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  • 1.
    Aghaeinezhadfirouzja, S.
    et al.
    Department of Electronics Engineering, Shanghai Jiao Tong University, Shanghai, China.
    Liu, H.
    Department of Electronics Engineering, Shanghai Jiao Tong University, Shanghai, China.
    Balador, Ali
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems. RISE SICS Västerås, Sweden.
    Practical 3-D beam pattern based channel modeling for multi-polarized massive MIMO systems2018In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 18, no 4, article id 1186Article in journal (Refereed)
    Abstract [en]

    In this paper, a practical non-stationary three-dimensional (3-D) channel models for massive multiple-input multiple-output (MIMO) systems, considering beam patterns for different antenna elements, is proposed. The beam patterns using dipole antenna elements with different phase excitation toward the different direction of travels (DoTs) contributes various correlation weights for rays related towards/from the cluster, thus providing different elevation angle of arrivals (EAoAs) and elevation angle of departures (EAoDs) for each antenna element. These include the movements of the user that makes our channel to be a non-stationary model of clusters at the receiver (RX) on both the time and array axes. In addition, their impacts on 3-D massive MIMO channels are investigated via statistical properties including received spatial correlation. Additionally, the impact of elevation/azimuth angles of arrival on received spatial correlation is discussed. Furthermore, experimental validation of the proposed 3-D channel models on azimuth and elevation angles of the polarized antenna are specifically evaluated and compared through simulations. The proposed 3-D generic models are verified using relevant measurement data.

  • 2.
    Bakhshi, Zeynab
    et al.
    RighTel, Iran.
    Balador, Ali
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems. RISE SICS, Västerås, Sweden.
    Mustafa, Jawad
    RISE SICS, Västerås, Sweden.
    Industrial IoT Security Threats and Concerns by Considering CISCO and Microsoft IoT reference Models2018In: IEEE WCNCW 2018 IEEE WCNCW 2018: 2018 IEEE Wireless Communications and Networking Conference Workshops, 2018, p. 173-178Conference paper (Refereed)
    Abstract [en]

    This paper investigates security concerns and issues for Industrial Internet of Things (IIoT). The IIoT is an emerging transformation, bringing great values to every industry. Although this rapid alter in industries create values, but there are concerns about security issues, most of which would be still unknown due to the novelty of this platform. In order to provide a guideline for those who want to investigate IoT security and contribute to its improvement, this paper attempts to provide a list of security threats and issues on the cloud-side layer of IoT, which consists of data accumulation and abstraction levels. For this reason, we choose Cisco and Microsoft Azure IoT Architecture as reference models. Then, two layers of Cisco reference architecture model have been chosen to be investigated for their security issues. Finally, consideration of security issues has been briefly explained.

  • 3.
    Balador, Ali
    SICS Swedish ICT Västerås AB, Sweden.
    A Token-Based MAC Protocol for Achieving High Reliability in VANET2016In: BMW Summer School 2016 BMWSS 2016, Bad Wörishofen, Bavaria, Germany, 2016Conference paper (Refereed)
    Abstract [en]

    Safety applications developed for vehicular environments require every vehicle to periodically broadcast its status information (beacon) to all other vehicles, thereby avoiding the risk of car accidents in the road. Due to the high requirements on timing and reliability posed by traffic safety applications, the current IEEE 802.11p standard, which uses a random access Medium Access Control (MAC) protocol, faces difficulties to support timely and reliable data dissemination in vehicular environments where no acknowledgement or RTS/CTS (Request-to-Send/Clear-to-Send) mechanisms are adopted. In this paper, we propose the Dynamic Token-Based MAC (DTB-MAC) protocol. It implements a token passing approach on top of a random access MAC protocol to prevent channel contention as much as possible, thereby improving the reliability of safety message transmissions. Our proposed protocol selects one of the neighbouring nodes as the next transmitter; this selection accounts for the need to avoid beacon lifetime expiration. Therefore, it automatically offers retransmission opportunities to allow vehicles to successfully transmit their beacons before the next beacon is generated whenever time and bandwidth are available. Based on simulation experiments, we show that the DTB-MAC protocol can achieve better performance than IEEE 802.11p in terms of channel utilization and beacon delivery ratio for urban scenarios.

