Design of a FPGA-based baseband for MIMO TD-LTE BTS

A compact 2×2 MIMO analog baseband processing unit for the TD-LTE BTS transceiver system is presented in this paper. The designed system supports two independent transmitter and receiver. Data can be transmitted between the baseband and the digital baseband subsystem flexibly and conveniently by either the optical fibers or the LAN cable. The on-board FPGA can support the Common Public Radio Interface (CPRI) and the Gigabit Ethernet (GE) interface. It can also be used for some data processing such as the calibration, digital predistortion (DPD), etc. Measurement results of EVM with a 19.2MHz 16QAM signal and a 20MHz TD-LTE signal are 0.45%rms and 1.29%rms respectively, which verifies excellent performance of the baseband board. With RF board as well as power and controller board integrated together, the designed 2×2 compact MIMO analog baseband processing unit is implemented in the TD-LTE trial network successfully.