Pacific DataVision officials address key technical concerns raised about 900 MHz LMR-to-broadband proposal

Officials for Pacific DataVision (PDV) yesterday outlined potential solutions to address technical concerns raised by commenters in an FCC proceeding that is designed to examine a proposal to transition 3 MHz of 900 MHz LMR spectrum to broadband use during an interview with IWCE’s Urgent Communications.

Under the proposal submitted to the FCC by PDV and the Enterprise Wireless Alliance (EWA), PDV’s considerable spectrum holdings—purchased from Sprint last fall—in a 5×5 MHz block in the 900 MHz band would be aggregated into contiguous 3×3 MHz swaths. The remaining 2 MHz of spectrum would support all existing narrowband LMR systems and would be located at 935-937 MHz, under the initial proposal.

PDV Vice Chairman Morgan O’Brien said that PDV expects to assume any costs that incumbent licensees incur during the spectrum-realignment process to move LMR operations to “comparable facilities,” noting that many people on the PDV staff worked at Nextel Communications and are familiar with the challenges associated with spectrum realignment.

However, the initial comment period in the proceeding revealed some technical concerns with the original PDV proposal.

First, the initial PDV plan calls for the proposed broadband swath to be immediately adjacent to the licensed 940-941 MHz spectrum, where utilities have deployed automated meter infrastructure (AMI) gear that allows real-time monitoring of electricity usage and network-transmission data. O’Brien said that AMI receivers are “very sensitive,” so utilities would prefer that the AMI operations remain adjacent to narrowband LMR systems.

With this in mind, PDV has been working with representatives of key utilities to alter the proposed band plan to maintain the narrowband-AMI adjacency by moving the broadband swath lower in the 900 MHz band, O’Brien said. For various reasons, the current configuration being considered would maintain 0.5 MHz of narrowband operation between the AMI spectrum and PDV’s broadband swath, leaving 1.5 MHz of narrowband spectrum south of the PDV broadband airwaves.

“There is a substantial issue being raised; that is true,” O’Brien said. “What is also true is that there’s a potential solution to it that’s underway.”

This potential solution also could address another technical issue noted by commenters, which is the need for combiners used in LMR systems to be separated spectrally by at least 250 kHz to function properly. Under the initial proposal—where all 2 MHz of narrowband channels would be in a contiguous block—that could be challenging, O’Brien acknowledged.

“When you can pick channels from amongst 5MHz—400 channels—that’s one thing,” he said. “When you have to pick them out of 160 channels [2 MHz], that’s another.”