Filter Bank Multi Carrier (FBMC) based waveforms received recently a lot of interest due to their high frequency localization and hence their suitability to the fragmented spectrum utilization. In this paper, we analyze the doubly selective channel estimation aspect of the FBMC-OQAM waveform. We perform a frequency domain channel estimation using the Linear Minimum Mean Square Error (LMMSE) estimtator. In addition, we study the spreading effects of the FBMC filtering operation and the channel selectivity on the received symbol. This study is exploited later to offer a trade off between the complexity level of the LMMSE estimator and its performance accuracy. An analytical analysis of this study is provided and verified by Monte Carlo simulations.
Vehicle-to-Vehicle (V2V), Vehicle-to-Road Infrastructure (V2R) and Vehicle-to-Pedestrian (V2P) communications are paramount for paving the way for smarter, cleaner and safer cities and roads. We investigate on how three state-of-the-art Mobile Ad-Hoc Network (MANET) routing protocols behave over the IEEE 802.11p/WAVE stack, which has been recently been specified for Vehicular Ad-hoc Networks (VANETs): Ad-hoc On-Demand Distance Vector (AODV), Optimized Link State Routing (OLSR) and Destination-Sequenced Distance-Vector (DSDV). Based on ns-3 and BonnMotion simulations, we evaluate Packet Delivery Rate, Goodput, Routing Overhead and End-to-End Delay for different trajectories, average speeds, and network densities. Our results show that the DSDV and OLSR protocols have a better performance than AODV, for low-density and low-speed scenarios. Additionally, we have observed that when the number of Nodes (network density) or Nodes’ velocity increases, the OLSR protocol performs better than the other two.
In order to ensure driving safely, the driving safety assistance system must be able to aware of potential collision accidents in advance, especially significant for the intersection where traffic accidents occur more frequently. In the proposed approach, we utilized the widely adopted architecture of recurrent neural networks, Long-Short Term Memory networks (LSTM) architecture to form a deep stacked LSTM network which can accurately predict future longitudinal and lateral locations for vehicles. Considering that VANETs is one of the most important applications for improving the safety of driving, and in order to reduce the system's communication and computational costs, a vehicle intersection collision monitoring algorithm based on VANETs and uncertain trajectories is proposed. The algorithm is divided into two categories: uncertain trajectories prediction algorithm and vehicle collision monitoring algorithm. The proposed approach provides approximate answers to the user at the users required level of accuracy while achieving near-optimal communication and computational costs. Finally, extensive experiments were conducted to show the efficiency and efficacy of the proposed approach.
The aim of the smart level crossing project is to improve the safety of rail and road systems without compromising the regularity of trains. The LC must become interactive with its environment by integrating new communication technologies with the train and road users. These technologies will make it possible to adjust the closing time of the LCs according to the localization of the rail vehicle and its speed. The LC must interact better with the road, communicate with road users and prepare for the arrival of autonomous vehicles. This paper aims to describe the project of the french operator SNCF on new security at level crossing.
Nowadays, rail traffic is expected to evolve into a new era of "smart rail mobility", where trains, infrastructure, travelers and goods will be increasingly interconnected. Railway communications are required to support various high-data-rate applications, the communication system should be carefully designed, which makes railway scenario becomes an important communication scenario in the 5G era. Millimeter-wave (mmWave) bands and novel technologies like resource allocation, multiple access and multiple-output beam-forming are proposed in the realization of this goal. In this paper, the mmWave channel characteristics of rural railway scenario are studied via a calibrated ray-tracing simulator. The large-scale parameters of the channel characteristics, including the path loss, root-mean-square (RMS) delay spread, Rician K-factor, angular spreads, and cross-polarization ration (XPR) are explored. The statistical properties, decorrelation distance and cross-correlations are analyzed. The studied channel characteristics can be practically used to support the link level and system level design of the communication system in the similar environments.
