| 1. |
|
|
| 2. |
- 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.
|
|
| 3. |
- Dao, Van-Lan, 1987-, et al.
(författare)
-
Defeating Jamming Attacks in Downlink Pairwise NOMA Using Relaying
- 2023
-
Konferensbidrag (refereegranskat)abstract
- 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.
|
|
| 4. |
- Dao, Van-Lan, et al.
(författare)
-
Defeating Jamming Using Outage Performance Aware Joint Power Allocation and Access Point Placement in Uplink Pairwise NOMA
- 2021
-
Ingår i: IEEE Open Journal of the Communications Society. - 2644-125X. ; 2, s. 1957-1979
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
|
|
| 5. |
- Dao, Van-Lan, 1987-, et al.
(författare)
-
Outage Performance Comparison of Adaptive Relaying Schemes Subject to Jamming
- 2023
-
Konferensbidrag (refereegranskat)abstract
- 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.
|
|
| 6. |
- Dao, Van-Lan, et al.
(författare)
-
Outage Performance of Pairwise NOMA Allowing a Dynamic Decoding Order and Optimal Pairs of Power Levels
- 2020
-
Ingår i: IEEE Open Journal of the Communications Society. - Sweden : IEEE OJCOMS. - 2644-125X. ; 1, s. 1886-1906
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
|
|
| 7. |
- Dao, Van-Lan, 1987-
(författare)
-
Tailoring Pairwise Non-Orthogonal Multiple Access to the Requirements of Critical Cyber-Physical Systems
- 2021
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Within the context of Industry 4.0, many devices have become more intelligent and connected, leading to challenges on how to meet the stringent requirements on latency and reliability in networks of critical cyber-physical systems. In particular, timely channel access and high reliability are of essence to guarantee real-time deadlines. To this end, time-division multiple-access (TDMA) schemes are often used in industrial applications to get contention-free access to the channel. Using pairwise non-orthogonal multiple access (NOMA) on top of such an existing TDMA scheme has recently emerged as a promising solution. With pairwise NOMA, two nodes are served simultaneously using the same time-frequency resources but with different power levels. To separate the signals, successive interference cancellation is used at the receiver. In addition, by adjusting the power allocation, pairwise NOMA can easily switch to TDMA by assigning zero power to one user, if and when needed. Due to this flexibility, pairwise NOMA can be integrated into existing wireless networks and schedulers with improved performance as a result. In particular, if pairwise NOMA could be tailored to the requirements of systems of collaborating cyber-physical systems, it would be possible to enhance performance in terms of latency and reliability, while still providing timely channel access to critical users using TDMA. This is the scope of the thesis work.In order to evaluate the communication reliability for each user in the system as well as for the overall system, the individual outage probability (IOP) and the overall outage probability (OOP) are of essence, but have so far not been available for pairwise NOMA used on top of TDMA. In this thesis work, closed-form expressions for the IOP and the OOP of both uplink and downlink NOMA are derived – also in the presence of a mobile smart jammer. Using these performance metrics, insightful guidelines on the impact of some key parameters on the communication reliability such as power allocation, decoding order, node placements and so on are provided. It should be noted that the conclusions on node placement can be used for smart user pairing, but also for placement of access points (AP) or even mobile APs, using a UAV. Moreover, by formulating a non-cooperative game between a malicious smart mobile jammer and a friendly mobile AP serving two friendly sensor nodes simultaneously, Nash equilibrium points are obtained to reduce power consumption for the AP, while satisfying the communication reliability requirements. Using the derived expressions for OOP and IOP to select proper settings for pairwise NOMA, it is shown that NOMA can be tailored to ensure user fairness, provide timely channel access and high reliability, which is useful for enhancing performance of critical cyber-physical systems even in the presence of jamming.
