5G New Radio Non-terrestrial Networks Multiuser Precoding

This works reviews 3 ^rd generation partnership project (3GPP) New Radio procedures for closed-loop multiuser precoding, evaluates their application to non-terrestrial (NTN) scenarios, and proposes adaptions to proficiently exploit their interference mitigation performance. Based on a qualitative evaluation, we demonstrate that Type II codebooks are not suitable for most of the antenna configurations we may find in multibeam satellite systems, whereas Type II port selection codebooks need to be modified to report on the L strongest beams. Numerical simulations utilizing consolidated 3GPP scenarios show that the minimum L varies depending on the terminal link quality. In addition, we show that current 3GPP quantization of the coefficients to be reported limits the system performance, and an extra bit would be at least required for both magnitude and phase in order to attain significant gains. The proposed modifications can be easily included in the standard since they do not represent a significant change with respect to the current specification.