  • 4.
    Balador, Ali
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems. RISE SICS, Vadies, Sweden.
    Bai, C.
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Sedighi, F.
    Niroo Research Institute, Iran.
    A Comparison of Decentralized Congestion Control Algorithms for Multiplatooning Communications2019In: 2019 IEEE International Conference on Pervasive Computing and Communications Workshops, PerCom Workshops 2019, Institute of Electrical and Electronics Engineers Inc. , 2019, p. 674-680Conference paper (Refereed)
    Abstract [en]

    To improve traffic safety, many Cooperative Intelligent Transportation Systems (C-ITS) applications rely on exchange of periodic safety messages between vehicles. However, as the number of connected vehicles increases, control of channel congestion becomes a bottleneck for achieving high throughput. Without a suitable congestion control method, safety critical messages such as Cooperative Awareness Messages (CAMs) may not be delivered on time in high vehicle density scenarios that can lead to dangerous situations which can threaten people's health or even life. The Decentralized Congestion Control (DCC) algorithm defined by European Telecommunications Standards Institute (ETSI), becomes a vital component of C-ITS applications to keep channel load under control and below a predefined threshold level. In this paper, we aim to analyze and evaluate the performance of a number of DCC protocols including ETSI DCC by providing a comparison between them for the multiplatooning application by using several widely-used evaluation metrics.

  • 5.
    Balador, Ali
    et al.
    SICS Swedish ICT Västerås AB, Sweden.
    Böhm, Annette
    Halmstad University, Sweden.
    Calafate, Carlos T.
    Universitat Politecnica de Valencia, Spain.
    Cano, Juan-Carlos
    Universitat Politecnica de Valencia, Spain.
    A Reliable Token-Based MAC Protocol for V2V Communication in Urban VANET2016In: IEEE International Symposium on Personal, Indoor and Mobile Radio Communications PIMRC 16, Valencia, Spain, 2016Conference paper (Refereed)
    Abstract [en]

    Safety applications developed for vehicular environments require every vehicle to periodically broadcast its status information (beacon) to all other vehicles, thereby avoiding the risk of car accidents in the road. Due to the high requirements on timing and reliability posed by traffic safety applications, the current IEEE 802.11p standard, which uses a random access Medium Access Control (MAC) protocol, faces difficulties to support timely and reliable data dissemination in vehicular environments where no acknowledgement or RTS/CTS (Request-to-Send/Clear-to-Send) mechanisms are adopted. In this paper, we propose the Dynamic Token-Based MAC (DTB-MAC) protocol. It implements a token passing approach on top of a random access MAC protocol to prevent channel contention as much as possible, thereby improving the reliability of safety message transmissions. Our proposed protocol selects one of the neighbouring nodes as the next transmitter; this selection accounts for the need to avoid beacon lifetime expiration. Therefore, it automatically offers retransmission opportunities to allow vehicles to successfully transmit their beacons before the next beacon is generated whenever time and bandwidth are available. Based on simulation experiments, we show that the DTB-MAC protocol can achieve better performance than IEEE 802.11p in terms of channel utilization and beacon delivery ratio for urban scenarios.

  • 6.
    Balador, Ali
    et al.
    SICS Swedish ICT Västerås AB, Sweden.
    Böhm, Annette
    Halmstad University, Sweden.
    Uhlemann, Elisabeth
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Calafate, Carlos T.
    Universitat Politecnica de Valencia, Spain.
    Cano, Juan-Carlos
    Universitat Politecnica de Valencia, Spain.
    A Reliable and Efficient Token-Based MAC Protocol for Platooning Applications2016In: 12th Swedish National Computer Networking Workshop SNCNW 2016, 2016Conference paper (Refereed)
    Abstract [en]

    Platooning is both a challenging and rewarding application. Challenging since strict timing and reliability requirements are imposed by the distributed control system required to operate the platoon. Rewarding since considerable fuel reductions are possible. As platooning takes place in a vehicular ad hoc network, the use of IEEE 802.11p is close to mandatory. However, the 802.11p medium access method suffers from packet collisions and random delays. Most ongoing research suggests using TDMA on top of 802.11p as a potential remedy. However, TDMA requires synchronization and is not very flexible if the beacon frequency needs to be updated, the number of platoon members changes, or if retransmissions for increased reliability are required. We therefore suggest a token-passing medium access method where the next token holder is selected based on beacon data age. This has the advantage of allowing beacons to be re-broadcasted in each beacon interval whenever time and bandwidth are available. We show that our token-based method is able to reduce the data age and considerably increase reliability compared to pure 802.11p.

