Salah MERNIZ - Academia.edu (original) (raw)

Papers by Salah MERNIZ

Nowadays, Vehicular ad hoc Networks (VANETs) gained a significant place in Intelligent Transport ... more Nowadays, Vehicular ad hoc Networks (VANETs) gained a significant place in Intelligent Transport Systems (ITS). Their objective is to provide road users with useful services such as safety, infotainment and traffic management, by integrating information and communication technology into vehicles and transport infrastructure. As a result, the design of an efficient VANET routing protocol is very important. Traditional architecture of the network impose particular communication solution implementation. This implementation often fail to fully support the constraints of VANET like topology dynamic changes. The cross-layer design paradigm was introduced as an alternative to develop more efficient and robust communication protocols. This paper presents an overview of the main works that have applied a cross-layer technique to improve the routing function of a VANET.

Proceedings of the 2nd International Conference on Networking, Information Systems & Security

The complexity level of hardware design has increased extensively, and consequently it became sub... more The complexity level of hardware design has increased extensively, and consequently it became subject of errors. That's why it is extremely important to verify the correctness of designs, especially in critical systems like those of security. The problem is that the typical Hardware Description Languages (HDLs) like VHDL and Verilog are made mostly for description and simulation purposes; however, the simulation is insufficient validation technique in complex designs such as the cryptographic circuits. Thus, formal verification has become an important technique towards establishing the correctness of hardware designs; nonetheless it still faces many challenges; which make it a worth-while research problem. This paper presents an approach to formally verify the cryptographic circuits. It consists of using a purely functional framework namely Haskell to describe both the behavioral and structural descriptions. In addition, such approach relies on the use of hierarchy and modularity techniques in order to reduce the design complexity, and hence simplify the verification task. Last but not least we use Lava which is an HDL embedded into Haskell that allows checking automatically the safety and equivalence properties of circuits in several ways. To show the potential features of the proposed approach, we applied it to the Data Encryption Standard (DES) circuit, which is a symmetric block cipher. Thereafter, a methodological design approach for the verification of the design implementation against the specification is presented.

Springer eBooks, 2017

A Vehicular Ad hoc Network (VANET) is an interconnection of vehicles that communicate through wir... more A Vehicular Ad hoc Network (VANET) is an interconnection of vehicles that communicate through wireless technologies. It offers to road users a wide variety of applications which can be classified into four main categories: safety, road traffic, comfort and infotainment. This paper deals with safety applications. Their main goal is to detect critical road conditions (e.g. accidents, black ice, etc.) and/or send notifications to other vehicles in the network. An effective dissemination of such a message relies on multi-hop retransmissions. Thus an explicit or implicit cooperation between vehicles is needed in order to relay the message over a wide area. The main challenge is to avoid the broadcast storm problem. This paper proposes an efficient segment-delay based method that divides the road into several segments depending on the network density and utilises a waiting time update technique to expedite the dissemination process with respect to network performance.

Journal of High Speed Networks, Jul 29, 2022

In recent years, vehicular communication systems have taken an important place in Intelligent Tra... more In recent years, vehicular communication systems have taken an important place in Intelligent Transport Systems (ITS). These systems are designed on self-organizing networks, known as Vehicular Ad hoc NETworks (VANETs). Their objective is to struggle against road safety problems and road traffic congestion by integrating information and communication technologies in road infrastructures and vehicles. VANET differs from other types of ad hoc networks by high mobility and very dynamic topology. Consequently, the design of an efficient VANET routing protocol becomes a challenging task. Many routing schemes with QoS (Quality of Service) have been proposed in the literature for VANET, to satisfy the performances required by the different applications running upon such networks. Cross-layer designs, which make it possible to exchange and share information between the different layers of the network, have shown to be efficient in VANETs. This paper proposes an improved version of the geographic Greedy algorithm as a cross-layer routing protocol for VANETs. The cooperation between the network layer and the lower layers involves three cyber-physical parameters: Speed, position and Signal-to-Noise Ratio (SNR). The simulation results over the Network Simulator-3 (NS3) demonstrated the effectiveness of the proposed solution in terms of end-to-end delay, throughput and packet delivery ratio.

International Journal of Internet Technology and Secured Transactions, 2020

We propose a reliable dissemination protocol for broadcasting safety messages in vehicular ad hoc... more We propose a reliable dissemination protocol for broadcasting safety messages in vehicular ad hoc networks called Segment Delay Based Broadcasting Protocol (SDBP). The protocol has a twofold goal: limiting the risk of interference and reducing the dissemination time. To achieve these goals, two mechanisms are proposed. The first one divides vehicle's coverage area into several segments depending on the local density. Thereafter, the priority to relay a message is given to nodes that are in the farthest segment from the source node. The second mechanism allows reducing the waiting time thanks to a periodic update process. The performances of SDBP have been studied in an environment with multiple concurrent data traffics. The goal was to validate its capacity when the radio channel becomes overloaded. The comparison study (in terms of delivery ratio, dissemination time, forwarders and redundancy packets ratio) shows that SDBP outperforms two VANETs' broadcasting protocols.

