In this paper, we study the strong stability in the M/G/1 queueing system with breakdowns and rep... more In this paper, we study the strong stability in the M/G/1 queueing system with breakdowns and repairs after perturbation of the breakdown's parameter. Using the approximation conditions in the classical M/G/1 system, we obtain stability inequalities with exact computation of the constants. Thus, we can approximate the characteristics of the M/G/1 queueing system with breakdowns and repairs by the classical M/G/1 corresponding ones.
Placement optimization of wireless mesh routers using firefly optimization algorithm
2018 International Conference on Smart Communications in Network Technologies (SaCoNeT), 2018
This paper addresses the problem of optimal router nodes placement (RNP) in a wireless mesh netwo... more This paper addresses the problem of optimal router nodes placement (RNP) in a wireless mesh network. This issue consists to determine the optimal positions of mesh routers that allow the optimization of the network performance with regards to client coverage and network connectivity. To solve this issue, a bio-inspired algorithm, called Firefly optimization algorithm, has been applied since it is an NP-hard issue. The obtained results demonstrate the effectiveness of our proposed approach when compared to the existing genetic algorithm.
This paper considers the problem of router node placement (WMN-RNP) in wireless mesh networks (WM... more This paper considers the problem of router node placement (WMN-RNP) in wireless mesh networks (WMN). A wireless mesh network consists of three kinds of nodes: mesh clients, mesh routers and gateways interconnected via radio links. The problem considered in this paper is the following: given a set of mesh clients deployed in a rectangular area, determine the best placement of mesh routers so that both client coverage and network connectivity are maximized. This issue is known to be NP-hard since it can be modeled as a facility location problem. To solve this issue, we propose to use a metaheuristic technique inspired from the interactions between molecules in chemical reactions to reach a low stable energy state, namely Chemical Reaction Optimization algorithm (CRO). A simulation tool has been developed to compare the performance of our CRO algorithm to the existing Genetic Algorithm (GA) and Simulated Annealing (SA). Simulation results show that our proposed algorithm can improve client coverage by 4.5% to 18% (3% to 17% respectively) and network connectivity by 5% to 61% (4.5% to 41% respectively) when compared to GA algorithm (SA algorithm respectively).
The placement of mesh routers in a mobile mesh network strongly influences the network performanc... more The placement of mesh routers in a mobile mesh network strongly influences the network performance. In particular, when the mesh clients are mobile, this deployment issue becomes more difficult to solve since mesh routers should adapt their locations to the dynamic network topology. In this letter, we propose to apply a simulated annealing algorithm to deal with the dynamic router node placement issue. The performance metrics considered when deploying these routers are: client coverage, network connectivity, and the average distance traveled by routers. Simulation results show a significant performance improvement in terms of client coverage and network connectivity and a considerable decrease in router movements.
AEU - International Journal of Electronics and Communications, 2018
Packet delivery delay minimization is a critical issue in Wireless Sensor Networks. In mission-cr... more Packet delivery delay minimization is a critical issue in Wireless Sensor Networks. In mission-critical applications, the sensed information is highly delaysensitive, and should be transmitted to the sink within a required delay. In this paper, we propose a new mixed integer linear programming model (MILP) to address the problem of end-to-end delay minimization of data transmission in delay-sensitive applications such as healthcare monitoring. The proposed model simultaneously guarantees 1) timely delivery data packets, 2) network reliability, 3) connectivity, and 4) flow preservation. We verify by computational experiments that the developed mixed integer linear model, using Cplex, is able to provide an optimal solution for timely data packet delivery of all our small and medium size problems.
