Deterministic and probabilistic QoS guarantees for the EF class in a DiffServ/MPLS domain

In the Differentiated Services (DiffServ) architecture, the Expedited Forwarding EF class has been proposed for applications requiring low end-to-end packet delay, low delay jitter and low packet loss (e.g. voice and video applications that are delay and jitter sensitive). In this paper, we focus on the quantitative Quality of Service (QoS) guarantee that can be granted to an EF flow in terms of end-to-end delay. Two approaches are presented. The deterministic one is based on a worst case analysis and leads to a deterministic bound which is infrequently reached. The probabilistic approach, based on the probability density function of the response time, is introduced to evaluate the probability of missing a given deadline. This study shows that delays much smaller than the deterministic bound can be guaranteed with probabilities close to one. An admission control derived from these results is then proposed, providing a probabilistic QoS guarantee to EF flows

An Orthogonal Air Pollution Monitoring Method (OAPM) Based on LoRaWAN

International audienceHigh accuracy air pollution monitoring in a smart city requires the deployment of a huge number of sensors in this city. One of the most appropriate wireless technologies expected to support high density deployment is LoRaWAN which belongs to the Low Power Wide Area Network (LPWAN) family and offers long communication range, multi-year battery lifetime and low cost end devices. It has been designed for End Devices (EDs) and applications that need to send small amounts of data a few times per hour. However, a high number of end devices breaks the orthogonality of LoRaWAN transmissions, which was one of the main advantages of LoRaWAN. Hence, network performances are strongly impacted. To solve this problem, we propose a solution called OAPM (Orthogonal Air Pollution Monitoring) which ensures the orthogonality of LoRaWAN transmissions and provides accurate air pollution monitoring. In this paper, we show how to organize EDs into clusters and sub-clusters, assign transmission times to EDs, configurate and synchronize them, taking into account the specificities of LoRaWAN and the features of the air pollution monitoring application. Simulation results corroborate the very good behavior of OAPM

Collision-Free Transmissions in an IoT Monitoring Application Based on LoRaWAN

International audienceWith the Internet of Things (IoT), the number of monitoring applications deployed is considerably increasing, whatever the field considered: smart city, smart agriculture, environment monitoring, air pollution monitoring, to name a few. The LoRaWAN (Long Range Wide Area Network)architecture with its long range communication, its robustness to interference and its reduced energy consumption is an excellent candidate to support such applications. However, if the number of end devices is high, the reliability of LoRaWAN, measured by the Packet Delivery Ratio (PDR), becomes unacceptable due to an excessive number of collisions. In this paper, we propose two different families of solutions ensuring collision-free transmissions. The first family is TDMA (Time-Division Multiple Access)-based. All clusters transmit in sequence and up to six end devices with different spreading factors belonging to the same cluster are allowed to transmit in parallel. The second family is FDMA (Frequency Divsion Multiple Access)-based. All clusters transmit in parallel, each cluster on its own frequency. Within each cluster, all end devices transmit in sequence. Their performance are compared in terms of PDR, energy consumption by end device and maximum number of end devices supported. Simulation results corroborate the theoretical results and show the high efficiency of the solutions proposed

TDMA-aware Routing Protocol for Multi-hop Communications in Vehicular Ad Hoc Networks

International audienceVehicular Ad-Hoc Networks (VANETs) have become an emerging technology due to the variety of their applicationsin Intelligent Transportation Systems (ITS). By creating a vehicular network, each vehicle can exchange information toinform drivers in other vehicles about the current status of the traffic flow or a dangerous situation. Multi-hop communicationsis an effective method that can be used for information exchange over distances greater than the transmission range of thetransmitting vehicle. However, it is a great challenge to ensure a stable multi-hop communication link with a low delivery delaydue to the high mobility of the vehicles involved. The goal of this paper is to design a TDMA aware Routing Protocolfor Multi-hop wireless vehicular ad hoc networks (TRPM) in order to provide the ability to transmit/receive packets over longdistances. The proposed routing scheme is based on a medium access control protocol, in which the intermediate vehicles areselected based on the TDMA scheduling. The simulation results reveal that our routing protocol significantly outperforms otherprotocols in terms of average end-to-end delay, average number of relay vehicles and the average delivery ratio

TDMA-based MAC Protocols for Vehicular Ad Hoc Networks: A Survey, Qualitative Analysis and Open Research Issues

