NEC's massive-element AAS, supporting a 28 GHz band, adopts a fully digital control system, which improves the precision of beamforming. The fully digital control system enables simultaneous beamforming in multiple directions from a single massive-element AAS unit and efficiently implements high-speed and high-capacity communication without interfering with adjacent users through spatial multiplexing.

In contrast, analog control systems require the installation of the same number of massive-element AASs as the number of beams, creating the issue of a larger footprint.

This digital control system is also capable of beamforming that takes into account multipath, a non-direct wave signal, and moderately adjusts beam directions to implement high-quality communication. This is in addition to beamforming that cancels out interference through multipath and reduces performance deterioration caused by inter-cell interference.

Fully digital control systems traditionally require a number of digital/analog signal and frequency converters. This generally increases power consumption, capacity and cost for the entire system. NEC, however, has successfully developed a massive-element AAS that adopts a fully digital control system with less power and more compact conversion functions through NEC's original technology.

"In order to effectively implement sophisticated services that apply 5G features from 2020 onward, it is essential to utilize 28 GHz and other high frequency radio bands, which enable the securing of wide bandwidth, and the utilization of beamforming," said Katsumi Tanoue, Deputy General Manager, Wireless Access Solution Division, NEC Corporation. "Moving forward, NEC will continue its efforts in development and demonstration tests for a massive-element active antenna base station system that delivers high speed, high capacity and massive connectivity."