World Wide Web (WWW) requests have continued to grow at an exponential rate for the reason that i... more World Wide Web (WWW) requests have continued to grow at an exponential rate for the reason that it, already, constitutes the dominant workload component for internet traffic (Wang 1999). The main implications related to this fact are the fastest and the easiest internet information access, the cheapest in use, the variety of information domains such as: scientific research, education, sport, teaching, business, etc. (Wang 1999). Also, the physical infrastructure internet network evolution represents another very important reason of this growth. Since the majority of web objects are requested by different clients, caching them improves, significantly, the web performances by reducing (1) the server overload, (2) the data volume transferred between servers and clients, (3) the band-width consumption, (4) the network overload surcharge, (5) the clients' average latency. Also, the caching improves the information availability. Nevertheless, the caching may increase, in some situations, (1) the data inconsistency rate, (2) the client latency in the case of a miss, and (3) the clients' average latency because of the limited number of clients per proxy. Also, the original server cannot have a clear idea about the clients' access model and the most popular files. Therefore, caching has become the important variable to fully actualize the future internet dream by carefully solving the problems in frequency and recency in objects (Abdullahi et al. 2015). The main key of the proxy cache efficiency is the document replacement policy that can reach high performances. Determining which part of the content is to be cached? What is the most appropriate time for caching? How the object would be cached (placed and replaced) and also at what path would the object be cached? (Abdullahi et al. 2015). All this is the main role of
Analytical modeling and performance study of the Enhanced Distributed Channel Access (EDCA) funct... more Analytical modeling and performance study of the Enhanced Distributed Channel Access (EDCA) function of the IEEE 802.11e standard has been the topic of various works available in the literature. Nevertheless, the Packet Fragmentation (PF) conceived by the IEEE 802.11 work group for decreasing the effect of noise-related losses on the performances of IEEE 802.11 networks, has not at all been taken into account in the analytical models proposed for evaluating the performance of the Opportunity Transmission Limit (TXOPLimit), which is a key parameter of the EDCA function for a Differentiated Service in an IEEE 802.11e network. While, the PF can be employed with the TXOPLimit, in order to boost the efficiency of the Contention Free Burst of both Voice and Video streams under noise-related losses. In this paper, we aim at extending the Markov chain models proposed for the IEEE 802.11e-EDCA network, in order to especially model the TXOPLimit, the PF and the Packet Error Rate. Besides, we elaborate a mathematical model to compute the saturation throughput of Access Categories, Voice, Video, Best Effort and Background. The achieved numerical results indicate, for the first time that, the PF permits boosting the TXOPLimit efficiency under noise-related losses. Thus, the saturation throughputs of both Voice and Video access categories are substantially enhanced.
This paper deals with the problem of routing in Mobile Ad hoc Networks (MANET). A mobile ad hoc n... more This paper deals with the problem of routing in Mobile Ad hoc Networks (MANET). A mobile ad hoc network is a collection of mobile devices deployed without any pre-established infrastructure or centralized administration. Routing is a very challenging issue since the appearance of this technology. The main goal of every routing protocol is to find a route between two communicating nodes while optimizing overall performances of the network. This paper introduces a novel routing protocol inspired from the nature and that should deal with the dynamic aspect of MANET. The used approach, called Intelligent Water Drops (IWD), mimics the processes that happen in the natural river systems, particularly, the actions that water drops perform in the rivers to find the shortest path to their destination (sea). In fact, it is observed that water drops of a river often find good paths among lots of possible paths in their ways from a source to a destination. We combined these ideas with a route failure prediction mechanism to develop a new routing protocol for MANETs called IWDRP. This prediction method is based on the received signal strength indicator. Further simulation results show that IWDRP is able to achieve better results in terms of packet delivery, end-to-end delay in comparison with AODV-BFABL. The achievement in this paper has certain reference value to the further study of the routing issue in MANETs.
Over the last three decades, many researchers and decision makers have investigated separately th... more Over the last three decades, many researchers and decision makers have investigated separately the issues of economic growth, profitability, and quality of life when thinking about business electricity sustainability. The correlations between these paradigms still remain at the stage of discussions, debates, and forecasts as a reaction to the occurred conflicts and disasters. There is a lack of real encryption that demonstrates their interactions. It is useful to materialize the expectations of stakeholders by mathematical modeling and providing answers to specific wants of each society according to its financial resources, its concrete societal objectives, especially to which kind of energy legacy it wants to contribute to future generations. It is imperative that experts assist decision makers, through transparent methods that seek consensus. To this end, the analytic hierarchy process (AHP) method was proposed as it has proven its efficiency in many areas of human activities. The outcomes were analyzed using this method, and the findings were compared and recommendations were made using other multi-criteria decisionmaking (MCDM) methods. As for energy sustainability, it is imperative to move toward renewable energy resources while trying to hold together the benefits, opportunities, costs, and risks (BOCR). We have retained that status quo is not sustainable.
