AT&T, T-Mobile don't want to reveal signal strength data

T-Mobile boasts that it operates the nation's "largest, fastest, and most reliable 5G network." AT&T once famously bragged that it offers "more bars in more places," and today claims that its network is the "best."

But neither carrier wants to provide actual signal strength data to the FCC as the agency works to improve the nation's broadband mapping data.

"Signal strength in a given area can be affected by a variety of factors unrelated to the availability of coverage or the broadband speeds in the area, such as spectrum band, network design and device operating capabilities," AT&T wrote to the FCC. "Signal strength is not a reliable predictor of consumer experience in a given area."

In its own filing to the FCC, T-Mobile agreed.

"Signal strength is not a useful metric for determining where certain mobile wireless speeds are and are not available," T-Mobile argued.

Congressional mapping requirements

This isn't the first time major US wireless network operators have balked at government requests for their mapping data.

"It would be premature for the commission to require wireless providers to submit coverage maps for 5G service at this time," AT&T wrote to the FCC in 2019.

Importantly, just months after AT&T's comment, the FCC released a report that found that Verizon, T-Mobile and US Cellular provided inaccurate coverage maps about 40% of the time.

Nonetheless, the mapping issue has returned to the fore following Congress' passage of the Broadband DATA Act, which requires the FCC to improve its broadband mapping data.

The agency has issued some preliminary guidelines over how it might do that, including a requirement that operators submit maps to the agency showing their Received Signal Strength Indicator (RSSI) or Reference Signal Received Power (RSRP) information.

Such data is sometimes referred to as "heat maps" because it helps to show operators' signal strength data in the same way that the number of bars of service on a customer's phone reflects the strength of their provider's signal in a particular location.

CTIA – the wireless industry's primary lobbying association – also argued the FCC should not collect signal strength data in the form of "heat maps." The association said collecting heat map data would impose "unnecessary burdens" on mobile network operators and create "consumer confusion."

Support for heat maps

Interestingly, the Competitive Carriers Association (CCA) – a trade group that represents the nation's smaller wireless network operators – disagreed. It argued that the FCC should collect signal strength data because doing so would "help ensure reliable coverage maps and will help in the comparison of maps across carriers."

"CCA continues to believe that RSSI and RSRP provide the best estimation of network performance and are effectively the calculated output of various parameters that will be used to generate coverage maps," the group wrote to the FCC.

To be clear, the FCC has proposed collecting a wide range of network-mapping data from wireless network operators and other service providers, as part of the agency's quest to provide accurate broadband maps for the US.

In addition to heat maps, the FCC also asked for data including in-vehicle coverage information as well as operators' "link budgets." That's noteworthy considering wireless network operators' link budgets can contain detailed information for all of the signal gains and losses between a transmitter and a receiver.

"The commission already is poised to receive an unprecedented amount of coverage data, including never-before-submitted link budgets, as well as propagation models that are expected to follow more rigorous standards," AT&T argued.

"Further, the link budgets now required by the commission will already contain information about signal strength data. Given all the information the commission already has required – and not yet reviewed – there really is no reason for the commission to require heat maps at this time."

The FCC has promised to make significant progress on its mapping effort later this year. Indeed, the NTIA – a sister government agency to the FCC – released its own broadband mapping data this week. The issue is key considering the Biden administration hopes to dole out billions of dollars to improve broadband connections across the country, spending that would be contingent on accurate broadband maps.

After all, the FCC's most recent effort to improve rural broadband allocated money for a number of questionable areas including the land immediately surrounding Apple's $5 billion headquarters.

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— Mike Dano, Editorial Director, 5G & Mobile Strategies, Light Reading | @mikeddano