scholarly journals Peak-to-Average Power Ratio reduction in Wavelet based OFDM using Modified Selective Mapping for Cognitive Radio Applications

2021 ◽  
Vol 18 (12) ◽  
Author(s):  
Arjun K R ◽  
Surekha T P
Keyword(s):  
Quality Of Service ◽  
Cognitive Radio ◽  
Linear Part ◽  
Cognitive Radios ◽  
Average Power ◽  
Power Ratio ◽  
Ofdm Systems ◽  
Radio System ◽  
Selective Mapping

The prospect of guaranteed quality of service for primary and secondary users in the expression of regulated Peak-to-Average Power Ratio (PAPR) and Bit Error Rate (BER) can be increased in Cognitive Radios using Wavelet based OFDM systems which localize spectrum in realms of time and frequency. However, cutting the Gordian knot of high PAPR associated with the Multi-Carrier Modulation schemes to operate in the linear part of the power amplifier nourishing the balance between PAPR and BER is difficult. In this paper, the phase of the subcarriers is altered by a value of finite, equally spaced phase shifts. The frame of Wavelet-based OFDM (WOFDM) with minimum PAPR guarantees the minimum quality of service (QoS) in terms of Throughput. BER is then identified and transmitted. This modification is applied to various Wavelets and compared amongst WOFDM and FFT-based OFDM schemes. The novelty of this paper lies in using Hadamard and/or Toeplitz matrix to generate phase sequences in a modified SLM technique of Wavelet-based OFDM systems while maintaining the minimum required QoS in Cognitive Radios. The result shows that the proposed technique reduces the PAPR compared to unmodified SLM techniques. HIGHLIGHTS Wavelet based OFDM systems localize spectrum in realms of time and frequency The sinusoid bases function in OFDM has been replaced by Wavelet bases Selective Mapping (SLM) is a popular technique towards PAPR reduction The primary function of the Cognitive Radio system is to identify the spectrum holes GRAPHICAL ABSTRACT

Peak-to-average power ratio in MIMO-OFDM systems using selective mapping

2003 ◽  
Vol 7 (12) ◽  
pp. 575-577 ◽  
Author(s):  
Yung-Lyul Lee ◽  
Young-Hwan You ◽  
Won-Gi Jeon ◽  
Jong-Ho Paik ◽  
Hyoung-Kyu Song
Keyword(s):  
Average Power ◽  
Power Ratio ◽  
Ofdm Systems ◽  
Mimo Ofdm ◽  
Selective Mapping

scholarly journals An Efficient Adaptive Technique with Low Complexity for Reducing PAPR in OFDM-Based Cognitive Radio

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Hefdhallah Sakran ◽  
Omar Nasr ◽  
Mona Shokair
Keyword(s):  
Cognitive Radio ◽  
Orthogonal Frequency Division Multiplexing ◽  
Average Power ◽  
Low Complexity ◽  
Papr Reduction ◽  
Modulation Scheme ◽  
Ofdm Systems ◽  
Cpu Time ◽  
Reduction Techniques ◽  
Selective Mapping

Cognitive radio (CR) is considered nowadays as a strong candidate solution for the spectrum scarcity problem. On standards level, many cognitive radio standards have chosen Non-Contiguous Orthogonal Frequency Division Multiplexing (NC-OFDM) as their modulation scheme. Similar to OFDM, NC-OFDM suffers from the problem of having a high Peak to Average Power Ratio (PAPR). If not solved, either the transmitted signal will be distorted, which will cause interference to primary (licensed) users, or the effeciency of the power amplifier will be seriously degraded. The effect of the PAPR problem in NC-OFDM based cognitive radio networks is worse than normal OFDM systems. In this paper, we propose enhanced techniques to reduce the PAPR in NC-OFDM systems. We start by showing that combining two standard PAPR reduction techniques (interleaver-based and selective mapping) results in a lower PAPR than using them individually. Then, an “adaptive number of interleavers” will be proposed that achieves the same performance of conventional interleaver-based PAPR reduction while reducing the CPU time by 41.3%. Finally, adaptive joint interleaver with selective mapping is presented, and we show that it gives the same performance as conventional interleaver-based technique, with reduction in CPU time by a factor of 50.1%.

scholarly journals Peak to Average Power Ratio Reduction Techniques

2021 ◽  
Vol 9 (VI) ◽  
pp. 4256-4261
Author(s):  
Mohan Reddy
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Average Power ◽  
Mapping Technique ◽  
Power Ratio ◽  
Ofdm Systems ◽  
Major Drawback ◽  
Reduction Techniques ◽  
Power Ratio Reduction ◽  
Selective Mapping ◽  
Clipping And Filtering

Multiple-input to multiple-output (MIMO) and orthogonal frequency division multiplexing (OFDM) are the utmost widely used wireless communication system because of its large benefits and advantageous. Though MIMO OFDM systems have high advantages there is a major drawback that makes the system noisy and the inefficient use of bandwidth. This drawback mainly occurred due to the spikes in the transmitting signal. These spikes make the value of peak to average power ratio of the signal high and results in distortion and noise in the signal. To avoid these spikes there are number of techniques introduced. We will discuss about the three methods namely partial transmit sequence, clipping and filtering method, Selective Mapping technique. All these methods are used to decrease the high peak to the average ratio by removing the spikes in the signal. And we will see the outputs obtained by using MATLAB software. Clipping and filtering technique would be the simplest technique to lower the peak to average power ratio while partial transmit technique is the most efficient method to diminish the peak to the average power ratio.

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