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Current safety-critical applications, found in domains such as automotive networking, automated industries, and control systems, require deterministic and latency-bounded end-to-end communication, currently not supported by best-effort networks. Time-Sensitive Networking (TSN) is the most feasible approach to fulfill such requirements. Originating from the wired domain, their application to the wireless domain is now attracting attention. Besides some advances in time synchronization and scheduling, essential policies such as association with a wireless TSN (W-TSN), have not been explored. This paper analyses the necessary tools for a prospective client to accomplish association with the W-TSN without affecting ongoing time-sensitive traffic. We introduce three beacon-based methods to pre-synchronize and pre-schedule nodes willing to associate with the network. On top of the first full-stack Software Defined Radio (SDR) based IEEE802.11/Wi-Fi design, the proposed approaches are developed and tested in a real-world environment. A delay analysis shows a worst-case association delay of up to 1.8 s, and high accuracy synchronization on prospective clients' association frame receptions, with 100% of on-time arrivals, even with challenging scheduling timeslots as short as 128 μ s. [ABSTRACT FROM AUTHOR]

• Fabrication of simple paper electrodes on electrochemical paper analytical device. • Do it yourself method for electrochemical paper analytical device. • Role of edge-plane sites and oxygen functionalities towards electrochemical sensing. • Electrochemical sensing of Trolox, an analogue of vitamin E. The development of electrochemical sensors as miniaturized and low-cost platforms for rapid and sensitive detection of biomolecules demands for disposable economically viable and easy manufacturable electrodes. Moreover affordable, sensitive, specific, user-friendly, and robust electrodes for sensing (ASSURES) applications through simple do it yourself (DIY) strategy is the need of the hour. This could be achievable only if substrate for electrodes are inexpensive, easily manufacturable and should be from reusable sources. Paper offers unique advantages such as, easily printable, impregnable and its innate cellulose structures make them biomolecules friendly. In addition, porous structure acts as good filter, and facilitates lateral flow. Considering aforementioned properties, herein paper has been explored as substrate for fabrication of electrochemical paper analytical device (e-PAD) with paper electrodes (PPE). Using simple photolithography and stamping technique, we could achieve hydrophobic and hydrophilic regions and 3-in-1 electrode patterns consists of working, counter and reference electrodes. The as-designed and developed PPE was further characterized by surface morphological and electrochemical studies. As a proof of concept, sensing utility of PPE for trolox (analogue of Vitamin E, an antioxidant) is also demonstrated by exploring the interplay between edge plane sites and oxygen functionalities. The calibration plot showed a linear range from 5 µM to 400 µM for trolox with detection limit of (S/N = 3) of 1.17 µM. The present findings demonstrated simple fabrication of PPE is possible unlike the widely used screen printing, inkjet printing, and laser scribing of electrodes onto different substrates, which requires sophisticated instrumentation and skilled personal. [ABSTRACT FROM AUTHOR]

This paper demonstrates how the complex interaction of a number of intrinsic and extrinsic taphonomic factors have differentially affected the relative preservation of the skeletal remains recovered from Beacon Island. These include: local geology and hydrology; flora and fauna; human interactions; and burial type (e.g. body position and number). The latter function to demonstrate that contemporary burials dating to 1629 can present markedly divergent taphonomic 'alterations', even those buried within close proximity to one-another. It is evident that alterations can arise in a very short-time frame (months to a few years) and their recognition in a modern context is thus of forensic relevance. These are accordingly illustrated and described relative to their potential to inform forensic interpretations in a modern case-work context. [ABSTRACT FROM AUTHOR]

This paper demonstrates how the complex interaction of a number of intrinsic and extrinsic taphonomic factors have differentially affected the relative preservation of the skeletal remains recovered from Beacon Island. These include: local geology and hydrology; flora and fauna; human interactions; and burial type (e.g. body position and number). The latter function to demonstrate that contemporary burials dating to 1629 can present markedly divergent taphonomic 'alterations', even those buried within close proximity to one-another. It is evident that alterations can arise in a very short-time frame (months to a few years) and their recognition in a modern context is thus of forensic relevance. These are accordingly illustrated and described relative to their potential to inform forensic interpretations in a modern case-work context. [ABSTRACT FROM AUTHOR]

A rectangular rapid flashing beacon (RRFB) is a pedestrian crosswalk countermeasure system that cautions drivers by providing them with real-time warning about the presence of pedestrians in an upcoming crosswalk. This paper investigated the safety effectiveness of existing RRFBs installed in the state of Florida between 2013 and 2018. Additionally, traffic volume, roadway characteristics, and land-use mix were included as explanatory variables. The study evaluated 154 treated sites with RRFB installations and 158 control sites with similar characteristics. Safety performance functions (SPF) were developed, and crash modification factors (CMF) were calculated using the empirical Bayes (EB) methodology for various crash types. A CMF of 0.31 for total pedestrian crashes was estimated, showing that RRFBs have the potential to reduce 69% of total pedestrian-involved crashes. CMF for total vehicular crashes and rear-end crashes were also investigated to ascertain whether RRFBs have adverse effects on rear-end crashes. CMF for total vehicular crashes was found to be 1.14, showing that RRFBs do not have positive effect in reducing total vehicular crashes. Similarly, it was observed that CMF for the rear-end crashes was 1.11, indicating RRFBs might have adverse effect on rear-end crashes because vehicles needs to slow down or stop due to the presence of pedestrians. CMFunctions for significant variables for pedestrian, rear-end, and total crash models were also estimated in this study. An economic analysis indicated that the implementation of RRFBs will yield a benefit to cost ratio (calculated over 3 years) of approximately 85.5 with a 4% discount rate. [ABSTRACT FROM AUTHOR]

GNSS is still not well applied in indoor environments. This is an important challenge for seamless positioning and navigation. Using other sensors to replace and connect is the mainstream practice at present. No matter what technology is used, the problem of real-time optimal station selection is faced in complex indoor environments. In this paper, we first verified the impact of random interference from walkers on positioning signals in an indoor environment. Based on this phenomenon, we proposed a novel real-time dynamic Beacons selection method (RD) in the field of indoor positioning. First, we introduced a machine learning algorithm for real-time anomaly detection of received signals from different Beacons. Then the Beacon selection is completed based on the real-time anomaly detection results and RSSI. In an indoor scene, we verified the positioning accuracy of three other methods when selecting various numbers of Beacons. Then we used the best selection strategies to compare with the RD method. Experiments showed that the RD method can use the least Beacons to obtain higher accuracy and stable positioning results. This paper provides a new idea for real-time optimal selection of signal sources in a complex indoor environment. [ABSTRACT FROM AUTHOR]