A radio channel measurement campaign with a maximum distance of 2.6 km was performed in China. In this paper, a detailed description of the channel measurement campaign including antenna setups, channel sounder configurations and other related info is given. The received signal level (RSL) is shown and compared with the Plain Earth Loss model (PEL), the ITU-R P.1546-2 model (ITU-R) and the Round Earth Loss model (REL). It can be found that the REL model matches the measured RSL best according to the values of the Root Mean Square Error (RMSE). The Power-delay profiles (PDPs) are demonstrated, from which the mean excess delay and the RMS delay spread are extracted. It can be found that the 90% of the mean excess delay and the RMS delay spread are within 4.3 ns and 113.3 ns according the corresponding Cumulative Distribution Functions (CDF), respectively. The Akaike Information Criterion (AIC) is used to estimated the best-fit amplitude distribution of the small-scale fading. The Two-Wave with Diffuse power (TWDP) model is found to be the best-fit model with more than 90% incident percentage in the whole route.
GNSS (Global Navigation Satellite System) positioning accuracy depends on a complicated interaction of various factors. According to the GNSS signal propagation trajectory, accuracy depends on the quality of the pseudorange and carrier phase measurements as well as the broadcasted ephemeris data. The factors are reflected by measurement error, a fundamental assumption is made as the error can be allocated to individual satellite pseudorange. It is common to separate a geometry-related quality factor from the measurement error which called the dilution of precision (DOP) and errors in the pseudo-range measurement called user-equivalent range error (UERE). UERE is further divided into signal-in-space range error (SISRE) and user equipment error (UEE). This paper mainly takes GPS as an example, considering environment obstruction in the HDOP calculation, and estimates the UERE value by modeling and empirical values. An algorithm is designed to determine the visibility of the satellite based on the fish-eye image. The actual data and the estimation results are also compared and the UERE estimation value is corrected. Finally, the results of the analysis are compared to obtain the conclusion that the GPS positioning error in an open environment is lower than that in the more obstructed environment, and one of the main reasons for different UERE in different scenarios is multipath error.
This paper presents the results of a preliminary apportionment of safety targets for virtual balise detection using Global Navigation Satellite Systems. In addition to describing an enhanced functional architecture supporting the virtual balise concept and the requirements engineering process for the derivation of tolerable hazard rates, the paper provides a summary of requirements for virtual balise detection and GNSS positioning in support of virtual balise detection.
Delay Tolerant Networks (DTNs) are sparse networks where complete direct end-to-end paths between source and destination can seldom be established. Routing mechanisms in DTN rely on the nodes’ mobility to connect disconnected nodes, carrying messages around the network to overcome path disconnection. The proactive DTN approach consists of introducing dedicated nodes whose only purpose is to establish communication between ordinary nodes, and relieve them from energy-consuming work, such as message routing and forwarding. This paper addresses the use of Unmanned Aerial Vehicles (UAVs) as DTN relays, introducing a proactive scheme called Deadline Triggered Pigeon with Travelling Salesman Problem with Deadlines (DTP-TSP-D). We envision a DTN where ground nodes can only communicate by flying UAVs with the capacity of carrying messages from one location to another. Each UAV either belongs to one node or to a cluster of nodes, and its role is to hover over their home-ground node (or ferrying around their home cluster) until they are triggered to deliver messages directed to other ground nodes. The triggering criterium is based on the deadlines of the messages present in the UAVs buffer, evaluating its ability to deliver all of them in time. It uses a developed TSP Genetic Algorithm to compute the route that achieves the most (timely) deliveries. The performance of DTP-TSP-D has been compared to dedicated node protocols found in the literature, namely SIRA and MRT-Grid. The performance metrics used were delivery ratio and average delay. The results show that DTP-TSP-D achieves higher delivery rates than its competitors, while keeping a consistent average delay.
