Full-Duplex Femto Base-Station With Antenna Selection: Experimental Validation

Full-Duplex (FD) is an emerging technology that allows the communication device to use the same frequency to simultaneously transmit and receive. The cancellation of the high power Self-Interference (SI) is the main challenge in FD systems. Hybrid SI mitigation and cancellation schemes in propagation, analog, and digital domains, have to be used in order to mitigate the SI. Antenna selection (AS) can be employed to select the best antenna, or set of antennas, that guarantees jointly the maximization of the desired signal, and the minimization of SI. In this paper, we aim to experimentally enable FD transmission in an indoor femto base-station (BS) with antenna selection. Receive antenna selection is combined with cross-polarization and antennas conditional placement in order to achieve the required SI cancellation. Half-duplex (HD) Uplink (UL) user-equipments (UE) are used to measure the effect of downlink (DL) SI on the UL reception at the FD BS receiver. Different scenarios are experimented in the testbed such as, changing the number of antennas, the type of isolation (vertical/horizontal), and the type of antennas (Omnidirectional/directional). Three AS criteria are used, and the performance of the system is evaluated in terms of bit-error-rate, sum-rate, residual SI, and FD/HD sum-rate enhancement ratio. The measurement results show that the proposed hybrid solution is feasible to enable FD transmission in the considered scenario.