IRJET- Overview of PAPR Reduction Techniques of OFDM System
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This document discusses techniques to reduce peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems. OFDM is used widely in modern telecommunications but suffers from high PAPR, which reduces power amplifier efficiency. The document reviews several common PAPR reduction techniques for OFDM including active constellation extension, tone reservation, selected mapping, partial transmit sequences, companding, and tone injection. It compares the advantages and drawbacks of each approach and concludes that no single technique can fully solve the PAPR problem on its own. System design must consider factors like data rate, complexity, bit error rate, and signal power in addition to PAPR reduction.
![International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 06 Issue: 03 | Mar 2019 www.irjet.net p-ISSN: 2395-0072
© 2019, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 7798
Overview of PAPR Reduction Techniques of OFDM System
Jaspreet Singh Deo1
1Assistant Professor, Khalsa College of Engineering and Technology, Punjab, India
---------------------------------------------------------------------***---------------------------------------------------------------------
Abstract - Orthogonal Frequency Division Multiplexing
(OFDM) is one of the efficient multicarrier modulation
scheme used in mobile Communications. The advantages of
OFDM includes the removal ofandInterSymbol Interference
(ISI) and Inter Carrier Interference (ICI)) in the signal [1].
However transmission of OFDM signals using power
amplifiers are unavoidably loss free due to high Peak to
Average Power Ratio (PAPR). There are couples of
techniques used to eradicate theissuediscussedherewithin.
Key Words: PAPR; PTS; OFDM; SLM; ICI; ISI; TR; HPA (High Power
Amplifier)
1. INTRODUCTION
OFDM is a frequency division multiplexing (FDM) and it is
used by the American National Defense Department for
military communications. In this subcarriers are orthogonal
with each other that increase the spectral efficiency of the
system. This technique was proposed by RW Chang in 1965,
and it was patented at the USPD and then after it was used in
military communication systems
2. OFDM System and PAPR
OFDM system
Orthogonal frequency division multiplexing (OFDM most
widely used for 4G and 5G telecommunications standards
modulation technology that includes digital radio
broadcasting, digital terrestrial television (DTT), wireless
local area networks (LANs), etc. It consists of transmitter
side and the receiver side [2].
OFDM transceiver
The basic principle of OFDM is to divide the existing
bandwidth into several sub-carriers. With the number of
sub-carriers, it gets more resistant to frequency selective
fading, as a result data rates also increasing. But, number of
sub-carriers cannot beincreasedarbitrarilybeyonda certain
level because it makes make transmission more sensitive to
the time incoherence of the channel.
Figure 1: OFDM system transmitter.
OFDM system transmitter
The received data is the information to be transmitted using
OFDM through the channel. This data is transformed into N-
parallel data streams with the help of serial to parallel
converter. Further, it can be modulatedandgiventotheIFFT
block as an input [3]. The parallel data is changed into serial
data with the help of parallel to serial converter. To cancel
the impact of ISI, cyclic prefix is introduced between two
symbols. The available baseband signal isupconvertedtoan
RF pass band signal with the use of a mixer or modulators.
Figure 2: OFDM System receiver.
PAPR
The OFDM signal has a high peak power when added in the
same phase at IFFT, it causes out-of-band radiation, it
further distorts the signals in adjacent bands. This reduces
the efficiency of power amplifiers and degrades the overall
performance of the OFDM system. PAPR increase the
complexity in the ADC and DAC, and it reduces the efficiency
of RF (radio frequency) amplifiers [4].
3. PAPR Reduction Techniques
The PAPR reduction includes coding, Active constellation
extension (ACE), Tone reservation (TR), Selected mapping
(SLM), Partial transmit sequences (PTS), Companding,Tone
injection (TI)
3.1 Active constellation extension (ACE)
In ACE, constellation points in some outer signal are
extended in each block outside of the constellation [5].
Advantages:
A. Less loss of data rate.
B. No extra information is required.
C. Less distortion of the original signal.
Drawbacks:
Require addition operations after FFT operation in
receiver.](https://image.slidesharecdn.com/irjet-v6i3938-190921091745/85/IRJET-Overview-of-PAPR-Reduction-Techniques-of-OFDM-System-1-320.jpg)
![International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 06 Issue: 03 | Mar 2019 www.irjet.net p-ISSN: 2395-0072
© 2019, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 7799
3.2 Tone reservation (TR)
It reserves few tones and assign them suitable values [6].
Advantages:
A. No distortion is introduced to the data bearing tones
B. No side information is required.
Drawbacks:
A. Improves the average energy per bit.
B. Loss of spectral efficiency.
C.
3.3 Selected mapping (SLM)
In this, some candidate data blocks are created and the one with
lowest PAPR is transmitted. [7].
Advantage:
A. No distortion is introduced.
B. Independent of number of carriers.
Drawback:
A. Extra information is required.
B. Corrupt BER performance.
3.4 Partial transmit sequences (PTS)
The subcarriers in each of the sub blocks are rotated by phase
factor, so the PAPR of the combination is minimized [8].
