e as the BER decreases with channel SNR. The SNR does not calculate the additional interference to UL data from LL data. We have tested the UL performance for different data rates, which is varied by QAM modulation index M (16, 32, and 64), and the power ratio g is selected as per (9.8). From the figure, we see overlapping BER performance for analytical and simulation results, which shows the correctness of our developed performance bound. This equation can be used to evaluate future works on LDM Table 9.1 OFDM Parameter Values parameters used for LDM No. of carriers simulation Single frame size 96 bits Total no of frame No. of pilot bits Cyclic extension 16 bits M. S. Islam et al. 16 QAM Simulation Analytical 32 QAM 64 QAM SNR (dB) Fig. 9.5 Performance comparison of LDM UL between simulation and analytical results for 16, 32, and 64 QAM modulation 16 QAM Upper Layer 16 QAM Lower Layer 32 QAM Lower Layer 64 QAM Lower Layer SNR (dB) Fig. 9.6 BER performance of LDM LL transmission for 16, 32, and 64 QAM constellation with a fixed UL data rate and OFDM. Another noticeable characteristic from the results is the increment of SNR values for similar BER performance as the data rate increases. Figure 9.6 compares the performance of UL and LL and evaluates their perfor- mance with our proposed IoT-user LDM usage models. The power ratio g is set fixed at - 10 dB in this analysis. We simulated the system with different data rate 9 Feasibility of LDM to Serve User-IoT Pairs in the Future Wireless Network Full Capacity Upper Layer Lower Layer SNR (dB) Fig. 9.7 Distribution of channel capacity between LDM UL and LL for fixed power ratio g combinations for the UL and LL. The UL data are fixed at 192 bits (16 QAM) per frame, while the LL data ranges from 192 bits (16 QAM), 240 bits (32 QAM), to 288 bits (64 QAM) per frame. The UL performance is unchanged with the different data rates of the LL. Moreover, we obtain a bit error rate of 10 4 at around 22 dB. In [22], the authors investigated the UL performance for QPSK with a stron