In addition to the traditional acoustic siren, an emergency vehicle can use wireless communication to warn other vehicles or traffic lights of its presence, either in vehicle-to-vehicle (V2V) or vehicle-to-infrastructure (V2I) mode. The use of this technology can reduce accident risks during emergency response trips, help save time, and eventually rescue lives. Yet, an algorithm is required to help vehicles and traffic lights to take the right actions upon receiving a vehicle-to-everything (V2X) message from a nearby emergency vehicle. For this goal, a collaborative algorithm was developed and deployed in a simulated road traffic scenario with traffic lights. This scenario was used to evaluate the performance of an ambulance using both V2X communications ruled by the proposed algorithm and the traditional siren. Results show that the performance of the ambulance improves globally when V2X communications are used rather than the siren, namely in terms of average trip distance and CO2 emission.
This paper discusses channel conditions at an intersection with low visibility for inter-vehicle communication systems. Communication performance is dependent on the channel, which means that channel prediction is essential to realize reliable communications. In this paper, the channel conditions are evaluated in the 700 MHz band using ray-trace simulations. The bit error rate (BER) performance of an orthogonal frequency-division multiplexing (OFDM) system based on the IEEE 802.11p standard is evaluated using simulated channel environments. The simulations show that the antenna height is significant and that the received power strength characteristics improve when antennas are set at lower positions on the vehicles. Additionally, the delay profiles obtained are approximated using mathematical functions. In line-of-sight (LOS) environments, the delayed path is similar to the power function. In non-line-of-sight (NLOS) environments, the channel can be approximated using a linear function or a quadratic function.
Automated vehicles are expected to solve traffic issues. Many projects of automated vehicles are ongoing all over the world. Under current law in Japan, the experiments of an automated vehicle without a driver in the car are prohibited in the real world. This means that level 4 or 5 automated vehicles are prohibited in the real world in SAE level definition. In Japan, the guide line was issued in 2017 for realizing the experiments of an automated vehicle without people in the vehicle in the real world. We proposed a prototype of remote type automated vehicle system, which was suitable for the guideline. In this demonstration paper, we introduce the automated vehicle system, and explain the system configuration, communication and results. The first experiment, which was demonstrated in Japan, will be explained briefly.
Elements of an emergency response operation over wide areas should be synchronized. For this, a communication infrastructure is advisable, since existing infrastructures can be compromised due to natural disasters or their overuse in the fallout. In order to assure connectivity, some emergency systems rely on robust and reliable radios that have the drawback of low bitrate, which provides a limitation on the supported traffic. In this work, the Battlefield Management System/Emergency Mobile Mesh (BMS/EMM) system's network performance is analyzed with data from a field test with a hierarchical deploy that uses robust and low bitrate radios.
This paper shows the research on correlation characteristic of MIMO channel based on the measurement conducted in high-speed scenario. The measurement data is collected continuously from the area covered by LTE base stations alongside the railway. By extracting LTE downlink cell-specific reference signal, channel impulse responding (CIR) can be calculated, and based on this the correlation characteristic of MIMO channels is investigated. The results show that the cross-correlation coefficient at the BS side is stronger than the UE side. And correspondingly the statistics of eigenvalues of channel correlation matrix and the interrelation between capacity and condition number are shown. Finally MIMO channel characteristic in different speed will be compared. All the field measurement results would be a profit reference for channel modelling.
Automated vehicles can currently drive in different traffic conditions, but there still exist situations that automated vehicles cannot handle efficiently and safely. When an automated vehicle reaches its functional system limits or encounters unexpected situations, a transition of control is needed to handover vehicle control to the driver. A transition of control requires that the driver obtains the full situation awareness and takes control of the primary driving tasks. Transition of control is expected to negatively impact traffic efficiency and safety. The latter impacts will be especially relevant in areas where multiple automated vehicles need to perform a transition of control simultaneously. To efficiently and safely deal with multiple transitions of control, novel traffic management measures are needed. These measures should take into account not only the automated vehicles, but also the overall traffic stream. This paper proposes different traffic management measures supported by C-ITS and designed to handle transitions of control in mixed traffic scenarios, where automated, connected and conventional vehicles coexist.
