A new Technique for reduction PAPR of OFDM signal on Multicarrier Communication.

1. Efficient Techniques for PAPR
Reduction in Multicarrier
Communication
Under the Guidance of Submitted by
Dr. PRIYANKA MISHRA MOHAMMED MONEIM
Assistant Professor 16SETBTECLE8008f

2. Contents
• Introduction
• Objectives
• Literature Survey
• Methodology
• Simulation Results and Discussion
• Conclusion and Future Work
• References

3. Introduction
OFDM (Orthogonal Frequency Division Multiplex), is multicarrier
modulation appropriate composed. The essential concept is to
transmit data, high data rate information.
by splitting the data into various interleaved, parallel bitstreams,
and every slice of these bitstreams modulates an independent
subcarrier. In this modulation, the channel spectrum is pushing
through a number of separated non-selective frequency sub-
channels. These sub-channels are used for one transmission link
between the transmitter-receiver. OFDM is expeditiously recognized
by the use of active signal processing method, fast-Fourier
Transform, in the transmitter-receiver.
•

4. Objectives
•Calculation of PAPR in an OFDM signal
•Reduction in PAPR using PTS
•Reduction in PAPR + DCT Technique

5. Literature Review
[1] Mattsson et al. (2008), found a very elegant analysis of the symbol error rate in a companded COFDM system. A
comment that we want to make is that it seems the noise power was constant] while the transmitted signal’s power
was increased as it got companded. It would in our opinion be more meaningful to compare the performance of the
companded signal to that of an uncompanded signal of equal power.
[2] Zhao et al. (2008), managed Peak-to-average power ratio (PAPR) reduction is a powerful tool that can increase
power efficiency and reduce distortion noise in MIMO-OFDM systems. Various PAPR metrics have been used in the
MIMO-OFDM literature without justifications regarding the physical mechanisms that support those PAR definitions.
In this paper, we show that in order to deliver high power efficiency, two MIMO-OFDM linear-scaling schemes are
possible: one that scales all MIMO branches with the samefactor and another that uses a different scaling factor for
each branch. For each system, we derive a meaningful PAR metricthat should be used.
[3] Aburakhia et al. (2009), figured out the major drawback of orthogonal frequency-division multiplexing (OFDM)
signals is their high peak-to-average power ratio (PAPR), which causes serious degradation in performance when a
nonlinear power amplifier (PA) is used. Companding trans-form (CT) is a well-known method to reduce PAPR without
restrictions on system parameters such as number of subcarriers, frame format and constellation type. Recently, a
linear nonsymmetrical companding transform (LNST) that has better performance than logarithmic-based transforms
such as-law companding was proposed. In this paper, a new linear companding transform (LCT) with more design
flexibility than LNST is proposed. Computer simulations show that the proposed transform has a better PAPR
reduction and bit error rate (BER) performance than LNST with better power spectral density (PSD).

6. [4] Chen (2009), considered the use of the partial transmit sequence (PTS) technique to reduce the peak-to-average power ratio
(PAPR) of an orthogonal frequency division multiplexing (OFDM) signal. The conventional PTS technique can provide good PAPR
reduction performance for OFDM signals; however, it requires an exhaustive search over all combinations of allowed phase factors,
resulting in high complexity. In order to reduce the complexity while still improving the PAPR statistics of an OFDM signal, a new
method using the Cross-Entropy (CE) method is proposed to reduce both the PAPR and the computational load. In the proposed CE
method, defined a score or fitness function based on the corresponding PAPR reduction performance. The score function is then
translated into a stochastic approximation problem which can be solved effectively. The simulation results show that the
performance of the proposed CE method provides almost the same PAPR reduction as that of the conventional exhaustive search
algorithm while maintaining low complexity.
[5] Wang et al. (2009), advised a new convex optimization strategy to both reduce the peak-to-average power ratio (PAPR) and the
PAPR variance of orthogonal frequency-division multiplexing (OFDM) symbols. There are three distinctions of this proposed
method as compared to existing methods: 1) PAPR, error vector magnitude (EVM), and free subcarrier power overhead are
constrained simultaneously; 2) the EVM constraint is root-mean-square EVM (RMS-EVM); and 3) an auxiliary parameter,, is used to
generate quasi-constant PAPR through our proposed binary search algorithm (here, quasi-constant refers to the condition that
most OFDM symbols’ PAPR values are within a small, preset neighborhood). Simulation results are provided to demonstrate the
effectiveness of the approach in comparison to others that consider.
[6] Hou et al. (2010), asseted Companding transform is a simple and efficient method in reducing the Peak-to-Average Power Ratio
(PAPR) of Orthogonal Frequency Division Multiplexing (OFDM) systems. In this paper, a novel nonlinear companding scheme is
proposed to reduce the PAPR and improve Bit Error Rate (BER) for OFDM systems. This proposed scheme mainly focuses on
compressing the large signals, while maintaining the average power constant by properly choosing transform parameters.
Moreover, analysis shows that the proposed scheme without de-companding at the receiver can also offer a good BER
performance. Finally, simulation results show that the proposed scheme outperforms other companding scheme in terms of
spectrum side-lobes, PAPR reduction and BER performance.

