The necessary elements of high‑level autonomous vehicles are starting to roll out as GM deploys Vehicle‑to‑Vehicle (V2V) systems in its vehicles, while Vehicle‑to‑Everything (V2X) test beds begin in Tampa, New York, and Wyoming.
It’s finally started: Automotive giant GM has begun V2V deployments with the rollout of dedicated short range radio (DSRC) in its 2017 Cadillac CTS models. The vehicles will be able to transmit and receive simple messages about location, heading and speed, over distances of up to 1000 feet at a rate of 10 messages per second, that is one message every 100 msec.
Per the original intent of V2V, Cadillac’s system allows vehicles to alert drivers of other vehicles to potentially hazardous situations ahead, giving them additional time to react. Common hazardous scenarios that prompt alerts are hard braking, slippery conditions and disabled vehicles. Drivers can also customize alerts to show in the instrument cluster and available heads‑up display.
Also, multiple V2V‑equipped vehicles create an ad hoc wireless network that allows for the transfer of information without relying solely on sight lines, good weather conditions or cellular coverage (Figure 2).
Figure 1: GM’s Cadillac division is deploying a V2V system in its CTS line that is capable of communicating over a range of 300 meters. (Image source: GM)
On the infrastructure side, shortly after Cadillac made its intentions known, both the Tampa and Wyoming Connected Vehicle (CV) Pilot Deployment Program websites went live, joining New York City’s program. The three locations were selected by the US Dept. of Transportation to receive a collective $45 million in funding to initiate a Design/Build/Test phase for its CV program. The premise of the program is that connected vehicles could save lives, enhance productivity, reduce vehicles’ environmental impact, and transform public agency operations for the better.
Each of the three sites have already spent 12 months of the 50‑month program preparing a deployment concept for a fast roll out (Figure 2). Now the program is in Phase 2, which involves designing, building, and testing the complex deployment of integrated wireless in‑vehicle, mobile device, and corresponding roadside technologies. This began in September and has been assigned a 20‑month time frame. The remaining months, or Phase 3, will be occupied with the maintenance and operation of the pilot programs.
Figure 2. The DoT’s CV Pilots Deployment Program has selected Tampa, New York, and Wyoming as pilot sites. All have completed Phase 1 concept development activities and have entered Phase 2 - Design/Deploy/Test. (Image source: ITS.DOT.gov)
The program participants already have the benefit of 75 MHz of spectrum in the 5.9‑GHz band. This was set aside in 1999 by the FCC, explicitly for the use of intelligent transportation systems (ITSs). The spectrum is however allocated differently per region. For example in Japan, they operate DSRC in 720 MHz band. How that spectrum is used is up to the technologists and the regulatory bodies.
To help take advantage of the spectrum and support the development of ITS applications, the IEEE 802.11p amendment to the 802.11 standard was implemented for wireless access in vehicular environments (WAVE). Among other things, it defines the exchange of data between high‑speed vehicles and between vehicles and infrastructure (V2I).
The critical aspects of this communication include latency and signal processing time, especially as designers and automotive engineers consider moving to Level 4 and eventually Level 5 autonomy. Let’s use an example to show the importance of response time.
A vehicle moving at 65 mph covers 95.33 feet (29 meters) in 1 second. In the case of the GM Cadillac CTS, it has a wireless communications range of almost 1000 feet (305 meters), so it has a 10‑second window in which to respond. If that response means stopping as quickly as possible, that might take up to 400 feet (122 meters) to do safely, from 65 mph. Subtracting that 400 feet leaves only 6 seconds for the vehicles to communicate the nature of the upcoming incident to allow it to stop in time. Factor in non‑line‑of‑sight issues, the potential for RF interference and possible latencies at the application layer, and the importance of minimizing any delays becomes clear.
Right now, the 2017 Cadillac CTS is the only vehicle on the market with V2V built in, so it can only talk with other Cadillac CTS’s. This of course limits the usefulness of the feature, so Cadillac is not charging for it, for now. However, as more vehicles get deployed, and the infrastructure gets developed and expands beyond Tampa, New York, and Wyoming, the V2X functionality will become more useful, and valuable. Much like any communications network, it will follow Metcalfe’s Law and become exponentially more valuable the number of nodes are added.
In the meantime, Cadillac is eager to work with any company, or country, looking to roll out DSRC. It may also soon have V2V companions, as Chrysler and Ford have already indicated their intent to roll out V2X technology. Volkswagen also announced recently that it would deploy DSRC technology in new vehicles as of 2019.
For more on V2X and autonomous driving, read our previous blog posts: How V2X can make our cars smarter and our streets safer and Autonomous vehicle’s Lego blocks take shape.
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