PERFORMANCE ANALYSIS OF OFDM AND CDMA BASED SATCOM SYSTEMS IN THE PRESENCE OF INTERFERENCE

Abstract

This research work focuses on the analysis of the interference mitigation capabilities of SATCOM systems based on two different techniques, CDMA and OFDMA. The aim of this research is to evaluate the BER for different values of SNR of both CDMA and OFDMA based SATCOM systems and compare their performance nuances to determine how well each system fared against different types of interference. The increased reliance on SATCOM, limited frequency spectrum and increasing demand for high-speed data rates and throughputs has made interference and jamming a significant concern. To mitigate interference, sustain the SATCOM link, ensure uninterrupted and secure communication, multiple interference mitigation strategies are adopted. Among the prevalent interference mitigation strategies, both CDMA and OFDMA hold prominence, yet OFDMA is solidifying its position as a frontrunner owing to its exceptional bandwidth efficiency, making it increasingly sought-after in contemporary SATCOM systems. By employing MATLAB simulations, an extensive evaluation was conducted to assess the effectiveness of CDMA and OFDMA amidst diverse interference forms, encompassing narrowband, wideband, and broadband interference that includes single tone interference, swept jamming and barrage jamming respectively under the influence of AWGN, Rayleigh and Rician Fading. In our analysis we found that both CDMA and OFDMA are remarkably resilient in mitigating narrowband interference yet falters in unison against broadband interference and exhibit similar decline in performance. Nevertheless, in the face of moderately challenging wideband interference, OFDMA invariably defeats CDMA as it is more resistant to wideband interference due to the use of a larger number of orthogonal subcarriers. Therefore, the choice of technique depends on the type of interference present in the system. Based on the results, we recommend the use of OFDMA-based SATCOM systems in scenarios where wideband interference is likely to occur. However, in scenarios where only narrowband interference is expected, CDMA-based SATCOM systems may be a viable alternative. Further research can be conducted to practically integrate these systems on the USRP platform to assess and optimize their performance under different interference scenarios and improve the overall reliability of SATCOM systems.