  • 7.
    Balador, Ali
    et al.
    Polytechnic University of Valencia, Valencia, Spain.
    Böhm, Annette
    Halmstad Universit, Sweden.
    Uhlemann, Elisabeth
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Calafate, Carlos T.
    Polytechnic University of Valencia, Valencia, Spain.
    Ji, Yusheng
    National Institute of Informatics, Tokyo, Japan.
    Cano, Juan-Carlos
    Polytechnic University of Valencia, Valencia, Spain.
    Manzoni, Pietro
    Polytechnic University of Valencia, Valencia, Spain.
    An Efficient MAC Protocol for vehicle platooning in automated highway systems2015In: Jornadas Sarteco 2015 JS 2015, Cordoba, Spain, 2015Conference paper (Refereed)
    Abstract [en]

    Lately, all the top truck manufacturers are investing considerable resources in the research and development of platooning systems which would allow vehicles to save fuel and improve safety by travelling in a close-following manner. The platoon-ing system requires frequent and reliable vehicle-to-vehicle communications. As platooning takes place in a vehicular ad hoc network, the use of IEEE 802.11p is close to mandatory. However, the 802.11p medium access method suffers from packet collisions and random delays. Most ongoing research suggests using TDMA on top of 802.11p as a potential remedy. However , TDMA requires synchronization and is not very flexible if the beacon frequency needs to be updated, the number of platoon members changes, or if re-transmissions for increased reliability are required. We therefore suggest a token-passing medium access method where the next token holder is selected based on beacon data age. This has the advantage of allowing beacons to be re-broadcasted in each beacon interval whenever time and bandwidth are available. We show that our token-based method is able to reduce the data age and considerably increase reliability considerably compared to pure 802.11p.

  • 8.
    Balador, Ali
    et al.
    Universitat Politecnica de Valencia, Spain.
    Calafate, Carlos T.
    Universitat Politecnica de Valencia, Spain.
    Cano, Juan-Carlos
    Universitat Politecnica de Valencia, Spain.
    Manzoni, Pietro
    Universitat Politecnica de Valencia, Spain.
    A Density-Based Contention Window Control Scheme for Unicast Communications in Vehicular Ad Hoc Networks2015In: International Journal of Ad Hoc and Ubiquitous Computing, ISSN 1743-8225, E-ISSN 1743-8233, Vol. 24, p. 65-75Article in journal (Refereed)
    Abstract [en]

    Achieving a well-designed medium access control MAC protocol is a challenging issue to improve communications efficiency due to the dynamic nature of vehicular ad hoc networks VANETs. IEEE 802.11p standard was selected as the best choice for vehicular environments considering its availability, maturity, and cost. The common problem in all IEEE 802.11 based protocols is scalability, exhibiting performance degradation in highly variable network scenarios. Experimental results for the IEEE 802.11-based MAC protocol show the importance of contention window adjustment on communications performance; however the vehicular communications community has not yet addressed this issue in unicast communication environments. This paper proposes a novel contention window control scheme for VANET environments based on estimating the network density, which is then used to dynamically adapt the CW size. Analysis and simulation results show that our proposal provides better overall performance compared with previous proposals, even in high network density scenarios.

  • 9. Balador, Ali
    et al.
    Calafate, Carlos T.
    Universitat Politecnica de Valencia, Spain.
    Cano, Juan-Carlos
    Universitat Politecnica de Valencia, Spain.
    Manzoni, Pietro
    Universitat Politecnica de Valencia, Spain.
    A Novel 802.11 Contention Window Control Scheme for Vehicular Environments2013In: Jornadas Sarteco 2013 JS 2013, 2013, p. 98-103Conference paper (Refereed)
    Abstract [en]

    Intelligent Transportation Systems (ITS) have attractive potential in order to decrease the ordi- nary traffic jams and avoid transportation disasters. Also, they are able to provide various infotainment services like browsing, reading e-mail or using social networks that makes a trip more interesting. In or- der to make it more efficient in real vehicular envi- ronments, achieving a well-designed Medium Access Control (MAC) protocol is a challenging issue due to the dynamic nature of VANETs, scalability issues, and the variety of application requirements. Differ- ent standardization organizations have selected IEEE 802.11 as the first choice for VANET environments considering its availability, maturity, and cost. The research results for IEEE 802.11 MAC protocol show the importance of contention window adjustment on the communications performance. The impact of ad- justing the contention window has been studied in MANETs, but the vehicular communication commu- nity has not yet addressed this issue thoroughly. This paper proposes e-HBCWC, a new contention window control scheme for VANET environments based on estimating the network condition. Analy- sis and simulation results using OMNeT++ in urban scenarios show that e-HBCWC clearly outperforms 802.11 DCF, even in very high network density, by increasing the packet delivery rate while decreasing the number of collisions and the end-to-end delay for unicast applications.