TELKOMNIKA Telecommunication Computing Electronics and Control, Oct 1, 2019

MAC Protocols enables sensor nodes of the same WSN to access a common shared communication channe... more MAC Protocols enables sensor nodes of the same WSN to access a common shared communication channel. Many researchers have proposed different solutions explaining how to design and implement these protocols. The main goal of most MACs protocols is how to prolong lifetime of the WSN as long as possible by reducing energy consumption since it is often impossible to change or to recharge sensors' batteries. The majority of these protocols designed for WSN are based on "duty-cycle" technique. Every node of the WSN operates on two periods: active period and sleep period to save energy. Until now (to our knowledge) there is no ideal protocol for this purpose. The main reason relies on the lack of standardization at lower layers (physical layer) and (physical) sensor hardware. Therefore, the MAC protocol choice remains application-dependent. A useful MAC protocol should be able to adapt to network changes (topology, nodes density and network size). This paper surveys MAC protocols for WSNs and discusses the main characteristics, advantages and disadvantages of currently popular protocols.

Bringing to the market intelligent vehicles is one of the current challenges faced by car manufac... more Bringing to the market intelligent vehicles is one of the current challenges faced by car manufacturers. These vehicles must be able to communicate in order to cooperate and be more effective. The issue of inter-vehicle communications is an active research topic. This paper proposes a reliable geographical broadcasting protocol which has a twofold goal: limiting the risk of interference and reducing the dissemination time. To achieve theses goals, two mechanisms are proposed. The first one divides the road (more precisely, each vehicle's coverage area) into several segments depending on the local density. Thereafter, the priority to relay a message is given to nodes that are in the farthest segment from the source node. The second mechanism allows to reduce the waiting time thanks to a periodic update process. This paper also analysis the performance of geographical broadcasting protocols in case of multiple simultaneous communications. The goal is to observe how these protocols behave when the radio channel becomes overloaded. The comparison study (in terms of packet loss and dissemination time) shows that the proposed protocol outperforms two other VANETs' broadcasting protocols.

During these last years, Intelligent Transport Systems (ITS) have experienced a great growth in b... more During these last years, Intelligent Transport Systems (ITS) have experienced a great growth in both areas: academic and industrial. ITS which aim to increase safety and comfort for users' transport, are essentially governed by Vehicular Ad hoc Networks: VANETs. In such networks, nodes represent smart vehicles that can communicate either between themselves to exchange traffic information or with roadside infrastructure to disseminate or request useful information. Therefore, the congestion control remains one of the most challenging problems of these networks. This paper surveys congestion control techniques, which are divided into three categories: Rate adaptation, Media access control (MAC) and trajectory based schemes. For each technique we give its principle, its merits and its limits. A comparative study with respect to some relevant metrics is given as well.

2017 IEEE 9th Latin-American Conference on Communications (LATINCOM)

Bringing to the market intelligent vehicles is one of the current challenges faced by car manufac... more Bringing to the market intelligent vehicles is one of the current challenges faced by car manufacturers. These vehicles must be able to communicate in order to cooperate and be more effective. The issue of inter-vehicle communications is an active research topic. This paper proposes a reliable geographical broadcasting protocol which has a twofold goal: limiting the risk of interference and reducing the dissemination time. To achieve theses goals, two mechanisms are proposed. The first one divides the road (more precisely, each vehicle's coverage area) into several segments depending on the local density. Thereafter, the priority to relay a message is given to nodes that are in the farthest segment from the source node. The second mechanism allows to reduce the waiting time thanks to a periodic update process. This paper also analysis the performance of geographical broadcasting protocols in case of multiple simultaneous communications. The goal is to observe how these protocols behave when the radio channel becomes overloaded. The comparison study (in terms of packet loss and dissemination time) shows that the proposed protocol outperforms two other VANETs' broadcasting protocols.

Journal of High Speed Networks

In recent years, vehicular communication systems have taken an important place in Intelligent Tra... more In recent years, vehicular communication systems have taken an important place in Intelligent Transport Systems (ITS). These systems are designed on self-organizing networks, known as Vehicular Ad hoc NETworks (VANETs). Their objective is to struggle against road safety problems and road traffic congestion by integrating information and communication technologies in road infrastructures and vehicles. VANET differs from other types of ad hoc networks by high mobility and very dynamic topology. Consequently, the design of an efficient VANET routing protocol becomes a challenging task. Many routing schemes with QoS (Quality of Service) have been proposed in the literature for VANET, to satisfy the performances required by the different applications running upon such networks. Cross-layer designs, which make it possible to exchange and share information between the different layers of the network, have shown to be efficient in VANETs. This paper proposes an improved version of the geogr...

