Real-Time mmWave Channel Sounding through Full Digital Beamforming with 3D Dual-Polarized Phased-Array Antennas
Derek Caudill, Jack Chuang, Sung Yun Jun, Camillo Gentile, Nada T. Golmie
We describe a 29.5 GHz channel sounder that individually digitizes, through time multiplexing, all antennas of multiple dual-polarized 8 x 8 phased arrays at the transmitter and receiver, and performs digital beamforming in post-processing to synthesize a steerable beam. To our knowledge, we are first to implement full digital beamforming with phased arrays, realized through highly stable Rubidium clocks and local oscillators coupled with precision over-the-air calibration techniques developed in house. By bypassing the time-consuming programming of steering weights that is inherent to analog beamforming, we can achieve a 3D double-omnidirectional dual-polarized channel sweep in just 1.3 ms, for real-time channel sounding. By in turn bypassing the coarse precision of analog weights, we can obtain quasi-ideal beam patterns through the effectively unlimited precision of digital weights, enabling fine weight tapering for sidelobe suppression and fine weight calibration for the hardware non-idealities of the system. This translates into 0.5° average estimation in 3D double-directional angle, as demonstrated by measurement results. The system was also demonstrated to operate up to a range of at least 150 m.
IEEE Transactions on Microwave Theory and Techniques
, Chuang, J.
, Jun, S.
, Gentile, C.
and Golmie, N.
Real-Time mmWave Channel Sounding through Full Digital Beamforming with 3D Dual-Polarized Phased-Array Antennas, IEEE Transactions on Microwave Theory and Techniques, [online], https://doi.org/10.1109/TMTT.2021.3104278, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=932077
(Accessed October 16, 2021)