A Tutorial on Near-Field Driven 6G Networks

With the advancement in the technological architecture of Sixth Generation (6G), the aspect of near-field-driven designs has become more prominent. Besides, the shift towards the reduction in greenhouse emissions has led to the introduction of the latest research trends and open research problems in green near-field communications. Unlike the previous review papers, this tutorial focuses on the need and impact of near-field on improving the performance of various 6G architectures and discusses the practical issues in near-field motivated designs. We aim to provide a comprehensive analysis and highlight the future research trends in (a) localization, channel estimation and beam training, from narrowband to wideband multiaccess communication and physical layer security by taking advantage of beamfocusing, (b) energy efficiency transmission with beamfocusing, (c) integrating the individual subsystems into the communication system to enhance the spectrum and energy efficiency to achieve multiple objectives from the single wireless communication system. A subsequent simulation of a QPSK modulated end-to-end system is shown to establish the fact that beamfocusing can lead to the spatial separation of users, granting beam focusing vector two degrees of freedom.