Papers by Chiraz Houaidia
2020 9th IFIP International Conference on Performance Evaluation and Modeling in Wireless Networks (PEMWN), 2020
A significant proportion of elderly population suffers from age-related health issues and differe... more A significant proportion of elderly population suffers from age-related health issues and different chronic diseases which leads to a progressive decline in physical and cognitive skills which prevents them to live independently in their home and to perform basic Activities of Daily Living (ADL). In this context, the integration of information and communication technologies (ICT) has resulted in a rapid emergence of pervasive healthcare systems such as Health Smart Homes which aim to monitor and evaluate the person’s health condition and their behavior in performing ADL and to avoid, as long as possible, the delays of recourse to healthcare institutions (e.g. nursing homes and hospitals). In this research, we propose a predictive model for detecting behavioural and health-related changes in a patient who is monitored continuously in an assisted living environment. We focus on keeping track of the evolution of the dependency level and detecting the loss of autonomy for elderly person using a Hidden Markov Model based approach. We were interested in including blood pressure in this predictive process as it is considered the primary risk factor for cardiovascular disease, stroke, kidney failure and many other diseases. Our simulation was applied on a empirical dataset that concerned 3046 old persons monitored over 9 years. The results show that our model accurately evaluates person’s dependency, follows its evolution of autonomy over the time and thus predicts moments of important changes.
2021 10th IFIP International Conference on Performance Evaluation and Modeling in Wireless and Wired Networks (PEMWN), 2021
Physical-layer network coding (PNC) can effectively improve wireless networks by extracting super... more Physical-layer network coding (PNC) can effectively improve wireless networks by extracting superimposed signals and transforming collision’s dilemma into an advantage. The proposition of higher layer methods (such as Data Link and Network Layer) explicitly designed for PNC can better enhance wireless network performances. Since the field of PNC is very vast and has several applications, the researchers of the higher layers find it very difficult to propose a suitable PNC system for their research, which has led to the scarcity of research works of this type. This article proposes a new classification method designed to help researchers choose the optimal method that suits their system. This paper is a complete guide for researchers of higher layers to discover the PNC field and improve wireless network performances.
Les reseaux sans fil mailles offrent une infrastructure pour interconnecter les stations d’acces ... more Les reseaux sans fil mailles offrent une infrastructure pour interconnecter les stations d’acces de reseaux de differentes technologies. Ils disposent d’une topologie maillee ou tous les routeurs sont connectes de proche en proche sans hierarchie centrale. Le routage des donnees, dans ce type de reseaux, doit etre realise tout en optimisant les ressources du reseau et en respectant au mieux les exigences de QoS des utilisateurs. Dans cette these, nous proposons un routage oriente qualite de service dans un reseau sans fil metropolitain grâce a une approche de type cross-layer. Nous avons commence par etudier l’impact des couches PHY et MAC sur le routage afin d’en deduire la meilleure combinaison protocolaire pour un reseau sans fil maille. Nous avons, par la suite, oriente notre travail sur l’etude du comportement du protocole de routage OLSR sous differentes metriques de routage. Les resultats de cette etude ont confirme les limites des metriques existantes a reproduire la qualite...
Computer Networks, 2017
In this paper, we address the problem of QoS support in an heterogeneous single-radio single-chan... more In this paper, we address the problem of QoS support in an heterogeneous single-radio single-channel multi-rate wireless mesh network. We propose a new routing metric that provides information about link quality, based on PHY and MAC characteristics, including the link availability, the loss rate and the available bandwidth. This metric allows to apprehend inter-flow interferences and avoid bottleneck formation by balancing traffic load on the links. Based on the conflict graph model and calculation of maximal cliques, we define a method to estimate the available bandwidth of a path which considers, in addition, intra-flow interferences. Finally, we propose a routing protocol that supports this metric and we study by simulation its performances compared to different existing routing metrics and protocols. The results revealed the ability of our protocol (LARM) to support the network scalability as well as its ability to choose routes with high throughput and limited delay.
This paper presents a novel metric, Residual Link Capacity based routing metric with Interference... more This paper presents a novel metric, Residual Link Capacity based routing metric with Interference Consideration (RLCIC), for accurately finding high-throughput paths in multihop wireless mesh networks. This metric is load-sensitive and aims to balance the traffic load according to the availability of a link to support additional flows. It reproduces with effectiveness the capacity of a link since it is based on its residual bandwidth. The RLCIC metric captures accurately the available path bandwidth information when considering both the intra-flow and the inter-flow interferences. The consistency of this metric is proved formally based on notions of graph theory
Connectivity and coverage are two crucial problems for wireless sensor networks. Several studies ... more Connectivity and coverage are two crucial problems for wireless sensor networks. Several studies have focused on proposing solutions for improving and adjusting the initial deployment of a wireless sensor network to meet these two criteria. In our work, we propose a new hierarchical architecture for sensor networks that facilitates the gathering of redundancy information of the topology. Several mobile robots must then relocate, in an optimized way, redundant sensors to achieve optimal connectivity and coverage of the network. Mobile robots have to cooperate and coordinate their movement. A performance evaluation is conducted to study the trade-off between the number of required robots and its impact on the rate of network connectivity and coverage.
