Mobile World Congress, running this week in Barcelona, is best-known as the launchpad for the hottest new smartphones. But especially this year, some of the most interesting connected devices are a little bigger: cars and trucks, especially those that drive themselves.

But a raft of challenges may prevent many autonomous cars will drive off the MWC exhibit floor onto the streets anytime soon, judging from chatter at the show. In a Monday session on autonomous automobiles, representatives of car makers and tech companies that supply them said many communications, social and regulatory issues still need to be solved before we can climb behind the wheel and relax.

Chief among the roadblocks is how long the commercial rollout of 5G wireless networks will take. The consensus among the speakers was that 5G, which promises low latency and high speed for data, was that 5G is critical for self-driving cars and trucks to become a reality.

“Autonomous driving without connectivity will be impossible,” said Nikolai Reimer, head of mobile online services and connectivity for Volkswagen AG. An IEEE standard in the same family as Ethernet — 802.11p – already promises to manage adequate vehicle-to-vehicle communications. But Reimer said vehicle-to-infrastructure connectivity, for cars to communicate with smart signals, signs and roads in order to see around curves and understand the current state of the road, requires reliable and ubiquitous 5G.

It’s not just cars, either. Daniela Gerd tom Markotten, head of digital services and solutions for Mercedes-Benz Trucks, pointed out that 750 billion euros worth of goods moves by truck each year in Europe – three-quarters of the entire logistics market. By 2050, transportation volume will triple, but she noted that “the road network will not be tripled.”

Moving beyond the current state of “partly automated” trucks currently licensed for public trial in Germany will require a wide range of developments, Gerd tom Markotten said: further improvement of sensors, reliable high-speed networks including the elimination of international roaming charges, suitable road signs, accurate digital maps and legislation that clarifies liability for highly automated and fully automated vehicles.

Alex Mangan, head of product marketing for the automotive mapping company HERE, said high-speed networking was essential for the kind of real-time map updating that’s key for autonomous cars. Maps, he said, are changing from being human-readable to machine-readable, but self-driving vehicles can’t rely on static maps to reflect dynamic driving conditions.

Mangan’s goal is to build a map once, then ask other cars to “heal” the map with current conditions in real time, creating a feedback loop. Think of updates such as those provided by Google Inc.’s Waze app, but ubiquitous and more accurate.

HERE, which is owned by BMW Group, Daimler AG and Audi AG with investment from Intel Corp., is building partnerships with other automakers. Partnerships also will be a critical part of an autonomous vehicle business. “Without sharing data across brands,” Mangan said, “realizing the vision of self-driving will not be possible.”

Dan Rosenbaum, a veteran journalist and publisher of Wearable Tech Insider, is at Mobile World Congress this week, covering key developments at the show for SiliconANGLE.

Photo: Mercedes-Benz