Time-Frequency Fusion-Based Identification of Multiple Access Schemes

To address the problem of multiple access scheme identification, a time-frequency fusion-based multiple access mode identification algorithm is proposed. The algorithm first divides multiple access technologies into two categories based on their signal characteristics: the first category includes Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), and Carrier Sense Multiple Access (CSMA), while the second category includes Code Division Multiple Access (CDMA) and Orthogonal Frequency Division Multiple Access (OFDMA). In the first category, TDMA and CSMA exhibit time-domain exclusivity, meaning that signals occupying the same spectrum cannot coexist in the time domain, while FDMA exhibits distinctive frequency-domain isolation. The algorithm then develops distinct decision rules for each category by leveraging their inherent signal patterns. For FDMA, TDMA, and CSMA schemes, the decision rules are designed based on transmission start-time regularity and the correlation between center frequencies and the number of users, while for CDMA and OFDMA schemes, the rules are established according to their characteristic spectral patterns. Finally, the algorithm establishes an optimized tolerance threshold selection strategy for the decision rules. Comprehensive computer simulations and theoretical analysis validate the proposed approach. The results demonstrate robust identification performance across all five multiple access schemes (FDMA, TDMA, CSMA, CDMA, and OFDMA).