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  • 1.
    Alderisi, Giuliana
    et al.
    University of Catania, Catania, Italy.
    Girs, Svetlana
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Lo Bello, Lucia
    University of Catania, Catania, Italy.
    Uhlemann, Elisabeth
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Björkman, Mats
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Probabilistic Scheduling and Adaptive Relaying for WirelessHART Networks2015Inngår i: 20th IEEE International Conference on Emerging Technologies and Factory Automation ETFA'15, 2015Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper deals with a way to probabilistically guarantee reliable packet delivery in WirelessHART based networks suitable for industrial control systems. We propose a new scheduling scheme, called Iterative Probabilistic Scheduling with Adaptive Relaying (IPS-AR), which consists of a static part (IPS) and a dynamic part (AR). IPS takes into account the channel characteristics and exploits relaying to achieve a minimum reliability threshold as requested by the supported industrial application. In the AR part, each relay node decides the packet to be sent based on online assessment of both the number of consecutive errors experienced by previous packets belonging to the same flow, as well as the number of copies of the packet currently available at the other relay nodes. This enables IPS-AR to achieve the desired reliability level while using the available re-sources in terms of time and bandwidth more efficiently.

  • 2.
    Balador, Ali
    et al.
    SICS Swedish ICT Västerås AB, Sweden.
    Böhm, Annette
    Halmstad University, Sweden.
    Uhlemann, Elisabeth
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    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 Applications2016Inngår i: 12th Swedish National Computer Networking Workshop SNCNW 2016, 2016Konferansepaper (Fagfellevurdert)
    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.

    Fulltekst (pdf)
    fulltext
  • 3.
    Balador, Ali
    et al.
    Universitat Politecnica de Valencia, Spain.
    Böhm, Annette
    Halmstad University, Sweden.
    Uhlemann, Elisabeth
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Calafate, Carlos T.
    Universitat Politecnica de Valencia, Spain.
    Cano, Juan-Carlos
    Universitat Politecnica de Valencia, Spain.
    A reliable token-based MAC protocol for delay sensitive platooning applications2015Inngår i: 2015 IEEE 82nd Vehicular Technology Conference, VTC Fall 2015 - Proceedings, Boston, MA, United States, 2015, s. Article number 7390813-Konferansepaper (Fagfellevurdert)
    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 considerably compared to pure 802.11p.

  • 4.
    Balador, Ali
    et al.
    Polytechnic University of Valencia, Valencia, Spain.
    Böhm, Annette
    Halmstad Universit, Sweden.
    Uhlemann, Elisabeth
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    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 systems2015Inngår i: Jornadas Sarteco 2015 JS 2015, Cordoba, Spain, 2015Konferansepaper (Fagfellevurdert)
    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.

  • 5.
    Balador, Ali
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Uhlemann, Elisabeth
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    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 strategies2018Inngår i: Sensors, E-ISSN 1424-8220, Vol. 18, nr 4, artikkel-id 955Artikkel i tidsskrift (Fagfellevurdert)
    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. 

    Fulltekst (pdf)
    fulltext
  • 6.
    Bello, L. L.
    et al.
    University of Catania, Catania, Italy.
    Åkerberg, J.
    ABB Corporate Research, Västerås, Sweden.
    Gidlund, M.
    Mid Sweden University, Sundsvall, Sweden.
    Uhlemann, Elisabeth
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Guest Editorial Special Section on New Perspectives on Wireless Communications in Automation: From Industrial Monitoring and Control to Cyber-Physical Systems2017Inngår i: IEEE Transactions on Industrial Informatics, ISSN 1551-3203, E-ISSN 1941-0050, Vol. 13, nr 3, s. 1393-1396, artikkel-id 7938563Artikkel i tidsskrift (Annet vitenskapelig)
  • 7.
    Bilstrup, Katrin
    et al.
    Högskolan i Halmstad, Inbyggda system (CERES).
    Böhm, Annette
    Högskolan i Halmstad, Inbyggda system (CERES).
    Lidström, Kristoffer
    Högskolan i Halmstad, Inbyggda system (CERES).
    Jonsson, Magnus
    Högskolan i Halmstad, Inbyggda system (CERES).
    Larsson, Tony
    Högskolan i Halmstad, Inbyggda system (CERES).
    Uhlemann, Elisabeth
    Högskolan i Halmstad, Inbyggda system (CERES).
    Report on the Collaboration between CVIS and CERES in the Project Vehicle Alert System (VAS)2009Rapport (Annet vitenskapelig)
    Abstract [en]

    In March 2007, an agreement was made for interchange of experiences between CVIS and the Centre for Research on Embedded Systems (CERES) at Halmstad University in Sweden. The majority of the work relating to this collaboration has been conducted within the CERES project Vehicle Alert System (VAS), aiming to use vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications to provide different types of warning messages. The main focus of the VAS project is on communication and in particular the lower layers of the communication stack are investigated. VAS involves academic researchers from Halmstad University as well as researchers from Volvo Technology, SP Technical Research Institute of Sweden and the company Free2move. This report presents the results of the VAS project, its publications, and other issues of interest both to the CVIS consortium as well as a broader scope.

  • 8.
    Bilstrup, Katrin
    et al.
    Högskolan i Halmstad, Inbyggda system (CERES).
    Uhlemann, Elisabeth
    Högskolan i Halmstad, Inbyggda system (CERES).
    Ström, Erik G.
    Chalmers.
    Medium access control in vehicular networks based on the upcoming IEEE 802.11p standard2008Inngår i: 15th World Congress on Intelligent Transport Systems and ITS America Annual Meeting 2008, World Congress on ITS , 2008, s. 4155-4167Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper, initial simulations are presented showing that the upcoming IEEE 802.11p standard is not suitable for traffic safety applications requiring reliable, low delay communication between vehicles. The medium access control procedure is one of the most important parts in the design of delay-constrained communication systems, and emerging vehicle safety applications put new stringent demands on timely and reliable delivery of data packets. The medium access procedure used in 802.11p is carrier sense multiple access, which is inherently unsuitable for time-critical data traffic since it is contention-based and cannot provide a finite upper bound on the time to channel access. The simulation results indicate that with IEEE 802.11p, channel access cannot be granted in a manner that is sufficiently predictable to support reliable, low-delay communications between vehicles on a highway.

  • 9.
    Bilstrup, Katrin
    et al.
    Högskolan i Halmstad, Inbyggda system (CERES).
    Uhlemann, Elisabeth
    Högskolan i Halmstad, Inbyggda system (CERES).
    Ström, Erik G.
    Chalmers.
    Bilstrup, Urban
    Högskolan i Halmstad, Inbyggda system (CERES).
    Evaluation of the IEEE 802.11p MAC method for vehicle-to-vehicle communication2008Inngår i: 68th IEEE Vehicular Technology Conference, 2008. VTC 2008-Fall: IEEE Vehicular Technology Conference (VTC) (2008), Piscataway, N.J.: IEEE Press , 2008, s. Article number 4657278-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper the medium access control (MAC) method of the upcoming vehicular communication standard IEEE 802.11p has been simulated in a highway scenario with periodic broadcast of time-critical packets (so-called heartbeat messages) in a vehicle-to-vehicle situation. The 802.11p MAC method is based on carrier sense multiple access (CSMA) where nodes listen to the wireless channel before sending. If the channel is busy, the node must defer its access and during high utilization periods this could lead to unbounded delays. This well-known property of CSMA is undesirable for time critical communications. The simulation results reveal that a specific node/vehicle is forced to drop over 80% of its heartbeat messages because no channel access was possible before the next message was generated. To overcome this problem, we propose to use self-organizing time division multiple access (STDMA) for real-time data traffic between vehicles. This MAC method is already successfully applied in commercial surveillance applications for ships (AIS) and airplanes (VDL mode 4). Our initial results indicate that STDMA outperforms CSMA for time-critical traffic safety applications in ad hoc vehicular networks.