When performing indoor tasks, miniature swarm robots are suffered from their small size, poor on-board computing power, and electromagnetic shielding of buildings, which means that some traditional localization methods, such as global positioning system (GPS), simultaneous localization and mapping (SLAM), and ultra-wideband (UWB), cannot be employed. In this paper, a minimalist indoor self-localization approach for swarm robots is proposed based on active optical beacons. A robotic navigator is introduced into a swarm of robots to provide locally localization services by actively projecting a customized optical beacon on the indoor ceiling, which contains the origin and the reference direction of localization coordinates. The swarm robots observe the optical beacon on the ceiling via a bottom-up-view monocular camera, and extract the beacon information on-board to localize their positions and headings. The uniqueness of this strategy is that it uses the flat, smooth, and well-reflective ceiling in the indoor environment as a ubiquitous plane for displaying the optical beacon; meanwhile, the bottom-up view of swarm robots is not easily blocked. Real robotic experiments are conducted to validate and analyze the localization performance of the proposed minimalist self-localization approach. The results show that our approach is feasible and effective, and can meet the needs of swarm robots to coordinate their motion. Specifically, for the stationary robots, the average position error and heading error are 2.41 cm and 1.44°; when the robots are moving, the average position error and heading error are less than 2.40 cm and 2.66°. [ABSTRACT FROM AUTHOR]

The integration of human-centric approaches has gained more attention recently due to more automated systems being introduced into our built environments (buildings, roads, vehicles, etc.), which requires a correct understanding of how humans perceive such systems and respond to them. This paper introduces an Immersive Virtual Environment-based method to evaluate the infrastructure design with psycho-physiological and behavioral responses from the vulnerable road users, especially for pedestrians. A case study of pedestrian mid-block crossings with three crossing infrastructure designs (painted crosswalk, crosswalk with flashing beacons, and a smartphone app for connected vehicles) are tested. Results from 51 participants indicate there are differences between the subjective and objective measurement. A higher subjective safety rating is reported for the flashing beacon design, while the psychophysiological and behavioral data indicate that the flashing beacon and smartphone app are similar in terms of crossing behaviors, eye tracking measurements, and heart rate. In addition, the smartphone app scenario appears to have a lower stress level as indicated by eye tracking data, although many participants do not have prior experience with it. Suggestions are made for the implementation of new technologies, which can increase public acceptance of new technologies and pedestrian safety in the future. [ABSTRACT FROM AUTHOR]

Navigation is often regarded as one of the most-exciting use cases for Augmented Reality (AR). Current AR Head-Mounted Displays (HMDs) are rather bulky and cumbersome to use and, therefore, do not offer a satisfactory user experience for the mass market yet. However, the latest-generation smartphones offer AR capabilities out of the box, with sometimes even pre-installed apps. Apple's framework ARKit is available on iOS devices, free to use for developers. Android similarly features a counterpart, ARCore. Both systems work well for small spatially confined applications, but lack global positional awareness. This is a direct result of one limitation in current mobile technology. Global Navigation Satellite Systems (GNSSs) are relatively inaccurate and often cannot work indoors due to the restriction of the signal to penetrate through solid objects, such as walls. In this paper, we present the Pedestrian Augmented Reality Navigator (PAReNt) iOS app as a solution to this problem. The app implements a data fusion technique to increase accuracy in global positioning and showcases AR navigation as one use case for the improved data. ARKit provides data about the smartphone's motion, which is fused with GNSS data and a Bluetooth indoor positioning system via a Kalman Filter (KF). Four different KFs with different underlying models have been implemented and independently evaluated to find the best filter. The evaluation measures the app's accuracy against a ground truth under controlled circumstances. Two main testing methods were introduced and applied to determine which KF works best. Depending on the evaluation method, this novel approach improved the accuracy by 57% (when GPS and AR were used) or 32% (when Bluetooth and AR were used) over the raw sensor data. [ABSTRACT FROM AUTHOR]

Rain is one of the most dominant factors for satellite communication systems link performance at frequencies above 10 GHz, increasing rapidly at higher frequencies. The prediction of time dynamics of the rain attenuation is required to improve the efficiency of various fade mitigation techniques (FMTs) to reduce signal fading. Fade duration and fade slope statistics are used to describe the dynamic behavior of attenuation experienced by radio communication links. The present study is based on experimental measurements from a Ka band (KaSAT) and Q band (AlphaSAT) beacon receiver at the frequencies 19. 7 GHz and 39. 4 GHz respectively. In this paper, annual and monthly variation of rain attenuation statistics for a temperate location Vigo, Spain is presented. Monthly variation of rain attenuation statistics is much larger than the yearly variation for the present location. This paper also analyzes the fade duration and fade slope statistics for both the bands. The conditional probability density function (PDF) of fade slope shows general symmetry between positive and negative slope values for both Ka and Q bands. All the measured statistics (1st order and 2nd order) are compared with the existing ITU-R and COST-205 models. Predictions of rain attenuation by both the models are close to the measured data. For fade duration statistics, as attenuation threshold increases, performance of both ITU-R and COST-205 models improves for Ka band. For Q band, COST model performs better compared to ITU-R model. Measured probability density function of fade slope fits with the ITU-R model more closely for Q band compared to Ka band. [ABSTRACT FROM AUTHOR]

Summary: Vehicular safety applications are based on broadcasting periodic safety beacons on the IEE802.11p control channel. The CSMA MAC scheme adopted in the IEE802.11p cannot ensure the strict timeline and the high reliability when broadcasting these real time and critical messages since it does not consider the high mobility of vehicles, the limited network resources, and the variant traffic densities. Therefore, the design of an effective MAC scheme that takes in consideration these parameters represents a challenging task. Furthermore, the fixed beaconing rate results an overload on the commination channel and collisions especially in dense situations that delay beacons broadcast. In this paper, we propose a novel hybrid MAC scheme for fast and reliable broadcast of safety beacons. At first, it relies on a time slot reuse policy that considers the mobility features of vehicles while reducing transmission collisions. In addition, it adapts mathematically the beaconing rate to the traffic density based on vehicular velocity at the aim of optimizing the performance of the wireless channel. Simulation results show that our proposal outperforms significantly the IEEE802.11p CSMA MAC scheme and upgrades the performance of vehicular networks in broadcasting periodic safety beacons. [ABSTRACT FROM AUTHOR]

