New generations of mobile communications are much more demanding in order to provide critical real-time services and extremely fast connections that have become feasible with 5G. A wider spectrum is needed to achieve such high data rates and millimeter-wave frequencies are used for this purpose. Adaptive beamforming is applied at base stations through active phased antenna arrays to shape and steer the beams at each user, so coverage distance is extended and resource sharing among users is more efficient. Different approaches to the design of active phased arrays for mm-wave base stations to realize the "one beam per user" concept are analyzed and compared. Particular attention to mutual interference between the beams is given. A novel aperiodic, uniformly-fed, active integrated antenna array design is presented as an appealing alternative to minimize user inference based on a multi-disciplinary array synthesis approach. Implementation challenges of such aperiodic array are investigated and the performance is compared to those of a periodic array. The complete design and its simulation results show an interference reduction around 6 dB and similar gain as compared to the regular array taken as reference.