2017 13th International Wireless Communications and Mobile Computing Conference (IWCMC), 2017

During these last years, Intelligent Transport Systems (ITS) have experienced a great growth in b... more During these last years, Intelligent Transport Systems (ITS) have experienced a great growth in both areas: academic and industrial. ITS which aim to increase safety and comfort for users' transport, are essentially governed by Vehicular Ad hoc Networks: VANETs. In such networks, nodes represent smart vehicles that can communicate either between themselves to exchange traffic information or with roadside infrastructure to disseminate or request useful information. Therefore, the congestion control remains one of the most challenging problems of these networks. This paper surveys congestion control techniques, which are divided into three categories: Rate adaptation, Media access control (MAC) and trajectory based schemes. For each technique we give its principle, its merits and its limits. A comparative study with respect to some relevant metrics is given as well.

2018 International Conference on Innovations in Information Technology (IIT), 2018

this article aims to improve two important previous studies, dealing with the congestion problem ... more this article aims to improve two important previous studies, dealing with the congestion problem for VANETs. After giving a brief description of each method, we identify their strong aspects and drawbacks, and we propose some improvements independently of each another. Then we propose a combination of these two methods into one scheme, which results in a general enhancement to the whole system, because it takes advantages of each method. Finally, we present the theoretical expected results of this refinement.

IET Computers & Digital Techniques, 2021

The merit of higher order functions for hardware description and transformation is widely acknowl... more The merit of higher order functions for hardware description and transformation is widely acknowledged by hardware designers. However, the use of higher order types makes their correctness proof very difficult. Herein, a new proof approach based on the principle of partial application is proposed which transforms higher order functions into partially applied first-order ones. Therefore, parameterised architectures modelled by higher order functions could be easily redefined only over first-order types. The proof could be performed by induction within the same specification framework that avoids translating the higher order properties between different semantics, which remains extremely difficult. Using the notion of parameterisation where verified components are used as parameters to build more complex ones, the approach fits elegantly in the incremental bottom-up design where both the design and its proof could be developed in a systematic way. The potential features of the proposed methodological proof approach are demonstrated over a detailed example of a circuit design and verification within a functional framework. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

2020 International Conference on Advanced Aspects of Software Engineering (ICAASE), 2020

Vehicular Ad hoc Network (VANET) has gained a lot of interest in academia and industry domains. H... more Vehicular Ad hoc Network (VANET) has gained a lot of interest in academia and industry domains. High speed of vehicles, rapid change in topology and environmental characteristics of the city make the routing in VANET a very challenging problem. Traditional VANET routing protocols where decisions are made solely on local neighborhood observations have shown poor network performance. In contrast, the use of the Software Defined Network (SDN) paradigm, which is based on the global traffic view, has proven to be efficient in improving such performance. Internet of Vehicles (IoV) has emerged as a new technology that extends VANET architectures such that to meet the ever growing Intelligent Transport Systems (ITS) requirements. This paper surveys both traditional and SDN-based VANET routing schemes with a comparative study involving the main relevant performance parameters. It also gives an investigation of integration of SDN into an IoV environment that has shown to be very beneficial with respect to network performances.

Lecture Notes in Computer Science, 2017

A Vehicular Ad hoc Network (VANET) is an interconnection of vehicles that communicate through wir... more A Vehicular Ad hoc Network (VANET) is an interconnection of vehicles that communicate through wireless technologies. It offers to road users a wide variety of applications which can be classified into four main categories: safety, road traffic, comfort and infotainment. This paper deals with safety applications. Their main goal is to detect critical road conditions (e.g. accidents, black ice, etc.) and/or send notifications to other vehicles in the network. An effective dissemination of such a message relies on multi-hop retransmissions. Thus an explicit or implicit cooperation between vehicles is needed in order to relay the message over a wide area. The main challenge is to avoid the broadcast storm problem. This paper proposes an efficient segment-delay based method that divides the road into several segments depending on the network density and utilises a waiting time update technique to expedite the dissemination process with respect to network performance.

