Multi-stream transmission in MIMO-FBMC systems

Abstract

This paper addresses the design of MIMO precoding and decoding techniques for the filter bank multicarrier (FBMC) modulation. Existing solutions give satisfactory performance in scenarios with high coherence bandwidth channels. With the aim of increasing the robustness against the channel frequency selectivity, we have rethought the problem, which results in a new subband processing. Simulation-based results show that the proposed solution can achieve similar bit error rates as the OFDMsolution, while the spectral efficiency is increased. These results are theoretically justified. As a conclusion, FBMC becomes attractive in frequency selective channels not only because it relaxes the frame synchronization with respect to OFDM, but also because it presents spatial multiplexing competitive results.Peer ReviewedPostprint (published version

Towards a non-error floor multi-stream beamforming design for FBMC/OQAM

“…Previous works in the literature have concluded that if no CP is transmitted, then the MIMO techniques originally designed for OFDM can be successfully applied to FBMC/OQAM only in high coherence bandwidth channels [4]. The authors in [4] show that robustness against multipath fading is provided to a higher extent assuming that the channel frequency response (CFR) is flat at the subcarrier level, while it varies on adjacent subcarriers.…”

“…The experimental validation conducted in this paper reveals that the coordinated beamforming performs close to OFDM and clearly improves [4]- [6]. The rest of the paper is organized as follows.…”

“…However, satisfactory results are only guaranteed if S = N R ≤ N T , where S is the number of streams spatially multiplexed on each subcarrier and N T , N R are respectively the number of transmit and receive antennas. Adopting the system model of [4], the iterative algorithm presented in [5] improves the results when S < min (N R , N T ). Unfortunately the processing developed in [5] does not mitigate ICI, which yields an error floor in some multiantenna configurations.…”

“…The authors in [4] show that robustness against multipath fading is provided to a higher extent assuming that the channel frequency response (CFR) is flat at the subcarrier level, while it varies on adjacent subcarriers. However, satisfactory results are only guaranteed if S = N R ≤ N T , where S is the number of streams spatially multiplexed on each subcarrier and N T , N R are respectively the number of transmit and receive antennas.…”

“…Unfortunately the processing developed in [5] does not mitigate ICI, which yields an error floor in some multiantenna configurations. The technique proposed in [6] improves the resilience against the channel frequency selectivity with respect to [4], [5], since no assumptions are made about the flatness of the channel. Nevertheless, the number of variables required to represent the system model increases, which has an impact on the complexity.…”