Coordinated beamforming for the multi-user MIMO downlink using FBMC/OQAM

Due to the fact that the out-of-band radiation of filter bank based multi-carrier modulation (FB-MC) is significantly lower compared to orthogonal frequency division multiplexing with the cyclic prefix insertion (CP-OFDM), it is beneficial to choose FB-MC over CP-OFDM for asynchronous scenarios or to achieve an effective utilization of spectrum holes. It is known, however, the state-of-the-art solutions for filter bank based multi-carrier with offset quadrature amplitude modulation (FBMC/OQAM) based space division multiple access (SDMA) cannot be employed when the total number of receive antennas of the users exceeds the number of transmit antennas at the base station. This fact motivates the design of a transmission scheme that is able to alleviate this dimensionality constraint. Therefore, we develop an intrinsic interference mitigating coordinated beamforming (IIM-CBF) algorithm where the precoding matrix and the decoding matrix are computed jointly and iteratively. The simulations results show that FBMC/OQAM based multi-user MIMO downlink systems where the proposed IIM-CBF technique is employed achieve similar bit error rate (BER) performances as their CP-OFDM based counterparts while having a higher spectral efficiency.