International Journal of Internet Technology and Secured Transactions, 2020

We propose a reliable dissemination protocol for broadcasting safety messages in vehicular ad hoc... more We propose a reliable dissemination protocol for broadcasting safety messages in vehicular ad hoc networks called Segment Delay Based Broadcasting Protocol (SDBP). The protocol has a twofold goal: limiting the risk of interference and reducing the dissemination time. To achieve these goals, two mechanisms are proposed. The first one divides vehicle's coverage area into several segments depending on the local density. Thereafter, the priority to relay a message is given to nodes that are in the farthest segment from the source node. The second mechanism allows reducing the waiting time thanks to a periodic update process. The performances of SDBP have been studied in an environment with multiple concurrent data traffics. The goal was to validate its capacity when the radio channel becomes overloaded. The comparison study (in terms of delivery ratio, dissemination time, forwarders and redundancy packets ratio) shows that SDBP outperforms two VANETs' broadcasting protocols.

International Journal of Embedded and Real-Time Communication Systems, 2015

Nowadays, processor micro-architectures are becoming more and more complex. Consequently, designe... more Nowadays, processor micro-architectures are becoming more and more complex. Consequently, designers increasingly need powerful abstraction and structuration mechanisms, as well as design methodologies that automatically and formally derive low-level concrete designs from high-level abstract ones. In this context, this paper proposes a methodology for RISC processor micro-architecture design. The proposed methodology uses mainly SysML to model both ISA and MA levels and the functional language CLEAN to describe them. Functional specifications in CLEAN are automatically generated from the ISA and MA models. These specifications, which are executable and formally verifiable, are used for simulation and verification. The proposed approach is validated by a case study that consists of designing the micro-architecture of MIPS processor. It shows how to easily model and generate CLEAN specifications describing the ISA and MA levels. It also illustrates, with multiple cases, how the generat...

International Journal of High Performance Systems Architecture, 2016

Due to the ever complexity of digital systems, there is a noticeable need for more abstract and s... more Due to the ever complexity of digital systems, there is a noticeable need for more abstract and structural mechanisms as well as design methodologies that systematically and formally derive low level concrete designs from high level abstract ones. To this aim, we present a methodological design approach that automatically generates a functional HDL code from SysML diagrams modeling hardware designs. The generated HDL code is both reliable and executable. While the first feature remains crucial for low level design refinements, the second one enables evaluating design performances at early stages. A case study involving the functional implementation of an ALU (Arithmetic Logic Unit) through Clean code generated from high level SysML diagrams is given, to practically show the potential features of the proposed approach.

Communications in Computer and Information Science, 2016

Experimental deployment of Cooperative Intelligent Transport Systems have been undertaken these l... more Experimental deployment of Cooperative Intelligent Transport Systems have been undertaken these last years. But a real deployment is lower than expected. One of the main reasons is the high cost of investments of Road Side Units on roads. Road operators need a lot of money in order to achieve this deployment. We suggest to reduce this investment by the deployment In this paper, we propose a combination of GPSR (Greedy Perimeter Stateless Routing) and an extension of Reactive Location Service denoted eRLS. They used to be combined, i.e. GPRS takes care of routing packets from a source to a destination and eRLS is called to get the destination position when the target node position is unknown or is not fresh enough. When a destination is not in the area of the sender, the exact position of the target is first looked for. An extra overhead is generated from the sender to the receiver since t is quite complicated to have an efficient Location System service as RLS. In the meantime, in deployed Cooperative Intelligent Transport Systems (C-ITS), fixed components are usually installed and denoted road side units (RSUs). In this paper we suggest to use these fixed RSUs to achieve the location service.

Proceedings of the 2016 Federated Conference on Computer Science and Information Systems, 2016

Greedy routing in VANETs requires some geographical informations, such as the source location and... more Greedy routing in VANETs requires some geographical informations, such as the source location and the destination location. The first one could be obtained using some localization devices like GPS receiver. However, the second one is provided by a location service. This later has a high overhead especially if it is implemented over V2V (vehicle to vehicle) communications. Many location services are well known as HLS, RLS, GLS. This paper is interested in reducing this overhead by using some Road Side Units (RSU) already deployed along the roads. We propose here a location service called "improved Reactive Location Service (iRLS)", which is an extension of the RLS service. The major difference is that RLS assumes only V2V communications and iRLS takes profit of a wireless backbone based on RSUs to catch the destination's position. This allows to reduce the overhead instead of flooding requests and also makes the communication faster since we will not have to wait to the request to reach the destination before receiving the response and then starting sending data. In our proposal, the closest RSU will reply with the actual location. In order to show the contribution of our approach, we have conducted some simulations that prove that iRLS outperforms any geographic protocol by using the V2I communications in terms of end-to-end delay which is one of the most important parameter. We considered also the ratio of packet received correctly by the destination vehicle (PDR), our protocol improves significantly this second parameter, and ensures more than 20% of packets received correctly Index Terms-VANETs; Location-based Services; Geographic Routing Protocols, .