  • 10.
    Bilstrup, Katrin
    et al.
    Högskolan i Halmstad, Inbyggda system (CERES).
    Uhlemann, Elisabeth
    Högskolan i Halmstad, Inbyggda system (CERES).
    Ström, Erik G.
    Högskolan i Halmstad, Inbyggda system (CERES).
    Bilstrup, Urban
    Högskolan i Halmstad, Inbyggda system (CERES).
    On the ability of the 802.11p MAC method and STDMA to support real-time vehicle-to-vehicle communications2009Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. 2009, nr 902414, s. 1-14Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Traffic safety applications using vehicle-to-vehicle (V2V) communication is an emerging and promising area within the intelligent transportation systems (ITS) sphere. Many of these new applications require real-time communication with high reliability, meaning that packets must be successfully delivered before a certain deadline. Applications with early deadlines are expected to require direct V2V communications, and the only standard currently supporting this is the upcoming IEEE 802.11p, included in the wireless access in vehicular environment (WAVE) stack. To meet a real-time deadline, timely and predictable access to the channel is paramount. However, the medium access method used in 802.11p, carrier sense multiple access with collision avoidance (CSMA/CA), does not guarantee channel access before a finite deadline. In this paper, we analyze the communication requirements introduced by traffic safety applications, namely, low delay, reliable, real-time communications.We show by simulation of a simple, but realistic, highway scenario, that vehicles using CSMA/CA can experience unacceptable channel access delays and, therefore, 802.11p does not support real-time communications. In addition, we present a potential remedy for this problem, namely, the use of self-organizing time division multiple access (STDMA). The real-time properties of STDMA are investigated by means of the same highway simulation scenario, with promising results.

  • 11.
    Bilstrup, Katrin
    et al.
    Högskolan i Halmstad, Inbyggda system (CERES).
    Uhlemann, Elisabeth
    Högskolan i Halmstad, Inbyggda system (CERES).
    Ström, Erik G.
    Chalmers, Gothenburg.
    Bilstrup, Urban
    Högskolan i Halmstad, Inbyggda system (CERES).
    On the ability of the IEEE 802.11p and STDMA to provide predictable channel access2009Inngår i: Proceedings of the 16th World Congress on Intelligent Transport Systems (ITS), 2009, s. 10-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Emerging traffic safety applications requiring low delay communications will need vehicle ad-hoc networks. The only communication standard currently supporting this is IEEE 802.11p. However, 802.11p uses the medium access method CSMA/CA, which has a major drawback: unbounded worst case channel access delay. We therefore propose an algorithm already in commercial use in the shipping industry: STDMA. With STDMA, nodes always get predictable channel access regardless of the number of competing nodes and the maximum delay is deterministic. In this paper we elaborated with different parameter settings for the two protocols with the aim of improving performance without altering the standards.

     

  • 12.
    Böhm, Annette
    et al.
    Högskolan i Halmstad, Centrum för forskning om inbyggda system (CERES).
    Jonsson, Magnus
    Högskolan i Halmstad, Centrum för forskning om inbyggda system (CERES).
    Uhlemann, Elisabeth
    Högskolan i Halmstad, Centrum för forskning om inbyggda system (CERES).
    Adaptive Cooperative Awareness Messaging for Enhanced Overtaking Assistance on Rural Roads2011Inngår i: IEEE Vehicular Technology Conference (VTC Fall 2011), Piscataway, N.J.: IEEE Press , 2011, s. Article number 609316211-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Cooperative traffic safety applications such as lane change or overtaking assistance have the potential to reduce the number of road fatalities. Many emerging traffic safety applications are based on IEEE 802.11p and periodic position messages, so-called cooperative awareness messages (CAM) being broadcasted by all vehicles. In Europe, ETSI defines a periodic report rate of 2 Hz for CAMs. Although a high report rate is the key to early hazard detection, the 2 Hz rate has been chosen to avoid congestion in settings where the vehicle density is high, e.g., on major highways and in urban scenarios. However, on rural roads with a limited number of communicating vehicles, a report rate of 2 Hz leads to unnecessary delay in cooperative awareness. By adapting the CAM report rate depending on the specific application and road traffic density, and by making use of the priority levels provided by the 802.11p quality of service mechanism, we show that hazards can be detected earlier and the available bandwidth is used more efficiently, while not overexploiting the network resources.

  • 13.
    Böhm, Annette
    et al.
    Halmstad University, Sweden.
    Jonsson, Magnus
    Halmstad University, Sweden.
    Uhlemann, Elisabeth
    Halmstad University, Sweden.
    Co-existing periodic beaconing and hazard warnings in IEEE 802.11p-based platooning applications2013Inngår i: ACM International Workshop on Vehicular Inter-Networking, Systems, and Applications ACM-VANET-13, 2013, s. 99-101Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A platoon of trucks driving at the same, mutually agreed speed while keeping a minimum inter-vehicle distance will reduce fuel consumption, enhance transport efficiency as well as improve the safety of other adjacent road users. The European profile of IEEE 802.11p for inter-vehicle communications uses a single 10 MHz control channel dedicated to safety-critical data, shared by periodic status updates, and event-triggered warnings. Coupled with the random access delay inherent to the 802.11p medium access method, the strict timing and reliability requirements of platoon applications are not easily met. To this end, we evaluate the effect of IEEE 802.11p-compliant send rate adaptations and message type prioritizations and the choice of warning dissemination strategy in a platooning scenario. Simulation studies of a platoon of 10-20 vehicles in a busy highway scenario show that a context-aware choice of send rate, priority class and dissemination strategy not only reduces the hazard warning dissemination delay but also has a significant effect on the throughput of periodic beacons.

  • 14.
    Böhm, Annette
    et al.
    Halmstad University, Sweden.
    Jonsson, Magnus
    Halmstad University, Sweden.
    Uhlemann, Elisabeth
    Halmstad University, Sweden.
    Performance comparison of a platooning application using the IEEE 802.11p MAC on the control channel and a centralized MAC on a service channel2013Inngår i: IEEE International Conference on Wireless and Mobile Computing, Networking and Communications WiMOB'13, 2013, s. 545-552, artikkel-id 6673411Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Recent advances in cooperative driving hold the potential to significantly improve safety, comfort and efficiency on our roads. An application of particular interest is platooning of trucks, where it has been shown that keeping a minimum inter-vehicle distance results in considerably reduced fuel consumption. This, however, puts high requirements on timeliness and reliability of the underlying exchange of control messages between platoon members. The European profile of IEEE 802.11p, recently adopted by ETSI, defines two message types to this end, periodic beacons for basic cooperative awareness (CAM) and event-triggered decentralized environmental notification messages (DENM), both of which will use one common control channel. IEEE 802.11p employs a random medium access protocol, which may experience excessive delays during high network loads. To mitigate these effects, ETSI standardizes a decentralized congestion control algorithm to, e.g., lower the CAM update frequency during high loads. However, this may prevent proper functionality of a platooning application. In this paper we propose a solution that instead uses a dedicated service channel for platooning applications and compare its performance to standard-compliant IEEE 802.11p inter-platoon communication on the control channel. Service channels typically have less strict requirements on send rates, data traffic types and medium access methods. Our service channel solution combines a random access phase for DENM with a centralized, scheduled access phase for CAM. Using a service channel enables us to guarantee timely channel access for all CAM packets before a specified deadline while still being able to provide a reasonable DENM dissemination delay.