|
|
| 8. |
- Dao, Van-Lan, 1987-
(författare)
-
Using Outage Probability to Tailor Communication Protocols Suitable for Cyber-Physical Systems Operating in Confined Areas
- 2023
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Some types of Cyber-Physical System (CPS) applications found within e.g., quarrying, mining, harbors, and construction sites, operate within confined areas. To guarantee that communications between nodes in such systems operate smoothly, the adopted wireless communication protocols must meet stringent requirements, even in the presence of interference and/or jamming. This thesis work targets finding performance metrics suitable for designing and evaluating wireless networks when used for CPSs in confined areas. Given the shortage of spectrum and the increased risk of cyber-attacks experienced lately, the protocols must also be adjusted to perform well when subject to strong interference and/or adversary jamming. Hence, to be useful in practice, metrics that can be recalculated during runtime are needed, such that they can be used not only to propose, select and tailor the communication protocols to fulfill the stringent CPS requirements but also to optimize their performance during runtime. The literature survey conducted in this thesis shows that a reliability metric in terms of thresholding the so-called outage probability is valuable for all design steps as well as for continuously optimizing the communications. However, since the outage probability is defined as the probability that an individual wireless link will experience outage, it does not address the reliability of the entire network within the confined area. The thesis work shows that it is possible to consider overall outage probabilities and evaluates the probability of outage for each individual packet from a specific source node to a final destination, including all possible links in the network. This way, it is possible to consider the overall outage for all packets within the network in the confined area. Outage probability measures are defined for different system models and closed-form expressions for the outage are derived for the Individual Outage Probability (IOP), the Overall Outage Probability (OOP), the IOP for one packet (IOPP), and the OOP for all packets (OOPP), with and without the presence of attackers and/or strong interference. These reliability metrics can be adopted to analyze the effects of a wide range of parameters such as power allocation, node positions, the use of relay nodes or retransmissions, etc. on the individual link, individual source packet, and overall network reliability. The analysis thereby makes it possible to provide a set of general guidelines for tailoring the protocols and enhance the communication reliability of all legitimate nodes in the CPS. Having the closed-form expressions readily available also enables recalculating and adjusting parameters faster in order to find the best solution to improve the communication reliability during runtime. The thesis work demonstrates how outage probability can be used to enhance system performance in several example scenarios, including a multiple access scheme, pairwise Non-Orthogonal Multiple Access (NOMA), mobile access points and/or relay nodes. The outage analysis can thereby be applied to an existing CPS application to enhance reliability, robustness, and flexibility while maintaining a low delay.
|
|
| 9. |
- Gorospe, Joseba, et al.
(författare)
-
Analyzing Inter-Vehicle Collision Predictions during Emergency Braking with Automated Vehicles
- 2023
-
Ingår i: International Conference on Wireless and Mobile Computing, Networking and Communications. - : IEEE Computer Society. - 9798350336672 ; , s. 411-418
-
Konferensbidrag (refereegranskat)abstract
- 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.
|
|
| 10. |
- Gutiérrez Peón, Pablo
(författare)
-
Dependable real-time communications for systems with integrated wired and wireless connectivity
- 2024
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Ensuring reliable and timely data communication between computer systems over the wireless transmission medium has been a widely accepted source of conflict for decades. Although wireless communication over licensed frequencies demonstrates that dependability and timeliness requirements can be met, important application areas such as industrial automation, automotive, avionics or robotics have been restricted to license-free transmission frequencies. In these frequencies, interference from other users must be tolerated, which can jeopardize the communication requirements. In addition, data communication technologies have evolved dramatically since their introduction in office and home environments. The evolution is based on the success of two specific local area network (LAN) technologies: Ethernet and Wi-Fi. This success has shifted the formerly wide range of dependable and real-time capable proprietary wired solutions towards standardized options based on Ethernet such as time sensitive networking (TSN), a step that the wireless counterpart based on Wi-Fi has yet to take. This thesis addresses these limitations and opportunities and attempts to provide a comprehensive overview of how wireless communication can be introduced not only as a replacement for wired solutions, but as a complement to them. The work addresses demanding and critical scenarios where dependability and real-time are required, but where a variety of other, often conflicting, requirements may also apply. The solutions are based on the high-throughput commercial off-the-shelf (COTS) hardware hardware based on Ethernet and Wi-Fi. They are outlined at the medium access control (MAC) level of the communication architecture, as this is important for managing access to communication resources. Dependability enhancement mechanisms are introduced, mainly targeting reliability by applying fault prevention and fault tolerance, utilizing the diversity of communication channels and focusing on communication resource scheduling. The solutions are supported and evaluated by a mixture of analysis methods, computer simulations and hardware implementation to take the state of the art one step further.
|
|
| 11. |
- Gutiérrez Peón, Pablo, et al.