Nowadays, Vehicular ad hoc Networks (VANETs) gained a significant place in Intelligent Transport ... more Nowadays, Vehicular ad hoc Networks (VANETs) gained a significant place in Intelligent Transport Systems (ITS). Their objective is to provide road users with useful services such as safety, infotainment and traffic management, by integrating information and communication technology into vehicles and transport infrastructure. As a result, the design of an efficient VANET routing protocol is very important. Traditional architecture of the network impose particular communication solution implementation. This implementation often fail to fully support the constraints of VANET like topology dynamic changes. The cross-layer design paradigm was introduced as an alternative to develop more efficient and robust communication protocols. This paper presents an overview of the main works that have applied a cross-layer technique to improve the routing function of a VANET.

Proceedings of the 2nd International Conference on Networking, Information Systems & Security

The complexity level of hardware design has increased extensively, and consequently it became sub... more The complexity level of hardware design has increased extensively, and consequently it became subject of errors. That's why it is extremely important to verify the correctness of designs, especially in critical systems like those of security. The problem is that the typical Hardware Description Languages (HDLs) like VHDL and Verilog are made mostly for description and simulation purposes; however, the simulation is insufficient validation technique in complex designs such as the cryptographic circuits. Thus, formal verification has become an important technique towards establishing the correctness of hardware designs; nonetheless it still faces many challenges; which make it a worth-while research problem. This paper presents an approach to formally verify the cryptographic circuits. It consists of using a purely functional framework namely Haskell to describe both the behavioral and structural descriptions. In addition, such approach relies on the use of hierarchy and modularity techniques in order to reduce the design complexity, and hence simplify the verification task. Last but not least we use Lava which is an HDL embedded into Haskell that allows checking automatically the safety and equivalence properties of circuits in several ways. To show the potential features of the proposed approach, we applied it to the Data Encryption Standard (DES) circuit, which is a symmetric block cipher. Thereafter, a methodological design approach for the verification of the design implementation against the specification is presented.

Springer eBooks, 2017

A Vehicular Ad hoc Network (VANET) is an interconnection of vehicles that communicate through wir... more A Vehicular Ad hoc Network (VANET) is an interconnection of vehicles that communicate through wireless technologies. It offers to road users a wide variety of applications which can be classified into four main categories: safety, road traffic, comfort and infotainment. This paper deals with safety applications. Their main goal is to detect critical road conditions (e.g. accidents, black ice, etc.) and/or send notifications to other vehicles in the network. An effective dissemination of such a message relies on multi-hop retransmissions. Thus an explicit or implicit cooperation between vehicles is needed in order to relay the message over a wide area. The main challenge is to avoid the broadcast storm problem. This paper proposes an efficient segment-delay based method that divides the road into several segments depending on the network density and utilises a waiting time update technique to expedite the dissemination process with respect to network performance.

Journal of High Speed Networks, Jul 29, 2022

In recent years, vehicular communication systems have taken an important place in Intelligent Tra... more In recent years, vehicular communication systems have taken an important place in Intelligent Transport Systems (ITS). These systems are designed on self-organizing networks, known as Vehicular Ad hoc NETworks (VANETs). Their objective is to struggle against road safety problems and road traffic congestion by integrating information and communication technologies in road infrastructures and vehicles. VANET differs from other types of ad hoc networks by high mobility and very dynamic topology. Consequently, the design of an efficient VANET routing protocol becomes a challenging task. Many routing schemes with QoS (Quality of Service) have been proposed in the literature for VANET, to satisfy the performances required by the different applications running upon such networks. Cross-layer designs, which make it possible to exchange and share information between the different layers of the network, have shown to be efficient in VANETs. This paper proposes an improved version of the geographic Greedy algorithm as a cross-layer routing protocol for VANETs. The cooperation between the network layer and the lower layers involves three cyber-physical parameters: Speed, position and Signal-to-Noise Ratio (SNR). The simulation results over the Network Simulator-3 (NS3) demonstrated the effectiveness of the proposed solution in terms of end-to-end delay, throughput and packet delivery ratio.

International Journal of Internet Technology and Secured Transactions, 2020

We propose a reliable dissemination protocol for broadcasting safety messages in vehicular ad hoc... more We propose a reliable dissemination protocol for broadcasting safety messages in vehicular ad hoc networks called Segment Delay Based Broadcasting Protocol (SDBP). The protocol has a twofold goal: limiting the risk of interference and reducing the dissemination time. To achieve these goals, two mechanisms are proposed. The first one divides vehicle's coverage area into several segments depending on the local density. Thereafter, the priority to relay a message is given to nodes that are in the farthest segment from the source node. The second mechanism allows reducing the waiting time thanks to a periodic update process. The performances of SDBP have been studied in an environment with multiple concurrent data traffics. The goal was to validate its capacity when the radio channel becomes overloaded. The comparison study (in terms of delivery ratio, dissemination time, forwarders and redundancy packets ratio) shows that SDBP outperforms two VANETs' broadcasting protocols.

