Adaptive Beamforming for Next Generation Cellular System

Abstract: In this work aMatlab model of a simplified LTE system has been implemented. The PUSCH and PDSCH signal chains has been used for reception and transmission of data and DM-RS symbols are used as pilots. Moreover, the model supports communication and interference between multiple users and base station antennas. The wireless channels are modeled as multi-path Rayleigh fading and are continuous in time such that multiple frames can be transmitted on a correlated channel. Three standardized multi-path delay profiles have been used for modeling users in pedestrian, vehicular and urban environments. Three beamforming algorithms have been implemented, maximumratio transmission, zero-forcing and regularized zeroforcing. This model is an extension to the current standard of LTE in the sense that the parameters of the model are scalable beyond what is currently in the standard. The different algorithms are compared in many different scenarios, including different modulation levels, delay profiles, number of user sharing the same resources, number of base station antennas, multi-layer transmissions and complexity. Maximumratio transmission is shown to be computationally less complex, while the zero-forcing algorithms are better at removing inter-user interference, especially as the number of users sharing the same resources grows for a constant number of base station antennas. Regularized zero-forcing is shown to outperform the other algorithms when looking at the entire SNR range.