## 4 Simulation Results
The reason was that the beamforming scheme  
Figure 7: Impact of ACK (acknowledgement) energy consumption. In Figure 10, the performance of throughput is normalized by each scheme energy. The result in Figure 10 shows that the IDF outperform the other schemes in spectral efficiency ranged between 0.1 and 0.8 in which at a spectral efficiency of 0.8, the IDF had a performance of 18.165 [kbits/s/Hz/J]. Whereas, the multi-hop scheme had the worst performance at a spectral of 0.8 in which it had a performance of 5.783 [kbits/s/Hz/J]. In addition, the performance gap between the IDF and ABF at a spectral efficiency of 0.8 was only different at 0.1%, which means the performance aws almost same. As the spectral efficiency increased more than 0.9, the ABF scheme had the best performance in a spectral efficiency range from 0.9 to 4 in which the performance values of the ABF, the DBF, the IAF, and the IDF schemes at a spectral efficiency of 1 were 25.994, 16.264, 19.057, and 21.899 [kbits/s/Hz/J], respectively. According to the result, the performance of the ABF achieved 15.7% better than the IDF at a spectral efficiency of 1. The reason was that diversity gain of the ABF scheme gave a better impact to the normalized throughput performance, which means that the gain of the the ABF scheme was stronger to the point where it complemented the energy consumption. Whereas, the multi-hop scheme was lower than the others between a spectral efficiency of 0.4 and 4 due to the short distance between the source node and destination node. Finally, the normalized throughput performance was maximized by using both of the IDF scheme or the ABF scheme according to spectral efficiency. In Figures 11 and 12, we present the throughput as SNR with eight schemes. In Figure 11, we show that the beamforming scheme outperformed the other schemes in overall a SNR range between \(-\)20 and 30 SNR range. The reason was that the beamforming scheme kept a very low outage probability compared with the single-hop scheme. At 0 dB SNR, the throughput values of the beamforming, the single-hop, the multi-hop, the cooperation, and the incremental cooperation schemes were 0.7165, 0.3678, 0.1041, 0.2497, and 0.4337 [bits/s/Hz], respectively. According to the result, the beamforming scheme achieved 85.4% better than the multi-hop scheme. As mentioned earlier, the incremental cooperative schemes used one or two slot up to the destination node feedback,  
Figure 10: Normalized throughput vs. spectral efficiency. which means that it always had the better throughput performance than the single-hop scheme. In the case of the single-hop scheme, it had a good performance when it approached a high SNR because it was strong enough to deliver a signal, and then the multi-hop and the DF, the AF schemes had the same performance in high SNR between 19 and 30 dB in which those have half of the single-hop performance because those always used two slots. In Figure 12, throughput was normalized by each scheme energy consumption. In low SNR ranged between \(-\)20 and 1 dB, the ABF scheme was more robust than the others in which at a SNR of 0 dB the performance values of the ABF, the DBF, the single-hop, the multi-hop, the DF, the IDF, the AF, and the IAF were 25.994, 16.264, 17.505, 6.374, 11.378, 21.899, 9.381, and 19.057 [kbits/s/Hz/J], respectively. According to the result, the ABF scheme achieved 75.4% better than the multi-hop scheme. Whereas, in a high SNR range between 2 and 30 dB the IDF scheme was better than the other schemes including the beamforming scheme because the incremental approach and decode-and-forward mechanism were advantageous to save the energy consumption. In addition, at SNR 10 dB the performance values of the ABF, the DBF, the single-hop, the multi-hop, the DF, the IDF, the AF, and the IAF were 35.089, 21.954, 43.057, 20.936, 18.947, 55.422, 18.52, and 55.237 [kbits/s/Hz/J], respectively. Based on the result, the IDF achieved 62.2% better than the multi-hop scheme.