TELKOMNIKA Telecommunication Computing Electronics and Control, Oct 1, 2019

MAC Protocols enables sensor nodes of the same WSN to access a common shared communication channe... more MAC Protocols enables sensor nodes of the same WSN to access a common shared communication channel. Many researchers have proposed different solutions explaining how to design and implement these protocols. The main goal of most MACs protocols is how to prolong lifetime of the WSN as long as possible by reducing energy consumption since it is often impossible to change or to recharge sensors' batteries. The majority of these protocols designed for WSN are based on "duty-cycle" technique. Every node of the WSN operates on two periods: active period and sleep period to save energy. Until now (to our knowledge) there is no ideal protocol for this purpose. The main reason relies on the lack of standardization at lower layers (physical layer) and (physical) sensor hardware. Therefore, the MAC protocol choice remains application-dependent. A useful MAC protocol should be able to adapt to network changes (topology, nodes density and network size). This paper surveys MAC protocols for WSNs and discusses the main characteristics, advantages and disadvantages of currently popular protocols.

Bringing to the market intelligent vehicles is one of the current challenges faced by car manufac... more Bringing to the market intelligent vehicles is one of the current challenges faced by car manufacturers. These vehicles must be able to communicate in order to cooperate and be more effective. The issue of inter-vehicle communications is an active research topic. This paper proposes a reliable geographical broadcasting protocol which has a twofold goal: limiting the risk of interference and reducing the dissemination time. To achieve theses goals, two mechanisms are proposed. The first one divides the road (more precisely, each vehicle's coverage area) into several segments depending on the local density. Thereafter, the priority to relay a message is given to nodes that are in the farthest segment from the source node. The second mechanism allows to reduce the waiting time thanks to a periodic update process. This paper also analysis the performance of geographical broadcasting protocols in case of multiple simultaneous communications. The goal is to observe how these protocols behave when the radio channel becomes overloaded. The comparison study (in terms of packet loss and dissemination time) shows that the proposed protocol outperforms two other VANETs' broadcasting protocols.

During these last years, Intelligent Transport Systems (ITS) have experienced a great growth in b... more During these last years, Intelligent Transport Systems (ITS) have experienced a great growth in both areas: academic and industrial. ITS which aim to increase safety and comfort for users' transport, are essentially governed by Vehicular Ad hoc Networks: VANETs. In such networks, nodes represent smart vehicles that can communicate either between themselves to exchange traffic information or with roadside infrastructure to disseminate or request useful information. Therefore, the congestion control remains one of the most challenging problems of these networks. This paper surveys congestion control techniques, which are divided into three categories: Rate adaptation, Media access control (MAC) and trajectory based schemes. For each technique we give its principle, its merits and its limits. A comparative study with respect to some relevant metrics is given as well.

2017 IEEE 9th Latin-American Conference on Communications (LATINCOM)

Bringing to the market intelligent vehicles is one of the current challenges faced by car manufac... more Bringing to the market intelligent vehicles is one of the current challenges faced by car manufacturers. These vehicles must be able to communicate in order to cooperate and be more effective. The issue of inter-vehicle communications is an active research topic. This paper proposes a reliable geographical broadcasting protocol which has a twofold goal: limiting the risk of interference and reducing the dissemination time. To achieve theses goals, two mechanisms are proposed. The first one divides the road (more precisely, each vehicle's coverage area) into several segments depending on the local density. Thereafter, the priority to relay a message is given to nodes that are in the farthest segment from the source node. The second mechanism allows to reduce the waiting time thanks to a periodic update process. This paper also analysis the performance of geographical broadcasting protocols in case of multiple simultaneous communications. The goal is to observe how these protocols behave when the radio channel becomes overloaded. The comparison study (in terms of packet loss and dissemination time) shows that the proposed protocol outperforms two other VANETs' broadcasting protocols.

Journal of High Speed Networks

In recent years, vehicular communication systems have taken an important place in Intelligent Tra... more In recent years, vehicular communication systems have taken an important place in Intelligent Transport Systems (ITS). These systems are designed on self-organizing networks, known as Vehicular Ad hoc NETworks (VANETs). Their objective is to struggle against road safety problems and road traffic congestion by integrating information and communication technologies in road infrastructures and vehicles. VANET differs from other types of ad hoc networks by high mobility and very dynamic topology. Consequently, the design of an efficient VANET routing protocol becomes a challenging task. Many routing schemes with QoS (Quality of Service) have been proposed in the literature for VANET, to satisfy the performances required by the different applications running upon such networks. Cross-layer designs, which make it possible to exchange and share information between the different layers of the network, have shown to be efficient in VANETs. This paper proposes an improved version of the geogr...

