to a traffic growth over both the control and the data planes of the mobile core network. It is expected that the traffic will increase more and more with the installation of the new generation of mobile networking (5G) as it offers more services that are intended to be connected over the same network in addition to the legacy ones. Therefore the 3GPP group has rethought the architecture of the New Generation Core (NGC) by defining its components as Virtualized Network Functions (VNF). However, scalability techniques should be envisioned in order to answer the needs, in term of resource provisioning, without degrading the Quality Of Service (QoS) already offered by hardware based core networks. Neural networks, and in particular deep learning, having shown their effectiveness in predicting time series, could be good candidates for predicting traffic evolution. In this paper, we proposed a novel solution to generalize neural networks while accelerating the learning process by using K-mean clustering, and a Monte-Carlo method. We benchmarked multiple types of deep neural networks using real operator's data in order to compare their efficiency in predicting the upcoming network load for dynamic and proactive resource provisioning. The proposed solution allow obtaining very good predictions of the traffic evolution while reducing by 50% the time needed for the learning phase.

International audience; In Content Delivery Networks (CDN), Quality of Experience (QoE) provides two major performance indicators that are availability and continuity of service. As a consequence, network robustness has become a major concern for network operators. TDF operates a traditional transport network for video and audio transport through multicast. Any failure on the network causes a recovery time implying loss and an impact in the content viewing. This illustrate that service continuity is a direct consequence of network availability. This work aims to propose a Software Defined Networking (SDN) architecture [1] in which a central controller uses its knowledge of the performance and bandwidth allocation to compute redundant disjoint multicast trees. Two maximally independent trees carrying the same stream over the network are deployed. When a failure occurs, at least one of the trees is still active, eliminating any discontinuity on the content viewing. This paper is focused on the Path Computation Element (PCE), which is based on previous works and the Suurballe-Tarjan algorithm [2]. Two algorithms are presented in this paper, which both fulfill the requirement of the architecture.

International audience; In content delivery network, Quality of Experience (QoE) provides two major performance indicators that are availability and continuity of service. As a consequence, network robustness has become a major concern for network operators. TDF operates a traditional transport network for video and audio transport. Any failure on the network causes a recovery time implying loss and an impact in the content viewing. This illustrate that service continuity is a direct consequence of network availability. This work aims to propose a Software Defined Networking (SDN) architecture in which the controller uses its knowledge of the performance and bandwidth allocation to compute redundant disjoint paths. Two maximally link-independent paths carrying the same stream over the network are deployed. When a failure occurs, at least one of the paths is still active, eliminating any discontinuity on the content viewing. This paper is focused on the Path Computation Element, which is based on Suurballe-Tarjan algorithm.

Recently, coding of 360° video contents has been investigated in the context of over-the-top streaming services. To be delivered using terrestrial broadcast, it is required to provide backward compatibility of such content to legacy receivers. In this paper, a novel layered coding scheme is proposed to address the delivery of 360° video content over terrestrial broadcast networks. One or several views are extracted from the 360° video and coded as base layers using standard HEVC encoding. Inter-layer reference pictures are built based on projected base-layers and are used in the enhancement layer to encode the 360° video. Experimental results show that the proposed approach provides substantial coding gains of 14.99% compared to simulcast coding and enables limited coding overhead of 5.15% compared to 360° single-layer coding.

International audience; The increasing popularity of linear services such as mobile TV, broadcasting live and sports events using mobile and portable devices, has led to a dramatic growth of the mobile data traffic. To deal with this traffic explosion, future networks have to increase the capacity offered to mobile communications, while at the same time trying to reduce their energy consumption. Actually, recent studies have shown that network cooperation is a promising candidate to deal with such issues. Based on these facts, this paper addresses the optimization of the energy efficiency of a hybrid network in which a broadcast and a unicast networks cooperate to deliver linear type of services to mobile and portable devices. Two optimization methods have been proposed to analytically find the optimal broadcast coverage area that maximizes the energy efficiency of the hybrid network. Simulation results show that using such a hybrid approach improves the overall energy efficiency.

