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Träfflista för sökning "WFRF:(Uhlemann Elisabeth 1971 ) "

Sökning: WFRF:(Uhlemann Elisabeth 1971 )

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1.
  • Balador, Ali, et al. (författare)
  • A Reliable and Efficient Token-Based MAC Protocol for Platooning Applications
  • 2016. - 12
  • Ingår i: 12th Swedish National Computer Networking Workshop (SNCNW 2016).
  • Konferensbidrag (refereegranskat)abstract
    • 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.
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2.
  • Balador, Ali, et al. (författare)
  • A Reliable Token-Based MAC Protocol for Delay Sensitive Platooning Applications
  • 2015
  • Ingår i: 2015 IEEE 82nd Vehicular Technology Conference (VTC2015-Fall). - [S.l.] : IEEE. - 9781479980918 - 9781479980901
  • Konferensbidrag (refereegranskat)abstract
    • 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. © 2015 IEEE.
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3.
  • Balador, Ali, et al. (författare)
  • An Efficient MAC Protocol for vehicle platooning in automated highway systems
  • 2015
  • Ingår i: Jornadas Sarteco 2015 JS 2015. - Cordoba, Spain.
  • Konferensbidrag (refereegranskat)abstract
    • 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 platooning 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.
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4.
  • Balador, Ali, et al. (författare)
  • Supporting Beacon and Event-Driven Messages in Vehicular Platoons through Token-Based Strategies
  • 2018
  • Ingår i: Sensors. - : MDPI AG. - 1424-8220. ; 18:4
  • Tidskriftsartikel (refereegranskat)abstract
    • 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.
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5.
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6.
  • Bilstrup, Katrin, et al. (författare)
  • On the ability of the 802.11p MAC method and STDMA to support real-time vehicle-to-vehicle communications
  • 2009
  • Ingår i: EURASIP Journal on Wireless Communications and Networking. - New York : Hindawi Publishing Corporation. - 1687-1472 .- 1687-1499. ; 2009:902414, s. 1-14
  • Tidskriftsartikel (refereegranskat)abstract
    • 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.
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7.
  • Böhm, Annette, 1975-, et al. (författare)
  • Co-Existing Periodic Beaconing and Hazard Warnings in IEEE 802.11p-Based Platooning Applications
  • 2013
  • Ingår i: VANET 2013 - Proceedings of the 10th ACM International Workshop on VehiculAr Inter-NETworking, Systems, and Applications. - New York, NY : ACM Press. - 9781450320733 ; , s. 99-101
  • Konferensbidrag (refereegranskat)abstract
    • 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.
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8.
  • Böhm, Annette, 1975-, et al. (författare)
  • Performance comparison of a platooning application using the IEEE 802.11p MAC on the control channel and a centralized MAC on a service channel
  • 2013
  • Ingår i: 2013 IEEE 9th International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob). - Piscataway, NJ : IEEE Press. - 9781479904280 ; , s. 545-552
  • Konferensbidrag (refereegranskat)abstract
    • 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 betweenplatoon 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. © 2013 IEEE.
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9.
  • Christoph, Mecklenbräuker, et al. (författare)
  • Vehicle-to-Vehicle Communications
  • 2012
  • Ingår i: Pervasive Mobile and Ambient Wireless Communications, Roberto Verdone and Alberto Zanella, editors. Springer. - London : Springer London. - 9781447123149 ; , s. 577-608
  • Bokkapitel (övrigt vetenskapligt/konstnärligt)
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10.
  • Dao, Van-Lan, 1987-, et al. (författare)
  • Dealing with Jamming Attacks in Uplink Pairwise NOMA Using Outage Analysis, Smart Relaying and Redundant Transmissions
  • 2024
  • Ingår i: Open Journal of the Communications Society. - : Institute of Electrical and Electronics Engineers (IEEE). ; 5, s. 112-126
  • Tidskriftsartikel (refereegranskat)abstract
    • 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.
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