OATAO is an open access repository that collects the work of Toulouse researchers and makes it fr... more OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible.
2013 27th International Conference on Advanced Information Networking and Applications Workshops, 2013
Current routing mechanisms proposed for adhoc networks are still feasibly applied in Wireless Mes... more Current routing mechanisms proposed for adhoc networks are still feasibly applied in Wireless Mesh Networks given their similarities. Many researchers have conducted numerous simulations for comparing the performances of these routing protocols under various conditions and constraints. Most made comparisons are not aware of PHY/MAC layers and their impact on routing performances. In this paper we study through simulations the impact of PHY/MAC protocols on higher layers. The considered protocols include three propagation models, ie., FreeSpace, TwoRayGround and Shadowing, three different PHY/MAC protocols specified IEEE 802.11 standards namely, 802.11b, 802.11s and 802.11n, and finally three routing protocols, ie., AODV, OLSR and HWMP. In a comparative way, we investigate the effectiveness of these protocols when they coexist on a wireless mesh network environment. Our results show that the routing strategy can significantly impact the network performance only if it is strongly linked to the characteristics of the lower layers.
2013 ACS International Conference on Computer Systems and Applications (AICCSA), 2013
OATAO is an open access repository that collects the work of Toulouse researchers and makes it fr... more OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible.
2013 9th International Wireless Communications and Mobile Computing Conference (IWCMC), 2013
This paper provides a description of a wireless mesh network testbed setup and a measurement-base... more This paper provides a description of a wireless mesh network testbed setup and a measurement-based performance evaluation of the Optimized Link State Routing (OLSR) protocol [7] under three different routing metrics. The considered metrics include hop-count, ETX and ETT. The network performances are evaluated in an indoor testbed formed by heterogeneous MIMO devices. A part of our tests was about the impact of 802.11n features on the network performances showing the importance of lower layers consideration. Our measurements point out the shortcoming of each metric and eventual optimizations towards a more efficient routing. Experimental results show that OLSR-ETT outperforms OLSR-ETX and OLSR-hopcount significantly in terms of packet loss, end-to-end delay, and efficiency.
Global Information Infrastructure Symposium - GIIS 2013, 2013
OATAO is an open access repository that collects the work of Toulouse researchers and makes it fr... more OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible.
International Journal of Space-Based and Situated Computing, 2014
In this paper we study through simulations the impact of PHY/MAC protocols on higher layers. In a... more In this paper we study through simulations the impact of PHY/MAC protocols on higher layers. In a comparative way, we investigate the effectiveness of some protocols when they coexist on a wireless mesh network environment. Results show that PHY/MAC parameters have an important impact on routing performances. Based on these results, we propose two traffic-aware routing metrics based on link availability. The information about the link availability/occupancy is picked up from lower layers using a cross-layer approach. The first metric is load-sensitive and aims to balance the traffic load according to the availability of a link to support additional flows. The second metric reproduces better the capacity of a link since it is based on its residual bandwidth. Using several real experiments, we have shown that our proposals can accurately determine better paths in terms of throughput and delay. Our experiments are carried out into an heterogeneous IEEE 802.11n based network running with OLSR routing protocol.
2011 IEEE Symposium on Computers & Informatics, 2011
Wireless sensor networks are often deployed in hardly accessible or hazardous fields. Their main ... more Wireless sensor networks are often deployed in hardly accessible or hazardous fields. Their main goal is to monitor the target field and transmit surveillance data to a sink. Therefore, connectivity of the sensor network and the coverage ratio of the monitored area are the most relevant concerns to reach these goals. In this paper, we propose to use several mobile robots to assist sensor networks redeployment in order to enhance the network connectivity and the coverage ratio of the monitored area. We model the sensor network as an islets-based topology and we propose to use robots to detect and heal connectivity and coverage holes availing the sensors redundancy. Preliminary simulations showed that our new scheme can significantly enhance the connectivity ratio of the initial network and improve the coverage ratio by using few numbers of robots.
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Papers by Chiraz Houaidia