Protected wetlands such as deltas, lakes or rivers provide a sanctuary for many endangered species. In order to protect these areas from illegal human interventions, it is necessary to monitor the unauthorized entrance of motor boats. In order to mitigate such an impact, we have developed a network of floating beacons for underwater acoustic monitoring, using LoRa communication modules operating at 433 MHz. Such beacons should be equipped with compact antennas. In this paper, we use a genetic algorithm approach to design the compact, monopole antennas required for the beacons; size constraints would apply not only to the radiating element but also to the ground plane. Although the antenna input is unbalanced, such a small ground plane may yield common mode currents on the antenna feeder, which distort the radiation pattern of the antenna. In order to investigate the effect of the common mode currents, we developed a distance averaging method, while, for characterizing the antenna, we used a single-antenna method. For the experimental validation of the system in real conditions, a continuous monitoring of the lake was carried out. During the monitoring, multiple events generated by incursions of motor boats were successfully detected and recorded. [ABSTRACT FROM AUTHOR]

• Pedestrians crossed significantly faster without alternative safety technologies. • Pedestrians waited for larger gaps to cross without alternative safety technologies. • Survey results indicate high levels of immersion and perception of risk within VR. • Survey results indicate higher perception of safety with safety technologies. • Pedestrians exhibited intentional unsafe darting behavior without safety technology. • Development of low-risk, immersive VR framework for analysis of pedestrian behavior. Virtual reality (VR) simulation offers a proactive, cost effective, immersive, and low risk platform for studying pedestrian safety. Within immersive virtual environments (IVEs), existing and alternative design conditions and intelligent transportation systems (ITS) technologies can be directly compared, prior to real-world implementation, to assess the impacts alternatives may have on pedestrian safety, perception, and behavior. Environmental factors can be controlled within IVEs so that test trials are replicable and directly comparable. Coupled with stated preference feedback, participants' observed preferences and behavior provide a comprehensive understanding of the impacts of proposed design alternatives. This research presents a case study of pedestrian behavior with three different mid-block crossing safety treatments modeled within a one-to-one scale IVE replication of a real-world location in Charlottesville, Virginia. The three safety treatments consider both passive and active collision avoidance designs and technologies, including (1) the existing painted crosswalk, (2) the addition of rectangular rapid flashing beacons (RRFBs), and (3) a pedestrian to everything (P2X) ITS phone application. Additionally, this paper demonstrates a VR simulation experimental design and framework for testing pedestrian safety treatments within naturalistic and replicable IVEs to assess both stated and observed preferences and behaviors of pedestrians. Repeated measures ANOVA indicated changes in both accepted gap size (p = 0.001) and crossing speed (p < 0.001) with alternative safety treatments. Generalized mixed models showed that pedestrians waited for statistically larger gap sizes (p = 0.02) without the assistance of alternative safety technologies (RRFBs and P2X application) and pedestrians crossed the street significantly faster (p = 0.001) without the alternative safety technologies, leading to unsafe dashing behavior. Through post-experiment surveys, it was found that participants perceived the As Built environment to be the least safe of the three treatments and that their sense of risk within the IVE was realistic. Considering both the observed crossing behavior and stated feedback, pedestrians exhibited intentionally unsafe darting behavior without assistive safety technology. This study demonstrates how VR simulation may be leveraged to study both stated preferences and observed behavior for understanding the safety implications of alternative roadway designs, providing a proactive approach for assessing and designing for pedestrian safety. [ABSTRACT FROM AUTHOR]

Emergency fire situations in tunnels can be especially dangerous when occurring in long underground or subsea tunnels, particularly when evacuation on foot is the only alternative. This paper presents the results from a study comparing different visual and acoustic measures to facilitate efficient and safe emergency evacuation and their effect on people's self-rescue behaviour in response to a tunnel fire. Eighty-one participants evaluated seven different scenarios in virtual reality with or without visual and acoustic supporting measures (i.e. signs, lights, acoustic beacons) to find their way to emergency doors. Objective behavioural data, such as orientation, and walking speed, were collected. The results suggest that the distance between the emergency doors increases uncertainty and affects the time to self-rescue significantly, with four times longer times for 500 m than 250 m between doors. Additionally, the use of continuous guiding lights positively supported orientation and walking speed, with 97 % of the participants finding their way and showing a reduction of time to reach the emergency door of 10–20 s. The study underscores the importance in the proper visual and acoustic evacuation measures for the wayfinding of emergency exits, improving self-rescue of people. • Visual and acoustic measures to support self-evacuation were tested. • The study examines the impact of different measures on users' behaviour during evacuation. • Virtual Reality was used as method for evaluating measures due to ethical issues. • Black smoke simulation was developed for the VR scenarios. • Both type, position and distance between measures highly impacted time to escape. [ABSTRACT FROM AUTHOR]

Singe-beacon localization technology can help Autonomous Underwater Vehicles (AUVs) to obtain precise positions by deploying only one beacon. It is considered as a promising way, benefiting from saving much time and labor compared with traditional Long-Baseline Localization (LBL). A typical single-beacon localization scheme contains two essential questions: the initial observability problem and long-endurance trajectory tracking problem. Aiming at these core problems, a comprehensive solution for single-beacon localization is described in this paper. An multi-hypothesis initial position discriminant method is proposed firstly, which helps to achieve accurate initial location based on observability analysis. Then, an Adaptive Network Fuzzy Inference System (ANFIS)-improved Extended Kalman Filter (EKF) method is proposed, in which single-beacon measuring information is fused with off-the-shelf sensors, including DVL, Compass, etc. ANFIS-EKF can help to improve trajectory tracking precisions by restraining the heavy loss of linearization in conventional EKF. Both simulation and field tests are conducted to verify the performance of the proposed algorithms. [ABSTRACT FROM AUTHOR]

A systematic oceanographic monitoring and management requires an effective marine tracking system. It helps the localization of different marine assets, their border control and in encountering emergency situations. Thus, a reliable marine tracking system is always required to ensure a safe marine environment for shippers, fishers, sailors and other marine assets. Nowadays due to the evolution in wireless sensor network (WSN) technology, their easy and inexpensive deployment can be seen in different fields such as agriculture, medical, industries and IoT. The implementation of WSN in the marine environment comes with various issues due to the complex behavior of the marine environment and thus affects the reliability of the system. In this paper, a WSN-based marine tracking protocol sailing is presented, which identifies the location of marine assets reliably through the genetic firefly (GEFIR) algorithm. The system comprises sensor nodes, sink nodes, server-client terminals and a base station. The protocol uses the application and contact layers to create a group of beacon nodes (boats) based on the geographical location to conserve energy and increase data reliability. GEFIR algorithm is implemented to give a precise and more convenient data to the WSN for the mariners. The results show a better performance for latency calculation through the WSN- and GEFIR-based sailing protocol. The system generates the alert to nodes (sailors) in case they are moving out from a specified region and sends their location for further communication. [ABSTRACT FROM AUTHOR]

