5G-LENA Alternative Rank and Precoding Matrix Indicator Selection Techniques

3rd Generation Partnership Project (3GPP) 5G New Radio (NR) requires users to provide feedback for the base stations, named Next Generation Node Bs (gNBs), to select the number of spatial streams and the precoding matrix, optimizing metrics like channel capacity.5G-LENA 3.1 offers an exhaustive search for the optimal Rank Indicator (RI) and Precoding Matrix Indicator (PMI) pair, constrained by the codebook.We also implement the unconstrained ideal precoding matrix and two codebook-based PMI/RI selection techniques from the literature.We propose a new heuristic method that reduces the search space with minimal system performance loss.Simulations show that it achieves 3.7x speedup with only a 3.3% throughput reduction compared to the exhaustive search.