  • 10.
    Balador, Ali
    et al.
    Universitat Politecnica de Valencia, Spain.
    Calafate, Carlos T.
    Universitat Politecnica de Valencia, Spain.
    Cano, Juan-Carlos
    Universitat Politecnica de Valencia, Spain.
    Manzoni, Pietro
    Universitat Politecnica de Valencia, Spain.
    Congestion Control for Vehicular Environments by Adjusting IEEE 802.11 Contention Window Size2013In: 13th International Conference on Algorithms and Architectures for Parallel Processing ICA3PP-2013, 2013, p. 259-266Conference paper (Refereed)
    Abstract [en]

    Medium access control protocols should manage the highly dynamic nature of Vehicular Ad Hoc Networks (VANETs) and the variety of application requirements. Therefore, achieving a well-designed MAC protocol in VANETs is a challenging issue. The contention window is a critical element for handling medium access collisions in IEEE 802.11, and it highly affects the communications performance. This paper proposes a new contention window control scheme, called DBM-ACW, for VANET environments. Analysis and simulation results using OMNeT++ in urban scenarios show that DBM-ACW provides better overall performance compared with previous proposals, even with high network densities.

  • 11.
    Balador, Ali
    et al.
    Universitat Politecnica de Valencia, Spain.
    Calafate, Carlos T.
    Universitat Politecnica de Valencia, Spain.
    Cano, Juan-Carlos
    Universitat Politecnica de Valencia, Spain.
    Manzoni, Pietro
    Universitat Politecnica de Valencia, Spain.
    DTB-MAC: Dynamic Token-Based MAC Protocol for Reliable and Efficient Beacon Broadcasting in VANETs2016In: The 13th Annual IEEE Consumer Communications & Networking Conference CCNC 2016, 2016, p. 109-114Conference paper (Refereed)
    Abstract [en]

    Most applications developed for vehicular environments rely on broadcasting as the main mechanism to disseminate their messages. However, in IEEE 802.11p, which is the most widely accepted Medium Access Control (MAC) protocol for vehicular communications, all transmissions remain unacknowledged if broadcasting is used. Furthermore, safety message transmission requires a strict delay limit and a high reliability, which is an issue for random access MAC protocols like IEEE 802.11p. Therefore, transmission reliability becomes the most important issue for broadcast-based services in vehicular environments. In this paper, we propose a hybrid MAC protocol, referred as Dynamic Token-Based MAC Protocol (DTB-MAC). DTB-MAC uses both a token passing mechanism and a random access MAC protocol to prevent channel contention as much as possible, and to improve the reliability of safety message transmissions. Our proposed protocol tries to select the best neighbouring node as the next transmitter, and when it is not possible, or when it causes a high overhead, the random access MAC protocol is used instead. Based on simulation experiments, we show that the DTB-MAC protocol can achieve better performance compared with IEEE 802.11p in terms of channel utilization and beacon delivery ratio.

  • 12. Balador, Ali
    et al.
    Calafate, Carlos T.
    Universitat Politecnica de Valencia, Spain.
    Cano, Juan-Carlos
    Universitat Politecnica de Valencia, Spain.
    Manzoni, Pietro
    Performance Evaluation of Realistic Vehicular Networks: A MAC Layer Perspective2014In: Simulation Technologies in Networking and Communications: Selecting the Best Tool for the Test / [ed] Al-Sakib Khan Pathan, Muhammad Mostafa Monowar, Shafiullah Khan, CRC Press, Taylor & Francis Group , 2014Chapter in book (Other academic)
  • 13.
    Balador, Ali
    et al.
    Univ. Politec. de Valencia, Valencia, Spain.
    Calafate, Carlos T.
    Univ. Politec. de Valencia, Valencia, Spain.
    Cano, Juan-Carlos
    Univ. Politec. de Valencia, Valencia, Spain.
    Manzoni, Pietro
    Univ. Politec. de Valencia, Valencia, Spain.
    Reducing Channel Contention in Vehicular Environments Through an Adaptive Contention Window Solution2013In: IFIP Wireless Days WD 2013, 2013Conference paper (Refereed)
    Abstract [en]