  • 15.
    Dao, Van-Lan
    et al.
    Mälardalens universitet, Akademin för innovation, design och teknik, Innovation och produktrealisering.
    Girs, Svetlana
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Uhlemann, Elisabeth
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Dealing with Jamming Attacks in Uplink Pairwise NOMA Using Outage Analysis, Smart Relaying and Redundant Transmissions2024Inngår i: Open Journal of the Communications Society, Vol. 5, s. 112-126Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study focuses on optimizing the performance of an uplink pairwise Non-Orthogonal Multiple Access (NOMA) scenario with and without the support of a relayer, while subject to jamming attacks. We consider two different relaying protocols, one where the sources and the destination are within range of each other and one where they are not. The relay node can be mobile, e.g., a mobile base station, an unmanned aerial vehicle (UAV) or a stationary node that is chosen as a result of a relay selection procedure. We also benchmark with a NOMA retransmission protocol and an Orthogonal Multiple Access (OMA) scheme without a relayer. We analyze, adjust and compare the four protocols for different settings using outage analysis, which is an efficient tool for establishing communication reliability for both individual nodes and the overall wireless network. Closed-form expressions of outage probabilities can be adopted by deep reinforcement learning (RL) algorithms to optimize wireless networks online. Accordingly, we first derive closed-form expressions for the individual outage probability (IOP) of each source node link and the relayer link using both pairwise NOMA and OMA. Next, we analyze the IOP for one packet (IOPP) for each source node considering all possible links between the source node to the destination, taking both phases into account for the considered protocols when operating in Nakagami-m fading channels. The overall outage probability for all packets (OOPP) is defined as the maximum IOPP obtained among the source nodes. This metric is useful to optimize the whole wireless network, e.g., to ensure fairness among the source nodes. Then, we propose a method using deep RL where the OOPP is used as a reward function in order to adapt to the dynamic environment associated with jamming attacks. Finally, we discuss valuable guidelines for enhancing the communication reliability of the legitimate system.

  • 16.
    Dao, Van-Lan
    et al.
    Mälardalens universitet, Akademin för innovation, design och teknik, Innovation och produktrealisering.
    Girs, Svetlana
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Uhlemann, Elisabeth
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Defeating Jamming Attacks in Downlink Pairwise NOMA Using Relaying2023Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This study explores an incremental relaying strategy in downlink pairwise Non-Orthogonal Multiple Access (NOMA), which involves multiple pairs of nodes near and far from the downlink destinations. The strategy aims to select a near destination node to relay the packet of a far destination node, considering the presence of jamming attacks. To this end, we first derive closed-form expressions for the individual outage probability (IOP) for both near and far destinations in Nakagami-m fading channels. Next, the overall IOP (OIOP) performance is defined as the maximum value among the obtained IOPs, ensuring fairness among the nodes. To optimize the system, simulated annealing algorithms are proposed to determine the best power allocation and the best relay-destination pairing. We can conclude that both the power allocation and the position/selection of the near destination node significantly impact the OIOP for a specific pair. However, in the case of multiple pairs of destinations, a good power allocation alone suffices for each pair, and fixed or even random destination pairing is satisfactory in the considered context.

  • 17.
    Dao, Van-Lan
    et al.
    Mälardalens universitet, Akademin för innovation, design och teknik, Innovation och produktrealisering.
    Girs, Svetlana
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Uhlemann, Elisabeth
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Outage Performance Comparison of Adaptive Relaying Schemes Subject to Jamming2023Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Proper relay selection (RS) plays a key role for improving the reliability of wireless networks, especially in the presence of jamming attacks and/or interferers. In this work, we consider several RS schemes from the literature, using e.g. channel gains and signal-to-interference plus noise ratio (SINR) to select a relayer and evaluate them using outage probability (OP). We also propose an RS scheme which is selecting relayers to maximize the communication reliability in terms of minimizing the OP. The suggested RS strategy also takes the effect of jamming attacks and/or interferers into account. Accordingly, an intensive investigation of the OP of all RS schemes considering also jammers' positions in various scenarios is conducted. The results suggest that a combination of RS schemes using channel gains and SINRs of all hops achieves the best communication reliability in scenarios with intensive interference. The sensitivity for channel estimation errors of the relaying schemes is also investigated. Finally, discussions about the obtained results together with the complexity of all RS schemes are presented before providing guidelines on which schemes should be used in which scenarios to improve the communication reliability.

  • 18.
    Dao, Van-Lan
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Hoang, Le-Nam
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Girs, Svetlana
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Uhlemann, Elisabeth
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Defeating Jamming Using Outage Performance Aware Joint Power Allocation and Access Point Placement in Uplink Pairwise NOMA2021Inngår i: IEEE Open Journal of the Communications Society, E-ISSN 2644-125X, Vol. 2, s. 1957-1979Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, an uplink pairwise Non-Orthogonal Multiple Access (NOMA) scenario using a mobile access point (AP) or an unmanned aerial vehicle in the presence of a jamming attack is considered. To mitigate the influence of the jamming attack, a joint power allocation and AP placement design is proposed. Accordingly, closed-form expressions of the overall outage probability (OOP) and the individual outage probability (TOP) considering imperfect channel state information for each of the source nodes the AP serves, are derived over Nakagami-m fading channels using dynamic decoding order and fixed pairwise power allocation. We conduct an investigation of the effect of different parameters such as power allocation, source node placements, AP placement, target rates, and jammer location on the OOP and the IOP performance. By adapting the power allocation and the AP placement to the jamming attack, the communication reliability can be increased significantly compared to neglecting the presence of the jammer or treating the jammer as noise. Since the malicious jammer and the AP have conflicting interests in terms of communication reliability, we formulate a non-cooperative game for the two players considering their positions and the power allocation of the NOMA nodes as their strategies and the OOP as utility function. We propose using hybrid simulated annealing - greedy algorithms to address the joint power allocation and AP placement problem for the cases of both a fixed and a mobile jammer. Finally, the Nash equilibrium points are obtained and then the UAV goes directly to this position and keeps staying there to save power consumption.

  • 19.
    Dao, Van-Lan
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Hoang, Le-Nam
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Girs, Svetlana
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Uhlemann, Elisabeth
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Outage Performance of Pairwise NOMA Allowing a Dynamic Decoding Order and Optimal Pairs of Power Levels2020Inngår i: IEEE Open Journal of the Communications Society, E-ISSN 2644-125X, Vol. 1, s. 1886-1906Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this article, we evaluate the overall outage probability (OOP) of pairwise Non-orthogonal Multiple Access (NOMA) for both uplink and downlink. We also propose a dynamic decoding order (DDO) together with a fixed pairwise power allocation (FPPA) scheme, in which the optimal decoding order is decided based on the instantaneous channel gains, and thereafter, a pair of power levels is assigned in accordance with the selected decoding order. Exact closed-form expressions of the OOPs for both uplink and downlink pairwise NOMA considering all proposed decoding orders over Nakagami- m fading are derived. Further, we find the optimal fixed power levels for different power allocation strategies so that the OOPs are minimized. Moreover, we investigate the influence of the distances between the source nodes and the access point (AP), the target transfer rates and the path-loss exponents on the OOPs for all cases of decoding orders. In addition, we benchmark our proposed DDO against other decoding orders in terms of the OOP. The results show that assigning optimal fixed power levels which takes the instantaneous decoding order into account not only improves the communication reliability, but also reduces the complexity and computational load at the AP.

  • 20.
    Dao, Van-Lan
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Tran, Hung
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Girs, Svetlana
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Uhlemann, Elisabeth
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Reliability and Fairness for CANT Communication Based on Non-Orthogonal Multiple Access2019Inngår i: 2019 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS WORKSHOPS (ICC WORKSHOPS), IEEE , 2019Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Recently, communication using unmanned aerial vehicles (LAVO as relay nodes has been considered beneficial for a number of applications. Moreover, nomorthogonM multiple access (NONIA) with users being assigned different signal passer levels while sharing the same tune-frequency domain has been found effective to enhance spectrum utilization and provide predictable access to the channel. Thus, in this paper we consider an UAV communication system with NOMA and propose a solution to find the optimal values for the user's power allocation coefficients (PA(s) needed to achieve the required levels of communication reliability. We present a closed-form expression for the PAC of each user and also propose an algori for finding the optimal altitude of the UAV required to satisfy the fairness condition for all users. Finally, we provide numerical mutinies and compare the results tar three types of communication environments.

