## 6 Numerical Results
### Performance in the Asymmetric Networks
Like the symmetric networks, we also evaluate the schemes from the perspective of minimal received SINR in order to evaluate the performance of the worst data stream. For the (4 \(\times\) 4, 1)\({}^{20}\) network in Figure 13, the JSCC-IA scheme with identical propagation delay can achieve about 2 dB higher minimal received SINR than the conventional IA system at the same \(E_{b}/N_{0}\). The RGS algorithm can further improve the performance, and provide an extra gain of 2 to 4 dB over the non-RGS JSCC-IA scheme from the low to high \(E_{b}/N_{0}\) regimes. The difference between the JSCC-IA schemes with identical and different propagation delays is small at low \(E_{b}/N_{0}\) regimes, and is no more than 1.5 dB  
Figure 12: The average experimental BER performances of the conventional IA scheme, the JSCC-IA schemes with identical/different propagation delays and the RGS JSCC-IA schemes with identical/different propagation delays in the (6 \(\times\) 6, 2)\({}^{18}\) asymmetric networks. at the high \(E_{b}/N_{0}\) regimes. Similarly, for the RGS JSCC-IA schemes, the different propagation delays do not have a significant impact on the minimal received SINR, and only yield slight degradation in the high \(E_{b}/N_{0}\) regimes. For the (6 \(\times\) 6, 2)\({}^{18}\) network in Figure 14, the total number of data steams is 36, which is much larger than that of the (4 \(\times\) 4, 1)\({}^{20}\) network. The minimal received SINR of the conventional IA system is further degraded by the stronger interference, and the best minimal received SINR is only 14 dB at \(E_{b}/N_{0}\) =14 dB. Figure 14: The average minimal received SINR of the conventional IA scheme, the JSCC-IA schemes with identical/different propagation delays and the RGS JSCC-IA schemes with identical/different propagation delays in the (6 \(\times\) 6, 2)\({}^{18}\) asymmetric networks. Figure 13: The average minimal received SINR of the conventional IA scheme, the JSCC-IA schemes with identical/different propagation delays and the RGS JSCC-IA schemes with identical/different propagation delays in the (4 \(\times\) 4, 1)\({}^{20}\) asymmetric networks. On the contrary, the JSCC-IA scheme with identical propagation delay can achieve much higher minimal received SINR, and exhibits a gain of 4 to 6 dB over the conventional IA system from the low to high \(E_{b}\)/\(N_{0}\) regimes. Moreover, the RGS algorithm can further improve the performance, and achieve about 2 dB higher minimal received SINR than the non-RGS JSCC-IA scheme with identical delay at \(E_{b}\)/\(N_{0}=\)14 dB. Although the performance of the JSCC-IA scheme with different propagation delays is inferior to that with the same delay, it still shows higher minimal received SINR than the conventional IA system. In addition, the RGS strategy can improve the performance, and the minimal received SINR of the RGS JSCC-IA system with different delays at \(E_{b}\)/\(N_{0}=\)14 dB is 17 dB, which is about 3 dB higher than that of the conventional IA system. Therefore, the proposed JSCC-IA and RGS JSCC-IA schemes can improve the performance of the worst data stream and reduce of the chance of communication outage. In addition, we also compare the average received SINR in order to provide a more thorough insight into the JSCC-IA schemes. For the (4 \(\times\) 4, 1)\({}^{20}\) network in Figure 15, the average received SINR of the JSCC-IA and RGS JSCC-IA schemes have almost the same value in the low \(E_{b}\)/\(N_{0}\) regimes, and they exhibit about 2 dB higher average received SINR over the conventional IA system under the same \(E_{b}\)/\(N_{0}\). On the other hand, when \(E_{b}\)/\(N_{0}\) increases, the proposed schemes show even better performances. Considering \(E_{b}\)/\(N_{0}=\) 14 dB, the RGS JSCC-IA schemes with identical and different propagation delays can provide about 4 and 3 dB higher average SINR than the conventional IA system, respectively. For the (6 \(\times\) 6, 2)\({}^{18}\) network in Figure 16, similar performances can be observed.