# Singular Value Decomposition Channel Estimation in STBC MIMO-OFDM System
## 5 Simulation Results
As can be seen from Figures 11 and 12, the BER curves of four channel estimation methods show a downward trend. The performance with the QPSK and 16 QAM modulation modes is presented in the CDT8 channel. The CDT8 channel has stronger frequency-selectivity than the CDT6 channel. However, the proposed SVD method still shows the advantages of channel estimation in MIMO-OFDM systems. In Figure 11, at the BER of \(5\times 10^{-2}\), compared with the threshold and LS methods, the SVD method has about 3.3 dB and 6.9 dB SNR gains, respectively. Figure 10: Comparisons of BER performance in the case of 64 QAM modulation at the static CDT6 channel. Figure 9: Comparisons of BER performance in the case of 16 QAM modulation at the static CDT6 channel. In Figure 12, at the BER of \(10^{-1}\), the SVD method outperforms the threshold and LS methods by about 7.1 dB and 12.7 dB SNR gains, respectively. The threshold channel estimation method does not perform well due to an inaccurate selection of the threshold. The SVD method can suppress the noise effectively and has better performance than threshold and LS channel estimation methods. Hence, the SVD channel estimation method can show obvious advantages in the CDT8 channel with a strong frequency-selectivity. Under the 16 QAM and 64 QAM modulation modes, the BER performance curves in Brazil A channel are shown in Figures 13 and 14, respectively. As can be seen from Figures 13 and 14, the proposed SVD channel estimation method can be well applied to the Brazil A channel. In Figure 13, at the BER of \(10^{-2}\), the SVD method outperforms the threshold method by about 4.9 dB SNR gains. At the BER of \(10^{-3}\), the SVD method outperforms the  
Figure 11: Comparisons of BER performance in the case of QPSK modulation at the static CDT8 channel. Figure 12: Comparisons of BER performance in the case of 16 QAM modulation at the static CDT8 channel. threshold method by about 3.1 dB SNR gains. In Figure 14, the SVD method has a good performance in the 64 QAM modulation scheme. With the increase of SNR, the BER curves of the LS and threshold methods decrease slowly due to the influence of AWGN. At the BER of \(6\times 10^{-2}\), the proposed SVD method has about 0.27 dB SNR gains than the MMSE method. Although the performance of the SVD method is only slightly better than that of the MMSE method, the selected singular values can recover the information of CSI to a great extent and suppress the noise at the same time. Under the 16 QAM and 64 QAM modulation modes, the BER performance curves in the Brazil B channel are shown in Figures 15 and 16, respectively. The strong frequency-selectivity of the Brazil B channel will reduce the BER performance of channel estimation methods. However, the SVD channel estimation method has a better performance than LS and threshold methods. In Figure 15, at the BER of \(10^{-1}\), the SVD method outperforms the  
Figure 14: Comparisons of BER performance in the case of 64 QAM modulation at the static Brazil A channel. Figure 6:0 Comparisons of BER performance in the case of 16 QAM modulation at the static Brazil A channel. threshold and LS methods by about 7.4 dB and 12.4 dB SNR gains, respectively. In Figure 16, the SVD method has a better performance than the threshold and LS methods under the Brazil B channel. The BER performance curves of the SVD channel estimation method decrease with the increase of SNR. At the BER of \(2\times 10^{-1}\), the proposed SVD method outperforms the MMSE method by about 0.3 dB SNR gains. Hence, the SVD channel estimation method can be used under the condition of the 64 QAM modulation and strong frequency-selectivity Brazil B channel. The computational complexity of four channel estimation methods is shown in Figure 6:1 It can be seen that there is no multiplication in the LS and threshold methods. Both the LS and threshold methods only need the \(N\) points division. Hence, the LS and threshold cha  
Figure 6:2 Comparisons of BER performance in the case of 64 QAM modulation at the static Brazil B channel.