Evaluating and Reducing the Envelope Fluctuations of OFDM Signals Based on Distortion Prediction

Frequenz ◽  
2017 ◽  
Vol 71 (1-2) ◽  
pp. 73-81
Author(s):  
Xiangyin Zhang ◽  
Xiaodong Zhu ◽  
Youxi Tang
Keyword(s):  
System Performance ◽  
Orthogonal Frequency Division Multiplexing ◽  
Nonlinear Distortion ◽  
Average Power ◽  
Frequency Division Multiplexing ◽  
Power Ratio ◽  
Frequency Division ◽  
Selective Mapping ◽  
Mapping Scheme ◽  
Ofdm Signals

Abstract Orthogonal frequency division multiplexing (OFDM) signals with large envelope fluctuations are prone to be affected by power amplifier (PA), resulting in degradation of system performance. Peak-to-average power ratio (PAPR) and cubic metric (CM) are commonly used as the reduction criteria of envelope fluctuations of OFDM signals. However, our analysis shows that minimizing the PAPR or CM does not necessarily mean the optimization of system performance, since both metrics are inadequate to quantify the distortion in nonlinear OFDM transmission. In this paper, we fully discuss the effects of PA nonlinearity on OFDM signals and propose a new metric called distortion component metric (DCM), which is closely related to the nonlinear distortion caused by the PA. We compare the system performance when several metrics are respectively used as the reduction criterion for the selective mapping scheme. It is shown that in the presence of memoryless or memory PA, the usage of DCM can provide better inband and out-of-band performance than PAPR and CM.

Demonstrating the Effect of Using Goppa Coding with Hybrid Selective Mapping and Partial Transmit Sequence Technique for PAPR Reduction in OFDM Systems

2020 ◽  
pp. 2150095
Author(s):  
Vandana Pundir ◽  
Anwar Ahmad
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Average Power ◽  
Frequency Division Multiplexing ◽  
Power Ratio ◽  
Frequency Division ◽  
Partial Transmit Sequence ◽  
Simulation Results ◽  
Power Ratio Reduction ◽  
Selective Mapping ◽  
Ratio Reduction

Orthogonal Frequency Division Multiplexing is a multi-carrier modulation technique which provides numerous advantages like high spectral efficiency, minimal interference, low multipath fading, etc. But Peak-to-average Power Ratio is a severe challenge in using such multiplexing technique as it introduces distortions in nonlinear devices. Various Peak-to-average Power Ratio reduction techniques have been investigated in the literature to improve the performance of Orthogonal Frequency Division Multiplexing systems. But, each of them suffers either from high complexity or degraded bit error rate or less spectral efficiency. For reducing Peak-to-average Power Ratio more effectively, a hybrid combination of Partial Transmit Sequence with Selective Mapping is detected to show better performance. In this paper, we have combined Goppa coding technique with this hybrid Selective Mapping and Partial Transmit Sequence for further improving the performance. Along with Peak-to-average Power Ratio reduction capability, the proposed technique also has inherent error control mechanism due to the use of coding. Based on the simulation results, we have concluded that the proposed technique provides good amount of Peak-to-average Power Ratio reduction than conventional techniques. The proposed technique is analyzed for different number of Orthogonal Frequency Division Multiplexing symbol candidates for Selective Mapping and different number of block divisions for Partial Transmit Sequence. Further, this technique is simulated for different number of subcarriers and modulation order and the simulation results are compared with each other. The proposed technique also shows better Bit error rate values for high Signal-to-Noise ratio.

scholarly journals Advantages of Spectrally Efficient Frequency Division Multiplexing Over Orthogonal Frequency Division Multiplexing

2020 ◽  
Vol 9 (8) ◽  
pp. 238-244
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Average Power ◽  
Frequency Division Multiplexing ◽  
Power Ratio ◽  
Frequency Division ◽  
Sphere Decoder ◽  
Symbol Rate ◽  
Transmission Length ◽  
Spectrally Efficient ◽  
The Impact

An analysis on Spectrally Efficient Frequency Division Multiplexing (SEFDM) is contrast with Orthogonal Frequency Division Multiplexing (OFDM) considering the impact on Peak to Average Power Ratio (PAPR) and nonlinearities within fibre. With respect to OFDM the sub-carriers in SEFDM signals are compressed adjacent to each other at a rate of frequency lesser than the symbol rate. At the receiver end we have utilized the Sphere Decoder which is used to recover the data to remunerate the Interference created by the compressed signals (ICI) faced in the system. This research shows the advantages by using SEFDM and evaluates its achievement. PAPR. when compared with OFDM, while effects of non-linear fibres are considered. The use of various formats of modulation going from 4-QAM to 32-QAM, shows that the SEFDM signals have a noteworthy increment in the transmission length with respect to ordinary signals.

scholarly journals AN EFFICIENT METHOD FOR PAPR REDUCTION IN OFDM SYSTEMS WITH REDUCED COMPLEXITY

2013 ◽  
pp. 96-100
Author(s):  
PRITANJALI KUMARI ◽  
US TRIAR
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Average Power ◽  
High Peak ◽  
Papr Reduction ◽  
Power Calculation ◽  
Frequency Division Multiplexing ◽  
Power Ratio ◽  
Frequency Division ◽  
Ofdm Systems ◽  
Reduced Complexity

Orthogonal Frequency Division Multiplexing (OFDM), widely used in digital wireless communication, has a major drawback of high Peak to Average Power Ratio (PAPR). A reduced complexity partial transmit sequence (PTS) scheme has been proposed to solve high peak to average power ratio (PAPR) of orthogonal frequency division multiplexing (OFDM) system. In the proposed PTS scheme, a function is generated by summing the power of time domain samples at time ‘n’ in each sub blocks, known as “Hn”.Only those samples, having Hn greater than or equal to a preset threshold value (αT) are used for peak power calculation during the process of selecting a candidate signal with the lowest PAPR for transmission. As compared to conventional PTS scheme, the proposed scheme achieves almost the same PAPR reduction performance with much lower computational complexity.

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