2017 13th International Wireless Communications and Mobile Computing Conference (IWCMC), 2017

During these last years, Intelligent Transport Systems (ITS) have experienced a great growth in b... more During these last years, Intelligent Transport Systems (ITS) have experienced a great growth in both areas: academic and industrial. ITS which aim to increase safety and comfort for users' transport, are essentially governed by Vehicular Ad hoc Networks: VANETs. In such networks, nodes represent smart vehicles that can communicate either between themselves to exchange traffic information or with roadside infrastructure to disseminate or request useful information. Therefore, the congestion control remains one of the most challenging problems of these networks. This paper surveys congestion control techniques, which are divided into three categories: Rate adaptation, Media access control (MAC) and trajectory based schemes. For each technique we give its principle, its merits and its limits. A comparative study with respect to some relevant metrics is given as well.

2018 International Conference on Innovations in Information Technology (IIT), 2018

this article aims to improve two important previous studies, dealing with the congestion problem ... more this article aims to improve two important previous studies, dealing with the congestion problem for VANETs. After giving a brief description of each method, we identify their strong aspects and drawbacks, and we propose some improvements independently of each another. Then we propose a combination of these two methods into one scheme, which results in a general enhancement to the whole system, because it takes advantages of each method. Finally, we present the theoretical expected results of this refinement.

IET Computers & Digital Techniques, 2021

The merit of higher order functions for hardware description and transformation is widely acknowl... more The merit of higher order functions for hardware description and transformation is widely acknowledged by hardware designers. However, the use of higher order types makes their correctness proof very difficult. Herein, a new proof approach based on the principle of partial application is proposed which transforms higher order functions into partially applied first-order ones. Therefore, parameterised architectures modelled by higher order functions could be easily redefined only over first-order types. The proof could be performed by induction within the same specification framework that avoids translating the higher order properties between different semantics, which remains extremely difficult. Using the notion of parameterisation where verified components are used as parameters to build more complex ones, the approach fits elegantly in the incremental bottom-up design where both the design and its proof could be developed in a systematic way. The potential features of the proposed methodological proof approach are demonstrated over a detailed example of a circuit design and verification within a functional framework. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

2020 International Conference on Advanced Aspects of Software Engineering (ICAASE), 2020

Vehicular Ad hoc Network (VANET) has gained a lot of interest in academia and industry domains. H... more Vehicular Ad hoc Network (VANET) has gained a lot of interest in academia and industry domains. High speed of vehicles, rapid change in topology and environmental characteristics of the city make the routing in VANET a very challenging problem. Traditional VANET routing protocols where decisions are made solely on local neighborhood observations have shown poor network performance. In contrast, the use of the Software Defined Network (SDN) paradigm, which is based on the global traffic view, has proven to be efficient in improving such performance. Internet of Vehicles (IoV) has emerged as a new technology that extends VANET architectures such that to meet the ever growing Intelligent Transport Systems (ITS) requirements. This paper surveys both traditional and SDN-based VANET routing schemes with a comparative study involving the main relevant performance parameters. It also gives an investigation of integration of SDN into an IoV environment that has shown to be very beneficial with respect to network performances.

Lecture Notes in Computer Science, 2017

A Vehicular Ad hoc Network (VANET) is an interconnection of vehicles that communicate through wir... more A Vehicular Ad hoc Network (VANET) is an interconnection of vehicles that communicate through wireless technologies. It offers to road users a wide variety of applications which can be classified into four main categories: safety, road traffic, comfort and infotainment. This paper deals with safety applications. Their main goal is to detect critical road conditions (e.g. accidents, black ice, etc.) and/or send notifications to other vehicles in the network. An effective dissemination of such a message relies on multi-hop retransmissions. Thus an explicit or implicit cooperation between vehicles is needed in order to relay the message over a wide area. The main challenge is to avoid the broadcast storm problem. This paper proposes an efficient segment-delay based method that divides the road into several segments depending on the network density and utilises a waiting time update technique to expedite the dissemination process with respect to network performance.