  • 21.
    Dao, Van-Lan
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Tran, Hung
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Girs, Svetlana
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Uhlemann, Elisabeth
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Reliability and Fairness for UAV Communication Based on Non-Orthogonal Multiple Access2019Inngår i: 2019 IEEE International Conference on Communications Workshops (ICC Workshops), 2019, nr 53Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Recently, communication using unmanned aerial vehicles (UAVs) as relay nodes has been considered beneficial for a number of applications. Moreover, non-orthogonal multiple access (NOMA) with users being assigned different signal power levels while sharing the same time-frequency domain has been found effective to enhance spectrum utilization and provide predictable access to the channel. Thus, in this paper we consider an UAV communication system with NOMA and propose a solution to find the optimal values for the user’s power allocation coefficients (PACs) needed to achieve the required levels of communication reliability. We present a closed-form expression for the PAC of each user and also propose an algorithm for finding the optimal altitude of the UAV required to satisfy the fairness condition for all users. Finally, we provide numerical examples and compare the results for three types of communication environments.

  • 22.
    Fernandez, Z.
    et al.
    Information and Communication Technologies Area, Ikerlan Technology Research Centre, Mondragón, Spain.
    Val, I.
    Information and Communication Technologies Area, Ikerlan Technology Research Centre, Mondragón, Spain.
    Mendicute, M.
    Signal Theory and Communications Area, Mondragon University, Mondragón, Spain.
    Uhlemann, Elisabeth
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Analysis and Evaluation of Self-Organizing TDMA for Industrial Applications2019Inngår i: IEEE International Workshop on Factory Communication Systems - Proceedings, WFCS, Institute of Electrical and Electronics Engineers Inc. , 2019Konferansepaper (Fagfellevurdert)
    Abstract [en]

    With the Industry 4.0 revolution, the inclusion of wireless communications with real-time requirements has been gaining popularity in industrial applications. As existing wireless technologies do not fully satisfy the stringent requirements of the most critical industrial applications, wired, centralized networks are often used. However, when the application requires mobility, there is no other way than to use wireless communications. Further, in applications where the topology changes dynamically and a large number of devices are mobile, centralized protocols are less suitable. Unfortunately, most decentralized medium access protocols are not predictable, and thereby not able to fulfil the real-time requirements. To address these challenges, in this paper Self-Organizing Time Division Multiple Access (STDMA) is analysed to assess its suitability for use in industrial applications. The analysis has been carried out through simulations under a multipath dispersed time-variant industrial channel while subject to a variable Doppler shift. To this end, several metrics such as channel access delay, slot occupation distribution (SOD), packet losses and packet inter-arrival time (PIAT) have been evaluated, using OMNeT++ in combination with the VEINS framework. 

  • 23.
    Girs, Svetlana
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Bergblomma, Marcus
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Uhlemann, Elisabeth
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. Halmstad University, Sweden.
    Štimac, Barbara
    University of Zagreb, Zagreb, Croatia .
    Björkman, Mats
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Design of Channel Measurement Guidelines for Characterization of Wireless Industrial Environments2013Rapport (Annet vitenskapelig)
    Abstract [en]

    Providing reliable and timely communication in wireless industrial systems requires careful design of error control schemes able to tackle the bit error patterns typically occurring in these environments. As most error control schemes target some specific characteristics of a wireless channel, the selection of channel model is crucial for proper performance assessment. There are a number of widely used channel models, but the question of the most appropriate choice of model for industrial environments still remains largely open. Not many indoor measurement campaigns have focused on industrial environments with their own specific characteristics. In this paper we present a set of measurement guidelines aiming to characterize industrial environments such that suitable channel models can be selected to properly evaluate error control schemes targeting reliable and timely wireless communications in industrial environments. 

    Fulltekst (pdf)
    fulltext
  • 24.
    Girs, Svetlana
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Uhlemann, Elisabeth
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Björkman, Mats
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Adopting FEC and Packet Combining to Increase the Performance of IWSNs Using Relaying2015Inngår i: International Conference on Computing and Network Communications CoCoNet'15, 2015, s. 90-97Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Industrial networks can benefit significantly from introduction of wireless communication. However, wireless systems suffer from much higher packet error rates than wired networks do, making it difficult to obtain sufficient reliability within application deadlines. One promising approach to increase the reliability of wireless communication systems without causing excessive additional delays is to exploit spatial diversity. However, often in industrial networks it is not possible to place the relay nodes optimally. Due to this not even relay nodes located close to the source are able to receive the source packets missing at the destination correctly and consequently they cannot assist by relaying. Therefore, to benefit even further from relaying, additional measures should be taken both to increase the number of the correct packets at the relay nodes and to allow the destination to recover more correct packets. Consequently, the focus of this work is schemes enabling relaying, forward-error-correction (FEC) and packet combining without causing additional delays or complexity such that it is possible to use off the shelf transceivers. The results show that the introduction of FEC and packet combining does improve performance by enabling relay nodes to help more often. However, the exact gain depends on the specific FEC scheme used and, in particular, the size of the preamble and other fields that must be left uncoded, but still be received correctly, to be able to use FEC on the received packet.

  • 25.
    Girs, Svetlana
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Uhlemann, Elisabeth
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. Halmstad University.
    Björkman, Mats
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Increased Reliability of Reduced Delay in Wireless Industrial Networks Using Relaying and Luby Codes2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Providing reliable and timely communication in wireless industrial networks is crucial. Previous research has shown that relaying can aid in achieving this goal. We consider the case when relay resources are sparse such that each relay needs to aid e.g., three different sensor nodes and propose to combine relaying with Luby codes. We let the relay node construct a Luby coded packet using the three source packets as input. The destination can then use the Luby coded packet to recover an erroneous or lost source packet regardless of which source that packet belonged to. The performance evaluation shows that our proposed scheme significantly increases the number of correctly received packets before the corresponding deadlines, or alternatively that high reliability can be maintained even if fewer time slots are allocated for retransmissions, thus lowering the delay.

  • 26.
    Girs, Svetlana
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Uhlemann, Elisabeth
    Halmstad University.
    Björkman, Mats
    Mälardalens högskola, Akademin för innovation, design och teknik.
    The Effects of Relay Behavior and Position in Wireless Industrial Networks2012Inngår i: 2012 9th IEEE International Workshop on Factory Communication Systems, May 21-24, 2012 Lemgo, Germany: Proceedings, 2012, s. 183-190Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In wireless industrial networks, providing reliable and timely communication is crucial. Previous research has shown that relaying can be used to achieve this goal. However, we have found that different types of wireless channels encountered in industrial environments affect the benefits as well as the best behavior and position of relay nodes. We consider two types of behavior: the relay node always retransmits or it only retransmits if it has obtained a correct copy of the packet. We evaluate different positions of the relay node by conducting simulations for two types of fading channels: with and without line of sight. The results clearly show that the benefits, the best behavior and position of a relay node depends on the wireless channel, whether or not the bit errors appear randomly or in bursts and also on the distance between the source and the final destination.

  • 27.
    Girs, Svetlana
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Willig, Andreas
    Univ Canterbury, Canterbury, New Zealand.
    Uhlemann, Elisabeth
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Bjoerkman, Mats
    Halmstad Univ, Halmstad, Sweden.
    On the Role of Feedback for Industrial Wireless Networks Using Relaying and Packet Aggregation2014Inngår i: 2014 IEEE INTERNATIONAL CONFERENCE ON INDUSTRIAL TECHNOLOGY (ICIT), 2014, s. 743-748Konferansepaper (Fagfellevurdert)
    Abstract [en]

    To be accepted for use in industrial applications, wireless technologies must offer similar performance in terms of reliability and timeliness as provided by current wired solutions. Wireless channels, introducing time-varying packet error rates, impose a significant challenge to fulfill these requirements. One way to improve reliability in industrial wireless networks is to use relaying, whereas packet aggregation is a method that can reduce delay. Hence, in this paper, we propose to use a combination of relaying and packet aggregation. Based on the type of feedback provided by the controller, the relay node can choose the most suitable way to use its allocated time slots such that more packets can reach the controller before their deadlines. The results show that allowing this kind of flexibility at the relay node results in performance improvements. The more flexibility, the greater the gain, and thus further improvements can be made by adjusting the schedule to take different types of feedback into account.

