# A Partitioned IRS-Aided Transmit SM Scheme for Wireless Communication
## 5 Simulation Results
In Figure 5, the effect of partitioning on the IRS is illustrated by making a BER performance comparison between PIRS-TSM and unpartitioned IRS-TSM in the above 3 configurations, respectively. Specifically, in the IRS-TSM scheme, during each transmission, all IRS reflecting elements work at phase shifts to cancel the channel phases from the activated antenna to the IRS then to the Rx in order to maximize the SNR at the Rx. We can observe that the reliability of signal transmission is significantly improved by partitioning on the IRS, especially at high SNR. Taking the scenario of \(N_{t}=2,M=8\) as an example. Select the points of PIRS-TSM at \(-11\) dB and \(-1\) dB as the low-SNR and high-SNR comparison points, respectively. To match the BER performance of PIRS-TSM at \(-11\) dB, the IRS-TSM scheme requires an approximate 8.5 dB SNR gain. Notably, this performance gap widens significantly in the high-SNR region, where IRS-TSM demands a 16 dB SNR gain to achieve the same BER as PIRS-TSM at \(-1\) dB. This trend highlights the enhanced effectiveness of PIRS-TSM in high-SNR scenarios, attributed to its optimized IRS partitioning and phase alignment mechanisms. Figure 6 investigates the effect of carrying symbols on the transmission performance of the system with the same IRS partitioning method, by making a comparison of the BER  
Figure 4: Theoretical and computer simulation results for PIRS-TSM with 3 different configurations when SE is 4 bit/s/Hz and 6 bit/s/Hz, respectively. Figure 5: Performance comparison between PIRS-TSM and IRS-TSM with 3 different configurations when SE is 4 bit/s/Hz. performance among the PIRS-TSM, PIRS-TSSK, PIRS-TGSSK, and PIRS-FGSSK schemes. The system parameters are still uniformly configured as \(\mathrm{SE}=4\) bit/s/Hz, \(N=128\). The performance curves of the proposed PIRS-TSM scheme for the three aforementioned configurations are given. For the required SE of 4 bit/s/Hz, the number of transmit antennas for PIRS-TSSK should be \(N_{t}=16\), and the PIRS-TGSSK scheme needs 7 transmit antennas and 2 activated antennas. The number of transmit antennas for the PIRS-FGSSK scheme, which has a flexible number of activated antennas, is set as \(N_{t}=8\). The reasons for choosing the number of transmit antennas in these schemes are as follows: for PIRS-TSSK, SE = log \(N_{t}\), so \(N_{t}\) is set as 16 to achieve an SE of 4 bits/s/Hz. For PIRS-TGSK, the number of possible transmit antenna combinations is \(\binom{N_{t}}{N_{t}}\) with \(N_{s}\) denoting the number of activated antennas. Because the number of activated antenna combinations must be a power of 2, \(C=2^{a}\) combinations are utilized, with \(\mathrm{SE}=a=\left|\log_{2}\binom{N_{t}}{N_{t}}\right|\) bit/s/Hz. Therefore, \(N_{t}=7\) and \(N_{s}=2\) can achieve an SE of 4 bits/s/Hz. For PIRS-FGSSK, the number of activated antennas is flexible, we set \(N_{t}=8\) to achieve an SE of 4 bits/s/Hz. It can be seen that the BER performance of the PIRS-TSM scheme is superior to the other three schemes. For example, when \(\mathrm{BER}=10^{-2}\), PIRS-TSM with \(N_{t}=2\) and \(M=8\) achieves about 14 dB, 12 dB, and 8 dB SNR gain compared with PIRS-TGSSK, PIRS-TSSK, and PIRS-FGSSK, respectively.