This paper presents a low-cost measurement method for MIMO antenna performance assessment based on the open-source OpenAirInterface initiative. A first measurement is presented with a prototype with 8 antennas at 2.6 GHz integrated into a 140×140×40mm femto cell and using Laser Direct Structuring (LDS) technique. The setup is validated trough a beamforming gain measurement in a MISO 4×1 configuration in LTE TDD mode. We achieved the expected 6 dB beamforming gain between a SISO and 4×1 MISO configuration.