Learning Based CSI Look Up Table: A Novel Vector Quantization Approach for High Accuracy CSI Reconstruction

To fully exploit the benefits of spatial multiplexing gains within Frequency Division Duplex (FDD) Multiple-Input Multiple-Output (MIMO) systems, the development of a robust Channel State Information (CSI) feedback compression methodology with low over- the-air CSI overhead while achieving high reconstruction accuracy is critical. Such methodology must be able to effectively reduce communication overhead without compromising system level performance. Traditional codebook-based approach, as outlined in the 3rd Generation Partnership Project (3GPP) standards encounters significant challenges to balance air-interface overhead and computational complexity. In this paper, we introduce a novel and adaptable Deep Leaning (DL) based CSI codebook technique leveraging vector quantization known as the CSI-Look-Up Table (CSI-LUT). Our numerical results show that the CSI - L UT has potential in reducing > 90 % of CSI overhead for max rank 1 while still achieving better average reconstruction accuracy and system level performance than traditional codebook-based approach. We anticipate that such advancements will play a pivotal role in enhancing the efficiency and performance of CSI feedback in MIMO systems, contributing significantly to the evolving landscape of 5G and beyond.

I. Introduction

MIMO stands as a promising technique aimed at enhancing spectrum and energy efficiency in the context of next-generation wireless system [1], [2]. However, this advancement introduces new challenges, particularly with regard to base stations (B S). The next-generation B S (gNB) must acquire real-time CSI for precoding purposes, a requirement accentuated in FDD systems. Downlink CSI acquisition involves two primary steps. First, the UE estimates the downlink CSI by utilizing the received pilot signals transmitted by the BS. Subsequently, the UE relays this estimated downlink CSI to the BS via the uplink control channel. In the context of massive MIMO systems, where the BS is equipped with a large number of antennas, the resulting CSI dimension becomes extensive, necessitating significant feedback overhead.