Evaluating RF Hardware Characteristics for Automotive JCRS Systems Based on PMCW-CDMA at 77GHz

Abstract

Joint communications and radar sensing (JCRS) applications are currently being hailed as the innovation of the next generation of mobile communications. The combination of communications and sensor technology on one hardware platform offers various advantages, such as significant savings in space and costs. The two technologies are no longer being optimized and developed side by side, as has been the case in the past, but jointly. The physical channel is used by both simultaneously, including the transmitter and receiver structures, which must be optimized for the combined application. This inevitably leads to an influence on the performance of both systems. In this work, this influence is considered and analyzed with respect to the effects of the radio frequency components. For this purpose, our previously published code-division multiple access (CDMA)-based and vehicle-to-vehicle-focused model is extended to a JCRS model and evaluated according to the achieved bit error rate as well as the mean deviation of the detected distance and velocity in Simulink. The influence of the non-ideal hardware components (mixers, power amplifier, low noise amplifier, filter, antenna) and characteristics (S-parameters, non-linearity of the amplifiers and the noise) on the sensing and communications are analyzed and compared in this automotive context. The results reveal that the noise of the low noise amplifier at the receiver side has the most decisive influence. In contrast, the noise generated by the power amplifier at the transmitter has no effect due to the relatively high signal power. The non-linearity of amplifiers at the transmitter also significantly impacts the available sensing range by limiting and compressing signal power. Besides, the phase noise with a frequency offset higher than 10 MHz can increase the communications and sensing error rate. In contrast, the influence of S-parameters is negligible, as the performance of communications and sensing is almost unchanged with different S-parameters. In the future, the proposed single-target scene will be further extended to a multi-target one.INDEX TERMS CDMA, connected vehicles, joint communications and radar sensing, RF hardware characteristics, modeling, physical layer, PMCW, 77 GHz.