Nokia says it isn’t proposing a new concept, but it is asking the FCC to change its rules for the E band to enable the deployment of smaller, more visually attractive antennas for 5G.
Specifically, Nokia is asking the FCC to amend its microwave rules to reduce the minimum antenna gain from 43 dBi to 38 dBi, which would allow for deploying lower gain antennas where the use case demands it while retaining the discretion to deploy higher gain antennas where applicable. The E band refers to spectrum at 71-76 GHz and 81-86 GHz, or 70/80 GHz.
In a recent presentation (PDF) to the FCC, Nokia explained that a 38 dBi gain is necessary for street level applications for various reasons, including the visual impact and weight/space constraints on street furniture. Not all cell sites are served by fiber, especially at street level for 5G millimeter wave and small cell deployments, so microwave remains in demand.
Nokia acknowledged in its filing that its request is nothing new. The Fixed Wireless Communications Coalition (FWCC) asked for such a change as far back as 2012 and has reiterated the growing need for smaller antennas. Last year, the coalition told the commission (PDF) that the demanding requirements for data capacity limit most backhaul connections to either fiber or point-to-point microwave, and in some environments, fiber is too expensive or impossible to install, leaving microwave as the only practical option.
"For emerging ‘small cell’ backhaul applications, including the necessarily small cells for 5G services, 70/80 GHz is often the best choice,” the FWCC said. “The very high available radio bandwidth—up to 10 GHz total—can manage needed data loads, while the high directivity and space attenuation simplify designs for frequency reuse.”
Indeed, Nokia and FWCC garnered the support of 5G Americas, which last month (PDF) urged the commission to act with haste to amend its rules to allow a minimum gain of 38 dBi for directional antennas in the E band. To tap the E band’s full potential, it’s essential to allow service providers greater flexibility to decide antenna size based on the use case, according to the organization.
T-Mobile has been one of the champions for more flexible antenna standards in the E band. The operator told the commission last year that it found the E band to be ideally suited for providing LTE and 5G links due to its light licensing approach and 10 gigahertz of available spectrum. At the time, it said it had conducted extensive tests with partner Ceragon Networks showing how current E band antenna rules are not well suited to supporting the extensive antenna deployments needed for expanding LTE and 5G networks.