Realistic beamforming design using SRS-based channel estimate for ns-3 5G-LENA module

Beamforming (BF) is a key procedure to overcome propagation limits in millimeter-wave bands but also to extend network coverage in sub 6 GHz bands, as considered in recent 3GPP and IEEE communication standards. Up to date, ns-3 included various ideal BF methods, in which an ideal channel state acquisition is assumed and no BF overhead is considered. However, ns-3 lacks the implementation of realistic BF methods, in which the overhead needed to perform BF-related procedures and the errors due to a non-ideal channel state acquisition are taken into account. A way to perform realistic BF is to rely on Sounding Reference Signals (SRS) for channel estimation and then determine the best BF vectors based on the channel estimate. In this paper, we first present an abstraction model to perform BF using SRS-based channel estimation, and then we provide the implementation details of 5G New Radio (NR)-compliant SRSs and new realistic BF methods using SRS-based channel estimate, as included in the ns-3 5G-LENA simulator. Simulations are provided to compare realistic BF and ideal BF methods, for different propagation scenario conditions and SRS transmitted powers.