(författare)
-
Network Fault Tolerance by Means of Diverse Physical Layers
- 2020
-
Ingår i: IEEE International Conference on Emerging Technologies and Factory Automation, ETFA. - : Institute of Electrical and Electronics Engineers Inc.. - 9781728189567 ; , s. 1697-1704
-
Konferensbidrag (refereegranskat)abstract
- 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.
|
|
| 12. |
- Hasan, Shahriar, 1991-, et al.
(författare)
-
Characterization of Transient Communication Outages Into States to Enable Autonomous Fault Tolerance in Vehicle Platooning
- 2023
-
Ingår i: IEEE OPEN JOURNAL OF INTELLIGENT TRANSPORTATION SYSTEMS. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 2687-7813. ; 4, s. 101-129
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
|
|
| 13. |
- Hasan, Shahriar, 1991-, et al.
(författare)
-
Cooperative Automated Emergency Braking for CAVs under Time-Varying Communication Delays
- 2023
-
Ingår i: IAVVC 2023 - IEEE International Automated Vehicle Validation Conference, Proceedings. - : Institute of Electrical and Electronics Engineers Inc.. - 9798350322538
-
Konferensbidrag (refereegranskat)abstract
- 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.
|
|
| 14. |
- Hasan, Shahriar, 1991-
(författare)
-
On Transient Communication Outages among Collaborating Connected and Automated Vehicles
- 2023
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Recent advances in wireless technology facilitating Vehicle-to-Vehicle (V2V) communication have paved the way towards connected and more cooperative Intelligent Transportation Systems (ITSs), enhancing road safety and sustainability. Connected and Automated Vehicles (CAVs) can exchange information with one another and their surrounding infrastructure, thereby enabling cooperative automated maneuvering such as vehicle platooning. In platooning, a group of CAVs follows the longitudinal and lateral movements of a Lead Vehicle (LV) through V2V communication and onboard sensors to form a close-knit vehicle train. Collaborating CAVs hold the potential to revolutionize transportation by enabling, e.g., enhanced safety, fuel efficiency, road efficiency, and overall mobility. However, wireless communication, a key enabling technology for collaborating CAVs, is often subject to transient outages due to irregular packet losses, which are caused by factors such as attenuation, fading and interference. An automated platoon of CAVs must remain fail-operational during such transient communication outages to stay as safe as before the outage, even if the inter-vehicle distances are short. Furthermore, a platoon may encounter road hazards, requiring emergency braking to transition into a fail-safe state. Traditionally, communication outages have been treated as permanent faults or failures, which is a worst-case scenario that has little practical value. More recent attempts to model wireless communication as either on or off as a function of time are still too pessimistic and may lead to safety distances which are unnecessarily long. To this end, this thesis proposes to characterize the nature of transient wireless communication outages into finer granularities so that, e.g., the vehicles in a platoon can adapt to the currently available information, prioritize safety, and still remain as efficient as possible. Such characterization also enables formulating a state machine in which the states represent various fail-operational, emergency braking, and fail-safe states as a function of the instantaneous communication quality. An approach involving changing states by switching controllers and adjusting inter-vehicle gaps is developed to keep a platoon fail-operational during runtime. In addition, several emergency braking strategies are proposed to minimize the LV's stopping distance while avoiding inter-vehicle collisions when transitioning the platoon into a fail-safe state. The thesis also employs Machine Learning (ML) for real-time prediction of communication outages and collision risks during emergency braking, enabling proactive collision avoidance measures. A simulation tool named PlatoonSAFE, using realistic traffic mobility models, has been developed to evaluate the proposed algorithms. Rigorous simulation studies demonstrate that the characterization of communication outages into finer granularities enables fault tolerance and provides a more balanced trade-off between fuel efficiency, string stability, and LV tracking compared to the traditional way of modeling communication outages. Finally, the ML tool and the outage model enable fuel-efficient platooning at high speed while still being able to respond to road hazards by enabling fast emergency braking.
|
|
| 15. |
- Hasan, Shahriar, 1991-, et al.