  • 28.
    Girs, Svetlana
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Willig, Andreas
    University of Canterbury, Canterbury, New Zealand.
    Uhlemann, Elisabeth
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. Halmstad University, Halmstad, Sweden.
    Björkman, Mats
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    On the Role of Feedback for Industrial Networks Using Relaying and Packet Aggregation2013Rapport (Annet vitenskapelig)
    Abstract [en]

    To be accepted for use in industrial applications, wireless technologies must offer similar performance in terms of reliability and timeliness as provided by current wired solutions. Wireless channels, introducing time-varying packet error rates, impose a significant challenge to fulfill these requirements. One way to improve reliability in industrial wireless networks is to use relaying, whereas packet aggregation is a method that can reduce delay. Hence, in this paper, we propose to use a combination of relaying and packet aggregation. Based on the type of feedback provided by the controller, the relay node can choose the most suitable way to use its allocated time slots such that more packets can reach the controller before their deadlines. The results show that allowing this kind of flexibility at the relay node results in performance improvements. The more flexibility, the greater the gain, and thus further improvements can be made by adjusting the schedule to take different types of feedback into account.

  • 29.
    Girs, Svetlana
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Willig, Andreas
    University of Canterbury, UK.
    Uhlemann, Elisabeth
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. Halmstad University.
    Björkman, Mats
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Scheduling for source relaying with packet aggregation in industrial wireless networks2016Inngår i: IEEE Transactions on Industrial Informatics, ISSN 1551-3203, E-ISSN 1941-0050, Vol. 12, nr 5, s. 1855-1864Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The interest in wireless communication systems for industrial applications has grown significantly over the last years. More flexible, easier to install and maintain, wireless networks present a promising alternative to the currently used wired systems. However, reliability and timeliness requirements at present met by wired networks also need to be fulfilled by wireless solutions. Packet errors introduced when packets travel through wireless channels imply a significant challenge to fulfill these requirements. Relaying has been recognized to improve the reliability in industrial wireless networks without causing additional delay. Furthermore, the recent results have shown that relaying combined with packet aggregation significantly outperforms simple relaying. However, it is not always cost efficient to introduce additional relay nodes into an industrial network and hence, in this paper, we propose using a combination of relaying and packet aggregation at the source nodes. The results show that when relaying and aggregation are used at the source nodes, the transmission schedule plays a crucial role. A schedule adapting to the varying channel conditions improves performance substantially. By carefully choosing which packet to aggregate, even further improvements can be achieved.

  • 30.
    Girs, Svetlana
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Willig, Andreas
    University of Canterbury, Canterbury, New Zealand.
    Uhlemann, Elisabeth
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. Halmstad University, Halmstad, Sweden .
    Björkman, Mats
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Scheduling transmissions in industrial networks using source relaying and packet aggregation2015Inngår i: 11th IEEE World Conference on Factory Communication Systems WFCS'15, 2015Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Wireless networks present a promising alternative to the currently used wired systems as they are more flexible, easier to install and maintain. However, requirements on reliability and timeliness which at present are met by wired networks, also need be fulfilled by wireless solutions.Relaying and packet aggregation have been recognised as viable tools to do this. However, introducing additional relay nodes into an industrialnetwork is costly. Hence, in this paper we propose to use a combination of relaying and packet aggregation performed by the source nodes themselves. The results show that our proposal improves performance considerably, but also that the transmission schedule plays a crucial role. A schedule adapting to the varying channel conditions, improves the performance substantially. By carefully choosing which packet to aggregate, even further improvements can be achieved.

  • 31.
    Gorospe, Joseba
    et al.
    Mondragon Unibertsitatea, Spain.
    Hasan, Shahriar
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Islam, Mir Riyanul
    Mälardalens universitet, Akademin för innovation, design och teknik.
    Gomez, Arrate Alonso
    Mondragon Unibertsitatea, Spain.
    Girs, Svetlana
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Uhlemann, Elisabeth
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Analyzing Inter-Vehicle Collision Predictions during Emergency Braking with Automated Vehicles2023Inngår i: International Conference on Wireless and Mobile Computing, Networking and Communications, IEEE Computer Society , 2023, Vol. 2023-June, s. 411-418Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Automated Vehicles (AVs) require sensing and perception to integrate data from multiple sources, such as cameras, lidars, and radars, to operate safely and efficiently. Collaborative sensing through wireless vehicular communications can enhance this process. However, failures in sensors and communication systems may require the vehicle to perform a safe stop or emergency braking when encountering hazards. By identifying the conditions for being able to perform emergency braking without collisions, better automation models that also consider communications need to be developed. Hence, we propose to employ Machine Learning (ML) to predict inter-vehicle collisions during emergency braking by utilizing a comprehensive dataset that has been prepared through rigorous simulations. Using simulations and data-driven modeling has several advantages over physics-based models in this case, as it, e.g., enables us to provide a dataset with varying vehicle kinematic parameters, traffic density, network load, vehicle automation controller parameters, and more. To further establish the conditions for inter-vehicle collisions, we analyze the predictions made through interpretable ML models and rank the features that contribute to collisions. We also extract human-interpretable rules that can establish the conditions leading to collisions between AVs during emergency braking. Finally, we plot the decision boundaries between different input features to separate the collision and non-collision classes and demonstrate the safe region of emergency braking.

  • 32.
    Gutiérrez Peón, Pablo
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. TTTech Computertechnik AG, Vienna, Austria.
    Rodríguez, Pedro Manuel
    IK4-IKERLAN, Arrasate-Mondragón, Spain.
    Fernández, Zaloa
    IK4-IKERLAN, Arrasate-Mondragón, Spain.
    Pozo Pérez, Francisco Manuel
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Uhlemann, Elisabeth
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Val, Iñaki
    IK4-IKERLAN, Arrasate-Mondragón, Spain.
    Steiner, Wilfried
    TTTech Computertechnik AG, Austria.
    Cognitive Radio for Improved Reliability in a Real-Time Wireless MAC Protocol based on TDMA2017Inngår i: International Conference on Emerging Technologies And Factory Automation ETFA'17, 2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Wireless communications enables introduction of Internet of Things (IoT) in industrial networks. Unfortunately, real-time guarantees required for many IoT applications, may be compromised in wireless networks due to an unreliable transmission medium. A key component in enabling real-time communications is the medium access control (MAC) layer and its ability to effectively avoid concurrent transmissions that causes deadline misses. Also, deploying the network in a harsh interference environment can lead to low reliability. Time diversity, based on transmitting several copies of the same data at different instants, increases reliability but at the expense of increased jitter and bandwidth. A more efficient resource utilization is expected from cognitive radio, which dynamically takes into account the status of the wireless environment before performing transmissions. This paper proposes a wireless MAC protocol based on scheduled timeslots to avoid concurrent transmissions, combined with two different mechanisms to increase reliability, one based on time diversity and another on cognitive radio. The protocol and its mechanisms to enhance reliability are compared in different interference scenarios, and show that cognitive radios achieves better performance than time diversity, especially when the interference is produced by a jammer.

    Fulltekst (pdf)
    fulltext
  • 33.
    Gutiérrez Peón, Pablo
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. TTTech Computertechnik AG, Vienna, Austria., Mälardalens högskola , Vasteras, Sweden.
    Steiner, W.
    TTTech Computertechnik AG, Vienna, Austria.
    Uhlemann, Elisabeth
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Network Fault Tolerance by Means of Diverse Physical Layers2020Inngår i: IEEE International Conference on Emerging Technologies and Factory Automation, ETFA, Institute of Electrical and Electronics Engineers Inc. , 2020, s. 1697-1704Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Wired networks are deployed in scenarios requiring the highest levels of performance in terms of reliability and timeliness. Unfortunately, broken wires might permanently compromise the network operation unless fault tolerance mechanisms are in place. Fault tolerance is commonly achieved by replicating the wired network components, but this paper examines the use of a wireless backup network, since the wireless physical layer (PHY) is not expected to display permanent failures due to broken wires. Two mechanisms at medium access control (MAC) level are presented to take advantage of the wireless backup network: one allocating redundancy statically and one dynamically. Without loss of generality, redundancy is applied using the standard mechanisms from IEEE 802.3 (Ethernet) and IEEE 802.11 (Wi-Fi). The performance increase added by the backup network is studied both analytically and by simulation, showing considerable improvements in a very compromised midsize wired network. © 2020 IEEE.

