Authors : Mohamed I. Shujaa and Laith Falah Mohammed Hassan
Abstract: The Orthogonal Frequency Division Multiplexing (OFDM) technique is one of the recognized technologies in the wireless communications because of its resistance to frequency selective fading channel. The major element affecting nonlinearity is the High-Power Amplifier (HPA) when operated almost to a saturation point. The memory HPA makes the OFDM signal to suffer from degradation in its performance. In this study, the proposed Adaptive Filter Predistorter (AFP) and Simplicial Canonical Piecewise Linear (SCPWL) digital predistorters are used to eliminate the side effects of the HPA. Signal to Noise Ratio (SNR) vs. Bit Error Rate (BER) is taken as a normative of system performance. The results of the simulation present the strong performance of the proposed method for eliminating the nonlinearity and the memory effects of the HPA over SCPWL predistorter. The AFP has been provided a low BER under all situations. The SCPWL has been produced a very high BER under a memory HPA and better BER under a memoryless HPA. The Input Back Off (IBO) and Output Back Off (OBO) have been computed under memory HPA in three cases: without predistorter with SCPWL and with proposed. The IBO has been equal to (0.3982), (0.2992) and (0.2074) and the OBO has been equal to (0.1814), (0.1229) and (0.1252), respectively.
Mohamed I. Shujaa and Laith Falah Mohammed Hassan, 2018. Adaptive Filter for a Memory HPA Distortion in OFDM Signals. Journal of Engineering and Applied Sciences, 13: 6225-6231.