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Mobile and Wireless Communications-Physical layer development and implementation 2012 Part 5

Tham khảo tài liệu 'mobile and wireless communications-physical layer development and implementation 2012 part 5', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Performance of Wireless Communication Systems with MRC over Nakagami-m Fading Channels 71 the measure of the difference between different PDF s. The results are shown in Table 1. As observed from Table 1 the difference in MSE sense between the PDF computed for K 100 000 and that computed for K 100 is extremely small 10- 26.2482 and the convergence is fast. Note however that the convergence rate depends on the system parameters as evident from Figure 1. K MSE 1 10-2.2726 10 10-3.1351 20 10-3.8496 30 10-4.5195 50 10-5.9959 70 10-10.9634 100 10-26.2482 Table 1. MSE s between the PDF s computed for different K s and the PDF computed for K 100 000 with the branch power-correlation matrix Rxi . Fig. 3. Bit error probability comparisons for different fading orders with BPSK modulation and branch power and branch correlation matrix of the Case 2 with the branch powercorrelation matrix Rxi . 72 Mobile and Wireless Communications Physical layer development and implementation Practicality of the derived results The question that remains to be answered is whether the performances of MRC wireless systems over Nakagami-m fading channels would vary significantly when the fading orders are changing to the nearest integers from half of Fig. 4. Bit error probabilities of an MRC receiver derived in 35 using the MGF derived in 15 and the MGF given in Zhang 2003 for the Cases 2 and 3 with L 4 branches and the branch power-correlation matrix Rxi for BPSK modulation. We investigate this question through numerical results. Figure 2 presents the outage probabilities for different values of fading orders. The results presented in Figure 2 are for a SNR threshold h 2dB the branch power vector Q1 and branch correlation matrix given in 42 . As seen in Figure 2 among the four fading orders only one is rounded from 0.5 to 1 but the difference in outage probability is already significant especially at high SNR s. The same is observed for BEP performance given in Figure 3. These observations are .