(författare)
-
PlatoonSAFE : An Integrated Simulation Tool for Evaluating Platoon Safety
- 2023
-
Ingår i: IEEE Open Journal of Intelligent Transportation Systems. - : Institute of Electrical and Electronics Engineers Inc.. - 2687-7813. ; 4, s. 325-347
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
|
|
| 16. |
- Hasan, Shahriar, 1991-, et al.
(författare)
-
Prediction of Communication Delays in Connected Vehicles and Platoons
- 2023
-
Ingår i: 2023 IEEE 97TH VEHICULAR TECHNOLOGY CONFERENCE, VTC2023-SPRING. - : IEEE. - 9798350311143
-
Konferensbidrag (refereegranskat)abstract
- 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.
|
|
| 17. |
- Nhan Vo, Van, et al.
(författare)
-
On Communication Performance in Energy Harvesting WSNs Under a Cooperative Jamming Attack
- 2020
-
Ingår i: IEEE Systems Journal. - 1932-8184 .- 1937-9234. ; 14:4, s. 4955-4966
-
Tidskriftsartikel (refereegranskat)abstract
- In this article, we consider the system performance of an energy harvesting (EH) wireless sensor network in terms of reliable communications when subjected to a cooperative jamming attack. A set of strategically located nodes acting as cluster heads (CHs) transfer energy to the wireless sensors within range, forming a cluster. The sensors use this energy to transmit data to the CHs, which, in turn, deliver the information to a base station (BS) using nonorthogonal multiple access. The BS processes the collected information and synchronizes the operation of all CHs. Furthermore, there exist two adversaries, namely, a jamming attacker and an eavesdropper, who cooperate to attack the considered system. To protect against this attack, the CHs should be controlled by suitable power allocation coefficients obtained from the security constraints of the CHs. Using these constraints, closed-form expressions are derived to find the power allocation coefficients that will enable reliable and secure communication. In addition, we propose an interference channel selection policy for the sensor-to-CHs links and CHs-to-BS links to improve the reliability of communication while enhancing energy utilization. Finally, an algorithm for finding the optimal EH time is also proposed.
|
|
| 18. |
- Peón, P. G., et al.
(författare)
-
Time-Sensitive Networking's Scheduled Traffic Implementation on IEEE 802.11 COTS Devices
- 2023
-
Ingår i: Proceedings - 2023 IEEE 29th International Conference on Embedded and Real-Time Computing Systems and Applications, RTCSA 2023. - : Institute of Electrical and Electronics Engineers Inc.. - 9798350337860 ; , s. 167-175
-
Konferensbidrag (refereegranskat)abstract
- Wired real-time network deployments based on time-sensitive networking (TSN) are becoming increasingly popular in several application fields including industrial automation and the automotive area. This is to a great extent due to the scheduled traffic (ST; IEEE 802.1Qbv), a TSN mechanism that precisely triggers transmissions at pre-defined instants from a set of independent hardware queues. Unfortunately, the wireless counterparts based on IEEE 802.11 (Wi-Fi) currently lack standardized or functional solutions that would be able to fulfill strict real-time requirements. This work proposes the use of ST over IEEE 802.11, taking advantage of an existing but overlooked mechanism from commercial off-the-shelf (COTS) equipment. An extensive set of tests, spanning different implementation configurations, traffic patterns, and levels of interference evaluates the proposal in terms of reliability and delivery delays and serves as a proof of concept. The tests also evaluate the much-needed clock synchronization quality of an out-of-the-box software-only implementation of the precision time protocol (PTP) due to its relevance in enabling ST.
|
|
| 19. |
- Quach, T. X., et al.