  • 34.
    Gutiérrez Peón, Pablo
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. TTTech Computertechnik AG, Vienna, Austria.
    Uhlemann, Elisabeth
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Steiner, Wilfried
    TTTech Computertechnik AG, Vienna, Austria.
    Björkman, Mats
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    A Wireless MAC Method with Support for Heterogeneous Data Traffic2015Inngår i: IECON 2015 - 41st Annual Conference of the IEEE Industrial Electronics Society, 2015, s. 3869-3874, artikkel-id 7392703Konferansepaper (Fagfellevurdert)
    Abstract [en]

    An important aspect of any communication technology is its medium access method, being responsible for sharing the medium among users. For delay-sensitive applications, such as industrial control systems, timely and reliable channel access is of essence. Hence, existing protocols like HART and TTEthernet use a time-triggered medium access approach. However, as the nature of industrial control systems change and evolve, there is a growing need to provide wireless access and support data traffic with mixed requirements. While technologies like WirelessHART can offer timely and reliable access to the wireless medium, only one type of data traffic is usually supported. In this paper, we therefore propose and evaluate three different medium access methods for wireless communications, all capable of supporting three different data traffic classes: time-triggered, rate-constrained and best-effort traffic. In particular, different options on how to handle best-effort traffic, using scheduled time-slots or contention, are evaluated, showing for all the proposals different drawbacks and benefits depending on additional requirements on e.g., hardware, protocol overhead and resistance to interference.

  • 35.
    Gutiérrez Peón, Pablo
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. TTTech Computertechnik AG, Vienna, Austria.
    Uhlemann, Elisabeth
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Steiner, Wilfried
    TTTech Computertechnik AG, Vienna, Austria.
    Björkman, Mats
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Applying Time Diversity for Improved Reliability in a Real-Time Heterogeneous MAC Protocol2017Inngår i: 2017 IEEE 85TH VEHICULAR TECHNOLOGY CONFERENCE (VTC SPRING), 2017, artikkel-id 8108663Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Supporting real-time applications over wireless networks is challenging for several reasons. The medium access control (MAC) layer has a key role in enabling real-time guarantees by providing bounded access time to the transmission medium. Unfortunately, even when timely access is granted, transmissions can still be compromised, specially in the wireless domain, due to the unreliable transmission medium. A common way to increase the reliability of a communication system is to apply redundancy in the form of time diversity, i.e., transmitting several copies of the same message at different points in time. In this paper we propose a wireless MAC protocol capable of handling traffic with different levels of criticality and where transmissions and retransmissions are tailored to deadlines, so that the reliability of the communication system is increased and real-time guarantees can be provided. We focus on the traffic scheduling problem, and extend an already existing solution, Time-Triggered Ethernet, suitable for real-time traffic over wired multi-hop networks. The extension enables transmission of heterogeneous traffic over hybrid wired-wireless networks, and provides timely retransmissions in the wireless segment, such that the real-time guarantees are met. Further, we are able to schedule traffic to better cope with interference patterns of different duration, frequency and level of persistence. The results show that the MAC protocol can be successfully applied to combat different kinds of interference while meeting real-time deadlines.

    Fulltekst (pdf)
    fulltext
  • 36.
    Gutiérrez Peón, Pablo
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Uhlemann, Elisabeth
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Steiner, Wilfried
    TTTech Computertechnik AG, Austria.
    Björkman, Mats
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Applying Time Diversity for Improved Reliability in a Real-Time Wireless MAC Protocol2016Rapport (Annet vitenskapelig)
    Abstract [en]

    Supporting real-time applications over wireless networks is challenging for several reasons. However, the inherent advantages due to wireless access like reduced wiring or the possibility to transmit between moving components are still desirable in many application domains. In particular, wireless support to applications with traffic having diverse time and safety requirements is desirable. The medium access control (MAC) layer plays a key role in enabling real-time guarantees, since it provides access to the transmission medium. Unfortunately, even if timely access is guaranteed, transmissions can still be compromised due to the unreliable wireless medium. A common way to increase the reliability of a communication system is to apply redundancy in the form of time diversity, i.e., transmitting several copies of the same message at different points in time. In this paper we propose a wireless MAC method in where transmissions and retransmissions are tailored to deadlines, so that the reliability of the communication system is increased and real-time guarantees can be provided. The proposal enables coexistence of three different traffic classes: time-triggered, rate-constrained and best-effort. Further, we have analysed the effect of different protocol configurations subject to interference with different duration, frequency, and level of persistence. The results show that different protocol settings can be successfully applied to combat different kinds of interference to improve transmission reliability and timeliness.

  • 37.
    Gutiérrez Peón, Pablo
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Uhlemann, Elisabeth
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Steiner, Wilfried
    TTTech Computertechnik AG.
    Björkman, Mats
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Medium Access Control for Wireless Networks with Diverse Time and Safety Real-Time Requirements2016Inngår i: 42nd Annual Conference of the IEEE Industrial Electronics Society IECON 2016, 2016, s. 4665-4670, artikkel-id 7794095Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The communication in-between embedded systems present in cars and planes, requires real-time networks. Up to now, fieldbus technologies like PROFIBUS and CAN have covered the demand for predictable communications in embedded systems. However, these fieldbuses do not suit some of the emerging application domains, that need more flexibility, support for dynamic traffic flows, different traffic classes, high throughput, and the inclusion of wireless capabilities. To this end, we propose several different medium access control (MAC) schemes with support for traffic with diverse time and safety requirements. We have calculated the worst case channel access delay for each proposal, and also simulated them in OMNeT++ to analyse and compare their performance in terms of average access delay and packet collisions as a function of different protocol settings and traffic patterns e.g., the channel load, data traffic emerging from one sender only versus evenly distributed between all senders. Our results indicate that the more that is known about the data traffic, the better performance can be achieved by selecting an appropriate MAC protocol. Conversely, when nothing is known, one MAC protocol emerges as the best trade-off.

  • 38.
    Hasan, Shahriar
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Balador, Ali
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Girs, Svetlana
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Uhlemann, Elisabeth
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Towards emergency braking as a fail-safe state in platooning: A simulative approach2019Inngår i: IEEE Vehicular Technology Conference, Institute of Electrical and Electronics Engineers Inc. , 2019Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Platooning is anticipated to facilitate automated driving even with semi-automated vehicles, by forming road trains using breadcrumb tracing and Cooperative Adaptive Cruise Control (CACC). With CACC, the vehicles coordinate and adapt their speed based on wireless communications. To keep the platoon fuel-efficient, the inter-vehicle distances need to be quite short, which requires automated emergency braking capabilities. In this paper, we propose synchronized braking, which can be used together with existing CACC controllers. In synchronized braking, the leading vehicle in the platoon does not brake immediately, but instead communicates its intentions and then, slightly later, the whole platoon brakes simultaneously. We show that synchronized braking can avoid rear-end collisions even at a very high deceleration rate and with short inter- vehicle distances. Also, the extra distance travelled during the delay before braking can be compensated by enabling a higher deceleration, through coordinated synchronized braking.

