Vehicle to vehicle/infrastructure communication systems have a significant role to play in optimizing road traffic and improving road safety. In this context, two standards have emerged, namely ITS-G5 (IEEE 802.11p) and C-V2X (3GPP Release 14). The objective of this article is to compare both standards by evaluating the performance of both physical layers and associated MAC layers. The physical layer performance of a single link is first evaluated and used to derive performance in a loaded network where each user is scheduled by their respective MAC layer. Performance evaluation shows an advantage for the C-V2X for low levels of vehicles density while when the congestion increases the performance gap reduces until ITS-G5 eventually outperforms C-V2X. Finally, latency was also assessed for both communication systems.

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Cooperative Intelligent Transport Systems (C-ITS) are expected to fulfill the needs of various emerging road safety applications. In this work, we focus on improving C-ITS vulnerable road users safety by considering a Cooperative Collision Avoidance (CoCA) system. In this system, vehicles rely on onboard sensors in order to generate local occupancy maps that are transmitted by means of LTE-V2X connectivity to a fusion center. The latter executes the fusion of successfully received local maps, in order to generate a global occupancy map, which can reveal obstacles that could not be perceived based uniquely on standalone vehicle's perception means. The resulting map is broadcast to all connected vehicles in transmission range (i.e., even those who have not contributed to the global map) in order to announce a risk of collision. The main objective of this work is to evaluate the impact of LTE-V2X connectivity performance on the fusion result and to define the best compromises between the communication configuration, the definition of occupancy maps and obstacle detection capabilities.

Today approaches of radio localization for Low Power Wide Area networks do not provide sufficiently accurate ranging required by applications such as wearable health monitoring. Coherent multi-channel ranging or Phase-of-Flight (PoF) ranging provides significantly improved temporal resolution through the aggregation of sequentially transmitted narrowband signals for the same level coverage performance as legacy Time-of-Flight (ToF) ranging. This paper compares the performance of PoF and ToF under additive white Gaussian channels with both simulations and laboratory measurements. Field trials have been performed in a multipath outdoor environment and strong ranging biases are observed. Ranging bias estimators are introduced and evaluated to mitigate these damaging effects: thanks to the new approach, accuracy of 30 m in 90% of the cases may be obtained. This compares to 250 m when legacy ToF is considered.

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Vehicular communications, known under the name of V2X (Vehicle to Everything) are expected to grow fast in the next years, bringing for example safer driving conditions, optimized traffic management, energy reduction, etc.. Currently two short range-based technologies (ITS-G5, standardized in Europe by ETSI and derived from WiFi communications IEEE standards and LTE based Vehicle to Everything or LTE-V2X developed by 3GPP and derived from LTE) consider the use of 5.9 GHz ITS band for their deployment. While different countries are more or less advanced in terms of regulation definition for Intelligent Transport System (ITS), it seems clear that the same solution will not be necessarily worldwide deployed. This study compares performances of both technologies by means of system level simulation, in particular considering the European ITS-G5 protocol stack specification. In order to analyze system level performance, physical layer simulation is used to provide Packet Delivery Rate (PDR) versus Signal to Noise plus Interference Ratio (SINR). Then PDR curves are exploited to feed system level simulation aimed at providing statistics about Cooperative Awareness Message (CAM) transmission reliability, in typical urban scenario. The paper provides a brief description of the systems together with the definition of the assumptions and the key results related to the physical layer analysis; it follows with the description of the NS-3 simulator models used for system level simulation (with particular emphasis on PC5 Mode 4) and the discussion about the results which provide insight about the expected and the simulated behavior of both technologies, in particular comparative statistics with regards to CAM success ratio versus maximum communication distance are provided in order to compare the performance.

The interest for communications between vehicles and the infrastructure or other vehicles (V2X) has recently increased towards connected vehicle applications, and particularly cooperative collision avoidance (CoCA). In this paper, we evaluate the performance of LTE-V2X networks in the context of Intelligent Transportation Systems for traffic collision avoidance applications based on sharing occupancy maps between the infrastructure and the vehicles. We compare by simulation different LTE-V2X configurations under realistic conditions in an intersection scenario. Then, we evaluate every type of communication link (V2I and V2V) as a function of the density of vehicles. The results show the potential of the concept for V2X and the trade-offs in terms of reliability, capacity and latency.

This paper deals with optimized channel coding for OFDM transmissions (COFDM) over frequency-selective channels using irregular low-density parity-check (LDPC) codes. Firstly, we introduce a new characterization of the LDPC code irregularity called “irregularity profile.” Then, using this parameterization, we derive a new criterion based on the minimization of the transmission bit error probability to design an irregular LDPC code suited to the frequency selectivity of the channel. The optimization of this criterion is done using the Gaussian approximation technique. Simulations illustrate the good performance of our approach for different transmission channels