Utilities seek access to 4.9 GHz band

Utilities have their eye on the 4.9 GHz band, the band reserved for public-safety use, for smart-grid initiatives.

Earlier this year, the Utilities Telecom Council (UTC) proposed changes to the FCC that would make it easier for utilities to access the 4.9 GHz band. But, even without the rule changes proposed, a municipal utility can apply to obtain access to the 4.9 GHz licensed spectrum in their area, smart-grid vendor Tropos Networks recently declared.

In fact, the vendor announced this week new fixed mesh and mobile mesh routers, increasing its line of products that support the 4.9 GHz spectrum. In a technology brief released this week, Tropos said that public safety has primary access to the spectrum, but permanent fixed point-to-point systems are permitted.

The 4.9 GHz band consists of 18 channels and can be aggregated to allow channel bandwidths of 5, 10, 15 or 20 MHz . While the output power level allowed by the FCC varies with the size of the channel being used, it’s generally one to two watts, Tropos said. That power level is especially good for mesh communications technologies, although there is some interference in the band posed by U.S. Navy in some parts of the country and a small number of radio astronomy sites throughout the U.S., Tropos said.

The UTC, which is also asking the FCC for access to 700 MHz spectrum, believes that the FCC could increase the use of the 4.9 GHz band by changing the rules to allow greater use by utilities. The UTC claims that the rules discourage fixed use of the band for certain utility applications, such as meter reading. Municipal utilities are eligible for primary access to the 4.9 GHz band, but the UTC points out that there are less than 20 licenses held by these types of utilities.

Should the public-safety community be alarmed? Technology capabilities have changed significantly since the FCC gave public-safety primary access to the 4.9 GHz band in 2003. As Tropos noted, the exclusive licensing of the 4.9 GHz band was necessary to ensure that radio spectrum users would be free from the effects of interference. Today, modern signaling processing technologies mitigate interference. As such, unlicensed spectrum can now transmit highly reliable Wi-Fi signals. Moreover, the FCC has been heavily encouraging the notion of sharing spectrum and dynamic use of spectrum, such as in the white-space band.

I don’t know exactly how heavily used the 4.9 GHz band is used by public safety, but it appears the band is not crowded. Moreover, utility operations are synergistic with public safety. Couldn’t information be shared that would be valuable to both operations, such as electric outages?

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