In the latest filings surrounding interference between public-safety licensees and commercial carriers in the 800 MHz band, AT&T and Verizon offered a plan to mitigate interference in markets where they transition to power spectral density (PSD) operations and another public-safety licensee provided technical details about its interference problems.
AT&T and Verizon said they remain committed to providing adequate notice to public-safety agencies before transitioning any cellular market to PSD operations and to working closely with public safety after a PSD transition to quickly address any interference concerns through the established mitigation process in the commission’s rules.
The nation’s two largest carriers also said they will work with public safety to each identify six additional markets in which to conduct testing jointly with the local public-safety agencies at the new PSD limits set in the commission’s order based on the test plan that was developed by AT&T and public-safety agencies in Docket No. 13-202. After release of the commission’s order, AT&T and Verizon will consult with public safety about potential A block and B block markets for joint PSD testing of a variety of public-safety equipment operating in the 806 – 815/851 – 860 MHz band.
The testing will include markets operating under a wide range of conditions, take into account that the frequency range of public-safety radios may extend to 824/869 MHz, and include a representative sample of markets with both 800 MHz cellular A block and 800 MHz ESMR (817 – 924/862 – 869 MHz) operations. Following this consultation with public safety, AT&T and Verizon will contact the applicable public-safety agencies for each test market to coordinate the joint testing. Once complete, AT&T and Verizon will submit the results of the joint testing into the record.
AT&T and Verizon further agreed that after completing the joint market testing, they will each transition to PSD operations in the next 10 market areas in two phases. The first phase will involve advance notice to local public-safety agencies of a cluster of cellular base stations that will operate for 60 days at the PSD limits set out in the commission’s order, which will allow local public-safety agencies to assess operations in a localized area before the entire market area is transitioned, the carriers said.
Interference incidents will be addressed quickly through the established mitigation process in FCC rules, and information from those incidents will educate AT&T and Verizon on future deployments. During that 60-day period, if no unacceptable interference arises or those instances of unacceptable interference that do arise are effectively mitigated in cooperation with local public-safety agencies, then AT&T and Verizon will extend PSD to other base stations in that respective market, the filing said.
“This type of phased-in implementation across these additional AT&T and Verizon market areas will permit public safety to gain additional insights into potential impacts on a broad array of localized public-safety equipment and deployments,” the filing said. “Detailed testing in 12 cellular markets coupled with phased deployment in 20 additional markets and the actual experience from markets where AT&T has received waivers and deployed PSD will provide a sufficient foundation of real-world evidence to assure public-safety agencies across the country that the relief requested in this docket will not increase the potential for interference to their devices or networks.”
AT&T and Verizon said the potential exists for operating cellular base stations at even higher PSD limits that would not increase the potential for interference because public-safety agencies may be able to obtain the resources to acquire improved radios over time. To facilitate that process, AT&T and Verizon proposed that any commission order permit the flexibility to conduct additional joint market testing and phased rollouts consistent with the process proposed and a timeline for operators to transition to higher base station PSD limits as appropriate. More specifically, the order should permit higher PSD limits immediately in those cellular markets where public-safety licensees do not reasonably plan to operate in the 800 MHz band and within no more than five years in all other markets following successful completion of the joint market testing.
In November 2014, the FCC released a report and order and further notice of proposed rulemaking (NPRM) that amended the commission’s rules for cellular services. The FCC also proposed supplementing its existing effective radiated power (ERP) limits for the cellular service with alternative limits based on PSD. The commission also proposed increasing cellular power levels in rural areas and potentially incorporating power flux density (PFD) limits near cellular base stations.
The FCC requested comment, but the commission has not issued final rules.
In a separate filing, the Port Authority of New York and New Jersey filed technical documents showing harmful RF interference on its 800 MHz National Public Safety Planning Advisory Committee (NPSPAC) channels that rendered portable radio receivers inoperable within the vicinity of an 800 MHz RF transmitted by wireless carriers in the area.
“We must note that these exhibits depict merely a snapshot of the radio frequency environment when the harmful RFI was experienced,” the filing said. “We have also reported other harmful RFI instances through the 800 MHz RF interference reporting webpage at www.publicsafety800mhzinterference.com.”
The filing said the wireless carriers have generally been responsive and cooperative with the port authority. “However, this remediation does not preclude similar harmful RFI on other occasions as we are unable to predict the location, duration or timing of future occurrences,” the port authority said. “We conjecture that increased cellphone use in the area triggers the serving cell site(s) to increase their ERP.”
Public-safety agencies should report any interference through the website established under the 800 MHz rebanding rules at http:// https://www.publicsafety800mhzinterference.com.