Aiming at the low accuracy of Bluetooth-Low-Energy ranging and positioning in NLOS environment, a non-line of sight (NLOS) Bluetooth-Low-Energy ranging method based on the NLOS Bluetooth-Low-Energy ranging model and an NLOS Bluetooth-Low-Energy positioning algorithm based on the TLS method and the triangular positioning algorithm are proposed. Firstly, an line-of-sight (LOS) Bluetooth-Low-Energy ranging model is established by RSSI value and actual distance between the Bluetooth-Low-Energy beacon and the terminal equipment. Secondly, based on the LOS Bluetooth-Low-Energy ranging model and the threshold-corrected RSSI peak, an NLOS Bluetooth-Low-Energy ranging model is established. Thirdly, the NLOS RSSI value is processed by the NLOS Bluetooth-Low-Energy ranging model to obtain the optimal ranging value. Finally, high precision positioning coordinates can be obtained by using NLOS Bluetooth-Low-Energy positioning algorithm and optimal Bluetooth-Low-Energy ranging. In this paper, two experiments are carried out, and the experimental results show that: in the range of 7 m, the average ranging accuracy of the improved NLOS Bluetooth-Low-Energy ranging method is 0.37 m, which is improved 49.19% when compared to the traditional method's results. The average positioning accuracy is 0.4 m using the positioning algorithm proposed in this paper. Therefore, in NLOS environment, the proposed ranging method and positioning algorithm can significantly improve the accuracy of Bluetooth-Low-Energy ranging and positioning. [ABSTRACT FROM AUTHOR]

Summary: The beacon transmission method in vehicular networks has to consider the mobility feature of vehicles and use the wireless channel more efficiently in order to broadcast safety‐related beacons with high reliability while respecting strict deadlines. The time division multiple access (TDMA) scheme has been proposed to improve the effectiveness of the IEEE 802.11p CSMA MAC protocol, but it is challenged with access and merging collisions caused by inefficient strategies in allocating time slots and mobile hidden terminal problems. In this paper, we propose colored velocity‐based TDMA (CVTDMA), an original colored scheduling scheme for the broadcast of safety beacons on the control channel. Based on vehicles speed and colors that it assigns to time slots according to their occupation statuses, it mitigates the mobility effect and maximizes the reuse of slots while avoiding collisions. The simulation results show that our protocol uses the wireless channel much more effectively than the default one defined in IEEE 802.11p. [ABSTRACT FROM AUTHOR]

The paper explains a concept of a vehicle molecular spring suspension whose stiffness in middle stage can be as low as 13 N/mm. The design of this suspension spring on the basis of a hydrophobic nanoporous material is introduced. The test methods of determining the static and dynamic mechanical properties of the novel suspension spring are described. The rationality of experimental design and the accuracy of theoretical analysis is proved by the negligible error between experimental results and theoretical analysis. The vibration isolation test results show that the natural frequency of the suspension can be as low as 1.06 Hz. [ABSTRACT FROM AUTHOR]

Association attacks aim to manipulate WiFi clients into associating with a malicious access point, by exploiting protocol vulnerabilities and usability features implemented on the network managers of modern operating systems. In this paper we classify association attacks based on the network manager features that each attack exploits. To validate their current validity status, we implement and test all known association attacks against the network managers of popular operating systems, by using our Wifiphisher tool. We analyze various strategies that may be implemented by an adversary in order to increase the success rate of association attacks. Furthermore, we examine the behavior of association attacks against upcoming security protocols and certifications for IEEE 802.11, such as WPA3, Wi-Fi Enhanced Open and Easy Connect. Our results show that even though the network managers have hampered the effectiveness of some known attacks (e.g. KARMA), other techniques (e.g. Known Beacons) are still active threats. More importantly, our results show that even the newer security protocols leave room for association attacks. Finally, we describe novel detection and prevention techniques for association attacks, as well as security controls based on user awareness. [ABSTRACT FROM AUTHOR]

In periodic data-gathering, sensors can switch on the transceiver only during packet transmission to save energy. Exact clock-synchronization is challenging to achieve because of error present in synchronization protocols. Clock-disagreement increases with time in the absence of synchronization. This paper proposes an Energy-efficient Multi Beacon Guard method (EMBG) to decrease the energy consumption by minimizing the awake time of sender and receiver by periodically switching on and off the receivers during the guard-time. We determine the optimal number-of-times the receiver needs to wake up along with the wake-up intervals to collectively minimize the total energy consumption of the sender–receiver pair during transmission. This paper shows the effectiveness of EMBG in energy conservation and compares with existing approaches using ns2 simulation. [ABSTRACT FROM AUTHOR]

At the turn of the 20th and 21st centuries, Global Navigation Satellite Systems (GNSSs) dominated navigation in air, sea, and land. Then, medium-range and long-range terrestrial navigation systems (TNSs) ceased to be developed. However, with the development of GNSS jamming and spoofing techniques, the TNSs are being re-developed, such as the Enhanced Loran. The Polish Ministry of Defense plans to develop and implement a medium-range backup navigation system for the Polish Navy which will operate in the Baltic coastal zone. This plan is a part of the global trend. This paper presents the concept of a reserve TNS (RNS) that is based on the signal Doppler frequency (SDF) location method. In 2016, the concept of the RNS, which is based on stationary radio beacons located on coastal lighthouses, has been presented. From the military viewpoint, the use of the mobile radio beacons, which may change their location, is more justified. Therefore, the paper presents an idea of using the mobile beacons for this purpose. In this paper, effectiveness of the mobile RNS is shown based on simulation studies. [ABSTRACT FROM AUTHOR]

Accurate sensor localization is a crucial requirement for the deployment of underwater acoustic sensor networks (UASNs) in a large variety of applications. However, the asynchronous clock, stratification effect and mobility characteristics of underwater environment make it challenging to realize accurate node localization for UASNs. This paper develops an autonomous underwater vehicle (AUV) aided localization solution for UASNs, subjected to asynchronous clock, stratification effect and mobility constraints in cyber channels. A hybrid architecture including surface buoys, AUVs, active and passive sensor nodes, is first presented to construct a cooperative location-aware network. Then, an iterative least squares estimator is developed for AUVs to capture the unknown water current parameters, through which the relationship between propagation delay and location estimation can be established. With the assistance of AUVs, two asynchronous localization algorithms are designed to estimate the locations of active and passive sensor nodes. Particularly, motion and ray compensation strategies are jointly employed to improve the localization accuracy. It is worth noticing that, the proposed localization algorithms incorporate the current field estimation into the localization process of UASNs, and more importantly, they can eliminate the influences of asynchronous clock, stratification effect and node mobility together. Moreover, performance analyses for the proposed localization solution are also presented. Finally, simulation and experimental results reveal that the node localization accuracy in this paper can be significantly improved as compared with the other works. [ABSTRACT FROM AUTHOR]