International Journal of Internet Technology and Secured Transactions, 2020

We propose a reliable dissemination protocol for broadcasting safety messages in vehicular ad hoc... more We propose a reliable dissemination protocol for broadcasting safety messages in vehicular ad hoc networks called Segment Delay Based Broadcasting Protocol (SDBP). The protocol has a twofold goal: limiting the risk of interference and reducing the dissemination time. To achieve these goals, two mechanisms are proposed. The first one divides vehicle's coverage area into several segments depending on the local density. Thereafter, the priority to relay a message is given to nodes that are in the farthest segment from the source node. The second mechanism allows reducing the waiting time thanks to a periodic update process. The performances of SDBP have been studied in an environment with multiple concurrent data traffics. The goal was to validate its capacity when the radio channel becomes overloaded. The comparison study (in terms of delivery ratio, dissemination time, forwarders and redundancy packets ratio) shows that SDBP outperforms two VANETs' broadcasting protocols.

International Journal of Embedded and Real-Time Communication Systems, 2015

Nowadays, processor micro-architectures are becoming more and more complex. Consequently, designe... more Nowadays, processor micro-architectures are becoming more and more complex. Consequently, designers increasingly need powerful abstraction and structuration mechanisms, as well as design methodologies that automatically and formally derive low-level concrete designs from high-level abstract ones. In this context, this paper proposes a methodology for RISC processor micro-architecture design. The proposed methodology uses mainly SysML to model both ISA and MA levels and the functional language CLEAN to describe them. Functional specifications in CLEAN are automatically generated from the ISA and MA models. These specifications, which are executable and formally verifiable, are used for simulation and verification. The proposed approach is validated by a case study that consists of designing the micro-architecture of MIPS processor. It shows how to easily model and generate CLEAN specifications describing the ISA and MA levels. It also illustrates, with multiple cases, how the generat...

International Journal of High Performance Systems Architecture, 2016

Due to the ever complexity of digital systems, there is a noticeable need for more abstract and s... more Due to the ever complexity of digital systems, there is a noticeable need for more abstract and structural mechanisms as well as design methodologies that systematically and formally derive low level concrete designs from high level abstract ones. To this aim, we present a methodological design approach that automatically generates a functional HDL code from SysML diagrams modeling hardware designs. The generated HDL code is both reliable and executable. While the first feature remains crucial for low level design refinements, the second one enables evaluating design performances at early stages. A case study involving the functional implementation of an ALU (Arithmetic Logic Unit) through Clean code generated from high level SysML diagrams is given, to practically show the potential features of the proposed approach.

Communications in Computer and Information Science, 2016

Experimental deployment of Cooperative Intelligent Transport Systems have been undertaken these l... more Experimental deployment of Cooperative Intelligent Transport Systems have been undertaken these last years. But a real deployment is lower than expected. One of the main reasons is the high cost of investments of Road Side Units on roads. Road operators need a lot of money in order to achieve this deployment. We suggest to reduce this investment by the deployment In this paper, we propose a combination of GPSR (Greedy Perimeter Stateless Routing) and an extension of Reactive Location Service denoted eRLS. They used to be combined, i.e. GPRS takes care of routing packets from a source to a destination and eRLS is called to get the destination position when the target node position is unknown or is not fresh enough. When a destination is not in the area of the sender, the exact position of the target is first looked for. An extra overhead is generated from the sender to the receiver since t is quite complicated to have an efficient Location System service as RLS. In the meantime, in deployed Cooperative Intelligent Transport Systems (C-ITS), fixed components are usually installed and denoted road side units (RSUs). In this paper we suggest to use these fixed RSUs to achieve the location service.

Proceedings of the 2016 Federated Conference on Computer Science and Information Systems, 2016

Greedy routing in VANETs requires some geographical informations, such as the source location and... more Greedy routing in VANETs requires some geographical informations, such as the source location and the destination location. The first one could be obtained using some localization devices like GPS receiver. However, the second one is provided by a location service. This later has a high overhead especially if it is implemented over V2V (vehicle to vehicle) communications. Many location services are well known as HLS, RLS, GLS. This paper is interested in reducing this overhead by using some Road Side Units (RSU) already deployed along the roads. We propose here a location service called "improved Reactive Location Service (iRLS)", which is an extension of the RLS service. The major difference is that RLS assumes only V2V communications and iRLS takes profit of a wireless backbone based on RSUs to catch the destination's position. This allows to reduce the overhead instead of flooding requests and also makes the communication faster since we will not have to wait to the request to reach the destination before receiving the response and then starting sending data. In our proposal, the closest RSU will reply with the actual location. In order to show the contribution of our approach, we have conducted some simulations that prove that iRLS outperforms any geographic protocol by using the V2I communications in terms of end-to-end delay which is one of the most important parameter. We considered also the ratio of packet received correctly by the destination vehicle (PDR), our protocol improves significantly this second parameter, and ensures more than 20% of packets received correctly Index Terms-VANETs; Location-based Services; Geographic Routing Protocols, .