Band-Oriented Predistorter for Fully Connected Hybrid Antenna Arrays

Fully connected hybrid antenna arrays (FC-HA) are attractive, low-complexity alternatives to the fully digital array architecture. However, the sub-array architecture performance is limited by reduced beamforming gain because of array partitioning. In this study, we provide a theoretical analysis of the connection between a wideband digital predistorter (DPD) and its equivalent for a fully connected antenna array (AA). Then, we propose new hardware-efficient band-oriented architecture by moving all AA-specific DPD calculations into the analog radio frequency site. To our knowledge, this is the first band-oriented DPD architecture for FC-HA. In the proposed DPD, the unified digital cores are common for all power amplifiers (PAs) in the array. This enables a set of PAs to be linearized with a single, multi-core DPD. The performances of the proposed band-oriented DPD were evaluated with the help of computer simulation. The simulation results demonstrate that both the in-band and the out-of-band intermodulation distortion for all PAs in the array can be successively suppressed with a single multi-core DPD regardless of the individual beam’s directions. Unlike current all-digital state-of-the-art solutions, the proposed band-oriented DPD has a significantly low digital hardware complexity because of the digital core unification, thus reducing its power consumption requirement.