Node localization is one of the key technologies of Underwater Sensor Networks (UWSN). Because of the unique ocean environment conditions, beacon nodes are difficult to deploy precisely and move under the action of ocean currents and tides. Usually the beacon nodes are fixed to the sea floor through anchors and cables, and they can move within a certain range. Most existing localization algorithms do not take such mobility of beacon nodes into account, resulting in large localization errors. In order to overcome this disadvantage, this paper analyzes the characteristics of mobile-constrained beacon nodes and proposes a new localization algorithm in UWSN, namely, Mobile-constrained beacon based localization algorithm. It solves the problem that the position of beacon node is dynamic and imprecise. The unknown node can be located by the geometric relationship between the position of the anchor and the moving radius of the beacon node. In the calculation process, the polygonal area is transformed into a rectangular area, and the three-dimensional (3D) space is mapped into a two-dimensional (2D) space, the calculation process is simplified, and the feasibility of the algorithm is improved. The algorithm can be used both for 2D and 3D localization. Experiment results show that the algorithm proposed in this paper improves the localization accuracy, reduces the error rate of network node location, and has good practicality. [ABSTRACT FROM AUTHOR]

Biological systems are made up of components that change their actions (and interactions) over time and coordinate with other components nearby. Together with a large state space, the complexity of this behaviour can make it difficult to create concise mathematical models that can be easily extended or modified. This paper introduces the Beacon Calculus, a process algebra designed to simplify the task of modelling interacting biological components. Its breadth is demonstrated by creating models of DNA replication dynamics, the gene expression dynamics in response to DNA methylation damage, and a multisite phosphorylation switch. The flexibility of these models is shown by adapting the DNA replication model to further include two topics of interest from the literature: cooperative origin firing and replication fork barriers. The Beacon Calculus is supported with the open-source simulator bcs (https://github.com/MBoemo/bcs.git) to allow users to develop and simulate their own models. Author summary: Simulating a model of a biological system can suggest ideas for future experiments and help ensure that conclusions about a mechanism are consistent with data. The Beacon Calculus is a new language that makes modelling simple by allowing users to simulate a biological system in only a few lines of code. This simplicity is critical as it allows users the freedom to come up with new ideas and rapidly test them. Models written in the Beacon Calculus are also easy to modify and extend, allowing users to add new features to the model or incorporate it into a larger biological system. We demonstrate the breadth of applications in this paper by applying the Beacon Calculus to DNA replication and DNA damage repair, both of which have implications for genome stability and cancer. We also apply it to multisite phosphorylation, which is important for cellular signalling. To enable users to create their own models, we created the open-source Beacon Calculus simulator bcs (https://github.com/MBoemo/bcs.git) which is easy to install and is well-supported by documentation and examples. [ABSTRACT FROM AUTHOR]

The low-cost global navigation satellite systems combined with an inertial navigation system (GNSS/INS) used most frequently for vehicle localization show errors up to 10 m, approximately, even in open-sky environments such as highways. To reduce this error on highways, this paper proposes a localization method based on lane endpoints. Since a lane endpoint frequently appears on a road and can be detected in close proximity even by a low-cost monocular camera, it is a very useful landmark for precise localization. However, the lane width is generally less than 3.5 m, and the localization error from the GNSS is about 10 m. Therefore, if an ego-lane is not identified, the lane endpoints detected in an ego-lane can be falsely corresponded to the lane endpoints in the other lane of a map. This paper proposes an in-lane localization method that uses lane endpoints, the relation between a camera and a road, and the estimated vehicle's orientation from a map. In addition, this paper proposes an ego-lane identification method that generates a hypothesis about an ego vehicle position per lane by using the proposed in-lane localization method and verifies each hypothesis by the projection of lane endpoints and an additional landmark such as a road sign. The average error of the proposed in-lane localization method is 0.248 m on highways. The success rate of the proposed ego-lane identification method is 99.28% by one trial and reaches 100% by fusing the results. [ABSTRACT FROM AUTHOR]

Building spiking neural networks (SNNs) based on biological synaptic plasticities holds a promising potential for accomplishing fast and energy-efficient computing, which is beneficial to mobile robotic applications. However, the implementations of SNNs in robotic fields are limited due to the lack of practical training methods. In this paper, we therefore introduce both indirect and direct end-to-end training methods of SNNs for a lane-keeping vehicle. First, we adopt a policy learned using the Deep Q-Learning (DQN) algorithm and then subsequently transfer it to an SNN using supervised learning. Second, we adopt the reward-modulated spike-timing-dependent plasticity (R-STDP) for training SNNs directly, since it combines the advantages of both reinforcement learning and the well-known spike-timing-dependent plasticity (STDP). We examine the proposed approaches in three scenarios in which a robot is controlled to keep within lane markings by using an event-based neuromorphic vision sensor. We further demonstrate the advantages of the R-STDP approach in terms of the lateral localization accuracy and training time steps by comparing them with other three algorithms presented in this paper. [ABSTRACT FROM AUTHOR]

• Launch a new avenue to capture the effects of covariance between OD flows. • Propose a more generalized model for optimizing traffic count location problem. • Examine and discuss the mathematical properties of the proposed model. • Update stochastic link choice proportions using an adapted traffic flow simulator. Vehicular traffic between different Origin-Destination (OD) pairs for a typical hourly period may statistically correlate with each other. The covariance mainly generated from the daily variation of travel patterns, network topology, and trip chaining activities of household members can be particularly high during the morning peak hour. With the increasing attention on the OD demand variance and covariance in stochastic road networks, a new criterion is proposed in this paper for measuring the estimation accuracy of OD demand covariance. The mathematical properties of this proposed criterion are analyzed to better understand the relationship between the estimation errors of mean and covariance of OD demands. This paper aims to investigate how to optimize the traffic count locations for minimizing the weighted maximum deviation of estimated mean and covariance of OD demands from the "true" values. To consider the effects of stochastic OD demands on the traffic count location problem in the proposed model, link choice proportions are regarded as stochastic variables and updated by an adapted traffic flow simulator in this study. Both the weighted-sum approach and bi-objective approach are examined with the adaption of the firefly algorithm (FA) to solve the single-objective and bi-objective problems. Numerical examples are presented to demonstrate the effects, with and without considering the covariance of the OD demands for the optimization of traffic count locations. [ABSTRACT FROM AUTHOR]

