NCTA, Wi-Fi Alliance push for 5.9 GHz sharing

The National Cable & Telecommunications Association (NCTA) and the Wi-Fi Alliance are continuing their arguments for updating the commission's rules and permitting unlicensed operations in the U-NII-4 portion of the 5 GHz band to meet the demands for Wi-Fi.

The problem is, the auto industry wants the commission to preserve the 5.9 GHz band and its channelization as designed for Dedicated Short Range Communications (DSRC), even though, NCTA points out, DSRC proponents have not made significant strides in using the band, allowing 75 megahertz to lay fallow for more than a decade. "By comparison, Wi-Fi in the 5 GHz band has delivered broadband access to hundreds of millions of consumers every day. Sharing in the 5.9 GHz b and should reflect this fact," NCTA told the commission last week.

To be clear, NCTA says, it supports efforts to use wireless technology to make Americans safer on the road. But it describes a way of sharing in the band that can preserve safety functions while also permitting wider use of Wi-Fi. A report by CableLabs concludes that the National Highway Traffic Safety Administration's (NHTSA) objectives for DSRC can be served through a single 10 megahertz-wide channel. A second 10 megahertz channel may enable the development of real-time Vehicle to Infrastructure (V2I) safety applications over the longer term, but it is unclear that such services will be implemented, the report says.

"In examining the channel plans of Wi-Fi and DSRC, we find an opportunity for coexistence of the two technologies through frequency separation," the CableLabs report says. "In particular, the rechannelization of the 5.9 GHz band in accordance with IEEE 802.11ac, the latest wireless networking standard, can provide DSRC with up to 30 megahertz of exclusive-use spectrum in the upper portion of the 5.9 GHz band, more than enough to fully enable the core safety functions of DSRC."

The Wi-Fi Alliance notes that the commission in 2014 decided not to adopt rules for the U-NII-4 band and instead continue technical analyses in conjunction with the National Telecommunications and Information Association (NTIA) and industry stakeholders. "These technical analyses have taken too long," the Wi-Fi Alliance wrote in its filing, adding that the commission should proceed expeditiously with conducting the testing necessary to make capacity in the U-NII-4 band available for unlicensed operations.

However, the Motor & Equipment Manufacturers Association (MEMA) isn't on board with sharing protocols before they are thoroughly examined, tested, validated and ensured to be safe under current and future deployments. "Any call for re-channelization of the 5.9 GHz band would significantly interrupt the future of safer mobility, hinder developments in transportation safety, and result in massive financial losses to the vehicle industry, government agencies, technical standards development organizations, academia and scores of research entities," MEMA told the commission.

The organization said that advocates for sharing the 5.9 GHz band have argued that the vehicle industry should simply wait for 5G cellular systems or LTE Direct or 5G Direct Systems, but it says that there is a substantial difference between how a cellular phone works and how vehicle DSRC works. The DSRC communications protocols are designed for very low latency communication and network congestion management, permitting the rapid transfer of information used for collision warning and avoidance among nearby vehicles. Cellular-based technology has "too many delays to be effective for this function," MEMA said. "Any system that uses a cellular tower has latencies that are too long to use for collision warning systems. This has been demonstrated repeatedly in testing. As for the 5G direct systems, these do not exist yet and are not validated or tested."

At least two FCC commissioners have shown an interest in sharing in the 5.9 GHz band. More than a year ago, Commissioners Michael O'Rielly and Jessica Rosenworcel rallied around the idea, saying there are ways to use it for Wi-Fi while protecting the DSRC systems that are intended for road safety.

For more:
- see this NCTA filing
- see this Wi-Fi Alliance filing
- see this MEMA filing

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