For safety driving technology, GNSS (Global Navigation Satellite System) is one of important techniques. GNSS can estimate various positions, such as vehicles, pedestrians and bicycles. In this paper, we focus on RTK (Real Time Kinematic) positioning for estimating a vehicle's position. In urban area, it is difficult to solve RTK calculation because signals from satellites are often shaded by buildings and re-acquisition is often happened. In order to reduce harmful effect by the above problems, we will propose the cooperative positioning method. The proposal uses two receivers on a vehicle. Phase transition can be estimated from the other receiver. If the wrong signal reception is happened at the one receiver, the phase correction can be calculated by the other receiver.
It is widely accepted that Vessel Monitoring Systems (VMS) are currently a fundamental tool in the control of fishing activity. While larger vessels, because of their fishing capabilities, are the main target of this control, it is starting to be clear that by not monitoring smaller vessels, an important part of the Global Fishing effort is left uncontrolled, not because of the fishing capabilities of the single vessels themselves, but by the large numbers of vessels they represent. However, unlike larger vessels, these smaller boats have limited or no resources, and therefore installing the monitoring devices raises challenges that do not exist in their traditional VMS counterparts. Starting by identifying the main concepts that would be interesting to keep from the traditional VMS and the ones that would have to be adapted, options were taken, a mobile unit was then designed, built and tested. Proprietary HW was developed so that the unit would be well adapted to the monitoring purpose in mind at a reasonable cost. A SW application for the microcontroller was also developed and showed that it was possible to achieve the required monitoring with this device. The mobile unit developed is small enough to be carried in one hand and it's energetically autonomous for a period of several months by using a small lithium battery and having an average power consumption of less than 50mW.
Advanced applications in intelligent transport systems (ITS) are based on V2X (vehicle-to-everything) communications. In order to share information about, e.g., vehicle status, critical events or perceived objects in the vicinity, respective services suggest direct communication links (device-to-device) among vehicles, as introduced in ITS-G5 and Cellular-V2X. A mayor challenge for direct communications systems is the utilization of available radio resources.In this work, we present a resource scheduling scheme based on vehicle locations, aiming to maximize the reliability of message transmission in highway scenarios, considering a given bandwidth. The scheme consists of two steps: first we determine the optimal distance between vehicles utilizing equivalent radio resources. We extend our previous work and provide a closed form solution for the outage probability. The quasi-convex expression can be solved with standard optimization algorithms. In the second step, we propose radio resource allocation strategies that rely on the optimal scheduling distance. Finally, we evaluate the performance of our proposed scheme compared to a fixed scheduling distance.
In high speed railway environment, the orthogonal frequency division multiplexing (OFDM) system is especially susceptible to the carrier frequency offset (CFO). The existence of the impulsive noise reduces the effectiveness of the conventional optimal receiver which is designed solely for additive white Gaussian noise. First, we introduce the impulsive noise from the origin, classification and three mainstream detection algorithms aspects. Furthermore, four impulsive noise models are described including three memoryless models and a memory model. Then, we propose a detecting and suppressing scheme. The frequency offset is compensated in the designed beamforming network. The simulation results indicate that the impulsive noise is detrimental to the estimation of the Doppler frequency offset (DFO) and oscillator frequency offset (OFO). The effectiveness of the considered receivers in terms of the symbol error rate (SER) performs well in contrast to the other algorithms.
Filter Bank Multi Carrier (FBMC) based waveforms received recently a lot of interest due to their high frequency localization and hence their suitability to the fragmented spectrum utilization. In this paper, we analyze the doubly selective channel estimation aspect of the FBMC-OQAM waveform. We perform a frequency domain channel estimation using the Linear Minimum Mean Square Error (LMMSE) estimtator. In addition, we study the spreading effects of the FBMC filtering operation and the channel selectivity on the received symbol. This study is exploited later to offer a trade off between the complexity level of the LMMSE estimator and its performance accuracy. An analytical analysis of this study is provided and verified by Monte Carlo simulations.
