Adaptive beamforming schemes for SC-FDMA systems with insufficient cyclic prefix

When the duration of the cyclic prefix is shorter than that of the channel impulse response duration in single carrier-frequency division multiple access (SC-FDMA) systems, inter-symbol interference (ISI) and inter-carrier interference (ICI) will degrade the system performance. Previously, this problem was solved by a blind beamforming scheme with considering the effects of carrier frequency offsets (CFOs) based on the eigenanalysis in a batch mode [5]. In this paper, adaptive algorithms are proposed to find the beamforming weight vectors without using reference signals. The proposed adaptive algorithms show competitive performance compared to the previous proposed algorithm under the insufficient cyclic prefix (CP), the effects of CFOs, and the co-channel interference scenarios. The simulation results reveal that the proposed adaptive algorithms provide better performance than the previously proposed algorithm in higher mobility environments.