Channel Estimation for Extremely Large-Scale Massive MIMO: Far-Field, Near-Field, or Hybrid-Field?

Extremely large-scale massive MIMO (XL-MIMO) is a promising technique for future 6G communications. However, existing far-field or near-field channel model mismatches the hybrid-field feature in practical XL-MIMO system. Thus, and estimation schemes cannot be directly used to accurately estimate channel. To solve this problem, we propose an efficient scheme by modeling Specifically, firstly reveal of channel, where different scatters may region. Then, capture feature, which contains both path components. Finally, scheme, components are respectively estimated. Simulation results show that proposed performs better than schemes.