FPGA Prototype and Real Time Analysis of Multiuser Variable Rate CI-GO-OFDMA

The narrow-band-IoT and other higher standards require efficient multiple access schemes that allow more number of users using variable rates to achieve a low peak-to-average power ratio (PAPR) and resistance against deep fades. In this paper, a multicarrier scheme is proposed that supports multiuser with variable rates based on carrier interferometry (CI) codes, i.e., CI-group orthogonal-orthogonal frequency-division multiple access (CI-GO-OFDMA). The bit-error-rate performance of the proposed scheme is carried out on the third-generation partnership project standardized pedestrian channel. Furthermore, a new architecture is designed and an efficient methodology is developed for the proposed scheme, which is prototyped on the commercially available virtex5 FPGA device for real-time analysis. The PAPR performance for the proposed scheme in the MATLAB simulation as well as in the fixed point hardware is compared and found almost the same, which justifies its significance. The challenging issue lies in the real-time testing and analyzing the baseband CI-GO-OFDMA signal from the digital-to-analog converter on the spectrum analyzer and the mixed signal oscilloscope in the laboratory experimental setup. Measurements like the experimental error of the FPGA prototype, occupied bandwidth, main lobes channel power, and side lobes channel power are reported to study the behavior of the scheme in the real-time scenario.