Extremely Large-Scale Array System: Cooperative NFC or FFC?

Even that near-field communication (NFC) significantly improves the performance due to the unique spherical-wave channel model in electromagnetic propagation, its future application in communications is still with boundedness, which suffers from the constrained communication distance. In this letter, we investigate a cooperative relaying NFC and far-field communication (FFC) coexisting system with extremely large-scale array (XL-array), where one far user is out of Rayleigh distance from base station (BS), as well as the scenarios from BS to the near relay/user and from the near relay/user to far user are NFCs. Specifically, the closed-form and asymptotic expressions for achievable capacity are respectively derived. In addition, simulation and numerical results confirm the correctness and superiority of our proposed schemes, which show that the capacity improvement from NFC effectively compensates the performance loss from the half-duplex principle, even providing a better profit compared with FFC.