**5.2. BER performance**

The BER performance of proposed WiMAX is evaluated here. In this study, the channel is assumed to be known perfectly at the receiver. The modulated signal is affected by SUI multipath channels and AWGN. Figure 18 shows the effect of different values of µ on the proposed system. In the following µ=13 is chosen to compromise between CCDF and BER performance. In Figure 19, at BER=10-4, SNR over SUI 1 decreases by 8.2 dB better than the conventional system. The amount of improvement in SNR at BER=10-4 over SUI 3 and SUI 5 is 7.8 dB,and 5.2 dB better than the conventional system by using µ- law as shown in Figures 20 and 21, respectively.

**Figure 14.** CCDF of PAPR with different µ (16-QAM constellation)

**Figure 15.** CCDF Performance comparisons with 16QAM.

**5.1. CCDF performance**

52 Selected Topics in WiMAX

for reduction where CR = 2.

**5.2. BER performance**

and 21, respectively.

modulation are used, respectively.

10-2

**Figure 14.** CCDF of PAPR with different µ (16-QAM constellation)

CCDF

10-1

100

Figure 14 shows the performance improvement of the proposed system over a conventional system, i.e., without PAPR reduction, for the µ- law for different value of µ using 16 QAM signal mapping. At the probability of 10-3, the PAPR is almost 1.1 dB, 2.55 dB, 4 dB and 4.5 dB smaller than conventional system, for µ=2, µ=4, µ=13 and µ=64, respectively. The same results are obtained when A-law is considered. Figure 15 shows the CCDF performance of the companding method at µ=13 compared with that of the system that is used clipping technique

Figures 16 and 17 show the improvements which are obtained when 64 QAM and QPSK

The BER performance of proposed WiMAX is evaluated here. In this study, the channel is assumed to be known perfectly at the receiver. The modulated signal is affected by SUI multipath channels and AWGN. Figure 18 shows the effect of different values of µ on the proposed system. In the following µ=13 is chosen to compromise between CCDF and BER performance. In Figure 19, at BER=10-4, SNR over SUI 1 decreases by 8.2 dB better than the conventional system. The amount of improvement in SNR at BER=10-4 over SUI 3 and SUI 5 is 7.8 dB,and 5.2 dB better than the conventional system by using µ- law as shown in Figures 20

> Conventional With companding,µ=2 With companding,µ=4 With companding,µ=13 With companding,µ=64

<sup>0</sup> <sup>2</sup> <sup>4</sup> <sup>6</sup> <sup>8</sup> <sup>10</sup> <sup>12</sup> <sup>14</sup> 10-3

PAPR0 [dB]

**Figure 16.** CCDF of PAPR with the proposed system (64QAM).

Figure 22 shows the system performance over AWGN only, where the amount of improvement in SNR is 10.7 dB at BER=10-4 than the conventional system. The BER performance of the companding method compared with the system that is used clipping technique where CR = 2 and CR=1.4 is shown in Figure 23.

0 5 10 15 20 25 30 35 40

0 5 10 15 20 25 30 35 40

SNR [dB]

Without Peak reduction With Proposed Method

PAPR Reduction in WiMAX System http://dx.doi.org/10.5772/55380 55

Without Peak reduction With Proposed Method

SNR [dB]

10-5

**Figure 19.** BER Performances over SUI 1 and AWGN.

10-5

**Figure 20.** BER Performance over SUI 3 and AWGN.

10-4

10-3

BER

10-2

10-1

100

10-4

10-3

BER

10-2

10-1

100

**Figure 17.** CCDF of PAPR with the proposed system (QPSK).

**Figure 18.** BER Performance with different µ.

**Figure 19.** BER Performances over SUI 1 and AWGN.

0 2 4 6 8 10 12 14

0 5 10 15 20 25 30

SNR [dB]

Without companding With companding µ=2 With companding µ=13 With companding µ=64 Conventional With companding,µ=4 With companding,µ=13

PAPR0 [dB]

10-3

**Figure 17.** CCDF of PAPR with the proposed system (QPSK).

10-5

**Figure 18.** BER Performance with different µ.

10-4

10-3

BER

10-2

10-1

100

10-2

CCDF

10-1

100

54 Selected Topics in WiMAX

**Figure 20.** BER Performance over SUI 3 and AWGN.

0 5 10 15 20 25 30 35

With companding,µ=13 With clipping CR=2 With clipping CR=1.4

PAPR Reduction in WiMAX System http://dx.doi.org/10.5772/55380 57

SNR [dB]

We have investigated the PAPR in the WiMAX system. We investigates the simulation performance of WiMAX OFDM PHY Layer in the Presence of Nonlinear Power Amplifier and the new method is suggested to reduce PAPR where the simulation results show that, the peak power reduces by about 4 dB and SNR also decreases more than 5 dB at BER =10-4. The Stanford University Interim (SUI) channel models are selected for the wireless channel in the simulation.

Moreover the equalizer performance with SUI multipaths channel is explained.

\*Address all correspondence to: shokair\_1999@hotmail.com i\_shokair@yahoo.com

Dept. of Electrical Communication, Faculty of Electronic Engineering, El-Menoufia Universi‐

10-5

and Hifzalla Sakran

**Figure 23.** BER Performance comparisons.

**6. Summary**

**Author details**

ty El-Menoufia, Egypt

Mona Shokair\*

10-4

10-3

BER

10-2

10-1

100

**Figure 21.** BER Performances over SUI 5 and AWGN.

**Figure 22.** BER Performance over AWGN only.

**Figure 23.** BER Performance comparisons.