Advantage:
A. Less distortion is introduced.
B. Less complex.
Drawbacks:
A. Side information is required
3.5 Companding
In this technique, the small signals are enlarged while compressing
the large signals. The compression is done out at the transmitter
end. The Compression of the signal decreases the high peaks, as a
result PAPR is reduced [9].
Advantage: Less distortion is introduced.
Drawback: Loss of data rate.
Tone injection (TI)
The TI technique, basic idea is to increase the constellation size so
each point present in the original constellation could be mapped
into various equivalent points. Inanoriginalconstellationpoint,the
equivalent constellation points are added so PAPR reduced. The
calculation of the sub-carrier time domain signals also gives
lowered PAPR [9].
Advantage: No data rate loss.
Drawback: Require modulo-D addition, after an FFT operation
in the receiver.
4. CONCLUSIONS
In this paper, it is compared and analyses different PAPR reduction
techniques. However, no technique solely eradicatePAPRproblem.
Before implementing the technique various other factors like
maintaining data rate,computationalcomplexity,BER,signalpower
should also be taken into acknowledgement.
REFERENCES
1. Litwin, Louis, Pugel, Michael (2001) The principles of OFDM. RF Signal
Processing, pp. 30-48.
2. Yao Y, Ma S, Hu J (2013) A PAPR reduction scheme with residue
number system for OFDM. EURASIP Journal on Wireless Communications
and Networking, pp. 1-11.
3. Bingiham J (1990) Multicarrier modulation for data transmission: an
idea whose time has come. IEEE Commun Mag 28(5): 5-14.
4. Han SH, Lee JH (2005) An overview of peak-to-average power ratio
reduction techniques for multicarrier transmission. IEEE Wirel Commun
12(2): 56-65.
5. Lee BM, Kim Y (2013) An adaptive clipping and filtering technique for
PAPR reduction of OFDM signals. Circuits, Systems and Signal Processing
32(3): 1335-1349.
6. Wang YC, Luo ZQ (2011) Optimized Iterative Clipping and Filtering for
PAPR Reduction of OFDM Signals. IEEE Trans Commun 59(1): 33-37.
7. Jeon HB, Shin DJ (2011) A low complexity SLM scheme using additive
mapping sequences for PAPR reduction of OFDM signals. IEEE Trans
Broadcast 57(4): 866-874.
8. Chen Ye (2014) PAPR reduction of OQAM-OFDM signals using
segmental PTS scheme with low complexity. IEEE Trans Broadcast 60(1):
141-147.
9. Li CP, Wang SH (2010) Novel low complexity SLM schemes for PAPR
reduction in OFDM systems. IEEE Trans Signal processing 58(5): 2916-
2921.](https://image.slidesharecdn.com/irjet-v6i3938-190921091745/85/IRJET-Overview-of-PAPR-Reduction-Techniques-of-OFDM-System-2-320.jpg)
IRJET- Overview of PAPR Reduction Techniques of OFDM System
- 1. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 06 Issue: 03 | Mar 2019 www.irjet.net p-ISSN: 2395-0072 © 2019, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 7798 Overview of PAPR Reduction Techniques of OFDM System Jaspreet Singh Deo1 1Assistant Professor, Khalsa College of Engineering and Technology, Punjab, India ---------------------------------------------------------------------***--------------------------------------------------------------------- Abstract - Orthogonal Frequency Division Multiplexing (OFDM) is one of the efficient multicarrier modulation scheme used in mobile Communications. The advantages of OFDM includes the removal ofandInterSymbol Interference (ISI) and Inter Carrier Interference (ICI)) in the signal [1]. However transmission of OFDM signals using power amplifiers are unavoidably loss free due to high Peak to Average Power Ratio (PAPR). There are couples of techniques used to eradicate theissuediscussedherewithin. Key Words: PAPR; PTS; OFDM; SLM; ICI; ISI; TR; HPA (High Power Amplifier) 1. INTRODUCTION OFDM is a frequency division multiplexing (FDM) and it is used by the American National Defense Department for military communications. In this subcarriers are orthogonal with each other that increase the spectral efficiency of the system. This technique was proposed by RW Chang in 1965, and it was patented at the USPD and then after it was used in military communication systems 2. OFDM System and PAPR OFDM system Orthogonal frequency division multiplexing (OFDM most widely used for 4G and 5G telecommunications standards modulation technology that includes digital radio broadcasting, digital terrestrial television (DTT), wireless local area networks (LANs), etc. It consists of transmitter side and the receiver side [2]. OFDM transceiver The basic principle of OFDM is to divide the existing bandwidth into several sub-carriers. With the number of sub-carriers, it gets more resistant to frequency selective fading, as a result data rates also increasing. But, number of sub-carriers cannot beincreasedarbitrarilybeyonda certain level because it makes make transmission more sensitive to the time incoherence of the channel. Figure 1: OFDM system transmitter. OFDM