We propose in this article a M/G/c/c state dependent queuing model for road traffic flow. The mod... more We propose in this article a M/G/c/c state dependent queuing model for road traffic flow. The model is based on finite capacity queuing theory which captures the stationary density-flow relationships. It is also inspired from the deterministic Godunov scheme for the road traffic simulation. We first present a reformulation of the existing linear case of M/G/c/c state dependent model, in order to use flow rather than speed variables. We then extend this model in order to consider upstream traffic demand and downstream traffic supply. After that, we propose the model for two road sections in tandem where both sections influence each other. In order to deal with this mutual dependence, we solve an implicit system given by an algebraic equation. Finally, we derive some performance measures (throughput and expected travel time). A comparison with results predicted by the M/G/c/c state dependent queuing networks shows that the model we propose here captures really the dynamics of the road traffic.
This chapter deals with power systems reliability including technical, economical, and decisional... more This chapter deals with power systems reliability including technical, economical, and decisional aspects. Knowing that almost 90% of failures occur in the distribution systems, great interest was dedicated to this part of the system, and the first work was oriented to reliability indices defined as objectives to attempt and as performance measures in the electricity market. Some works deal with the managers' behavior, and the customers reactions are modeled using economic criteria in uncertain future and inspired from game theory. When studying components, degradation models were introduced and combined with the effects of socks to study the reliability changing during system operation. In some works, the correlation between maintenance policies and reliability aspects was highlighted. In a recent work, considering the importance of new technologies integration and renewable energy insertion to power systems, it was revealed that reliability aspects and energy sustainability are two fundamental issues of progress in a given society.
Performance modeling of the IEEE 802.15.4e TSCH enabling both shared and dedicated links in industrial WSNs
Computing, 2021
Time Slotted Channel Hopping (TSCH) is one of the Medium Access Control methods proposed in the I... more Time Slotted Channel Hopping (TSCH) is one of the Medium Access Control methods proposed in the IEEE 802.15.4e standard to deal with the requirements of the industrial Wireless Sensor Networks (WSNs), especially in terms of high reliability and low latency. The key feature of the TSCH method is the combination between a time slotted access with a channel hopping, while considering both shared and dedicated links. The latter are essential for ensuring transmissions without loss and additional delays. Therefore, the objective we are seeking to reach in this paper is to demonstrate the benefit use of dedicated links on industrial WSNs-based 802.15.4e TSCH method. To this end, we propose an analytical model-based Markov chains for the TSCH method taking into account the dedicated links, and we estimate the transmission probability $$\tau $$ τ of a data packet. The latter will be then used to develop others analytical models, in order to derive a number of performance metrics, namely the average access delay, the reliability, the throughput, and the energy consumption. Furthermore, to validate the analytical model, we perform extensive simulations-based Monte-Carlo. Finally, to give credibility to the obtained simulation results, we compute $$95\%$$ 95 % confidence intervals. Numerical results show that increasing the number of dedicated links reduces significantly the retransmission probability offering best network performances in terms of average access delay, reliability and throughput.
Performance Enhancement of Cache Consistency Mechanism in Mobile Computing Environment
2021 5th International Symposium on Multidisciplinary Studies and Innovative Technologies (ISMSIT), 2021
In the context of mobile computing, the cache memory technique turns out to be the most widely us... more In the context of mobile computing, the cache memory technique turns out to be the most widely used and the most effective solution to improve several quantities, namely: (1) the bandwidth consumption, (2) the information availability, and (3) the node latency. particularly in the Internet of Things (IoT) environment, where objects have limited storage and computing capacities. However, this solution may cause some cache management issues, specifically data consistency and data replacement. In this paper, we strive to assess the relationship between the consistency mechanism’s performance and the implemented replacement strategy and determine whether they are correlated or not. Afterward, we focus on improving the caching consistency mechanism’s performance based on the Time To Live principle (TTL) using the IoT-Data lifetime and the data Variable-TTL. Therefore, two based-TTL consistency mechanisms were implemented and evaluated using three replacement strategies: LFU (Least Frequently Used), LRU (Least Recently Used), and LFRU (Least Frequently Recently Used). The simulation experiments show that the consistency mechanism performance strongly depends on the implemented replacement strategy, which can significantly improve the performance, particularly in terms of data availability and end-user latency. In addition, the relative frequency and the variable-TTL considerably improve the wireless mobile caching performance.
