The European Commission’s decision to approve the WiFi-like ITS-G5 specification for connected car communications, rather than rival cellular-based C-2VX, splits the auto industry down the middle, but is far from the end of the road in the standards war.
Recent months have seen intense lobbying of the EU’s executive arm from both sides. As we reported in July, the Commission was in receipt of a letter urging that it should back C-V2X, signed by BMW, Daimler, Ford, PSA Groupe, SAIC Motor, Deutsche Telekom, Telefonica, Vodafone, Ericsson, Huawei, Intel, Qualcomm, Nokia, Samsung and Savari.
This group argued that opting for ITS-G5 would set back the European auto industry by favoring a standard that locked auto makers into a technology “which, despite its name, has no relationship to 5G technology and certainly no evolutionary path toward compatibility with 5G”. They contend support for ITS-G5 would place Europe at an economic disadvantage compared with China and the US, where C-V2X is emerging as a strong technology candidate for C-ITS (Cooperative Intelligent Transport Systems).
However, there was equally intense petitioning from the ITS-G5 group, including Volkswagen, highlighting a paper published by Siemens which argued that ITS-G5 was more mature and met all the key requirements of V2V and V2X communication while C-V2X did not, at least yet. Examples include the ability to operate in a very dynamic environment with high relative speeds between transmitters and receivers, and support for extremely low latency (below 50ms) in safety-related applications, notably for the pre-crash sensing warning message.
This paper seems to have swayed the EC, because the prospect of improved road safety is the key factor determining its connected car technology choices for now. The paper argued ITS-G5 technology was tailor-made for road safety applications because of its low latency and its ability, shared with most wireless protocols, to communicate beyond line of sight. Its properties are deemed by the EU to make it suitable for numerous safety applications, including electronic emergency brake lights, distance-keeping in platoons of trucks and in future for future higher levels autonomous driving, being crucially designed to operate at short range.
However, the decision to approve ITS-G5 over C-V2X is not quite as momentous as has been suggested in some quarters. It reflects the fact that ITS-G5 is more mature and ready to roll, while 5G is still emerging, even if the first wave of standards has been frozen. The C-V2X camp is, indeed, correct to point out that ITS-G5 is a misnomer because it is not aligned at all with the 5G roadmap and will not coexist readily with it. By contrast C-V2X has an additional layer for local communications, designed to run in parallel with cellular communications.
C-V2X employs two complementary transmission modes, with a direct short range mode for communication V2V or between vehicles and nearby roadside infrastructure, or road users such as cyclists and pedestrians. In this mode, C-V2X is quite independent of cellular networks but designed to dovetail with them. Then the second mode is called network communications over the conventional mobile infrastructure to receive information about road conditions and traffic in the area, or for infotainment generally. The C-V2X camp therefore argues that it can do everything ITS-G5 can locally while being much better suited to receiving broadcast services without being dependent on nearby access points by the roadside.
The local mode of C2-V2X has already been demonstrated for warning vehicles of queues or road works ahead so that they can slow down smoothly without hard braking, as well as avoiding collisions through broadcasting of vehicle identity, position, speed and direction. It has also been demonstrated extending a vehicle’s electronic horizon, detecting hazards around a blind corner or obscured by fog, high vehicles or undulations in the landscape.
Pressure on the EU to approve C-V2X as soon as it is deemed mature enough will now be stronger than ever and it will surely do so. It is likely that both the 802.11 and cellular versions will coexist and be supported in the same cars, even though at the moment most automakers have come down on one side or the other.
This is because autonomous driving will be a safety critical application requiring high levels of resilience and the two together will cater both for absence of roadside WiFi infrastructure and places such as tunnels where cellular communications may not be available. That is why there is also traction behind ad hoc V2V protocols as back up in say remote locations where neither Wi-Fi nor cellular are available but other vehicles may be around.