    Intelligent Transportation Systems (ITS) are attracting growing attention both in industry and academia due to the advances in wireless communication technologies, and a significant demand for a wide variety of applications targeting this kind of environments are expected. In order to make it usable in real vehicular environments, achieving a well-designed Medium Access Control (MAC) protocol is a challenging issue due to the dynamic nature of Vehicular Ad Hoc Networks (VANETs), scalability issues, and the variety of application requirements. Different standardization organizations have selected IEEE 802.11 as the first choice for VANET environments considering its availability, maturity, and cost. The contention window is a critical parameter for handling medium access collisions by the IEEE 802.11 MAC protocol, and it highly affects the communications performance. The impact of adjusting the contention window has been studied in Mobile Ad-Hoc Networks (MANETs), but the vehicular communications community has not yet addressed this issue thoroughly. This paper proposes a new contention window control scheme, called DBM-ACW, for VANET environments. Analysis and simulation results using OMNeT++ in a highway scenario show that DBM-ACW provides better overall performance compared with previous proposals, even with high network densities.

  • 14.
    Balador, Ali
    et al.
    RISE SICS Västerås, Sweden.
    Ericsson, Niclas
    RISE SICS Västerås, Sweden.
    Bakhshi, Zeynab
    RighTel, Iran.
    Communication Middleware Technologies for Industrial Distributed Control Systems: A Literature Review2018In: International Conference on Emerging Technologies And Factory Automation ETFA'17, 2018Conference paper (Refereed)
    Abstract [en]

    Industry 4.0 is the German vision for the future of manufacturing, where smart factories use information and communication technologies to digitise their processes to achieve improved quality, lower costs, and increased efficiency. It is likely to bring a massive change to the way control systems function today. Future distributed control systems are expected to have an increased connectivity to the Internet, in order to capitalize on new offers and research findings related to digitalization, such as cloud, big data, and machine learning. A key technology in the realization of distributed control systems is middleware, which is usually described as a reusable software layer between operating system and distributed applications. Various middleware technologies have been proposed to facilitate communication in industrial control systems and hide the heterogeneity amongst the subsystems, such as OPC UA, DDS, and RT-CORBA. These technologies can significantly simplify the system design and integration of devices despite their heterogeneity. However, each of these technologies has its own characteristics that may work better for particular applications. Selection of the best middleware for a specific application is a critical issue for system designers. In this paper, we conduct a survey on available standard middleware technologies, including OPC UA, DDS, and RT-CORBA, and show new trends for different industrial domains.

  • 15.
    Balador, Ali
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Kouba, A.
    Polytechnic Institute of Porto, Porto 4249-015, Portugal.
    Cassioli, D.
    University of L'Aquila, L'Aquila, 67100, Italy.
    Foukalas, F.
    Technical University of Denmark, Kongens Lyngby, 2800, Denmark.
    Severino, R.
    Polytechnic Institute of Porto, Porto 4249-015, Portugal.
    Stepanova, D.
    Finnish Meteorological Institute, 99600 Sodankylä, Finland.
    Agosta, G.
    Politecnico di Milano ,Via G. Ponzio 32, Milano, I-20133, Italy.
    Xie, J.
    Group Technology & Research, DNV GL, Veritasveien 1, Norway.
    Pomante, L.
    University of L'Aquila, L'Aquila, 67100, Italy.
    Mongelli, M.
    CNR-IEIIT ,via De Marini 6, Genova, 16149, Italy.
    Pierini, P.
    Intecs S.p.A., Pisa, 56121, Italy.
    Petersen, S.
    SINTEF ICT, Trondheim, 7465, Norway.
    Sukuvaara, T.
    Finnish Meteorological Institute, 99600 Sodankylä, Finland.
    Wireless Communication Technologies for Safe Cooperative Cyber Physical Systems2018In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 18, no 11, article id 4075Article in journal (Refereed)
    Abstract [en]

    Cooperative Cyber-Physical Systems (Co-CPSs) can be enabled using wireless communication technologies, which in principle should address reliability and safety challenges. Safety for Co-CPS enabled by wireless communication technologies is a crucial aspect and requires new dedicated design approaches. In this paper, we provide an overview of five Co-CPS use cases, as introduced in our SafeCOP EU project, and analyze their safety design requirements. Next, we provide a comprehensive analysis of the main existing wireless communication technologies giving details about the protocols developed within particular standardization bodies. We also investigate to what extent they address the non-functional requirements in terms of safety, security and real time, in the different application domains of each use case. Finally, we discuss general recommendations about the use of different wireless communication technologies showing their potentials in the selected real-world use cases. The discussion is provided under consideration in the 5G standardization process within 3GPP, whose current efforts are inline to current gaps in wireless communications protocols for Co-CPSs including many future use cases.

