Channel modeling is a fundamental task for the design and evaluation of wireless technologies and networks, before actual prototyping, commercial product development and real deployments. The recent trends of current and future mobile networks, which include large antenna systems, massive deployments, and high-frequency bands, require complex channel models for the accurate simulation of massive MIMO in mmWave and THz bands. To address the complexity/accuracy trade-off, a spatial channel model has been defined by 3GPP (TR 38.901), which has been shown to be the main bottleneck of current system-level simulations in ns-3. In this paper, we focus on improving the channel modeling efficiency for large-scale MIMO system-level simulations. Extensions are developed in two directions. First, we improve the efficiency of the current 3GPP TR 38.901 implementation code in ns-3, by allowing the use of the Eigen library for more efficient matrix algebra operations, among other optimizations and a more modular code structure. Second, we propose a new performance-oriented MIMO channel model for reduced complexity, as an alternative model suitable for mmWave}/THz bands, and calibrate it against the 3GPP TR 38.901 model. Simulation results demonstrate the proper calibration of the newly introduced model for various scenarios and channel conditions, and exhibit an effective reduction of the simulation time (up to 16 times compared to the previous baseline) thanks to the various proposed improvements.

翻译：信道建模是在实际原型开发、商业产品部署之前，对无线技术与网络进行设计与评估的基础任务。当前及未来移动网络的发展趋势——包括大规模天线系统、密集部署以及高频段——要求采用复杂信道模型来精确模拟毫米波和太赫兹频段的大规模MIMO。为权衡复杂度与精度，3GPP定义了空间信道模型（TR 38.901），该模型已被证实是当前ns-3系统级仿真的主要瓶颈。本文聚焦于提升大规模MIMO系统级仿真的信道建模效率，从两个方向进行扩展。首先，通过允许使用Eigen库实现更高效的矩阵代数运算，并结合其他优化措施及模块化代码结构，改进了ns-3中现有3GPP TR 38.901实现代码的效率。其次，提出一种面向性能的低复杂度MIMO信道模型，作为适用于毫米波/太赫兹频段的替代方案，并基于3GPP TR 38.901模型对其进行了校准。仿真结果表明，新引入的模型在多种场景和信道条件下均实现了正确校准，并借助各项改进有效降低了仿真时间（相比先前基准模型最高可减少16倍）。