Exploitating the Wavenumber-Domain MlSO Channel with Uniform Linear Array

As sixth-generation (6G) networks move toward higher carrier frequencies and larger antenna apertures, wireless systems increasingly operate in the near-field, demanding a physically consistent model that explicitly highlights the wavenumber-domain channel characteristics. In this paper, we establish an analytical wavenumber-domain channel modeling for multiple-input single-output (MISO) transmissions based on the Weyl expansion. Our model reveals that the effective channel coefficients of uniform linear arrays (ULAs) can be derived as a one-dimensional integral with respect to the zeroth-order Hankel function of the first kind in the wavenumber-domain. This modeling allows us to exploit the channel characteristics directly in the wavenumber-domain. Particularly, we derive the wavenumber-domain expression of multiuser interference, whose value is sensitive to the wavenumber-domain aliasing due to the presence of the Dirichlet kernel. The asymptotical orthogonality condition that eliminates the aliasing is then derived, which requires the antenna spacing is no larger than half of the wavelength. The avoidance of wavenumber-domain aliasing can significantly reduce the multiuser interference (MUI) and improve the communication performance, which is explicitly verified by our numerical results under the same aperture size and transmit power.