Uplink Performance of Cell-Free Massive MIMO with Rate-Splitting

Cell-free (CF) massive multiple-input multiple-output (MIMO) system has emerged as a highly promising technology, primarily due to its ability to improve coverage and performance. However, one of the key challenges is their reliance on perfect channel state information (CSI). To address this issue, we propose the incorporation of a rate-splitting (RS) strategy, which has been proven to effectively mitigate the negative impact of imperfect CSI. In this paper, we investigate CF massive MIMO systems that utilize the RS strategy. We derive a closed-form expression for the RS-assisted CF massive MIMO system in the uplink, while accounting for pilot contamination. We also present four decoding schemes that can be implemented in practical systems. Our extensive simulations reveal that CF massive MIMO systems utilizing the RS strategy outperform those that do not in terms of sum spectral efficiency (SE). These findings emphasize the effectiveness of RS technology in mitigating the negative effects of imperfect CSI in CF massive MIMO systems. The insights gained from this research can serve as a basis for the design and optimization of future CF massive MIMO systems, ultimately improving their performance and expanding their applicability in diverse scenarios.