Autonomous vehicles, on the ground and in the air, are the next big evolution in human mobility. While autonomous driving in highway scenarios is already possible using only the vehicles sensors, the complex scenarios of big cities with all its different traffic participants is still a vision. Cellular Vehicle-to-Everything (C-V2X) communication is a necessary enabler of this vision and and an emerging field of interest in today's research. However, to the best of our knowledge open source simulators essential for open research do not exist yet. In this work we present our open source C-V2X mode 4 simulator based on the discrete-event network simulator ns-3. To analyze the performance of C-V2X mode 4 using our simulator, we created a worst case scenario and the 3GPP reference Manhattan grid scenario using the microscopic traffic simulator SUMO. We also added the WINNER+ B1 channel model to ns-3, as this is also used by 3GPP. Our results show, that C-V2X is scalable to 250 vehicles within a worst case scenario on a playground of 100 m x 100 m, with respect to the LTE rel. 14 V2X requirements. For the more realistic Manhattan grid scenario, the performance is better, as to be expected. We also analyzed the Packet Inter-Reception time with an outcome of max. 100 ms for more than 99 % of all transmissions. In addition, we investigated the impact of the Resource Reservation Period and the Resource Reselection Probability on the system's Packet Reception Ratio.

Digitally modulated radar systems, such as phase-modulated continuous wave (PMCW), often struggle with high bandwidth demands for fine-range resolutions, posing challenges for cost-effective automotive applications. To address this issue, we propose a stepped-frequency PMCW (SF-PMCW) radar waveform in which the instantaneous bandwidth of a single pulse is extensively reduced while the range resolution is beyond the theoretical limit imposed by the instantaneous bandwidth. The proposed waveform spans a synthetic bandwidth across multiple pulses, achieving range estimates comparable to those typically achieved with higher instantaneous bandwidths. Simultaneously, the requirements for analog-to-digital converters (ADCs) are relaxed. Simulations have been performed to demonstrate the performance. The results indicate that the proposed SF-PMCW waveform with an instantaneous bandwidth of 100MHz can achieve range estimates as good as a PMCW waveform with an instantaneous bandwidth of 1GHz.

Commercial automotive radar systems for advanced driver assistance systems (ADASs) have relied on frequency-modulated continuous wave (FMCW) waveforms for years due to their low-cost hardware, simple signal processing, and established academic and industrial expertise. However, FMCW systems face several challenges, including limited unambiguous velocity, restricted multiplexing of transmit signals, and susceptibility to interference. This work introduces a unified automotive radar signal model and reviews the alternative modulation schemes such as phase-coded frequency-modulated continuous wave (PC-FMCW), phase-modulated continuous wave (PMCW), orthogonal frequency-division multiplexing (OFDM), orthogonal chirp division multiplexing (OCDM), and orthogonal time frequency space (OTFS). These schemes are assessed against key technological and economic criteria and compared with FMCW, highlighting their respective strengths and limitations.

Advanced driver assistance systems (ADASs) rely heavily on the resilient spatial perception of the surrounding environment of vehicles enabled by sensor systems, such as radio detection and ranging (RADAR), light detection and ranging (LIDAR), and cameras. The electric/electronic (E/E) architecture of the vehicle must ensure that the sensor systems and data gathering and processing for the perception operate under all circumstances. However, certain factors can affect the resilience of the sensor system and the supporting E/E architecture, such as internal software failures and external weather conditions. This paper provides a comprehensive review of the latest developments in automotive sensor systems and architectures, highlighting potential disturbances and presenting corresponding countermeasures for hardware and software failures. We also identify challenging applications and assess the requirements for resilience to make these applications feasible under all circumstances. Based on this review, we propose a comprehensive framework for developing resilient sensor systems and architectures that can serve as a basis for further research towards fully automated driving.

This paper presents a novel method for the identification and resolution of targets with ambiguous velocities within a single measurement cycle of a phase-modulated continuous wave (PMCW) radar system based on multi-hypothesis Doppler shift compensation. The Doppler shift is first compensated by assuming that the velocities of all targets are unambiguous. Since targets with velocity ambiguity cannot be perfectly compensated in their range profiles based on this assumption, ambiguities can be identified after the range correlation processing. The range correlation processing for ambiguous targets is then repeated under multiple velocity hypotheses. The velocity hypothesis with the best sidelobe suppression is considered the correct velocity. As a result, the Doppler shift compensation in the range profile is achieved as well. Simulation results show that the proposed method can simultaneously resolve velocity ambiguities and compensate for the Doppler shift induced increased sidelobe level in the range profile.

In phase-modulated continuous wave (PMCW) radar systems, fine range resolution typically requires high instantaneous bandwidths, necessitating fast-sampling analog-to-digital converters (ADCs). However, these ADCs are expensive and power-consuming. Consequently, due to their affordable hardware implementation, today's automotive radar systems still mainly employ analog frequency-modulated continuous wave (FMCW) waveforms. A larger bandwidth without requiring fast-sampling ADCs can also be synthesized by transmitting consecutive pulses in a coherent processing interval (CPI) at incremented carrier frequencies. To enable PMCW with low-data-rate ADCs, this paper proposes an improved stepped-frequency PMCW (SF-PMCW) waveform and evaluates its performance against a stepped-frequency FMCW (SF-FMCW) radar system in a simulated environment. The results indicate that the proposed SF- PMCW waveform can yield superior target detection capabilities with comparable system parameters.