The quality of services (QoS) has a key role to improve the performances of the collaborative mob... more The quality of services (QoS) has a key role to improve the performances of the collaborative mobile learning. However, many factors can limit it such as the cache management policies, the collaboration architecture, a heavy communication, etc. Therefore, we are interested in developing an impeccable learning system supporting cache management, collaboration architecture decisiveness, based mobile agent and web services standardization. The aim is to improve the quality of mobile learning services in term of information availability (hit rates and byte hit rates), learners' average latency and the cognitive profiles of students. Consequently, we implemented four removal policies named Least Frequently Used (LFU), First In First Out (FIFO), Least Recently Used (LFU) and Size. In addition, we proposed and evaluated three collaboration architectures based mobile agent named Sequential, Random and diffusion mechanism. Experimental results show that our system improves the cognitive profiles of students and reduces the learners' average latency. Furthermore, the experience and the performance results gained from this system prove that the removal policies performances depend on the learning method of each student and its collaboration patterns. For this raison, it is advantageous to allow the student to choose and/or change the removal policy during each learning session. However, diffusion mechanism provides the best performances in term of learners' average latency.
Distributed geolocalisation based on nearest neighbor heuristic, in wireless sensor networks
2014 4th International Symposium ISKO-Maghreb: Concepts and Tools for knowledge Management (ISKO-Maghreb), 2014
Localization in wireless sensor networks, whose nodes are deployed randomly, is to determine rela... more Localization in wireless sensor networks, whose nodes are deployed randomly, is to determine relative or absolute coordinates of nodes. The use of localization mechanisms is essential for both the communication protocols (geographic routing), and for some applications (vehicle tracking, critical event detection). In this paper, we proposed a location protocol called RSSI-LCN (Received Signal Strength Indicator with Location based on Closest Neighbor), which combine two concepts, the first is the RSSI mechanism for calculating distance, based on the property of proportionality of transmitted signal attenuation compared to the distance, the second concept is the traverse network method, based on heuristic of nearest neighbor. The simulation results and analysis show that our protocol minimize the energy consumption through the completion of the localization algorithm before the traversing all the network. The advantage of the RSSI-LCN protocol is that it is very economical in power consumption, and is suitable for dense sensor networks.
In this paper, we study the strong stability in the M/G/1 queueing system with breakdowns and rep... more In this paper, we study the strong stability in the M/G/1 queueing system with breakdowns and repairs after perturbation of the breakdown's parameter. Using the approximation conditions in the classical M/G/1 system, we obtain stability inequalities with exact computation of the constants. Thus, we can approximate the characteristics of the M/G/1 queueing system with breakdowns and repairs by the classical M/G/1 corresponding ones.
Placement optimization of wireless mesh routers using firefly optimization algorithm
2018 International Conference on Smart Communications in Network Technologies (SaCoNeT), 2018
This paper addresses the problem of optimal router nodes placement (RNP) in a wireless mesh netwo... more This paper addresses the problem of optimal router nodes placement (RNP) in a wireless mesh network. This issue consists to determine the optimal positions of mesh routers that allow the optimization of the network performance with regards to client coverage and network connectivity. To solve this issue, a bio-inspired algorithm, called Firefly optimization algorithm, has been applied since it is an NP-hard issue. The obtained results demonstrate the effectiveness of our proposed approach when compared to the existing genetic algorithm.
This paper considers the problem of router node placement (WMN-RNP) in wireless mesh networks (WM... more This paper considers the problem of router node placement (WMN-RNP) in wireless mesh networks (WMN). A wireless mesh network consists of three kinds of nodes: mesh clients, mesh routers and gateways interconnected via radio links. The problem considered in this paper is the following: given a set of mesh clients deployed in a rectangular area, determine the best placement of mesh routers so that both client coverage and network connectivity are maximized. This issue is known to be NP-hard since it can be modeled as a facility location problem. To solve this issue, we propose to use a metaheuristic technique inspired from the interactions between molecules in chemical reactions to reach a low stable energy state, namely Chemical Reaction Optimization algorithm (CRO). A simulation tool has been developed to compare the performance of our CRO algorithm to the existing Genetic Algorithm (GA) and Simulated Annealing (SA). Simulation results show that our proposed algorithm can improve client coverage by 4.5% to 18% (3% to 17% respectively) and network connectivity by 5% to 61% (4.5% to 41% respectively) when compared to GA algorithm (SA algorithm respectively).
