Terahertz (THz) frequencies have recently garnered considerable attention due to their potential to offer abundant spectral resources for communication, as well as distinct advantages in sensing, positioning, and imaging. Nevertheless, practical implementation encounters challenges stemming from the limited distances of signal transmission, primarily due to notable propagation, absorption, and blockage losses. To address this issue, the current strategy involves employing ultra-massive multi-input multi-output (UMMIMO) to generate high beamforming gains, thereby extending the transmission range. This paper introduces an alternative solution through the utilization of cell-free massive MIMO (CFmMIMO) architecture, wherein the closest access point is actively chosen to reduce the distance, rather than relying solely on a substantial number of antennas. We compare these two techniques through simulations and the numerical results justify that CFmMIMO is superior to UMMIMO in both spectral and energy efficiency at THz frequencies.

翻译：太赫兹（THz）频段因其能为通信提供丰富的频谱资源，并在感知、定位和成像方面具有独特优势，近期受到了广泛关注。然而，实际部署面临着信号传输距离受限的挑战，这主要归因于显著的传播、吸收和阻挡损耗。为了解决这一问题，当前策略是采用超大规模多输入多输出（UMMIMO）技术来产生高波束赋形增益，从而延长传输距离。本文提出了一种替代方案，即利用无蜂窝大规模MIMO（CFmMIMO）架构，通过主动选择最近的接入点来缩短距离，而非仅仅依赖大量天线。我们通过仿真对比了这两种技术，数值结果表明，在太赫兹频段，CFmMIMO在频谱效率和能量效率方面均优于UMMIMO。