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WiFi at odds with industry in transport networks stand-offs

As all kinds of vehicles become wirelessly connected, there are mounting tensions between the WiFi community and the industry stakeholders, from carmakers to train operators. The heritage of high walls between vertical industries’ own private networks and open public wireless is feeding into conflicting views on future standards, now that the telco and transport sectors are coming together.

For instance, the US national rail operator Amtrak is asking the FCC for a waiver on certain conditions for the WiFi network it plans to build along its premium Northeast Corridor route. But WiFi players claim this might cause problems for other users, highlighting the stand-off between verticals’ need for connectivity that is optimized for their particular needs, and the requirement to provide good quality wireless for all consumers.

Amtrak wants the FCC to let it operate trackside network (TSN) as a fixed point-to-point system in the UNII-1 and UNII-3 bands, on its most heavily used route, which connects Washington DC to Boston via New York. About 750,000 passenger trips per day take place on this line, and the WiFi service is struggling.

The rail operator currently uses WiFi built around in-train access points which are supported by multiple concurrent 3G and 4G links, supplied by the four main MNOs, and aggregated by a single control unit in one ‘brain car’. This brain car has antennas on its roof which support backhaul to Amtrack’s East Coast data center. However, this system is complex and overloaded, and the rail company is also concerned that, if grandfathered unlimited data plans cease, it will either face high monthly fees or have to restrict usage.

Its solution is to build its own private TSN – a trend which is seen in many verticals, including rail transport, round the world. The UK’s rail infrastructure operator, Network Rail, for example, has said it would be keen to take advantage of 5G capabilities for its TSN, but lacks confidence that the MNOs will be able or willing to support all the required capabilities – such as ultra-reliability – on their public networks.

Network slicing may address some of these issues, if the business model can be worked out, but transport firms face the challenges of rising data usage right now.

Amtrak says that, if it adheres to current rules governing the UNII-1 band, it would have to deploy three times as many trackside access points as it currently does in UNII-3. However, the rules are different for a point-to-point fixed system. It argues that, although its TSN is not a fixed network, it works like a fixed P2P system because the location of its transmitters is always known, because trains cannot move beyond Amtrak’s right of way. “It’s not inappropriate to characterize Amtrak’s TSN as having characteristics typical of fixed operations,” says its filing to the FCC.

However, the WiFi Alliance (WFA) says Amtrak’s waiver request contains a brief examination of the potential interference to satellite operations caused by its proposed system, but “it does not meaningfully consider potential interference to UNII- devices.”  Amtrak says the issue will be avoided with the use of directional antennas with a narrow beamwidth,  but the WFA is not satisfied.

“Amtrak must conduct testing of interference potential, perhaps using the ‘proof-of-concept’ TSN Amtrak has already constructed in Delaware, and provide that data to the Commission and to the public to ensure that existing operations are protected,” it wrote in a comment in response to the Amtrak submission. These tests should include coexistence measurement of existing WiFi systems placed in a “worst case scenario” in which the train passes close to residential and commercial structures.

On the roads, there are signs of a wider split between different connectivity standards. On the WiFi side, the community is pushing 802.11p, a strand of the IEEE specifications which is specifically optimized for V2X communications, and is the basis of the ETSI ITS-G5 standard in the 5 GHz band. This is in  pole position in the US,  but China is more favorable to the 3GPP alternative, LTE-V, while Europe, according to Nokia, is stuck in the middle.

Yet a unified base of devices and equipment for the global car market will be essential to achieve maximum economies of scale, accelerate uptake, support roaming and pave the way to the autonomous vehicle.

Thorsten Robrecht, VP of advanced mobile networks solutions at Nokia, told Telecoms.com: “To be as effective as possible, we need to ensure that connectivity is consistent throughout the world. Unfortunately there is a debate over which direction to go with the standards. Europe is stuck in the middle, getting pressure from both sides to comply.”

While 5G, and virtualized networks which support many types of connectivity, may paper over the cracks, that still leaves years of uncertainty, which Robrecht believes has already slowed progress in autonomous car development in Europe.

In July, a group of cellular and automotive stakeholders announced a new set of tests aiming to prove that LTE has a key role to play in the adoption of autonomous vehicles and the improvement their integration with smart cities. Audi, Toyota, Deutsche Telekom and Huawei have been working to demonstrate the performance levels which can be expected of LTE-V, with a view to using the technology in road safety and traffic efficiency applications.

Meanwhile, the 802.11p WiFi spec uses the 5 GHz band, which is already rather crowded, and seems vulnerable to even worse performance if a substantial number of cars and street infrastructure begin to occupy those channels.

LTE-V might make a lot of sense for those countries that don’t use the FCC regulations, which currently include a dedicated piece of the 5.9GHz band that has been allocated for Dedicated Short Range Communications (DSRC) – although lobbying from the cable industry might mean that the DSRC bandwidth that has been provisioned for V2X communication might be stricken from the FCC book and given over to WiFi devices.

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