When lives are at stake, proceed cautiously


IT behemoth Cisco and automaker giant Toyota are locked in a struggle over a chunk of radio spectrum known as the dedicated short-range communications (DSRC) spectrum (5.9 GHz band).

Cisco wants the spectrum band to open up to sharing with Wi-Fi devices, while Toyota wants to keep the spectrum for use by wireless auto safety technology.

Automakers have been working on technology that would enable vehicles to communicate with each other in the DSRC band in order to avoid accidents. They are expressing concern that sharing the spectrum with unlicensed wireless devices could lead to interference that would jeopardize wireless vehicle safety systems that use that spectrum.

Cisco and the many other companies that depend on Wi-Fi for their products want the band opened up to sharing with Wi-Fi devices. They argue that the spectrum can be shared without significant interference with other users.

The next generation of Wi-Fi, 802.11ac, already uses the 5 GHz band to provide mobile broadband speeds. The FCC is proposing making an additional 195 megahertz of spectrum available for Wi-Fi in the 5 GHz band, a 35 percent expansion. However, this expansion would push Wi-Fi use into the 5.9 GHz band, something that automakers oppose.

The House Energy and Commerce Committee was a leader in pushing the FCC and the National Telecommunications and Information Administration (NTIA) to open up the 5 GHz spectrum to greater Wi-Fi use.

The committee's subcommittee on communications and technology held a hearing last week to examine the FCC's proposal to expand Wi-Fi use in the 5 GHz band. "The 5 GHz ecosystem is teeming with existing uses. From critical government radar systems to commercial satellites, there are a host of licensed services that are already deployed in this band," explained subcommittee Chairman Greg Walden (R-Ore.) in his opening statement (.pdf).

"Today we will also hear from one of the promising, but unrealized, licensed uses of this band: intelligent transportation systems for smarter, safer vehicles. However, it is important to also note that 5 GHz is also currently being used for Wi-Fi and other unlicensed uses. Thanks to technical rules that limit power and require certain mitigation technologies, these systems are currently meeting our licensed and unlicensed needs without interfering with one another," Walden added.

John Kenney, principal researcher at the Toyota InfoTechnology Center, argued in his prepared testimony (.pdf) that interference "that results in delayed or missed driver warnings will undermine the system's entire foundation, rendering it essentially useless and putting the entire future of DSRC technology in the United States at risk. Although we are strongly committed to the technology, the automobile industry cannot responsibly deploy 'safety-of-life' DSRC technology unless the possibility of harmful interference from unlicensed devices is ruled out."

Bob Friday, vice president and chief technology officer for Cisco, argued (.pdf) that the widespread use of mobile devices by various industries and education institutions have led to a shortage of spectrum for Wi-Fi device use. Cisco predicts that by 2017 two-thirds of all Internet traffic will be carried over Wi-Fi networks.

"There is a looming spectrum crunch, which if not addressed, will slow productivity, economic growth and American technology leadership...Adding more spectrum for broadband and Wi-Fi is critical for future growth of mobile networks and the American economy," Friday testified.

While there are strong arguments on both sides, it seems to me that the interference issue has to be studied by the FCC very closely because lives would be at stake. If non-interference cannot be guaranteed, perhaps other spectrum could be found to accommodate the explosion in Wi-Fi use. - Fred