Passive Radar at the Roadside Unit to Configure Millimeter Wave Vehicle-to-Infrastructure Links

Abstract

Millimeter wave (mmWave) vehicular channels are highly dynamic, and the communication link needs to be reconfigured frequently. In this work, we propose to use a passive radar receiver at the roadside unit to reduce the training overhead of establishing an mmWave communication link. Specifically, the passive radar will tap the transmissions from the automotive radars of the vehicles on the road. The spatial covariance of the received radar signals will be estimated and used to establish the communication link. We propose a simplified radar receiver that does not require the transmitted waveform as a reference. To leverage the radar information for beamforming, the radar azimuth power spectrum (APS) and the communication APS should be similar. We outline a radar covariance correction strategy to increase the similarity between the radar and communication APS. We also propose a metric to compare the similarity of the radar and communication APS that has a connection with the achievable rate. We present simulation results based on ray-tracing data. The results show that: (i) covariance correction improves the similarity of radar and communication APS, and (ii) the radar-assisted strategy significantly reduces the training overhead, being particularly useful in non-line-of-sight scenarios.

Leveraging Sensing at the Infrastructure for mmWave Communication

“…An interesting application to this end is the estimation of mmWave channel's spatial covariance based on radar data. One approach is to put a passive radar receiver at the RSU that captures the signals transmitted by the automotive radars of the vehicles on the road [13]. Based on the radar received signals, the spatial covariance of the radar is constructed.…”

Site-Specific Online Compressive Beam Codebook Learning in mmWave Vehicular Communication

“…Side information, ubiquitous in vehicular communication, can be exploited for efficient mmWave channel estimation or beam alignment [8]- [14]. Different types of side information can be obtained from sensors mounted on vehicles, including radar, LiDAR and GPS [15]- [19]. Side information can be shared among vehicles by different wireless protocols such as dedicated short-range communication (DSRC), LTE or mmWave communication [1], [20], [21].…”