Adaptive-type smart antennas do not usually operate on the deployed universal mobile telecommunication system (UMTS) scenarios, although UTRA (UMTS terrestrial radio access) foresees their operation and they would improve capacity especially in mixed-service environments. This paper describes the implementation of a software radio-based version of an adaptive antenna, named ADAM, that can be used with any standard Node B, both in the up- and downlinks. This transparent operational feature has been made possible by the partial cancelation algorithm applied in the uplink by means of a common beamforming vector. Firstly, a general description of the system as well as the theory of its operation are described. Next, the hardware architecture is presented, showing the real implementation. Also a complete software description is done. Finally, results are presented, obtained from both simulation and real implementation, showing the improvement obtained with the adaptive antenna as compared with a typical sectored one. Performance results obtained in the initial tests show that ADAM prototype provides an SINR increase of 12.5 and 6.5 dB over a conventional sectored antenna in the uplink and downlink, respectively. System-level simulation results are presented, showing the throughput increase obtained with ADAM. These findings provide evidence of the capacity improvement achieved with the ADAM prototype.