7. [7] Shin et al. (2013), found a peak-to-average-ratio (PAPR) reduction scheme based on a weighted orthogonal frequency-division multiplexing (OFDM)
signal is proposed to reduce the PAPR without distortion in removing the weight at the receiver side. In the proposed scheme, a weight is imposed on
each discrete OFDM signal via a certain kind of a band limited signal, and an OFDM signal formed with the weighted discrete data is then considered
before a high power amplifier (HPA), whereas the original signal can be recovered completely at the receiver side. Meanwhile, the time duration
needed to transmit the weighted OFDM signal is the same as the time duration for the original OFDM signal. The effectiveness of the proposed scheme
is evaluated with computer simulations. According to numerical results, the PAPR of the weighted OFDM signal is smaller than that of the clipping and
filtering (C&F) method and the bit-error-rate (BER) performance of the weighted OFDM system is improved compared with the C&F method. Here, the
proposed method is simpler than the C&F method.
[8] Rabie et al. (2014), considered Impulsive-noise (IN) over power-line channels can cause serious performance degradations. As such, many IN
mitigation techniques have been proposed in the literature, the most common of which is the blanking technique. The conventional way to implement
this technique, however, requires prior knowledge about the IN characteristics to identify the optimal blanking threshold (OBT). When such knowledge
cannot be obtained, the performance deteriorates rapidly. To alleviate this, proposed a lookup table (LUT)-based algorithm with uniform quantization
to utilize estimates of the peak-to-average power ratio at the receiver to determine the OBT. To fully evaluate the performance of the proposed
method, investigated the impact of quantization bits on the system performance in terms of signal-to-noise ratio (SNR) and symbol error rate under
various IN scenarios. The results reveal that a 5-bit LUT is sufficient to achieve a gain of up to 3-dB SNR improvement relative to the conventional
blanking method. It will also be shown that to maintain good performance, the resolution of quantization must be increased especially when the IN
probability of occurrence is relatively high.
[9] Polyanskiy et al. (2014), considered a problem of forward error-correction for the additive white Gaussian noise (AWGN) channel. For finite
blocklength codes, the backoff from the channel capacity is inversely proportional to the square root of the block length. In this paper, it is shown that
the codes achieving this tradeoff must necessarily have peak-to-average power ratio (PAPR) proportional to logarithm of the block length. This is
extended to codes approaching capacity slower, and to PAPR measured at the output of an orthogonal frequency division multiplexing modulator. As a
by-product, the convergence of (Smith’s) amplitude-constrained AWGN capacity to Shannon’s classical formula is characterized in the regime of large
amplitudes. This converse-type result builds upon recent contributions in the study of empirical output distributions of good channel codes.

