Measurement-based Geometrical Characterization of the Vehicle-to-Vulnerable-Road-User Communication Channel

Vehicle-to-vulnerable road user (V2VRU) communications have the ability to provide 360 degrees of awareness to both vehicles and vulnerable road users (VRUs) to prevent accidents. An accurate V2VRU channel model in critical accident scenarios is essential to develop a reliable communications system. Therefore, extensive wideband single-input and single-output (SISO) channel measurement campaigns at 5.2 GHz were carried out in open-field and urban environments. Accident prone scenarios between a vehicle and a cyclist as well as between a vehicle and a pedestrian are considered. In this paper, locations of the scatterers in the propagation environment are estimated. We propose a method to extract specular MPCs from the estimated time variant channel impulse response (CIR) based on the density of neighboring MPCs. The specular MPCs are then tracked using a novel tracking algorithm based on the multipath component distance (MCD) approach. Each path is then related to a physical scatterer in the propagation environment by employing a joint delay-Doppler estimation. According to the results, single and double bounce reflections from buildings and parked vehicles are identified in line-of-sight (LoS) situation. In non-LoS (NLoS) situation, scattering from nearby trees as well as reflections from traffic signs and lampposts beneath the trees canopy are identified

Path Loss Models and Large Scale Fading Statistics for C-Band Train-to-Train Communication

The profound knowledge of wireless propagation is essential for wireless communication between vehicles. To evolve and test communication standards we need channel models in representative environments to neither over-, nor underestimate the effect of the surrounding environment and the movement of the vehicles; typical environments for railway communication are railway station, open field and hilly environments. We introduce train-to-train (T2T) path loss models and large scale fading statistics based on channel sounder measurement data as a first step towards a geometry-based stochastic channel model (GSCM). The models represent the mentioned typical environments for railway applications. We compare the results with previous published intelligent transportation system (ITS-G5) measurement based models and highlight the differences

Vehicular-to-Pedestrian Channel Models

Protect vulnerable road users with reliable vehicle-to-pedestrian (V2P) communications to reduce accidents Accurate V2P channel models to design reliable V2P communications Comparison of vehicle-to/everything (V2X) channels Related work on V2P channel models V2P path loss model

Measurement-Based Analysis on Vehicle-to-Vehicle Connectivity in Tunnel Environment

Vehicular ad hoc network (VANET) brings an excellent solution to ensure road safety and transportation efficiency in critical environment like tunnel. Particularly, radio link connectivity of vehicle-to-vehicle (V2V) significantly influences the performance of VANETs. The communication range of the radio systems is a random variable in reality due to the channel fading effect. Therefore, the connectivity model between vehicles in realistic environment is a key for accurate evaluation of system performances. In this paper, we study the V2V connectivity performance in the presence of channel randomness for tunnel environment. Firstly, based on channel measurement campaign, empirical path loss (PL) and small-scale fading channel models are established. Secondly, we study the influence of large-scale fading parameters on V2V connectivity. Thirdly, based on real small-scale fading characteristics, we derive the V2V connectivity probability between any two vehicles under Nakagami fading channel for one-dimensional VANET, and give the closed-form of V2V connectivity probability. Finally, we study the influences of various parameters (i.e., Nakagami fading factor, vehicle density, and neighbor order) on V2V connectivity performance. Results show that with the Nakagami fading shape factor increases, the connectivity probability increases. The shadowing fading can improve connectivity in the VANET; the path loss exponent, transmission distance, and signal-to-noise ratio (SNR) threshold have a negative impact on connectivity probability. The transmit power, vehicle density, and path loss threshold value have a positive impact on connectivity

Covid-19 effects on students' teaching and learning perspectives in Malaysian varsities