system transmitter The received data is the information to be transmitted using OFDM through the channel. This data is transformed into N- parallel data streams with the help of serial to parallel converter. Further, it can be modulatedandgiventotheIFFT block as an input [3]. The parallel data is changed into serial data with the help of parallel to serial converter. To cancel the impact of ISI, cyclic prefix is introduced between two symbols. The available baseband signal isupconvertedtoan RF pass band signal with the use of a mixer or modulators. Figure 2: OFDM System receiver. PAPR The OFDM signal has a high peak power when added in the same phase at IFFT, it causes out-of-band radiation, it further distorts the signals in adjacent bands. This reduces the efficiency of power amplifiers and degrades the overall performance of the OFDM system. PAPR increase the complexity in the ADC and DAC, and it reduces the efficiency of RF (radio frequency) amplifiers [4]. 3. PAPR Reduction Techniques The PAPR reduction includes coding, Active constellation extension (ACE), Tone reservation (TR), Selected mapping (SLM), Partial transmit sequences (PTS), Companding,Tone injection (TI) 3.1 Active constellation extension (ACE) In ACE, constellation points in some outer signal are extended in each block outside of the constellation [5]. Advantages: A. Less loss of data rate. B. No extra information is required. C. Less distortion of the original signal. Drawbacks: Require addition operations after FFT operation in receiver.
- 2. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 06 Issue: 03 | Mar 2019 www.irjet.net p-ISSN: 2395-0072 © 2019, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 7799 3.2 Tone reservation (TR) It reserves few tones and assign them suitable values [6]. Advantages: A. No distortion is introduced to the data bearing tones B. No side information is required. Drawbacks: A. Improves the average energy per bit. B. Loss of spectral efficiency. C. 3.3 Selected mapping (SLM) In this, some candidate data blocks are created and the one with lowest PAPR is transmitted. [7]. Advantage: A. No distortion is introduced. B. Independent of number of carriers. Drawback: A. Extra information is required. B. Corrupt BER performance. 3.4 Partial transmit sequences (PTS) The subcarriers in each of the sub blocks are rotated by phase factor, so the PAPR of the combination is minimized [8]. Advantage: A. Less distortion is introduced. B. Less complex. Drawbacks: A. Side information is required 3.5 Companding In this technique, the small signals are enlarged while compressing the large signals. The compression is done out at the transmitter end. The Compression of the signal decreases the high peaks, as a result PAPR is reduced [9]. Advantage: Less distortion is introduced. Drawback: Loss of data rate. Tone injection (TI) The TI technique, basic idea is to increase the constellation size so each point present in the original constellation could be mapped into various equivalent points. Inanoriginalconstellationpoint,the equivalent constellation points are added so PAPR reduced. The calculation of the sub-carrier time domain signals also gives lowered PAPR [9]. Advantage: No data rate loss. Drawback: Require modulo-D addition, after an FFT operation in the receiver. 4. CONCLUSIONS In this paper, it is compared and analyses different PAPR reduction techniques. However, no technique solely eradicatePAPRproblem. Before implementing the technique various other factors like maintaining data rate,computationalcomplexity,BER,signalpower should also be taken into acknowledgement. REFERENCES 1. Litwin, Louis, Pugel, Michael (2001) The principles of OFDM. RF Signal Processing, pp. 30-48. 2. Yao Y, Ma S, Hu J (2013) A PAPR reduction scheme with residue number system for OFDM. EURASIP Journal on Wireless Communications and Networking, pp. 1-11. 3. Bingiham J (1990) Multicarrier modulation for data transmission: an idea whose time has come. IEEE Commun Mag 28(5): 5-14. 4. Han SH, Lee JH (2005) An overview of peak-to-average power ratio reduction techniques for multicarrier transmission. IEEE Wirel Commun 12(2): 56-65. 5. Lee BM, Kim Y (2013) An adaptive clipping and filtering technique for PAPR reduction of OFDM signals. Circuits, Systems and Signal Processing 32(3): 1335-1349. 6. Wang YC, Luo ZQ (2011) Optimized Iterative Clipping and Filtering for PAPR Reduction of OFDM Signals. IEEE Trans Commun 59(1): 33-37. 7. Jeon HB, Shin DJ (2011) A low complexity SLM scheme using additive mapping sequences for PAPR reduction of OFDM signals. IEEE Trans Broadcast 57(4): 866-874. 8. Chen Ye (2014) PAPR reduction of OQAM-OFDM signals using segmental PTS scheme with low complexity. IEEE Trans Broadcast 60(1): 141-147. 9. Li CP, Wang SH (2010) Novel low complexity SLM schemes for PAPR reduction in OFDM systems. IEEE Trans Signal processing 58(5): 2916- 2921.