A Closed-Loop Loop Reciprocity Calibration Method for Massive MIMO in Terrestrial Broadcasting Systems
Abstract: Massive multi-input input multioutput (MIMO) is believed to be an effective technique for future terrestrial broadcasting systems. Reciprocity calibration is one of the major practical challenges for massive MIMO systems operating in time-division time duplexing mode. A new closed closed-loop reciprocity calibration method is investigated in this paper which can support online calibration with a higher accuracy compared to the existing methods. In the first part of the proposed method, an optimized relative calibration is introduced using the same structu structure re of traditional relative calibration, but with less impaired hardware in the reference radio chain. In the second part, a test device (TD) (TD)-based based calibration is proposed which makes online calibration possible. An experiment setup is built for the measurement measure of the base station hardware impairments and TD TD-based based calibration implementation. Simulation results and the error vector magnitude of UE received signal after calibration show that the performance of our proposed method is improved significantly comp compared ared to the existing relative calibration methods.