8. [ 13] Agiwal et al. (2016), focuses on next generation 5G wireless communications lies in providing very high data rates (typically of Gbps order), extremely low latency, manifold
increase in base station capacity, and significant improvement in users’ perceived quality of service (QoS), compared to current 4G LTE networks. Ever increasing proliferation of
smart devices, introduction of new emerging multimedia applications, together with an exponential rise in wireless data (multimedia) demand and usage is already creating a
significant burden on existing cellular networks. 5G wireless systems, with improved data rates, capacity, latency, and QoS are expected to be the panacea of most of the current
cellular networks’ problems. In this survey, make an exhaustive review of wireless evolution toward 5G networks. first discuss the new architectural changes associated with the
radio access network (RAN) design, including air interfaces, smart antennas, cloud and heterogeneous RAN. Subsequently, make an in-depth survey of underlying novel mm-wave
physical layer technologies, encompassing new channel model estimation, directional antenna design, beam forming algorithms, and massive MIMO technologies. Next, the details
of MAC layer protocols and multiplexing schemes needed to efficiently support this new physical layer are discussed. also look into the killer applications, considered as the major
driving force behind 5G. In order to understand the improved user experience, provide highlights of new QoS, QoE, and SON features associated with the 5G evolution. For
alleviating the increased network energy consumption and operating expenditure, make a detail review on energy awareness and cost efficiency. As understanding the current status
of 5G implementation is important for its eventual commercialization, also discuss relevant field trials, drive tests, and simulation experiments.
[14] Tanab et al. (2016), analyzed that the main target of resource allocation (RA) is to efficiently utilize the available resources. Generally, there are no changes in the available
spectrum, thus static spectrum allocation policies were adopted. However, these allocation policies lead to spectrum underutilization. In this regard, cognitive radio networks
(CRNs) have received great attention due to their potential to improve the spectrum utilization. In general, efficient spectrum management and resource allocation are essential and
very crucial for CRNs. This is due to the fact that unlicensed users should attain the most benefit from accessing the licensed spectrum without causing adverse interference to the
licensed ones. The cognitive users or called secondary users (SUs) have to effectively capture the arising spectrum opportunities in time, frequency, and space to transmit their data.
Mainly, two aspects characterize the resource allocation for CRNs: (i) primary (licensed) network protection and (ii) secondary (unlicensed) network performance enhancement in
terms of quality-of-service (QoS), throughput, fairness, energy efficiency, etc. CRNs can operate in one of three known operation modes: interweave, overlay, and underlay. Among
which the underlay CR mode is known to be highly efficient in terms of spectrum utilization. This is because the unlicensed users are allowed to share the same channels with the
active licensed users under some conditions. In this paper, provide a survey for resource allocation in underlay CRNs. In particular, first define the RA process and its components
for underlay CRNs. Second, provide a taxonomy that categorizes the RA algorithms proposed in literature based on the approaches, criteria, common techniques, and network
architecture.
[15] Tehrani et al. (2016), focussed on development of mobile communication networks to support a wide range of superfast broadband services has led to massive capacity demand.
This problem is expected to be a significant concern during the deployment of the 5G wireless networks. The demand for additional spectrum to accommodate mobile services
supporting higher data rates and having lower latency requirements, as well as the need to provide ubiquitous connectivity with the advent of the Internet of Things (IoT) sector, is
likely to considerably exceed the supply, based on the current policy of exclusive spectrum allocation to mobile cellular systems. Hence, the imminent spectrum shortage has
introduced a new impetus to identify practical solutions to make the most efficient use of scarce licensed bands in a shared manner. Recently, the concept of dynamic spectrum
sharing has received considerable attention from regulatory bodies and governments globally, as it could potentially open new opportunities for mobile operators to exploit spectrum
bands whenever they are underutilised by their owners, subject to service level agreements. Although various sharing paradigms have been proposed and discussed, the impact and
performance gains of different schemes can be scenario-specific, and may vary depending on the nature of the sharing players, the level of sharing and spectrum access scheme. In
this article, study the main concepts of dynamic spectrum sharing, different sharing scenarios, as well as the major challenges associated with sharing of licensed bands.