  • 39. Hasan, Shahriar
    et al.
    Girs, Svetlana
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Uhlemann, Elisabeth
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Characterization of Transient Communication Outages Into States to Enable Autonomous Fault Tolerance in Vehicle Platooning2023Inngår i: IEEE OPEN JOURNAL OF INTELLIGENT TRANSPORTATION SYSTEMS, ISSN 2687-7813, Vol. 4, s. 101-129Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The benefits of platooning, e.g., fuel efficiency, road throughput enhancement, driver offload, etc., have sparked an interest in a more connected, intelligent, and sustainable transportation ecosystem. However, efficient platooning is realized through wireless communications, characterized by transient connectivity, which is caused by occasional packet losses. Being a safety-critical system of systems, a platoon must be fail-operational even during transient connectivity. Moreover, a platoon should be capable of transitioning into a fail-safe state upon encountering a hazard. To this end, we propose a strategy for classifying the transient communication outages incurred by platooning vehicles into states. Furthermore, a state machine using these states to enable safe automated platooning is proposed that also defines the transitions between the states based on the nature and levels of transient connectivity and hazards. To achieve this, a graceful degradation and upgradation method is proposed, such that the platoon can remain fail-operational by adjusting, e.g., the automated controller and/or the inter-vehicle gaps based on the current communication quality. An emergency braking strategy is also proposed to enable a fast transition into a fail-safe state, should the platoon encounter a hazard. Rigorous simulation studies show that the proposed strategies enable fault-tolerant automated platooning also during transient connectivity.

  • 40.
    Hasan, Shahriar
    et al.
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Girs, Svetlana
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Uhlemann, Elisabeth
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Cooperative Automated Emergency Braking for CAVs under Time-Varying Communication Delays2023Inngår i: IAVVC 2023 - IEEE International Automated Vehicle Validation Conference, Proceedings, Institute of Electrical and Electronics Engineers Inc. , 2023Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Connected and Automated Vehicles (CAVs) have the potential to significantly improve road safety, fuel efficiency, and traffic flow by forming platoons with short inter-vehicle gaps, enabled by vehicle-to-vehicle communications and onboard sensors. However, wireless connectivity for CAVs is subject to time-varying delays, which can significantly impact platoon safety during emergency braking. To this end, this paper evaluates the communication delays incurred by platoon vehicles during emergency braking under various data and traffic densities. Additionally, an emergency braking strategy named adaptive emergency braking is proposed and compared with five other strategies based on their ability to meet the functional requirements of collision avoidance and minimizing the stopping distance of the platoon lead vehicle, which are crucial for transitioning a platoon to a fail-safe state. Moreover, the emergency braking strategies are evaluated through rigorous simulations, considering non-functional criteria such as required inter-vehicle gaps, maximum allowable deceleration rates, and their robustness under time-varying communication delays. 

  • 41.
    Hasan, Shahriar
    et al.
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Gorospe, J.
    Mondragon Unibertsitatea, Electronics and Computer Science Department, Arrasate, 20500, Spain.
    Girs, Svetlana
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Gomez, A. A.
    Mondragon Unibertsitatea, Electronics and Computer Science Department, Arrasate, 20500, Spain.
    Uhlemann, Elisabeth
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    PlatoonSAFE: An Integrated Simulation Tool for Evaluating Platoon Safety2023Inngår i: IEEE Open Journal of Intelligent Transportation Systems, ISSN 2687-7813, Vol. 4, s. 325-347Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Platooning is highly tractable for enabling fuel savings for autonomous and semi-autonomous cars and trucks. Safety concerns are one of the main impediments that need to be overcome before vehicle platoons can be deployed on ordinary roads despite their readily available technical feasibility. Simulation studies remain vital for evaluating platoon safety applications primarily due to the high cost of field tests. To this end, we present PlatoonSAFE, an open-source simulation tool that promotes the simulation studies of fault tolerance in platooning by enabling the monitoring of transient communication outages during runtime and assigning an appropriate performance level as a function of the instantaneous communication quality. In addition, PlatoonSAFE facilitates the simulation of several emergency braking strategies to evaluate their efficacy in transitioning a platoon to a fail-safe state. Furthermore, two Machine Learning (ML) models are integrated into PlatoonSAFE that can be employed as an onboard prediction tool in the platooning vehicles to facilitate online training of ML models and real-time prediction of communication, network, and traffic parameters. In this paper, we present the PlatoonSAFE structure, its features and implementation details, configuration parameters, and evaluation metrics required to evaluate the fault tolerance of platoon safety applications. 

  • 42.
    Hasan, Shahriar
    et al.
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Gorospe, Joseba
    Mondragon Unibertsitatea, Elect & Comp Sci Dept, Arrasate Mondragon, Spain..
    Gomez, Arrate Alonso
    Mondragon Unibertsitatea, Elect & Comp Sci Dept, Arrasate Mondragon, Spain..
    Girs, Svetlana
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Uhlemann, Elisabeth
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Prediction of Communication Delays in Connected Vehicles and Platoons2023Inngår i: 2023 IEEE 97TH VEHICULAR TECHNOLOGY CONFERENCE, VTC2023-SPRING, IEEE , 2023Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Automated vehicles connected through vehicle-tovehicle communications can use onboard sensor information from adjacent vehicles to provide higher traffic safety or passenger comfort. In particular, automated vehicles forming a platoon can enhance traffic safety by communicating before braking hard. It can also improve fuel efficiency by enabling reduced aerodynamic drag through short gaps. However, packet losses may increase the delay between periodic beacons, especially for the rear vehicles in a platoon. If the connected vehicles can forecast link quality, they can assign different performance levels in terms of intervehicle distances and also facilitate the designing of safer braking strategies. This paper proposes a strategy for incorporating machine learning algorithms into, e.g., the lead vehicle of a platoon to enable online training and real-time prediction of communication delays incurred by connected vehicles during runtime. The prediction accuracy and its suitability for making safety-critical decisions during, e.g., emergency braking have been evaluated through rigorous simulations.

  • 43.
    Hoang, L. -N
    et al.
    Halmstad University, Halmstad, Sweden.
    Uhlemann, Elisabeth
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. Halmstad University, Halmstad, Sweden.
    Jonsson, M.
    Halmstad University, Halmstad, Sweden.
    A framework for reliable exchange of periodic and event-driven messages in platoons2015Inngår i: 2015 IEEE International Conference on Communication Workshop, ICCW 2015, 2015, s. 2471-2476Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Platooning is widely considered a promising approach to decrease fuel consumption by reducing the air drag. However, in order to achieve the benefits of aerodynamic efficiency, the inter-vehicle distances must be kept short. This implies that the intra-platoon communication must not only be reliable but also able to meet strict timing deadlines. In this paper, we propose a framework that reliably handles the co-existence of both time-triggered and event-driven control messages in platooning applications and we derive an efficient message dissemination technique. We propose a semi-centralized time division multiple access (TDMA) approach, which e.g., can be placed on top of the current standard IEEE 802.11p and we evaluate the resulting error probability and delay, when using it to broadcast periodic beacons and disseminating event-driven messages within a platoon. Simulation results indicate that the proposed dissemination policy significantly enhances the reliability for a given number of available time-slots, or alternatively, reduces the delay, in terms of time-slots, required to achieve a certain target error probability, without degrading the performance of co-existing time-triggered messages.

  • 44.
    Hoang, L. -N
    et al.
    Halmstad University, Halmstad, Sweden.
    Uhlemann, Elisabeth
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. Halmstad University, Halmstad, Sweden.
    Jonsson, M.
    Halmstad University, Halmstad, Sweden.
    An efficient message dissemination technique in platooning applications2015Inngår i: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 19, nr 6, s. 1017-1020, artikkel-id 7066951Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Autonomous driving in road trains, a.k.a. platooning, may reduce fuel consumption considerably if the inter-vehicle distances are kept short. However, to do this, the intra-platoon communication must not only be reliable but also able to meet strict deadlines. While time-triggered messages are the foundation of most distributed control applications, platooning is likely to also require dissemination of event-driven messages. While much research work has focused on minimizing the age of periodic messages, state-of-the-art for disseminating event-driven messages is to let all nodes repeat all messages and focus on mitigating broadcast storms. We derive an efficient message dissemination scheme based on relay selection which minimizes the probability of error at the intended receiver(s) for both unicast and broadcast, without degrading the performance of co-existing time-triggered messages. We present a full analysis of the resulting error probability and delay, when relayers, selected by our algorithm, are used to disseminate messages within a platoon. Numerical results indicate that the proposed relaying policy significantly enhances the reliability for a given delay.

