CDM-based 4-Channel Digital Beamforming Transmitter Using a Single DAC

In recent years, digital beamforming (DBF) is gaining more attention for next generation directional communication systems such as 5G, thanks to its flexibility for beamstearing compared with that of both analog- and hybrid-beamforming. However, conventional digital beamforming requires the use of independent Digital to Analog converter (DAC) and RF chain for each antenna element, which poses significant challenges in cost, power and heat management. In this work, we report for the first time a novel low-cost solution with reduced hardware complexity in DBF. Digital beamformed multiple baseband signal is designed to feed different antenna elements through a single DAC. Coding schemes were implemented in digital baseband domain, while decoding was done in analog RF domain. The decoded signals are tested before connected with antenna for proof-of-concept. The demonstrated technique provides cost and size reduction of the array system, while keeping the integrity of the signals and beam pattern.