Spatial domain exploitation through 3D beamforming serves as a critical technology enabler for performance enhancement in the Fifth Generation New Radio (5G NR) specification. This is realized at the gNodeB (gNB) through the integration of massive antenna element arrays that facilitates 3D spatial multiplexing. However, these systems with high-directional transmissions also represent a threat to incumbent services such as radar and satellites. These incumbents already operate in midband spectrum\textemdash{}including the 4.4-4.9 GHz and 7.125-7.4 GHz bands\textemdash{}that are currently being evaluated for future cellular deployments. Here, we present the first work that evaluates the transmitted Effective Isotropic Radiated Power (EIRP) of a gNB in 3D space, using the 3GPP Release-18 standard for FR-1 instead of theoretical analyses of beam nulling, which can be simplistic. We shed light on the problems requiring attention with the EIRP profile in 3D space for existing codebook designs predefined in 3GPP: i) interference from a gNB does not depend only on the worst-case beamforming direction, but on a variety of beamforming directions due to side-lobes; ii) advanced antenna systems (AAS) architecture and antenna port configurations play a crucial role in average 3D EIRP, which are implementation dependent, and iii) we introduce two beam nulling methods, which achieve a 11 dB power reduction toward a target direction, with 3.5-4.5 dB SNR loss in UE link performance at a 10^{-4} bit error rate (BER) across modulation schemes under ideal and practical channel estimation, a higher loss compared to predictions from theoretical analyses.

翻译：三维波束赋形对空间域的利用是第五代新空口（5G NR）标准中提升性能的关键技术。该技术通过gNodeB（gNB）集成大规模天线阵列实现三维空间复用。然而，此类高方向性传输系统也对雷达、卫星等现有业务构成威胁。这些现有业务已在中频段（包括当前正在评估用于未来蜂窝部署的4.4-4.9 GHz和7.125-7.4 GHz频段）运行。本文首次基于3GPP Release-18 FR-1标准而非简化的波束零陷理论分析，评估了gNB在三维空间中的实际有效全向辐射功率（EIRP）。我们揭示了3GPP预定义码本设计中与三维EIRP方向图相关的待解决关键问题：i）gNB的干扰不仅取决于最差情况波束赋形方向，还受旁瓣引起的多种波束赋形方向影响；ii）先进天线系统（AAS）架构与天线端口配置（取决于具体实现）对平均三维EIRP起决定性作用；iii）我们引入两种波束零陷方法，可在目标方向实现11 dB功率抑制，同时在理想信道估计和实际信道估计条件下，不同调制方案在10^{-4}误码率（BER）时用户设备链路性能的SNR损失为3.5-4.5 dB，该损失高于理论分析预测值。