01/25/2021 | Press release | Distributed by Public on 01/24/2021 19:08
However, in the millimeter-wave frequency band, challenges to applying Massive-MIMO techniques include difficulty in achieving stable connections and spatial multiplexing due to the characteristics of radio waves, such as short wavelength and large attenuation due to reflection and shielding.
NEC has established itself as a leader in digital beamforming technology and has commercialized Massive-MIMO in the sub 6 frequency band (*3). Moreover, NEC has developed digital coordination technology among antenna elements distributed in the millimeter-wave frequency band and conducted verification activities to solve the problems of indoor mobile communications, such as shadowing and diffraction of propagation paths (*4).
Against this background, NEC conducted propagation and transmission trials in a real office environment using a distributed-MIMO technique for the Radio Units (RU) of a 28 GHz band base station system, demonstrating simultaneous connections with multiple terminals and increased capacity. Specifically, NEC developed a technology to effectively calibrate phase and amplitude in response to the difficulty in calibrating and coordinating the phase and amplitude between distributed antennas. As a result, NEC achieved approximately 3 times the number of simultaneous connections and transmission capacity when compared to cases where a distributed-MIMO system is not used.
NEC will continue to carry out 5G demonstration experiments for enabling stable and high transmission speeds in environments where stable millimeter-wave communication is difficult due to obstacles and densely arranged terminals, such as offices and stadium seating, aiming to contribute to the development of millimeter-wave mobile access networks and building ecosystems among operators and venders.
Furthermore, NEC will continue its initiatives for creating new social value by providing 'NEC Smart Connectivity' (*5) for connecting data generated by people and things and reaching beyond conventional thinking in support of network performance.