The COVID-19 pandemic has had dramatic effects on the socio-economic and well beings of Malaysians. The objective of the study is to find the effects of the pandemic on university students both on the technical side, such as the sufficiency of infrastructure and the internet to support online teaching and learning (T&L), as well as on the social side, such as stress level and focus on the study. The nationwide study on the effect of the pandemic on Malaysian varsities students was conducted at the end of 2020. There are many important issues uncovered in this study ranging from the technical side, such as internet-ready programs, socio-economic side, to the psychological perspectives. It shall provide invaluable insights to the related ministries while preparing appropriate reactions during the recovery period. The survey revealed that almost 74% of students highlighted that internet coverage and connectivity was the main issue in online T&L. Although statistics show that 90% of Malaysian households have access to the internet, 49% of students reported that their internet connections were poor. The effects of the pandemic are far-reaching, students belonging to the most vulnerable category find themselves in the most non-conducive place to learn, and they are disturbed by siblings. The socio-economics impacts brought about by the pandemic cause ripple effects onto their families. The government distribution of relief aids has lessened the burden of many people, including students; nevertheless, much improvement could be made, especially in the internet facility and coverage

V2V Channel Modeling at 5.2 GHz for Highway Environment

To design and evaluate vehicle-to-vehicle (V2V) communication systems in intelligent transportation system (ITS), it is important to understand the propagation mechanisms and channel models of V2V channels. This paper aims to analyze the channel models at 5.2 GHz for the highway environment in obstructed line-of-sight (OLoS) and line-of-sight (LoS) scenarios, particularly the vehicle connectivity probability derivation based on the propagation model obtained from measurement. First, the path loss (PL), shadow fading (SF), narrowband K-factor, and small-scale amplitude fading are analyzed. Results showed that the received signal magnitude follows Rice and Weibull distribution in LoS and OLoS scenarios, respectively. Second, we develop simple and low-complexity tapped delay line (TDL) models with a 10 MHz bandwidth for LoS and OLoS scenarios; in addition, we investigate the wideband K-factor, the root mean square delay spread (RMS-DS), and delay-Doppler spectrum. Third, we derive the closed form connectivity probability between any two vehicles in the presence of Weibull fading channel, and analyze the effects of Weibull fading channel and traffic parameters on connectivity. It is found that Weibull fading parameter, transmit power and vehicle density have positive impact on connectivity probability, PL exponent has negative impact on connectivity probability

Analysis of Communication Requirements for CACC in Stop-and-Go Behavior for Energy Efficient Driving

Electric Vehicles (EVs) nowadays suffer from range anxiety due to their short driving range and long battery recharging time. One solution to mitigate range anxiety problem is by reducing the unnecessary stop-and-go events to reduce energy consumption. Cooperative Adaptive Cruise Control (CACC) is one of the Vehicular Ad-hoc NETworks (VANETs) applications that can provide safe and smooth driving. In VANETs, all vehicles share their state information periodically by transmitting Cooperative Awareness Messages (CAMs) to their neighbors using Vehicle-to-Vehicle (V2V) communication. CACC exploits the state information of the neighboring vehicles to operate adaptive and energy efficient maneuver. To satisfy the CACC requirements, vehicles need to provide sufficient and accurate information. The precision of this information is highly dependent on the update rate of CAMs and on their communication range. High update rate and communication range can cause channel congestion and increase packet collisions. The focus in this paper is to determine the required update rate and communication range that satisfy the requirements of the CACC to reduce the energy consumption for EVs. Simulation results also show the benefit of using CACC on the energy consumption

Performance Evaluation of Traffic Information dissemination Protocols for Dynamic Route Planning Application in VANETs

Dynamic route planning is one of the ITS efficiency applications that reduce travel time and energy consumption. To perform efficient route planning, real-time traffic information should be collected and disseminated to vehicles on other road segments. vehicular ad-hoc networks (VANETs) are a promising technology that can provide the communication means to deliver the required traffic information. In this paper, we study and evaluate three dissemination protocols in realistic vehicular scenarios. The evaluated protocols are geocast-based beacon piggybacking protocol, a low-overhead adaptation of it and greedy perimeter stateless routing (GPSR). As performance metrics we measure the average end-to-end delay, average routing overhead and the packet delivery ratio as a function of traffic density. The goal is to find a reliable dissemination protocol that fulfills the application requirements and requires low routing overhead. Simulation results show that all three protocols achieve the requirements of dynamic route planning in end-to-end delay and packet delivery ratio. However, a significant reduction in the routing overhead can be achieved by the modified piggybacking protocol