International audience—Vehicular Ad-hoc NETworks (VANETs) have attracted a lot of attention in the research community in recent years due to their promising applications. VANETs help improve traffic safety and efficiency. Each vehicle can exchange information to inform other vehicles about the current status of the traffic flow or a dangerous situation such as an accident. Road safety and traffic management applications require a reliable communication scheme with minimal transmission collisions, which thus increase the need for an efficient Medium Access Control (MAC) protocol. However, the design of the MAC in a vehicular network is a challenging task due to the high speed of the nodes, the frequent changes in topology, the lack of an infrastructure, and various QoS requirements. Recently several Time Division Multiple Access (TDMA)-based medium access control protocols have been proposed for VANETs in an attempt to ensure that all the vehicles have enough time to send safety messages without collisions and to reduce the end-to-end delay and the packet loss ratio. In this paper, we identify the reasons for using the collision-free medium access control paradigm in VANETs. We then present a novel topology-based classification and we provide an overview of TDMA-based MAC protocols that have been proposed for VANETs. We focus on the characteristics of these protocols, as well as on their benefits and limitations. Finally, we give a qualitative comparison, and we discuss some open issues that need to be tackled in future studies in order to improve the performance of TDMA-based MAC protocols for vehicle to vehicle (V2V) communications

Using Road IDs to Enhance Clustering in Vehicular Ad hoc Networks

International audience—Vehicular ad hoc networks (VANETs) where vehicles act as mobile nodes is an instance of Mobile Ad hoc NETworks (MANETs), which are essentially developed for intelligent transportation systems. A challenging problem when designing communication protocols in VANETs is coping with high vehicle mobility, which causes frequent changes in the network topology and leads to frequent breaks in communication. The clustering technique is being developed to reduce the impact of mobility between neighboring vehicles. In this paper, we propose an Adaptive Weighted Cluster Protocol for VANETs, which is a road map dependent and uses road IDs and movement direction in order to make the clusters structure as stable as possible. The experimental results reveal that AWCP outperforms four other most commonly used clustering protocols in terms of control packet overhead, the packet delivery ratio, and the average cluster lifetime, which are the most usual metrics used for comparing performance

A Fully Distributed TDMA based MAC Protocol for Vehicular Ad Hoc Networks

—The Vehicular Ad-Hoc NETwork (VANET) consists of a set of vehicles moving on roads which can communicate with each other through ad hoc wireless devices. VANET has attracted a lot of attention in the research community in recent years with the main focus on its safety applications. One of the challenges for vehicular network is the design of an efficient Medium Access Control (MAC) protocol due to the hidden node problem, the high speed of the nodes, the frequent changes in topology, the lack of an infrastructure, and various QoS requirements. Motivated by this observation, we design a fully distributed and location-based TDMA scheduling scheme for VANETs networks, named DTMAC. The main goal of this work is to propose a MAC protocol that can provide fairness in accessing the transmission medium, as well as reduce access collision and merging collision under various conditions of vehicular density without having to use expensive spectrum and complex mechanisms such as CDMA or OFDMA. An analytical model of the average access collision probability and throughput are derived which can be used to evaluate the performance of DTMAC protocol as well as to validate the simulation results under different traffic conditions

A Multi-Objectif Genetic Algorithm-Based Adaptive Weighted Clustering Protocol in VANET

International audience—Vehicular Ad hoc NETwork (VANET) is the main component that is used recently for the development of Intelligent Transportation Systems (ITSs). VANET has a highly dynamic and portioned network topology due to the constant and rapid movement of vehicles. Recently, the clustering algorithms are widely used as the control schemes to make VANET topology less dynamic for MAC, routing and security protocols. An efficient clustering algorithm must take into consideration all the necessary information related to node mobility. In this paper, we propose an Adaptive Weighted Clustering Protocol (AWCP), specially designed for vehicular networks, which takes the highway ID, direction of vehicles, position, speed and the number of neighbors vehicles into account in order to enhance the network topology stability. However, the multiple control parameters of our AWCP, make parameter tuning a non-trivial problem. In order to optimize AWCP protocol, we define a multi-objective problem whose inputs are the AWCPs parameters and whose objectives are: providing stable cluster structure as possible, maximizing data delivery rate, and reducing the clustering overhead. We then face this multi-objective problem with the the Multi-Objective Genetic Algorithm (MOGA). We evaluate and compare its performance with other multi-objective optimization techniques: Multi-objective Particle Swarm Optimization (MOPSO) and Multi-objective Differential Evolution (MODE). The experiments analysis reveal that NSGA-II improves the results of MOPSO and MODE in terms of the spacing, spread, and ratio of non-dominated solutions and generational distance metrics used for comparison

A New Dynamic Urban Environment Air Pollution Monitoring Protocol Using WAVE (DAP-MP)

International audienc