9. [16] Haider et al. (2015), focussed on Cognitive radio (CR) is considered one of the prominent techniques for improving the utilization of the radio spectrum. A CR network (i.e.,
secondary network) opportunistically shares the radio resources with a licensed network (i.e., primary network). In this work, the spectral-energy efficiency trade-off for CR
networks is analyzed at both link and system levels against varying signal-to-noise ratio (SNR) values. At the link level, we analyze the required energy to achieve a specific spectral
efficiency for a CR channel under two different types of power constraint indifferent fading environments. In this aspect, besides the transmit power constraint, interference
constraint at the primary receiver (PR) is also considered to protect the PR from a harmful interference. Whereas at the system level, we study the spectral and energy efficiency for
a CR network that shares the spectrum with an indoor network. Adopting the extreme-value theory, able to derive the average spectral and energy efficiency of the CR network. It is
shown that the spectral efficiency depends upon the number of the PRs, the interference threshold, and how far the secondary receivers (SRs) are located. characterize the impact of
the multi-user diversity gain of both kinds of user son the spectral and energy efficiency of the CR network. analysis also proves that the interference channels (i.e., channels
between the secondary transmitter and PRs) have no impact on the minimum energy efficiency.
[17] Gaojie et al. (2015), proposed to apply full duplex transmission and dual antenna selection at secondary destination node. With the full duplex transmission, the secondary
destination node can simultaneously apply the receiving and jamming antenna selection to improve the secondary data transmission and primary secrecy performance respectively.
This describes an attractive scheme in practice: unlike that in most existing approaches, the secrecy performance improvement in the CR network is no longer at the price of the data
transmission loss. The outage probabilities for both the data transmission and physical layer secrecy are analysed. Numerical simulations are also included to verify the performance
of the proposed scheme.
[18] Haykin et al. (2015), focussed on Cognitive radio provides a basis for addressing the practical issue of spectrum scarcity. This issue has been raised due to the continuing advances
in wireless technology, which has led to ever-increasing demand for larger bandwidth. The issue of spectrum scarcity has been exacerbated due to inefficient use of the
electromagnetic spectrum. Adopting the novel idea of cognitive radio for secondary usage of underutilized spectrum results in the existence of two worlds of wireless
communications going on side by side: the legacy wireless world and the cognitive wireless world. Spectrum holes (i.e., the unused spectrum sub bands) are the medium through
which these two worlds dynamically interact. Releasing sub bands by primary users allows the cognitive radio users to sustain communication and perform their normal tasks.
Combination of the two wireless worlds can be viewed as a spectrum supply chain network, in which the legacy owners and their customers (primary users) play the role of the
suppliers and cognitive radios (secondary users) play the role of consumers. This paper discusses two classes of spectrum supply chain networks based on two regimes, one allows
open-access to the spectrum, and the other is a market driven regime. Each one of them has its own merits and suitability for a different environment; therefore, they have
complementary roles. Analytic models are developed for these two classes of networks, which allow for analysis of both equilibrium and transient behaviours.
[19] Hu et al. (2015), focuses on the fifth generation (5G) wireless networks are expected to achieve 1000 times higher capacity compared to the fourth generation (4G) wireless
networks. Thus, improving the spectrum efficiency (SE) is a crucial problem, which must be considered. Cognitive radio (CR) is considered as an effective approach to alleviate the
spectrum scarcity problem. In this paper, based on the location information of the primary transmitter (PT) and the CR network, estimate the distance between the PT and the
secondary transmitter (ST) and then propose a joint spectrum sensing and power allocation (JSS-PA) scheme to improve the SE of the CR network. In the JSS-PA scheme, focus on
jointly optimizing the sensing parameters and the transmit power of the secondary user (SU) such that the SE is maximized while the primary user (PU) outage constraint is
satisfied. When cooperative spectrum sensing is employed to detect the PU’s status, analyze two cooperative strategies, i.e., soft information fusion (SIF) and hard information
fusion (HIF). Under SIF strategy, the optimization of sensing and power (S-OSP, for short) algorithm is proposed to maximize the SE. Under HIF strategy, the optimization of
thresholds (H-OT, for short) algorithm is proposed, and then the optimization of sensing and power (H-OSP, for short) algorithm is proposed to find the optimal duration of local
sensing, the optimal transmit power of SU and the optimal final decision threshold.