Lunar Space exploration is currently accelerating, and manned and unmanned missions to the Moon are planned by several space agencies and private companies in the coming 5–10 years. The construction of the Lunar Orbital Platform Gateway (LOP-G) and plans to establish a more permanent human presence on the Lunar surface will increase the landing frequency and require the capability to safely soft-land successive missions in near proximity to each other. The lunar South Pole is one of the preferred locations for surface exploration due to the discovery of volatiles in the permanently shadowed craters at the poles. However, landing on the lunar South Pole of the Moon is challenging due to the illumination and loss of Earth line-of-sight conditions combined with complex topography. The increased interest in co-located lunar landings concurrent with construction of lunar infrastructure and a challenging landing area warrants new approaches in navigation technology. In this paper we present a concept for a system of radio beacons installed around the Shackleton crater rim "SR1" landing site on the lunar South Pole. We present considerations for optimal placement of the radio beacons based on the specific landing site topography and quantify our finding with dilution of precision (DOP) calculations. We present a novel method for deploying the radio beacons as penetrators with embedded thermoelectric generators (TEGs) for autonomous power generation. We present findings on beacon survivability, penetration depth, spin-stabilization of the penetrators and maximal theoretical power generation. • In-Situ navigation infrastructure for co-located, pin-point lunar landings. • Optimal placement and geometry of surface radio beacons using Dilution of Precision (DOP) analysis. • Deploying radio beacons as penetrators for fast installation and long-duration operation. • Autonomous power generation in penetrator beacons using thermoelectric generators. • Multiple Beacons for Lunar Powered Descent and Landing. [ABSTRACT FROM AUTHOR]

With a series of complex lunar exploration missions carried out, reliable autonomous navigation approaches for lunar probes are in demand. In this paper, aiming to obtain the position of the probes with high accuracy and computational efficiency, a novel passive positioning scheme for lunar probes is presented. We first designed a reference system including four beacons with known positions. Then, we proposed arctangent temporal interferometry (ATI) method for ambiguity resolution in displacement measurement. Moreover, the quad-beacon displacement search (QBDS) algorithm is proposed for 2-dimension (2D) position search, which enables accurate and computational-efficient 2D positioning for lunar probes. The simulation validations show the effectiveness of the proposed positioning scheme and algorithms. [ABSTRACT FROM AUTHOR]

This paper aims to design and implement an indoor localization method for mobile robots based on trilateration technique, Color Code signatures (CCs) as artificial passive beacons, and a depth camera. The artificial passive beacons are designed as three disks positioned one on top of the other's with different sizes and colors (primary colors only, RGB). The three disks share the same center. The designed beacons are placed on the ceiling to be visible from most locations within the room. The robot's model, controller, and localization method are implemented and evaluated inside the CoppeliaSim environment. The simulation results show that the CCs detecting algorithm enables the robot to discover the designed beacons, achieve an accurate localization and reach the target. [ABSTRACT FROM AUTHOR]

Aside from #MeToo and similar campaigns, sexual assault survivors use social media to disclose personal experiences. This paper uses a mixed-methods approach and draws on network ethnography (Howard, 2002) to explore the visibility of these 'everyday' sexual assault disclosures and how such disclosures further survivors' disclosure motivations. Social network analysis of 23 Twitter hashtags related to sexual assault shows minimal engagement with disclosive tweets, while interviews with survivors (N = 27) indicate that hashtagged disclosures can result in impactful interactions with other survivors, particularly via less visible social media channels, such as direct messages. In combination, results suggest (1) that survivor networks can and do form around mundane hashtags, and (2) that highly visible hashtagged disclosures act as beacons to other survivors and are employed in pursuit of motivations such as supporting other survivors and challenging stigma associated with sexual assault. [ABSTRACT FROM AUTHOR]

The bistatic backscatter architecture, with its extended range, enables flexible deployment opportunities for backscatter devices. In this paper, we study the placement of power beacons (PBs) in bistatic backscatter networks to maximize the guaranteed coverage distance (GCD), defined as the distance from the reader within which backscatter devices are able to satisfy a given quality-of-service constraint. This work departs from conventional energy source placement problems by considering the performance of the additional backscatter link on top of the energy transfer link. We adopt and optimize a symmetric PB placement scheme to maximize the GCD. The optimal PB placement under this scheme is obtained using either analytically tractable expressions or an efficient algorithm. Numerical results provide useful insights into the impacts of various system parameters on the PB placement and the resulting GCD, plus the advantages of the adopted symmetric placement scheme over other benchmark schemes. [ABSTRACT FROM AUTHOR]

Radio navigation systems (RNSs) are commonly applied in air, land and marine navigation. They are most often used for position determination. However, when comparing the definitions of this concept provided by global organisations, such as the International Association of Marine Aids to Navigation and Lighthouse Authorities (IALA), International Civil Aviation Organization (ICAO), International Maritime Organization (IMO) or International Telecommunication Union (ITU), it should be noted that the definitions presented differ significantly. Due to the ambiguity and numerous contradictions, the RNS classification varies depending on the definition of the term 'radio navigation' adopted, which poses serious interpretation problems. This article analyses the concept of radio navigation based on the most important global documents and legal acts on this issue. It points to fundamental differences in the understanding of the term and proposes the adoption of a new, uniform definition for air, land and marine navigation. Based on this definition, the current paper proposes a uniform RNS classification. The proposed definition of the concept of radio navigation and the resulting RNS classification are essential for the understanding of this term to achieve global uniformity and fundamental to the harmonious development of the scientific discipline of navigation. The current proposal should initiate a discussion on the meaning of the concept of radio navigation and the RNS classification. [ABSTRACT FROM AUTHOR]

In this paper, adaptive noise estimation is used along with a previously proposed Huber-based robust algorithm for cooperative localisation of Autonomous Underwater Vehicles (AUVs). The Huber-based robust cooperative localisation algorithm named Huber-based Iterative Divided Difference Filtering (HIDDF), proposed in our previous work, effectively achieved a robust result against abnormal measurement noise, enhanced the stability of the filtering algorithm and improved the performance of cooperative localisation state estimation. However, its performance could be significantly further improved if it could estimate the system's noise statistical properties online in real time and then adaptively adjust the filtering gain matrix accordingly. In this paper, a novel adaptive noise estimation algorithm is proposed based on a covariance matching method. The proposed algorithm is suitable for adaptively estimating Gaussian and non-Gaussian measurement as well as process noise. The efficacy of the proposed algorithm has been verified through simulation results. In order to further verify the effectiveness of the proposed algorithm in practical systems, lake tests were conducted. Then, based on offline test data, the performance of the cooperative positioning algorithm under dual-pilot and single-pilot schemes was simulated. The advantages and feasibility of the algorithm are analysed and compared through performance comparison. Cooperative localisation accuracy of the previously proposed Huber-based robust algorithm has been enhanced significantly when used with the proposed adaptive noise estimation algorithm. [ABSTRACT FROM AUTHOR]

