Performance Measurement of Real-time FPGA based OFDM System Implementation

The actual performance of OFDM-based communication systems and the simulation results often have significant differences. This paper investigates the performance measurement of our FPGA based real-time OFDM system, which has features on flexible and scalable architecture. The measured performances are emphasized on the throughput and packet-error-rate (PER) against signal-to-noise-ratio (SNR) and received-signal-strength-indicator (RSSI). Two FPGA based RF Transceiver boards are employed as transceivers implementation platform. The transmission experiments are done in FDD using 241 MHz downlink and 261 MHz uplink with 3.5 MHz bandwidth. The performance measurement is taken in an indoor environment under line-of-sight (LOS) conditions using four quarter-wave antennas from 0.5 m to 8 m distance range. We also observed the fluctuations of SNR upon distance variations for each MCS. From experimental results, the designed system can achieve the maximum throughput at 4.76 Mbps when employing MCS 4, while the minimum throughput is 0.991 Mbps when employing MCS 0. In addition, we also found the RSSI limit of the designed system which can be used to assess the quality of the designed receiver system as well as determining several parameters during system deployments.