Bandwidth and Energy Efficient Compact Multi-Antenna Systems for Connected Autonomous Vehicles

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Autonomous driving is a key enabler for Intelligent Transportation Systems (ITS), which are expected to have major impacts on several environmental, economic and social aspects. ITS promise to relieve driver from tedious tasks, improve driving efficiency and safety and reduce traffic jams, injuries and gas emissions. In ITS, seamless communications between vehicles are required and vehicular ad hoc networks (VANETs) will emerge to support autonomous driving. In VANETs, vehicle-to-vehicle (V-V) and vehicle-to-infrastructure (V-I) communications take place via wireless devices called on-board units (OBUs). OBUs are designated to operate under the 5.9 GHz dedicated short range communication (DSRC) standardized technology. Antenna systems, as part of OBUs, are responsible for transmitting and receiving the electromagnetic wave which carries the useful information message. Antenna systems are electromagnetic designs which are connected to specialized RF circuitry. In turn, such circuitry processes the information message before the transmission and after the reception by the antennas. The complete system includes the wireless vehicular environment (or vehicular channel) in which the electromagnetic wave propagates along the way from the transmitting to the receiving antenna. Such environment is inherently very complex and rapidly time varying due to its physical propagation mechanisms including three-dimensional (3-D) scattering, obstructed line-of-sight (LOS) and fast mobility of transmitter, receiver and surrounding objects (e.g., mobility of other vehicles). Multi-antenna systems include many antennas operating together in order to increase communication performance in complex wireless environments. Accordingly, compact multi-antenna designs that perform optimally and can be packed in the limited OBU space become of paramount importance to support vehicular communications. Such designs should take into account a series of factors as imposed by the RF circuit, in which the antenna is connected and the surrounding wireless vehicular environment, in which the information message is transmitted and received. We have to exploit every potential the vehicular channel offers in order to maximize performance. The termination RF circuit characteristics affect performance as well and have to be taken into account and compensated at the early design stage. The proposed research activity will incorporate both the characteristics of the vehicular channel and termination RF circuit to derive optimal compact multi-antenna systems for OBUs. Thus, complete "RF circuit/printed multi-antenna/vehicular channel" optimized end-to-end systems will arise. Optimization will take place by maximizing the bandwidth efficiency first, as a standard key performance indicator (KPI). Optimization adopting the energy efficiency KPI will then follow. Such KPI will be employed for the first time to evaluate performance of realistic compact multi-antenna systems. The description of concepts of operation (CONOPs) and KPIs with respect to the particular features of vehicular environments constitutes the first step. The adoption of a generic vehicular channel model, adaptable to any wireless environment and frequency of operation, will enable the design of optimized DSRC-5.9 GHz and mm-wave-60 GHz multi-antenna systems. Assessing the feasibility of using mm-wave frequency bands for vehicular communications will be one more achievement of the proposed research activity. The last step will be proof-of-concept demonstrators for both DSRC and mm-wave optimal multi-antenna systems.While the objective here is to present optimal "RF circuit/printed multi-antenna/vehicular channel" end-to-end systems for vehicular communications, this project could benefit the development of future 5G mm-wave and massive MIMO systems.