  • 16.
    Balador, Ali
    et al.
    Islamic Azad University, Tehran, Iran.
    Movaghar, Ali
    Sharif University of Technology, Tehran, Iran.
    Jabbehdari, Sam
    North Tehran Branch, Islamic Azad University, Tehran, Iran.
    History Based Contention Window Control (HBCWC) in IEEE 802.11 Mac Protocol in Error Prone Channel2010In: Journal of Computer Science, ISSN 1549-3636, E-ISSN 1552-6607, Vol. 6, no 2, p. 205-209Article in journal (Refereed)
    Abstract [en]

    Problem statement: IEEE 802.11 Medium Access Control (MAC) protocol is one of the most implemented protocols in this network. The IEEE 802.11 controls the access to the share wireless channel within competing stations. The IEEE 802.11 DCF doubles the Contention Window (CW) size for decreasing the collision within contending stations and to improve the network performances but it is not good for error prone channel because the sudden CW rest to CWmin may cause several collisions. Approach: The research to date has tended to focus on the current number of active stations that needs complex computations. A novel backoff algorithm is presented that optimizes the CW size with take into account the history of packet lost. Results: Finally, we compare the HBCWC with IEEE 802.11 DCF. The simulation results have shown 24.14, 56.71 and 25.33% improvement in Packet Delivery Ratio (PDR), average end to end delay and throughput compared to the IEEE 802.11 DCF. Conclusion: This study showed that monitoring the last three channel statuses achieve better delay and throughput that can be used for multimedia communications.

  • 17.
    Balador, Ali
    et al.
    Universitat Pompeu Fabra, Barcelona, Spain.
    Movaghar, Ali
    Sharif University of Technology, Tehran, Iran.
    Jabbehdari, Sam
    North Tehran Branch, Islamic Azad University, Tehran, Iran.
    Kanellopoulos, Dimitris
    University of Patras, Greece.
    A novel contention window control scheme for IEEE 802.11 WLANs2012In: IETE Technical Review, ISSN 0256-4602, E-ISSN 0974-5971, Vol. 30, no 4, p. 202-212Article in journal (Refereed)
    Abstract [en]

    In the IEEE 802.11 standard, network nodes experiencing collisions on the shared medium need a mechanism that can prevent collisions and improve the throughput. Furthermore, a backoff mechanism is used that uniformly selects a random period of time from the contention window (cw) that is dynamically controlled by the Binary Exponential Backoff (BEB) algorithm. Prior research has proved that the BEB scheme suffers from a fairness problem and low throughput, especially under high traffic load. In this paper, we present a new backoff control mechanism that is used with the IEEE 802.11 distributed coordination function (DCF). In particular, we propose a dynamic, deterministic contention window control (DDCWC) scheme, in which the backoff range is divided into several small backoff sub-ranges. In the proposed scheme, several network levels are introduced, based on an introduced channel state vector that keeps network history. After successful transmissions and collisions, network nodes change their cw based on their network levels. Our extensive simulation studies show that the DDCWC scheme outperforms four other well-known schemes: Multiplicative Increase and Linear Decrease, Double Increment Double Decrement, Exponential Increase Exponential Decrease, and Linear/Multiplicative Increase and Linear Decrease. Moreover, the proposed scheme, compared with the IEEE 802.11 DCF, gives 30.77% improvement in packet delivery ratio, 31.76% in delay, and 30.81% in throughput.

  • 18.
    Balador, Ali
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Uhlemann, Elisabeth
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Calafate, C. T.
    Universitat Politècnica de València, València, Spain.
    Cano, J. -C
    Universitat Politècnica de València, València, Spain.
    Supporting beacon and event-driven messages in vehicular platoons through token-based strategies2018In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 18, no 4, article id 955Article in journal (Refereed)
    Abstract [en]

    Timely and reliable inter-vehicle communications is a critical requirement to support traffic safety applications, such as vehicle platooning. Furthermore, low-delay communications allow the platoon to react quickly to unexpected events. In this scope, having a predictable and highly effective medium access control (MAC) method is of utmost importance. However, the currently available IEEE 802.11p technology is unable to adequately address these challenges. In this paper, we propose a MAC method especially adapted to platoons, able to transmit beacons within the required time constraints, but with a higher reliability level than IEEE 802.11p, while concurrently enabling efficient dissemination of event-driven messages. The protocol circulates the token within the platoon not in a round-robin fashion, but based on beacon data age, i.e., the time that has passed since the previous collection of status information, thereby automatically offering repeated beacon transmission opportunities for increased reliability. In addition, we propose three different methods for supporting event-driven messages co-existing with beacons. Analysis and simulation results in single and multi-hop scenarios showed that, by providing non-competitive channel access and frequent retransmission opportunities, our protocol can offer beacon delivery within one beacon generation interval while fulfilling the requirements on low-delay dissemination of event-driven messages for traffic safety applications. 

