Mixed Near- and Far-Field Communications for Extremely Large-Scale Array: An Interference Perspective

Understand

Extremely large-scale array (XL-array) is envisioned to achieve super-high spectral efficiency in future wireless networks.

• Different from the existing works that mostly focus on the near-field communications, we consider in this paper a new and practical scenario, called mixed near- and far-field communications, where there exist both near- and far-field users in the network.
• For this scenario, we first obtain a closed-form expression for the inter-user interference at the near-field user caused by the far-field beam by using Fresnel functions, based on which the effects of the number of BS antennas, far-field user (FU) angle, near-field user (NU) angle and distance are analyzed.
• We show that the strong interference exists when the number of the BS antennas and the NU distance are relatively small, and/or the NU and FU angle-difference is small.