From mMIMO to xMIMO: A Unified Design for Spatial Wideband Effect Mitigation

Large antenna apertures and/or ultra wideband (UWB) transmission engender the spatial wideband (SWB) effect, resulting in reduced array gain, spectral efficiency (SE), and higher bit error probability. To this end, this letter proposes a novel double-delay-phase precoding (DDPP) architecture that can be realized with a small number of true time delays (TTDs), mitigating the negative impact of the SWB effect. The numerical results, over the massive and extreme multiple-input multiple-output (MIMO) use cases and in the frequency range (FR)2 and FR3, showcase the effectiveness of the proposed DDPP in terms of the array gain, SE, and bit error rate (BER).