MIMO technology has been studied in textbooks for several decades, and it has been adopted in 4G and 5G systems. Due to the recent evolution in 5G and beyond networks, designed to cover a wide range of use cases with every time more complex applications, it is essential to have network simulation tools (such as ns-3) to evaluate MIMO performance from the network perspective, before real implementation. Up to date, the well-known ns-3 simulator has been missing the inclusion of single-user MIMO (SU-MIMO) models for 5G. In this paper, we detail the implementation models and provide an exhaustive evaluation of SU-MIMO in the 5G-LENA module of ns-3. As per 3GPP 5G, we adopt a hybrid beamforming architecture and a closed-loop MIMO mechanism and follow all 3GPP specifications for MIMO implementation, including channel state information feedback with precoding matrix indicator and rank indicator reports, and codebook-based precoding following Precoding Type-I (used for SU-MIMO). The simulation models are released in open-source and currently support up to 32 antenna ports and 4 streams per user. The simulation results presented in this paper help in testing and verifying the simulated models, for different multi-antenna array and antenna ports configurations.

翻译：MIMO技术已在教科书中研究数十年，并被4G和5G系统采用。由于近年来5G及未来网络的发展，旨在涵盖日益复杂的应用场景中的多种用例，因此有必要在真实部署前，利用网络仿真工具（如ns-3）从网络层面评估MIMO性能。迄今为止，广为人知的ns-3仿真器尚未集成针对5G的单用户MIMO（SU-MIMO）模型。本文详细阐述了实现模型，并对ns-3的5G-LENA模块中的SU-MIMO进行了全面评估。依据3GPP 5G标准，我们采用混合波束赋形架构与闭环MIMO机制，并遵循所有3GPP MIMO实现规范，包括基于预编码矩阵指示和秩指示的信道状态信息反馈，以及基于码本（采用适用于SU-MIMO的I型预编码）的预编码。仿真模型已开源发布，当前支持每用户最多32个天线端口和4个数据流。本文呈现的仿真结果有助于针对不同多天线阵列和天线端口配置，对仿真模型进行测试与验证。