Receive Diversity Options for Single Panel 4G-5G Antennas

Abstract

Using a single rectangular antenna panel enhances cellular capacity via vertical beamforming (e.g. “Full Dimension MIMO”) but may impact diversity gain. We compare the receive diversity performance of several single-panel signal processing techniques, including: subarrays (with wide or narrow beamwidths), pattern diversity (with various a priori azimuth offset beam steering), and Maximum Ratio Combining. Spatial fading correlation is obtained from the 3GPP TR 25.996 model. We assume a hybrid analog-digital beamformer and derive the SNR for any analog beamformer followed by an MRC digital stage. This allows us to apply various beamforming strategies to the antenna subarrays and determine if there is a benefit. In a simple azimuth-only, single user simulation we find:4R (i.e. 4 outputs) subarrays with narrow steered beams approaches the performance of 8RMRC, while a 4 dB shortfall is found for widebeam subarrays relative to MRC; and pattern diversity is competitive with widebeam subarrays for 4R but not 8R.