International audience; In this paper, we provide full-wave numerical results concerning the effective magnetic permeability of the rod-shaped ferrites which is useful in the calculation of the inductance or the efficiency of ferrite rod antennas. This study covers the circular cross-section ferrites with a centered winding fitting the diameter of the rod. A careful attention is taken to the simulation model, and obtained results are in better agreement with the measured coils than existing solution published earlier. © 2017, Electromagnetics Academy. All rights reserved.

International audience; In this paper, a measurement procedure allowing the characterization of active integrated antennas in terms of intermodulation distortion and compression point inside of a parallel plate cell is presented. The validity of the radiative measurement is shown and compared to the traditional guided procedure. A good agreement between the two methods shows that this approach allows the evaluation of the overall linearity behavior of arbitrary complex integrated antennas and can serve as a complementary tool when the traditional guided method cannot be applied. © 2017, Electromagnetics Academy. All rights reserved.

International audience; This paper studies the optimal broadcast coverage radius in a hybrid network from the perspective of network planning. The hybrid network is composed of a unicast and broadcast systems which cooperate to deliver linear services on portable and mobile devices. First we define a hybrid approach in which the coverage radius of the broadcast network is adjusted according to the distribution of the users in the service area. Then, by applying convex optimization methods, we derive a closed-form expression of the optimal broadcast coverage radius that maximizes the average capacity per user in the hybrid network. The results show that the closed-form expression of the broadcast coverage radius is in good agreement with the simulation results, which validates the theoretical approach.

International audience; This paper provides a theoretical analysis of the performance of an hybrid network composed of a broadband system and a broadcast system which cooperate to deliver linear services on portable and mobile devices. First, we propose a global system model for the hybrid network in which the coverage area of the broadcast system is adjusted with respect to the spatial distribution of the users. Then based on the number of users requesting the services, the model parameters are optimized to increase the capacity of the hybrid network while guaranteeing a given quality of service. By applying convex optimization techniques, we derive a closed-form expression of the optimal coverage radius of the broadcast system that maximizes the capacity of the hybrid network. Next, based on this theoretical model, we analyze the performances of the optimized hybrid network. The results show that, depending on the number of users requesting the service, significant improvements of the capacity and quality of service are achieved with the hybrid network. Finally, regarding the planning of a cooperative network, this paper can be used to determine the optimal planning parameters of the broadcasting system for the delivery of linear services.

International audience; Protocols engineering of IP/MPLS networks are constantly improving with new separated features and new resilience mechanisms. In the transportation of audiovisual signals domain we must compose with multicast protocols which are designed from other scientific developments. This audiovisual traffic due to his non springy nature presents a very huge sensitivity to network recovery after a failure and these effects can be amplified by end devices (encoding, decoding and MPEG IP encapsulation). In this way when we choose between engineering solutions the unique criterion of availability is not enough, we must complete by an impact analysis on the service made by the network resilience technics. In this paper, we propose a first approach to analyze the behavior of different protocols engineering to improve selection. We propose using Bayesian networks to compare performance on different criteria and we will illustrate with two engineering models. The results focus on a real improvement of availability by choosing the adapted engineering solution.

International audience; An exponential growth of the mobile data traffic is expected in future networks. The reason of this growth is related to the increasing popularity of linear services such as mobile TV, live and sports events, which may lead to the delivery of the same contents to a large audience. Recent studies have shown that network cooperation is a promising candidate to deal with such an issue. This paper investigates, from a planning perspective, the optimization of a hybrid unicast/broadcast network for linear services. We introduce an analytical approach with the aim of stating an optimization problem on the hybrid network configuration, namely in terms of the sharing between the unicast and broadcast modes to deliver a particular service. We show by simulation the existence of an optimal operation point which leads to the maximization of the overall throughput of the hybrid network under the constraint of a minimum service success rate.

Two efficient techniques are investigated for the evaluation of the human exposure to electromagnetic fields in terms of the on-site assessment of the specific absorption rate (SAR) using interpolation techniques and plane-wave decomposition. These methods allow evaluating, in an optimal manner, the induced electromagnetic field and the SAR in a human tissue using both the measurements and calculation resulting in the alleviation of imposed constraints on them. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1501–1505, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23406