Abstract Which wireless technology is able to meet the requirements of space launch vehicles in terms of latency, throughput and robustness? The IEEE 802.15.4e amendment has been designed to meet such requirements. More specifically, the Time Slotted Channel Hopping (TSCH) mode has been designed for industrial automation, process control and equipment monitoring. In this paper, we focus on the time needed by a joining node to detect beacons advertising the TSCH network. An Enhanced beacon is a TSCH frame that contains information on synchronization, channel hopping and timeslot used in the advertised network. However, the advertising policy is left unspecified by the IEEE 802.15.4e standard and is under the responsibility of a layer upper than the MAC one. Since beacons are broadcast, they are lost in case of collisions.The main problem is how to avoid such collisions? In this paper, we propose a Deterministic Beacon Advertising Algorithm, called DBA. The goal of DBA is to ensure that beacons are transmitted on all frequencies used by the TSCH network, regularly and without collision. With DBA, the exact value for the maximum time for a joining node to detect a beacon can be computed easily. We use the NS3 Simulator to evaluate this time as well as the number of message losses, considering different network topologies (star or multihop). We compare the performance of DBA with that of two algorithms existing in the state of the art. [ABSTRACT FROM AUTHOR]

In this paper, the ideas of deep auto‐encoder (DAE) and manifold learning are adopted to solve the problem of structural condition diagnosis. A scalable decentralized end‐to‐end unsupervised structural condition diagnostic framework is proposed. Three damage diagnosis mechanisms are clarified. The structural damage diagnosis approaches are presented from the latent coding domain and the time domain, respectively. In the latent coding domain, an undercomplete DAE is established to extract the distribution of the low‐dimensional manifold of the signal. On the contrary, in the time domain, an overcomplete DAE is adopted to extract the reconstruction error of the signal. Subsequently, normalized damage quantitative indicators are developed in the two domains. The damage localization method is also clarified. The proposed method can extract features directly from original vibration data without the need for additional signal preprocessing techniques. More importantly, the algorithm relies only on the output signals and does not require a numerical or scale model. This framework can be used to identify, locate, and quantify structural damages. The validity of the diagnostic framework is verified using a well‐designed laboratory benchmark structure. A large‐scale grandstand structure is further used to prove the ability of the proposed method for identifying slight structural damage caused by the loosening of joint bolts. The results clearly demonstrate an elegant performance of the proposed damage detection algorithm in structural condition assessment and damage localization. [ABSTRACT FROM AUTHOR]

Beacon broadcasting is of great importance in improving road safety and avoiding dangerous situations in vehicular ad hoc networks (VANETs). In order to support emerging vehicular applications such as autonomous driving, the reliability of beacon broadcasting becomes an indispensable issue which is also difficult given the highly dynamic topology and vehicle density. For the territories which are not covered with communication infrastructure, controlling and scheduling in a centralized way may not be applicable. Therefore, vehicle-to-vehicle (V2V) ad hoc communication is promising to address the ubiquitousness coverage concern. In this paper, a distributed network coding-based medium access control protocol (NC–MAC) is proposed to support V2V beacon broadcasting. We combine the preamble-based feedback mechanism, retransmissions, and network coding together to enhance broadcasting reliability. Extensive simulations are given to show the performance gain of NC–MAC protocol compared to the existing 5 G cellular vehicle-to-everything (C–V2X) MAC protocol in a wide range of scenarios including highway and urban vehicle traces generated by simulation of urban mobility (SUMO). The results show that the proposed protocol can improve the communication reliability as well as scalability. [ABSTRACT FROM AUTHOR]

Due to recent technological advancements, more diversified customer demand, and increasingly harder competition, traditional postal service systems have experienced significant changes all over the world. In Norway, through a strategic reform called post-in-shop, undertaken in 2013, most postal services are now provided at postal service counters located in retailer stores in order to improve accessibility, operational efficiency, and cost-effectiveness. This has led to a complex decision-making problem for the redesign of urban postal service networks across the country. In this paper, a two-stage method is proposed to solve a real-world urban postal service network redesign problem. First, two location models are employed to determine the optimal locations of postal service counters. In the second stage, a simulation model is built to evaluate the urban postal service system with different location and demand allocation plans under a realistic and stochastic environment. Among other insights, our results show that the proposed two-stage method can be used to effectively improve the accessibility of postal service networks by making optimal location-allocation decisions. [ABSTRACT FROM AUTHOR]

Due to practical limitations on size and cost, aerial vehicles generally cannot equip complicated sensors to form sensor array for target localization. In this paper, we investigate the direct position determination (DPD) of stationary source via single moving sensor. First, we analyze artificial signal structure and construct the DPD model with the frame periodicity of artificial signal. The model incorporates Doppler information extracted from both transformation frames and adjacent samples into target localization. Secondly, we consider the effect of oscillator instability and present an iterative solution for joint estimation of target location and phase noise caused by oscillator imperfection. The proposed technique fully exploits periodic structure of artificial wireless signal, which leads to significant enhancement in localization performance. Both theoretical analysis and simulations are presented to confirm its effectiveness. [ABSTRACT FROM AUTHOR]

Summary Identification of disturbances that pushes the power system towards insecure limits can assist in timely remedial measures to be taken for improving situation awareness. The information about event's signature is primarily available in the form of frequency or voltage signals obtained from phasor measurements units (PMUs) in real‐time. Proper evaluation of power system event characteristics enhances the situational awareness and assists system operator to develop required corrective measures for secure operations. In this paper, a fast and accurate algorithm is proposed to identify, classify and locate the events using minimum synchronized data for enhancing the situational awareness of the system. An index is developed with short window synchronized bus frequency data of 18 cycles to detect an event in the network. For identifying the type of event, the same data length bus voltage magnitude and frequency synchronized measurements are utilized to develop statistical measures based novel indices. A rule‐based inference from event's signature is also developed to validate the usefulness of indices for classification and location identification of the event. These extracted statistical indices are applied as input to the Random Forest Classifier to classify and locate the events in real‐time. The proposed approach captures real‐time synchronized data and is adaptive to system topological changes. The proposed comprehensive approach for situational awareness is applied to standard IEEE 39 Bus test system and IEEE 118 Bus test system. The results highlight the performance of the composite method for event identification, classification and location identification with less computational burden and high accuracy. [ABSTRACT FROM AUTHOR]

