The 3GPP’s sidelink D2D (Device to Device) communication, bypassing the base station, has come a long way since introduced for LTE in June 2014 under Release 12, when it was conceived primarily for public safety applications in situations when macro cellular connectivity may be unavailable. Following advances under successive releases, with more in the offing, sidelink is becoming integral to the 5G network architecture. This is occurring across several dimensions, including extending coverage to emerging resource constrained IoT devices, underpinning advanced automotive Cellular Vehicle to Everything (C-V2X) applications, and enabling the connectivity for high precision sensing and location awareness. Sidelink was quickly recruited for automotive connectivity because of its obvious fit for communications between vehicles or with nearby roadside infrastructure,…