A real-time FPGA-based implementation of a high-performance MIMO-OFDM transceiver featuring a closed-loop communication scheme

In this paper we present the FPGA implementation of a multi-antenna Orthogonal Frequency-Division Multiplexing (OFDM) transmitter and receiver featuring a closed-loop (CL) communication scheme. The PHY-layer development follows the specifications of the mobile WiMAX standard, whereas the limited MAC functionality is using custom specifications. In the implemented CL scheme, the transmitter applies a Transmit Antenna Selection (TAS) decision based on the instantaneous Channel State Information (CSI), which is calculated at the receiver and fed back to the transmitter. The RTL implementation addresses the challenge of efficiently accommodating two transmission schemes with optimal reuse of FPGA resources. The adaptive subcarrier allocation can be thoroughly evaluated only when prototyped in a real-time platform, such as the one described in this paper. The results verified that the CL system is performing better than its open-loop counterpart.