  • 45.
    Hoang, L. -N
    et al.
    Halmstad University, Halmstad, Sweden.
    Uhlemann, Elisabeth
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. Halmstad University, Halmstad, Sweden.
    Jonsson, M.
    Halmstad University, Halmstad, Sweden.
    Low Complexity Algorithm for Efficient Relay Assignment in Unicast/Broadcast Wireless Networks2017Inngår i: IEEE Vehicular Technology Conference (VTC) Proceedings, ISSN 1550-2252, Vol. June, artikkel-id 8108261Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Using relayers in wireless networks enables higher throughput, increased reliability or reduced delay. However, when building networks using commercially available hardware, concurrent transmissions by multiple relayers are generally not possible. Instead one specific relayer needs to be assigned for each transmission instant. If the decision regarding which relayer to assign, i.e., which relayer that has the best opportunity to successfully deliver the packet, can be taken online, just before the transmission is to take place, much can be gained. This is particularly the case in mobile networks, as a frequently changing network topology considerably affects the choice of a suitable relayer. To this end, this paper addresses the problem of online relay assignment by developing a low-complexity algorithm highly likely to find the optimal combination of relaying nodes that minimizes the resulting error probability at the targeted receiver(s) using a mix of simulated annealing and ant colony algorithms, such that relay assignments can be made online also in large networks. The algorithm differs from existing works in that it considers both unicast as well as broadcast and assumes that all nodes can overhear each other, as opposed to separating source nodes, relay nodes and destination nodes into three disjoint sets, which is generally not the case in most wireless networks. 

    Fulltekst (pdf)
    fulltext
  • 46.
    Hoang, L. -N
    et al.
    CERES, Halmstad University, Halmstad, Sweden.
    Uhlemann, Elisabeth
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. CERES, Halmstad University, Halmstad, Sweden.
    Jonsson, Magnus
    CERES, Halmstad University, Halmstad, Sweden.
    A novel relaying scheme to guarantee timeliness and reliability in wireless networks2016Inngår i: 2016 IEEE Globecom Workshops, GC Wkshps 2016 - Proceedings, Institute of Electrical and Electronics Engineers Inc. , 2016Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Many emerging applications based on wireless networks involve distributed control. This implies high requirements on reliability, but also on a predictable maximum delay and sometimes jitter. Further, many distributed control systems need to be constructed using off-the-shelf components, both due to cost constraints and due to interoperability with existing networks. This, in turn, implies that concurrent transmissions and multiuser detection are seldom possible. Instead, half-duplex time division multiple access (TDMA) is typically used. The total communication delay thereby depends on the packet error rate and the time until channel access is granted. With TDMA, channel access is upper-bounded and the jitter can be set to zero. With the aim to reduce the packet error rate given a certain deadline (a set of TDMA time-slots), we propose a novel relaying scheme, which can be implemented on top of off-the-shelf components. The paper includes a full analysis of the resulting error probability and latency. Numerical results show that the proposed relaying strategy significantly improves reliability given a certain maximum latency, or alternatively, reduces the latency, given a certain target reliability requirement.

  • 47.
    Hoang, Le-Nam
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Uhlemann, Elisabeth
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Jonsson, M.
    School of Information Technology, Halmstad University, Halmstad, Sweden.
    Relay Grouping to Guarantee Timeliness and Reliability in Wireless Networks2019Inngår i: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 23, nr 9, s. 1661-1664, artikkel-id 8737952Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Relaying can increase reliability, range, or throughput. In many cyber-physical systems (CPS), relaying is used to maximize reliability before a given deadline. Since concurrent transmissions are not supported by most CPS, time-division multiple access (TDMA) is typically used. However, a major drawback of relaying in TDMA is that pre-allocated time-slots are wasted if their respective transmitters do not have any correctly received packet to relay. Therefore, in this letter, we propose a novel relay grouping scheme to overcome this drawback. Numerical results show that the proposed scheme significantly enhances the reliability while guaranteeing the deadline for each message. 

  • 48.
    Hoang, Le-Nam
    et al.
    Halmstad Univ, CERES, Halmstad, Sweden..
    Uhlemann, Elisabeth
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. Halmstad Univ, CERES, Halmstad, Sweden.
    Jonsson, Magnus
    Halmstad Univ, CERES, Halmstad, Sweden..
    Relaying with Packet Aggregation for Half-Duplex All-to-All Broadcast in Time-Critical Wireless Networks2017Inngår i: 2017 IEEE GLOBECOM WORKSHOPS (GC WKSHPS), IEEE , 2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Wireless automation and control networks, with stringent latency and reliability requirements, typically use halfduplex communications combined with deadline-aware scheduling of time slots to nodes. To introduce higher reliability in legacy industrial control systems, extra time slots are usually reserved for retransmissions. However, in distributed wireless control systems, where sensor data from several different nodes must be timely and reliably available at all places where controller decisions are made, this is particularly cumbersome as all nodes may not hear each other and extra time slots imply increased delay. To enable all-to-all broadcast with manageable overhead and complexity in such systems, we therefore propose a novel relaying strategy using packet aggregation. The strategy assigns relayers to time slots, as well as determines which packets to aggregate in each slot, using a low-complexity algorithm such that ultra-reliable communications can be obtained with maintained end-to-end latency.

    Fulltekst (pdf)
    fulltext
  • 49.
    Ku, Bih-Yuan
    et al.
    National Taipei University of Technology, Taiwan .
    Uhlemann, Elisabeth
    Högskolan i Halmstad, Inbyggda system (CERES).
    Report on Rail Conference and Wireless Communications: [VTS News]2011Inngår i: IEEE Vehicular Technology Magazine, ISSN 1556-6072, E-ISSN 1556-6080, Vol. 6, nr 3, s. 111-117Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    The 2011 Joint Rail Conference (JRC) was held in Pueblo, Colorado, on March 16-18, 2011, immediately after the Association of American Railroads Research Review. The conference started with a technical tour of TTCi. The highlights of the technical tour were two on-site presentations on a full-scale train impact test and the field test of the positive train control (PTC) system. The tour attendees were given the opportunity to take a close look at the energy-absorption devices and sensors installed at various locations of the test car. The PTC presentation was held at the communications and train control (C&TC) test bed at the TTCi test track, which is the only CT&C test bed in North America. The 2012 Joint Rail Conference (JRC) will be held in Philadelphia in April 2012, and the IEEE Vehicular Technology Society (VTS) Land Transportation Division (LTD) will take the lead in the planning of the major technical forum onrail engineering in North America.

  • 50.
    Kunert, Kristina
    et al.
    Högskolan i Halmstad, Centrum för forskning om inbyggda system (CERES).
    Jonsson, Magnus
    Högskolan i Halmstad, Centrum för forskning om inbyggda system (CERES).
    Uhlemann, Elisabeth
    Högskolan i Halmstad, Centrum för forskning om inbyggda system (CERES).
    Exploiting time and frequency diversity in IEEE 802.15.4 industrial networks for enhanced reliability and throughput2010Inngår i: 2010 IEEE Conference on Emerging Technologies and Factory Automation (ETFA), 2010, s. Article number 5641347-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Industrial networks based on IEEE 802.15.4 are spreading, even though the joint requirement on predictability and reliability from industrial applications is hard to fulfil in wireless networks, and the data rate of IEEE 802.15.4 is rather low. With the goal of providing real-time guarantees, with increased reliability and throughput, we propose two multichannel network architectures based on IEEE 802.15.4 with predictable medium access, real-time analysis admission control and transport layer retransmissions. We evaluate the architectures in terms of reliability, utilization, delay, complexity, scalability and energy efficiency. The evaluations show that throughput and reliability can be enhanced through redundancy and concurrency in the frequency domain.

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