Beamwidth and Steering-Dependent Propagation Loss Modeling at 28GHz Over Urban Micro-Cellular (UMi) Scenarios

As a novel communication pattern, non-reciprocal beams employ narrow-width beams to transmit signals and wide-width beams to receive, which can achieve fast beam alignment quickly. To fully understand the channel characterization, we investigate the mmWave propagation path loss (PL) over this special pattern. First, we present a beam-filtered power angular spectrum (PAS) simulation method based on the 3GPP. Specifically, the main lobe width-related beam gain is used to shape the generated PAS. On this basis, we consider two cases, i.e., perfect beam alignment and misalignment. For the first case, we propose a novel exponential decay PL model instead of the inversely proportional relationship. Furthermore, we verify our proposal based on the measured data of 28GHz and the results show that it yields a smaller fitting root mean square error (RMSE). Regarding the latter case, we find that the beam steering-based additional PL can be regarded as the superposition of a deterministic Gaussian function and a stochastic Gaussian noise. Our findings provide insightful references for the implementation of beamwidth-dependent nonreciprocal beam patterns.