The placement of mesh routers in a mobile mesh network strongly influences the network performanc... more The placement of mesh routers in a mobile mesh network strongly influences the network performance. In particular, when the mesh clients are mobile, this deployment issue becomes more difficult to solve since mesh routers should adapt their locations to the dynamic network topology. In this letter, we propose to apply a simulated annealing algorithm to deal with the dynamic router node placement issue. The performance metrics considered when deploying these routers are: client coverage, network connectivity, and the average distance traveled by routers. Simulation results show a significant performance improvement in terms of client coverage and network connectivity and a considerable decrease in router movements.
AEU - International Journal of Electronics and Communications, 2018
Packet delivery delay minimization is a critical issue in Wireless Sensor Networks. In mission-cr... more Packet delivery delay minimization is a critical issue in Wireless Sensor Networks. In mission-critical applications, the sensed information is highly delaysensitive, and should be transmitted to the sink within a required delay. In this paper, we propose a new mixed integer linear programming model (MILP) to address the problem of end-to-end delay minimization of data transmission in delay-sensitive applications such as healthcare monitoring. The proposed model simultaneously guarantees 1) timely delivery data packets, 2) network reliability, 3) connectivity, and 4) flow preservation. We verify by computational experiments that the developed mixed integer linear model, using Cplex, is able to provide an optimal solution for timely data packet delivery of all our small and medium size problems.
World Wide Web (WWW) requests have continued to grow at an exponential rate for the reason that i... more World Wide Web (WWW) requests have continued to grow at an exponential rate for the reason that it, already, constitutes the dominant workload component for internet traffic (Wang 1999). The main implications related to this fact are the fastest and the easiest internet information access, the cheapest in use, the variety of information domains such as: scientific research, education, sport, teaching, business, etc. (Wang 1999). Also, the physical infrastructure internet network evolution represents another very important reason of this growth. Since the majority of web objects are requested by different clients, caching them improves, significantly, the web performances by reducing (1) the server overload, (2) the data volume transferred between servers and clients, (3) the band-width consumption, (4) the network overload surcharge, (5) the clients' average latency. Also, the caching improves the information availability. Nevertheless, the caching may increase, in some situations, (1) the data inconsistency rate, (2) the client latency in the case of a miss, and (3) the clients' average latency because of the limited number of clients per proxy. Also, the original server cannot have a clear idea about the clients' access model and the most popular files. Therefore, caching has become the important variable to fully actualize the future internet dream by carefully solving the problems in frequency and recency in objects (Abdullahi et al. 2015). The main key of the proxy cache efficiency is the document replacement policy that can reach high performances. Determining which part of the content is to be cached? What is the most appropriate time for caching? How the object would be cached (placed and replaced) and also at what path would the object be cached? (Abdullahi et al. 2015). All this is the main role of
Analytical modeling and performance study of the Enhanced Distributed Channel Access (EDCA) funct... more Analytical modeling and performance study of the Enhanced Distributed Channel Access (EDCA) function of the IEEE 802.11e standard has been the topic of various works available in the literature. Nevertheless, the Packet Fragmentation (PF) conceived by the IEEE 802.11 work group for decreasing the effect of noise-related losses on the performances of IEEE 802.11 networks, has not at all been taken into account in the analytical models proposed for evaluating the performance of the Opportunity Transmission Limit (TXOPLimit), which is a key parameter of the EDCA function for a Differentiated Service in an IEEE 802.11e network. While, the PF can be employed with the TXOPLimit, in order to boost the efficiency of the Contention Free Burst of both Voice and Video streams under noise-related losses. In this paper, we aim at extending the Markov chain models proposed for the IEEE 802.11e-EDCA network, in order to especially model the TXOPLimit, the PF and the Packet Error Rate. Besides, we elaborate a mathematical model to compute the saturation throughput of Access Categories, Voice, Video, Best Effort and Background. The achieved numerical results indicate, for the first time that, the PF permits boosting the TXOPLimit efficiency under noise-related losses. Thus, the saturation throughputs of both Voice and Video access categories are substantially enhanced.
