Description of Multi-user Transmit Beamforming Testbed
A multi-user transmit beamforming testbed is developed on the RRU/RRH as a TX and two UEs as RXs using USRPs to send two different payloads from the RRH to the two receivers (users) simultaneously in the same frequency band. The RRH uses X310 USRP radio as a composite radio with two channels. All radios for the transmitter are connected to the same PPS and 10 MHz clock generator (OctoClock-G CDA-2990) via cables of equal lengths. Besides the transmitter radios, two B210 USRP radios are used for the two receivers (users), one for each receiver. The receiver radios are also connected to the same 10 MHz clock generator. The implemented beamforming scenario is tested when users are moved in which the channel estimates from the receivers are used continuously to update the transmitted beams.