(författare)
-
Secrecy performance of cooperative cognitive radio networks under joint secrecy outage and primary user interference constraints
- 2020
-
Ingår i: IEEE Access. - : Institute of Electrical and Electronics Engineers Inc.. - 2169-3536. ; 8, s. 18442-18455
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we investigate the secrecy performance of a Cooperative Cognitive Radio Network (CCRN) in the presence of an eavesdropper (EAV). The secondary users (SUs) are subject to three constraints which include peak transmit power level and interference limitation with respect to the primary user (PU) as well as secrecy outage constraints due to the EAV. Secrecy outage is achieved when the EAV cannot decode the targeted signal, but communications in the secondary network is still possible (non-zero capacity exists). Approximation expressions of the secrecy outage probability and the probability of non-zero secrecy capacity are derived to evaluate the secrecy performance. Monte Carlo simulations are provided to examine the accuracy of the derived approximation expressions. Based on this, power allocation policies for the SUs are derived, satisfying all the constraints while maximizing the secrecy performance as well as the quality of service performance of the secondary network. It can be concluded that with knowledge of the channel state information (CSI) of the EAV it is possible to calculate the optimal value for the secrecy outage threshold of the secondary user (SU) which in turn allows maximizing the secrecy performance. Most interestingly, our numerical results illustrate that the secrecy performance of the system is much improved when the parameters obtained using the CSI of the EAV are calculated optimally. Thence, the system can adjust the power allocation so that no eavesdropping occurs even without reducing quality of service (QoS) performance compared to a network without any EAV.
|
|
| 20. |
- Sidorenko, Galina, 1985-
(författare)
-
Safety of Cooperative Automated Driving : Analysis and Optimization
- 2022
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- New cooperative intelligent transportation system (C-ITS) applications become enabled thanks to advances in communication technologies between vehicles(V2V) and with the infrastructure (V2I). Communicating vehicles share information with each other and cooperate, which results in improved safety, fuel economy, and traffic efficiency. An example of a C-ITS application is platooning, which comprises a string of vehicles that travel together with short inter-vehicle distances (IVDs).Any solution related to C-ITS must comply with high safety requirements in order to pass standardization and be commercially deployed. Furthermore, trusted safety levels should be assured even for critical scenarios.This thesis studies the conditions that guarantee safety in emergency braking scenarios for heterogeneous platooning, or string-like, formations of vehicles. In such scenarios, the vehicle at the head of the string emergency brakes and all following vehicles have to automatically react in time to avoid rear-end collisions. The reaction time can be significantly decreased with vehicle-to-vehicle (V2V) communication usage since the leader can explicitly inform other platooning members about the critical braking.The safety analysis conducted in the thesis yields computationally efficient methods and algorithms for calculating minimum inter-vehicle distances that allow avoiding rear-end collisions with a predefined high guarantee. These IVDs are theoretically obtained for an open-loop and a closed-loop configurations. The former implies that follower drives with a constant velocity until braking starts, whereas in the latter, an adaptive cruise control (ACC) with a constant-distance policy serves as a controller. In addition, further optimization of inter-vehicle distances in the platoon is carried out under an assumption of centralized control. Such an approach allows achieving better fuel consumption and road utilization.The performed analytical comparison suggests that our proposed V2V communication based solution is superior to classical automated systems, such as automatic emergency braking system (AEBS), which utilizes only onboard sensors and no communication. Wireless communication, enabling to know the intentions of other vehicles almost immediately, allows for smaller IVDs whilst guaranteeing the same level of safety.Overall, the presented thesis highlights the importance of C-ITS and, specifically, V2V in the prevention of rear-end collisions in emergency scenarios. Future work directions include an extension of the obtained results by considering more advanced models of vehicles, environment, and communication settings; and applying the proposed algorithms of safety guaranteeing to other controllers, such as ACC with a constant time headway policy.