  • 19.
    Eziama, E.
    et al.
    Windsor University, Canada.
    Jaimes, L. M. S.
    Universidad de Pamplona, Colombia.
    James, A.
    Federal University of Technology, Mina, Nigeria.
    Nwizege, K. S.
    Ken Saro-Wiwa Polytechnic, Bori, Nigeria.
    Balador, Ali
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Tepe, K.
    Windsor University, Canada.
    Machine learning-based recommendation trust model for machine-to-machine communication2019In: 2018 IEEE International Symposium on Signal Processing and Information Technology, ISSPIT 2018, Institute of Electrical and Electronics Engineers Inc. , 2019Conference paper (Refereed)
    Abstract [en]

    The Machine Type Communication Devices (MTCDs) are usually based on Internet Protocol (IP), which can cause billions of connected objects to be part of the Internet. The enormous amount of data coming from these devices are quite heterogeneous in nature, which can lead to security issues, such as injection attacks, ballot stuffing, and bad mouthing. Consequently, this work considers machine learning trust evaluation as an effective and accurate option for solving the issues associate with security threats. In this paper, a comparative analysis is carried out with five different machine learning approaches: Naive Bayes (NB), Decision Tree (DT), Linear and Radial Support Vector Machine (SVM), KNearest Neighbor (KNN), and Random Forest (RF). As a critical element of the research, the recommendations consider different Machine-to-Machine (M2M) communication nodes with regard to their ability to identify malicious and honest information. To validate the performances of these models, two trust computation measures were used: Receiver Operating Characteristics (ROCs), Precision and Recall. The malicious data was formulated in Matlab. A scenario was created where 50% of the information were modified to be malicious. The malicious nodes were varied in the ranges of 10%, 20%, 30%, 40%, and the results were carefully analyzed.

  • 20.
    Eziama, E.
    et al.
    Windsor University, Canada.
    Tepe, K.
    Windsor University, Canada.
    Balador, Ali
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Nwizege, K. S.
    Ken Saro-Wiwa Polytechnic, Bori, Nigeria.
    Jaimes, L. M. S.
    Grupo Ciencias Computacionales, Universidad de Pamplona, CA, Colombia.
    Malicious Node Detection in Vehicular Ad-Hoc Network Using Machine Learning and Deep Learning2019In: 2018 IEEE Globecom Workshops, GC Wkshps 2018 - Proceedings, Institute of Electrical and Electronics Engineers Inc. , 2019Conference paper (Refereed)
    Abstract [en]

    Vehicular Ad hoc Networks (VANETs) provide effective vehicular operation for safety as well as greener and more efficient communication of vehicles in the Dedicated Short Range Communication (DRSC). The dynamic nature of the vehicular network topology has posed many security challenges for effective communication among vehicles. Consequently, models have been applied in the literature to checkmate the security issues in the vehicular networks. Existing models lack flexibility and sufficient functionality in capturing the dynamic behaviors of malicious nodes in the highly volatile vehicular communication systems. Given that existing models have failed to meet up with the challenges involved in vehicular network topology, it has become imperative to adopt complementary measures to tackle the security issues in the system. The approach of trust model with respect to Machine/Deep Learning (ML/DL) is proposed in the paper due to the gap in the area of network security by the existing models. The proposed model is to provide a data-driven approach in solving the security challenges in dynamic networks. This model goes beyond the existing works conceptually by modeling trust as a classification process and the extraction of relevant features using a hybrid model like Bayesian Neural Network that combines deep learning with probabilistic modeling for intelligent decision and effective generalization in trust computation of honest and dishonest nodes in the network. 

