Impact of Effective Antenna Pattern on Estimation of Interference in Citizens Broadband Radio Service

This paper investigates the impact of antenna pattern modeling accuracy on performance evaluation in realistic Citizens Broadband Radio Service (CBRS) cellular networks. The current practice of using nominal antenna pattern of CBRS device (CBSD), as measured in anechoic chamber, for estimation of interference conditions between CBSDs does not address the antenna gain degradation and antenna pattern reshaping caused by angular spread in scattering propagation environment. System level simulations have been conducted using a model of commercially available antenna of CBSD in urban macro deployment scenario with full 3D channel model and proprietary algorithm for resources distribution. The result reveals that the value of interference between each pair of investigated CBSDs can be underestimated by 6 dB if nominal antenna pattern is assumed in link budget calculation instead of effective antenna pattern. This underestimation may lead to suboptimal channels distribution in real spectrum sharing environment of CBRS network and severe co-existence issues between CBSDs. Therefore, effective antenna pattern of CBSD, as determined for given scattering propagation conditions, should be used for more accurate modeling of interference during CBRS network planning, optimization, as well as network operation in spectrum sharing environment.