Based on the MGT positioning method, the performance of combined magnetic beacon is studied. The unit size of beacon is designed as D = 2 cm and L = 8 cm, the performance of different structure magnetic beacons combined have been studied and compared in detail, results show that the magnetic field intensity of cross structure is about 30000nT higher than the orthogonal structure which have generated sine waves. According to the TLS to filter the signal based on the regular tetrahedral gradient tensor measurement array. In the laboratory environment (Bearth=46157nT) to validate the model in this paper, the experimental results show that the array of two identical cross-combined permanent magnets will increase the magnetic induction value at the same distance by 1.7 times and the max-average positioning error on the 6 experimental paths is 1.52m. The implications of these findings particularly regarding the array rotation combined magnetic beacon may be useful for the high-precision magnetic position systems. [ABSTRACT FROM AUTHOR]

This paper considers secure communications for an underlay cognitive radio network (CRN) in the presence of an external eavesdropper (Eve). The secrecy performance of CRNs is usually limited by the primary receiver's interference power constraint. To overcome this issue, we propose to use an unmanned aerial vehicle (UAV) as a friendly jammer to interfere Eve in decoding the confidential message from the secondary transmitter. Our goal is to jointly optimize the transmit power and UAV's trajectory in the three-dimensional space to maximize the average achievable secrecy rate of the secondary system. The formulated optimization problem is nonconvex due to the non-convexity of the objective and non-convexity of constraints, which is very challenging to solve. To obtain a suboptimal but efficient solution to the design problem, we first transform it into a more tractable form and then develop an iterative algorithm for its solution by leveraging the inner approximation (IA) framework. Combining tools from IA framework and S-procedure, we further extend the proposed algorithm to a more realistic scenario, where the imperfect location information of ground nodes (including Eve, secondary receiver and primary receiver) is considered, resulting in the average worst-case secrecy rate. Extensive numerical results are provided to demonstrate the merits of the proposed algorithms over existing approaches. [ABSTRACT FROM AUTHOR]

In this paper, an air sector network (ASN) is built based on the obtained data describing the airspace of world. In the constructed network, nodes and edges represents the airports and airlines respectively. Based on the complex network and the entropy, we find that the airport rank obtained through the centrality and entropy theory is better than that derived through the traditional means. The improved entropy weight algorithm is used to reflect the location information of the nodes in the network, synthesize the centrality of the previous complex network, construct the importance evaluation matrix and finally calculate the ranking results of the importance of the nodes. Finally, through calculation, we found that the ranking result after comprehensive consideration is better than that being determined only through centrality, which illustrates the effectiveness of the method. [ABSTRACT FROM AUTHOR]

In Vehicular Adhoc Network, vehicles need to transmit their original mobility information, in order to maintain the communication reliability for efficient performance of the VANET application. However, some factors such as high broadcasting rate, affect the information accuracy and network reliability. For an effective broadcasting, which maintains network reliability and information accuracy, the broadcasting rate and number of beacons transmitting should be reduced. In this paper, a broadcasting algorithm namely, Traffic Condition Aware Customized Beacon Broadcasting Method (TCACBB) is proposed. TCA-CBB method works based on the traffic condition and adaptively fixes the broadcasting rate according to the current position of the vehicle. Adaptive Extended Kalman Filter (AEKF) is used to predict the current position at broadcasting vehicle side and receiver vehicle side. TCA-CBB is fragmented as (i) Broadcasting Vehicle Segment (BVS) and (ii) Adjacent Vehicle Segment (AVS). Each segment runs a position prediction algorithm called Adaptive Extended Kalman Filter (AEKF), to predict their current position to maintain position accuracy at both the sides. BVS gathers mobility information from Mobility Data Gathering Unit (MDGU) and Traffic Condition Estimation Unit (TCEU) supplies model parameters to the mobility information such as position, speed and direction gathered from MDGU. Self Position Estimation Unit (SPEU) predicts the current position of the Broadcasting Vehicle (BV). Based on the error threshold, the importance of the beacon message is estimated. If the beacon message is important, then it is constructed and scheduled for broadcasting by the Beacon construction and Broadcasting Unit (BCBU). Next Adjacent Vehicle Segment receives the beacon message by Beacon Message Receiving Unit (BMRU). Adjacent Position Estimator Unit (APEU) predicts the current position of the Adjacent Vehicle (AV). The accuracy of the Adjacent Vehicle Position relies on BV's current position. The omitted or lost beacon message is reconstructed using the information shared by the Broadcasting Vehicle. The performance of the proposed method is compared with existing methods such as PPBR, ABR and SAB. The results obtained by the proposed method shows that, TCA-CBB outperformance the existing works. [ABSTRACT FROM AUTHOR]

Collision avoidance and platooning applications require vehicle localization at cm-level accuracy and at least 50 Hz rate for full autonomy. The RADAR/LIDAR and camera based methods currently used for vehicle localization do not satisfy these requirements, necessitating complementary technologies. Visible light positioning (VLP) is a highly suitable complementary technology due to its high accuracy and high rate, exploiting the line-of-sight propagation feature of the visible light communication (VLC) signals from LED head/tail lights. However, existing vehicular VLP algorithms impose restrictive requirements, e.g., use of high-bandwidth circuits, road-side lights and certain VLC modulation strategies, and work for limited relative vehicle orientations, thus, are not feasible for general use. This paper proposes a VLC-based vehicle localization method that eliminates these restrictive requirements by a novel VLC receiver design and associated vehicular VLP algorithm. The VLC receiver, named QRX, is low-cost/size, and enables high-rate VLC and high-accuracy angle-of-arrival (AoA) measurement, simultaneously, via the usage of a quadrant photodiode. The VLP algorithm estimates the positions of two head/tail light VLC transmitters (TX) on a neighbouring vehicle by using AoA measurements from two QRXs for localization. The algorithm is theoretically analyzed by deriving its Cramer-Rao lower bound on positioning accuracy, and simulated localization performance is evaluated under realistic platooning and collision avoidance scenarios. Results demonstrate that the proposed method performs at cm-level accuracy and up to 250 Hz rate within a 10 m range under realistic harsh road and channel conditions, demonstrating its eligibility for collision avoidance and safe platooning. [ABSTRACT FROM AUTHOR]