  • 21.
    Eziama, Elvin
    et al.
    Windsor Univ, Windsor, ON, Canada..
    Tepe, Kemal
    Windsor Univ, Windsor, ON, Canada..
    Balador, Ali
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems. RISE SICS, Vasteras, Sweden..
    Nwizege, Kenneth Sorle
    Ken Saro Wiwa Polytech, Bori, Nigeria..
    Jaimes, Luz M. S.
    Univ Pamplona, Grp Ciencias Computac, Pamplona, Spain..
    Malicious Node Detection in Vehicular Ad-Hoc Network Using Machine Learning and Deep Learning2018In: 2018 IEEE GLOBECOM WORKSHOPS (GC WKSHPS), IEEE , 2018Conference paper (Refereed)
    Abstract [en]

    Vehicular Ad hoc Networks (VANETs) provide effective vehicular operation for safety as well as greener and more efficient communication of vehicles in the Dedicated Short Range Communication (DRSC). The dynamic nature of the vehicular network topology has posed many security challenges for effective communication among vehicles. Consequently, models have been applied in the literature to checkmate the security issues in the vehicular networks. Existing models lack flexibility and sufficient functionality in capturing the dynamic behaviors of malicious nodes in the highly volatile vehicular communication systems. Given that existing models have failed to meet up with the challenges involved in vehicular network topology, it has become imperative to adopt complementary measures to tackle the security issues in the system. The approach of trust model with respect to Machine/Deep Learning (ML/DL) is proposed in the paper due to the gap in the area of network security by the existing models. The proposed model is to provide a data-driven approach in solving the security challenges in dynamic networks. This model goes beyond the existing works conceptually by modeling trust as a classification process and the extraction of relevant features using a hybrid model like Bayesian Neural Network that combines deep learning with probabilistic modeling for intelligent decision and effective generalization in trust computation of honest and dishonest nodes in the network.

  • 22.
    Pau, Giovanni
    et al.
    Kore Univ Enna, Enna, Italy..
    Bazzi, Alessandro
    CNR, Rome, Italy..
    Campista, Miguel Elias M.
    Univ Fed Rio de Janeiro, Rio De Janeiro, Brazil..
    Balador, Ali
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Towards 5G and beyond for the internet of UAVs, vehicles, smartphones, Sensors and Smart Objects2019In: Journal of Network and Computer Applications, ISSN 1084-8045, E-ISSN 1095-8592, Vol. 135, p. 108-109Article in journal (Other academic)
  • 23.
    Sanandaji, Anahita
    et al.
    North Tehran Branch, Islamic Azad University, Tehran, Iran.
    Jabbehdari, Sam
    North Tehran Branch, Islamic Azad University, Tehran, Iran.
    Balador, Ali
    Universitat Politècnica de València, Valencia, Spain.
    Kanellopoulos, Dimitris
    University of Patras, Greece.
    MAC layer misbehavior in MANETs2013In: Journal of IETE Technical Review IETETR, ISSN 0974--597, Vol. 29, no 3, p. 324-335Article in journal (Refereed)
  • 24.
    Vo, Van Nhan
    et al.
    Duy Tan Univ, Danang, Vietnam.
    Tran, Hung Vinh
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Uhlemann, Elisabeth
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Truong, Quach Xuan
    VNU Univ Engn & Technol, Hanoi, Vietnam.
    So-In, Chakchai
    Khonkaen Univ, Appl Network Technol ANT Lab, Khon Kaen, Thailand..
    Balador, Ali
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Reliable Communication Performance for Energy Harvesting Wireless Sensor Networks2019In: 2019 IEEE 89TH VEHICULAR TECHNOLOGY CONFERENCE (VTC2019-SPRING), IEEE , 2019Conference paper (Refereed)
    Abstract [en]

    In this paper, we study the problem of how to provide reliable communications for energy harvesting (EH) wireless sensor network (WSN). Using the example of an autonomous quarry, where self-driving trucks autonomously collect and transport goods, there is a need for multiple wireless sensors collecting data about where and when goods can be collected, while guaranteeing reliable operation of the quarry. The vehicles transfer energy to the wireless sensors within range, forming a cluster. The sensors use this energy to transmit data to the vehicles. Finally, the vehicles relay information to an access point (AP). The AP processes the collected information and synchronize the operation of all vehicles. We propose an interference channel selection policy for the sensors-to-vehicles links and vehicles-to-AP links to improve the reliability of the communications, while enhancing the energy utilization. Accordingly, closed-form expression on how to achieve reliable communication within the considered system is derived and numerical results show that the proposed channel selection strategy not only improves the probability of achieving sufficiently reliable communication but also enhances the energy utilization.

1 - 24 of 24
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