Bench Talk

Everyone seems to be jumping on the IoT wireless connectivity bandwagon. At the local level, this consists of short-range solutions like Bluetooth, ZigBee, and Z-Wave. For longer-range communication, wireless providers of low-power wireless area network (LPWAN) offer solutions such as Sigfox and LoRaWAN. However, for autonomous vehicles, only two solutions are under consideration: A standard called IEEE 802.11p and, most recently, narrowband variants of LTE. The LPWAN providers are conspicuously absent in this discussion, even though there is no fundamental reason they cannot play some role in the autonomous environment.

To be safe enough to convince people to leave the driving to a machine, vehicles need what the military calls situational awareness: The ability to identify, process, and comprehend information about where they are and what is occurring around them. On vehicles, this data is generated by sensors on the vehicles themselves, and by sensors and camera on surrounding infrastructure such as traffic signals and street signs. The resulting information must be communicated wirelessly among the “participants” through a giant mesh of signals and processed in near-real time.

Both the IEEE 802.11p and wireless solutions are more or less on equal footing in terms of deployment. Discussions about how best to accomplish the communication portion of the challenge focus primarily on 802.11p because automakers have spent the last decade developing it and haven’t expressed much enthusiasm about an alternative. The IEEE 802.11p solution requires roadside units (RSUs) to communicate with vehicles, which are currently only used for wireless toll collection and have a long way to go toward other applications. On the other hand, wireless carriers say they already have a solution because their infrastructure is already in place; however, it has not been fully tested—a lengthy process to which 802.11p has already been subjected.

This means that Sigfox, LoRaWAN, and similar solutions that are currently being deployed in urban areas for IoT connectivity aren’t all that far behind, so there seems to be no reason they couldn’t be part of the mix. The electronics industry has already developed a wide range of solutions for Sigfox and LoRaWAN, such as the RN2483 LoRa transceiver module from Microchip Technology. It uses LoRaWAN’s Class A protocol to provide connectivity to any LoRaWAN-compliant network. For Sigfox, Microchip’s ATA8520 family of modules integrates an RF front end, microcontroller, and a Sigfox ID, with the activation code (PAC) and security key stored in the device firmware.  

The primary reason these LPWAN solutions aren’t being considered is because they were designed to serve more traditional IoT applications that stress low power consumption, as wireless-enabled IoT sensors must operate for many years from a small battery. To achieve this, Sigfox and LoRaWAN (and other such solutions) have extremely low data rates measured in kilobits per second. To serve the primary function of autonomous vehicle connectivity, they would have to transfer data at vastly higher data rates.

However, they still might be suited for related applications such as “smart” parking that enables vehicles to identify available parking spaces and automate billing. There are a variety of other similar applications for which they might be suited as well. Although no one is eager to add even more IoT connectivity standards to the autonomous vehicle scenario, the case could certainly be made that LPWAN providers have something to contribute.

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