A QoS Throughput Performance Measurement Comparison between UGS and BE Services of a Real-time FPGA Based OFDM Multi-user System Design Implementation

It is defined in IEEE 802.16e that there are five different Quality of Service (QoS) classes, which include: UGS, rtPS, nrtPS, ertPS, and BE. This paper compares the throughput performance measurement results between the UGS and BE scheduling services for every modulation and coding scheme (MCS), which have been implemented in our FPGA-based real-time OFDM multi-user system. There are two FPGA-based RF transceiver boards involved in the one-slot experiment and three FPGA-based RF transceiver boards involved in the two-slot experiment. The downlink transmission is done in FDD, using 241 MHz as the center frequency, and the uplink transmission is done in TDD, using 261 MHz as the center frequency. The transmission scenario used in this experiment is point-to-multipoint (P2MP). The throughput measurement is taken under LOS conditions using cables and quarter-wave antenna connections. We observed that the BE service has higher downlink and uplink throughput compared to the UGS service by utilizing one uplink slot. However, there are almost 50% drops in the throughput results for every MCS in the BE implementation when two uplink slots are utilized. There are some limitations to this experiment, involving the number of subscriber stations, a connection timeout issue, and the experimental condition. Therefore, it is advised to increase the number of subscriber stations and test the system under several wireless conditions for future development.