## 5 Experimental Results
### Performance and Computational Complexity of the Low Complexity Demodulation Method
#### 5.2.1 Performance Evaluation of Low Complexity Demodulation Method
As shown in Figure 9a-d, when the optimum threshold value was applied, regardless of the number of antennas, we show that the proposed method had almost the same performance as the ED method. In fact, the receiver did not know the ideal SNR, so we used the RSSI to estimate the threshold and compared the method applying estimated threshold with the method applying optimal thresholds. BER performance of two methods is illustrated in Figure 9e-h. There was a difference at about 0.001 dB when comparing the SET method applying the estimated threshold and the SET method applying the optimal threshold. Figure 10 shows the BER performance of the TCST method. Figure 10a-d shows the performance of the ED method [12] and the TCST method applying optimal thresholds for each SNR. As shown in the Figure 10a-d, the TCST method when the optimum threshold was applied showed the similar performance as the ED method regardless of the number of antennas. In the Figure 10e-h, we compared the performance of the TCST method applying the optimal threshold and the TCST method applying the threshold estimated via RSSI of the received signal. The TCST method using the estimated threshold has a 0.1 dB performance degradation. Figure 11 shows the performance when using the ED method and the SED method for data demodulation. The SED method had a performance degradation of 1 dB compared to other methods, but the calculation complexity was the lowest because no multiplication was used in the demodulation process. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & & \multicolumn{4}{c}{**\# of Antennas**} \\ \cline{3-6}  & & **1** & **2** & **4** & **8** \\ \hline \multirow{5}{*}{
\begin{tabular}{c} 0 \\ 5 \\ 10 \\ \end{tabular} } & Threshold & 1 & 0.5 & 0.25 & 0.125 \\  & Average \# of subcarrier & 51 & 51 & 51 & 51 \\  & Threshold & 0.632 & 0.158 & 0.079 & 0.04 \\  & Average \# of subcarrier & 51 & 51 & 51 & 51 \\  & Threshold & 0.2 & 0.05 & 0.025 & 0.013 \\  & Average \# of subcarrier & 51 & 51 & 51 & 51 \\  & Threshold & 0.063 & 0.016 & 0.008 & 0.004 \\  & Average \# of subcarrier & 51 & 51 & 51 & 51 \\  & Threshold & 0.01 & 0.005 & 0.01 & 0.023 \\  & Average \# of subcarrier & 51 & 51 & 51 & 37 \\  & Threshold & 0.003 & 0.013 & 0.026 & 0.019 \\  & Average \# of subcarrier & 51 & 50 & 34 & 21 \\  & Threshold & 0.013 & 0.02 & 0.018 & 0.038 \\  & Average \# of subcarrier & 50 & 42 & 28 & 1 \\  & Threshold & 0.004 & 0.014 & 0.014 & 0.028 \\  & Average \# of subcarrier & 48 & 37 & 15 & 1 \\  & Threshold & 0.008 & 0.001 & 0.021 & 0.013 \\  & Average \# of subcarrier & 47 & 31 & 1 & 1 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Data used in Euclidean distance calculation and optimal threshold for each SNR and number of antennas (TCST method). Figure 9: BER performance of SET method for the number of received (Rx) antennas (1, 2, 4, and 8). From (**a–d**), when adopting the optimal threshold values with increasing the number of Rx antennas from 1 to 8; from (**e–h**) when adopting threshold values calculated from the estimated RSSI (received signal strength indicator) with increasing the number of Rx antennas from 1 to 8. Figure 10: BER performance of TCST method for the number of received (Rx) antennas (1, 2, 4, and 8). From (**a–d**) when adopting the optimal threshold values with increasing the number of Rx antennas from 1 to 8; from (**e–h**) when adopting threshold values calculated from the estimated RSSI (received signal strength indicator) with increasing the number of Rx antennas from 1 to 8.