|
|
| 21. |
- Uhlemann, Elisabeth, 1971-
(författare)
-
Autonomous Vehicles Have Entered the Off-Road Market [Connected and Automated Vehicles]
- 2021
-
Ingår i: IEEE Vehicular Technology Magazine. - : Institute of Electrical and Electronics Engineers Inc.. - 1556-6072 .- 1556-6080. ; 16:2, s. 15-19
-
Tidskriftsartikel (refereegranskat)abstract
- The past year has taught us to expect the unexpected. While digital meetings have gotten increased momentum, the pandemic has put most other platforms for technical development on hold. I have written before in this column about the fact that autonomous vehicles are emerging. A few years ago, there was a sort of mental setback when several companies pioneering autonomous vehicle testing said that the task was more complex than people may think and that fully autonomous vehicles were much further into the future than it may appear from the outside. Based on the stories collected for this issue, however, it is apparent that autonomous off-road vehicles like baggage tractors, drone-based surveillance systems, and vehicles in mines or construction sites are already operational. This may have several different causes. From a researcher's perspective, I would say that it is not until you start to really dig into a topic that you realize its full complexity and how little you actually know. It is therefore likely that the company representatives expressing doubt about fully autonomous vehicles a few years back were behaving just like normal Ph.D. students who generally always doubt their ability before they start to produce sensational results. It is also likely that off-road vehicles are easier to design, in that they operate in a confined area that can be better controlled and defined. This also affects the communication abilities of the vehicles. Basically, all autonomous vehicles, whether they operate off- or on-road, need to be connected. In a confined area, it is possible to deploy Wi-Fi access points enabling reliable connectivity to the autonomous vehicles, coupled with teleoperating abilities for added safety. For on-road vehicles covering a larger geographical area, another type of connectivity is needed, which requires harmonization among technology providers, vehicle manufacturers, legislation, and spectrum authorities. One show-stopper in this respect is the recent spectrum setbacks in the United States, where the entire spectrum previously reserved for dedicated short range communication (DSRC), was given away to Wi-Fi and cellular technology [1]. The spectrum authorities in Europe and Australia support a technologically agnostic approach, but the setback in the United States is also affecting these markets as it is unclear what will happen with the huge investments already made in DSRC and its European counterpart called ITS-G5. However, as I wrote in a previous column, the vehicle industry is using this peculiar time to analyze and plan ahead. To this end, Waymo is simulating how the Waymo Driver would behave if involved in a fatal crash reconstructed from statistics obtained from the National Highway Traffic Safety Administration (NHTSA)?it turns out that autonomous vehicles avoid many accidents simply by following the traffic rules. In addition, Volvo Cars has launched a portal making different resources (such as car dashboard data, charge/fuel level, and distance traveled) available to developers and other third parties to build new services. When life gives you lemons, make simulations and share data.
|
|
| 22. |
- Uhlemann, Elisabeth, 1971-
(författare)
-
Every Effort Toward Traffic Safety Counts
- 2020
-
Ingår i: IEEE Vehicular Technology Magazine. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 1556-6072 .- 1556-6080. ; 15:2, s. 144-148
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
|
|
| 23. |
|
|
| 24. |
- Uhlemann, Elisabeth, 1971-
(författare)
-
Peculiar Times Being Used to Analyze and Plan Ahead [Connected and Autonomous Vehicles]
- 2020
-
Ingår i: IEEE Vehicular Technology Magazine. - Sweden : IEEE. - 1556-6072 .- 1556-6080. ; , s. 135-138
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Reports on trends and future market developments predicted for connected and autonomous vehicles. The web pilot aims to provide an online, public-facing platform for sharing automated driving system testing activities. When collecting news for this column, the author noticed a distinct absence of press releases announcing new products and services, partnerships, and field trials. Instead, already-collected data are being analyzed and annotated. Strategic plans and standards are being written, certification is being requested, and websites collecting planned activities are being launched. A few examples of practical development and collaboration can be found, but these are all anticipated to start or to be launched, and some collaborations have, instead, ended or, at least, been put on hold. The vehicle industry has paused and is using the time to plan ahead. In the meantime, smart connected things help out by, e.g., guarding prisons and sanitizing airports.
|
|