This paper deals with the problem of routing in Mobile Ad hoc Networks (MANET). A mobile ad hoc n... more This paper deals with the problem of routing in Mobile Ad hoc Networks (MANET). A mobile ad hoc network is a collection of mobile devices deployed without any pre-established infrastructure or centralized administration. Routing is a very challenging issue since the appearance of this technology. The main goal of every routing protocol is to find a route between two communicating nodes while optimizing overall performances of the network. This paper introduces a novel routing protocol inspired from the nature and that should deal with the dynamic aspect of MANET. The used approach, called Intelligent Water Drops (IWD), mimics the processes that happen in the natural river systems, particularly, the actions that water drops perform in the rivers to find the shortest path to their destination (sea). In fact, it is observed that water drops of a river often find good paths among lots of possible paths in their ways from a source to a destination. We combined these ideas with a route failure prediction mechanism to develop a new routing protocol for MANETs called IWDRP. This prediction method is based on the received signal strength indicator. Further simulation results show that IWDRP is able to achieve better results in terms of packet delivery, end-to-end delay in comparison with AODV-BFABL. The achievement in this paper has certain reference value to the further study of the routing issue in MANETs.
Over the last three decades, many researchers and decision makers have investigated separately th... more Over the last three decades, many researchers and decision makers have investigated separately the issues of economic growth, profitability, and quality of life when thinking about business electricity sustainability. The correlations between these paradigms still remain at the stage of discussions, debates, and forecasts as a reaction to the occurred conflicts and disasters. There is a lack of real encryption that demonstrates their interactions. It is useful to materialize the expectations of stakeholders by mathematical modeling and providing answers to specific wants of each society according to its financial resources, its concrete societal objectives, especially to which kind of energy legacy it wants to contribute to future generations. It is imperative that experts assist decision makers, through transparent methods that seek consensus. To this end, the analytic hierarchy process (AHP) method was proposed as it has proven its efficiency in many areas of human activities. The outcomes were analyzed using this method, and the findings were compared and recommendations were made using other multi-criteria decisionmaking (MCDM) methods. As for energy sustainability, it is imperative to move toward renewable energy resources while trying to hold together the benefits, opportunities, costs, and risks (BOCR). We have retained that status quo is not sustainable.
We propose in this article a M/G/c/c state dependent queuing model for road traffic flow. The mod... more We propose in this article a M/G/c/c state dependent queuing model for road traffic flow. The model is based on finite capacity queuing theory which captures the stationary density-flow relationships. It is also inspired from the deterministic Godunov scheme for the road traffic simulation. We first present a reformulation of the existing linear case of M/G/c/c state dependent model, in order to use flow rather than speed variables. We then extend this model in order to consider upstream traffic demand and downstream traffic supply. After that, we propose the model for two road sections in tandem where both sections influence each other. In order to deal with this mutual dependence, we solve an implicit system given by an algebraic equation. Finally, we derive some performance measures (throughput and expected travel time). A comparison with results predicted by the M/G/c/c state dependent queuing networks shows that the model we propose here captures really the dynamics of the road traffic.
This chapter deals with power systems reliability including technical, economical, and decisional... more This chapter deals with power systems reliability including technical, economical, and decisional aspects. Knowing that almost 90% of failures occur in the distribution systems, great interest was dedicated to this part of the system, and the first work was oriented to reliability indices defined as objectives to attempt and as performance measures in the electricity market. Some works deal with the managers' behavior, and the customers reactions are modeled using economic criteria in uncertain future and inspired from game theory. When studying components, degradation models were introduced and combined with the effects of socks to study the reliability changing during system operation. In some works, the correlation between maintenance policies and reliability aspects was highlighted. In a recent work, considering the importance of new technologies integration and renewable energy insertion to power systems, it was revealed that reliability aspects and energy sustainability are two fundamental issues of progress in a given society.
Performance modeling of the IEEE 802.15.4e TSCH enabling both shared and dedicated links in industrial WSNs
Computing, 2021
Time Slotted Channel Hopping (TSCH) is one of the Medium Access Control methods proposed in the I... more Time Slotted Channel Hopping (TSCH) is one of the Medium Access Control methods proposed in the IEEE 802.15.4e standard to deal with the requirements of the industrial Wireless Sensor Networks (WSNs), especially in terms of high reliability and low latency. The key feature of the TSCH method is the combination between a time slotted access with a channel hopping, while considering both shared and dedicated links. The latter are essential for ensuring transmissions without loss and additional delays. Therefore, the objective we are seeking to reach in this paper is to demonstrate the benefit use of dedicated links on industrial WSNs-based 802.15.4e TSCH method. To this end, we propose an analytical model-based Markov chains for the TSCH method taking into account the dedicated links, and we estimate the transmission probability $$\tau $$ τ of a data packet. The latter will be then used to develop others analytical models, in order to derive a number of performance metrics, namely the average access delay, the reliability, the throughput, and the energy consumption. Furthermore, to validate the analytical model, we perform extensive simulations-based Monte-Carlo. Finally, to give credibility to the obtained simulation results, we compute $$95\%$$ 95 % confidence intervals. Numerical results show that increasing the number of dedicated links reduces significantly the retransmission probability offering best network performances in terms of average access delay, reliability and throughput.
Performance Enhancement of Cache Consistency Mechanism in Mobile Computing Environment
2021 5th International Symposium on Multidisciplinary Studies and Innovative Technologies (ISMSIT), 2021
In the context of mobile computing, the cache memory technique turns out to be the most widely us... more In the context of mobile computing, the cache memory technique turns out to be the most widely used and the most effective solution to improve several quantities, namely: (1) the bandwidth consumption, (2) the information availability, and (3) the node latency. particularly in the Internet of Things (IoT) environment, where objects have limited storage and computing capacities. However, this solution may cause some cache management issues, specifically data consistency and data replacement. In this paper, we strive to assess the relationship between the consistency mechanism’s performance and the implemented replacement strategy and determine whether they are correlated or not. Afterward, we focus on improving the caching consistency mechanism’s performance based on the Time To Live principle (TTL) using the IoT-Data lifetime and the data Variable-TTL. Therefore, two based-TTL consistency mechanisms were implemented and evaluated using three replacement strategies: LFU (Least Frequently Used), LRU (Least Recently Used), and LFRU (Least Frequently Recently Used). The simulation experiments show that the consistency mechanism performance strongly depends on the implemented replacement strategy, which can significantly improve the performance, particularly in terms of data availability and end-user latency. In addition, the relative frequency and the variable-TTL considerably improve the wireless mobile caching performance.
The quality of services (QoS) has a key role to improve the performances of the collaborative mob... more The quality of services (QoS) has a key role to improve the performances of the collaborative mobile learning. However, many factors can limit it such as the cache management policies, the collaboration architecture, a heavy communication, etc. Therefore, we are interested in developing an impeccable learning system supporting cache management, collaboration architecture decisiveness, based mobile agent and web services standardization. The aim is to improve the quality of mobile learning services in term of information availability (hit rates and byte hit rates), learners' average latency and the cognitive profiles of students. Consequently, we implemented four removal policies named Least Frequently Used (LFU), First In First Out (FIFO), Least Recently Used (LFU) and Size. In addition, we proposed and evaluated three collaboration architectures based mobile agent named Sequential, Random and diffusion mechanism. Experimental results show that our system improves the cognitive profiles of students and reduces the learners' average latency. Furthermore, the experience and the performance results gained from this system prove that the removal policies performances depend on the learning method of each student and its collaboration patterns. For this raison, it is advantageous to allow the student to choose and/or change the removal policy during each learning session. However, diffusion mechanism provides the best performances in term of learners' average latency.
Distributed geolocalisation based on nearest neighbor heuristic, in wireless sensor networks
2014 4th International Symposium ISKO-Maghreb: Concepts and Tools for knowledge Management (ISKO-Maghreb), 2014
Localization in wireless sensor networks, whose nodes are deployed randomly, is to determine rela... more Localization in wireless sensor networks, whose nodes are deployed randomly, is to determine relative or absolute coordinates of nodes. The use of localization mechanisms is essential for both the communication protocols (geographic routing), and for some applications (vehicle tracking, critical event detection). In this paper, we proposed a location protocol called RSSI-LCN (Received Signal Strength Indicator with Location based on Closest Neighbor), which combine two concepts, the first is the RSSI mechanism for calculating distance, based on the property of proportionality of transmitted signal attenuation compared to the distance, the second concept is the traverse network method, based on heuristic of nearest neighbor. The simulation results and analysis show that our protocol minimize the energy consumption through the completion of the localization algorithm before the traversing all the network. The advantage of the RSSI-LCN protocol is that it is very economical in power consumption, and is suitable for dense sensor networks.
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