10. [20] Gupta et al. (2015), focussed on Internet of Things, some of the prime objectives or demands that need to be addressed are increased capacity, improved data rate, decreased latency, and better quality of
service. To meet these demands, drastic improvements need to be made in cellular network architecture. This paper presents the results of a detailed survey on the fifth generation (5G) cellular network
architecture and some of the key emerging technologies that are helpful in improving the architecture and meeting the demands of users. In this detailed survey, the prime focus is on the 5G cellular network
architecture, massive multiple input multiple output technology, and device-to-device communication(D2D).Along with this, some of the emerging technologies that are addressed in this paper include
interference management, spectrum sharing with cognitive radio, ultra-dense networks, multi-radio access technology association, full duplex radios, millimeter wave solutions for 5G cellular networks, and
cloud technologies for 5G radio access networks and software defined networks. In this paper, a general probable 5G cellular network architecture is proposed, which shows that D2D, small cell access
points, network cloud, and the Internet of Things can be a part of 5G cellular network architecture.
[21] Ahmad et al. (2015), focussed on Wireless Sensor Networks (WSNs) use the unlicensed Industrial, Scientific, and Medical (ISM) band for transmissions. However, with the increasing usage and demand of
these networks, the currently available ISM band does not suffice for their transmissions. This spectrum insufficiency problem has been overcome by incorporating the opportunistic spectrum access
capability of Cognitive Radio (CR) into the existing WSN, thus, giving birth to Cognitive Radio Sensor Network (CRSN). The sensor nodes in CRSNs depend on power sources that have limited power
supply capabilities. Therefore, advanced and intelligent radio resource allocation schemes are very essential to perform dynamic and efficient spectrum allocation among sensor nodes and to optimize the
energy consumption of each individual node in the network. Radio resource allocation schemes aim to ensure QoS guarantee, maximize the network life-time, reduce the inter-node and inter-network
interferences, etc. In this paper, present a survey of the recent advances in radio resource allocation in CRSNs. Radio resource allocation schemes in CRSNs are classified into three major categories, i.e.,
centralized, cluster-based and distributed. The schemes are further divided into several classes on the basis of performance optimization criteria that include energy efficiency, through put maximization, QoS
assurance, interference avoidance, fairness and priority consideration, and hand-off reduction.
[22] Hong et al. (2014), focussed on cognitive cellular network, which integrates conventional licensed cellular radio and cognitive radio into a holistic system, is a promising paradigm for the fifth generation
mobile communication systems. Understanding the trade-off between energy efficiency, EE, and spectral efficiency, SE, in cognitive cellular networks is of fundamental importance for system design and
optimization. This article presents recent research progress on the EE-SE trade-off of cognitive cellular networks. show how EE-SE trade-off studies can be performed systematically with respect to different
architectures, levels of analysis, and capacity metrics. Three representative examples are given to illustrate how EE-SE trade-off analysis can lead to important insights and useful design guidelines for future
cognitive cellular networks.
[23] Bicen et al. (2013), analyzed that cognitive radio (CR) nodes communicating with each other need to exchange licensed user detection information, i.e., perform spectrum
coordination, over a common control channel. The spectrum coordination can be fulfilled either via existing cognitive radio interface with time division or via a separate dedicated
radio, i.e., a common control interface (CCI), continuously. CR nodes with CCI can instantly exchange licensed user detection information and cease frame transmission, while
spectrum coordination can only be performed after the frame transmission period without CCI. Never the less, the impact of CCI incorporation into CR nodes in terms of common
performance metrics must be thoroughly assessed to evaluate the worthiness of additional radio cost. In this paper, an analytical framework is presented to assess the impact of CCI
incorporation into CR nodes for spectrum handoff. The developed framework enables analyzing potential benefits and disadvantages of employing CCI for spectrum handoff, in
terms of achievable delay, energy consumption, spectrum utilization and event estimation performance. Extensive performance evaluations are presented to illustrate the impact of
CCI utilization on efficiency of spectrum handoff. The network and communication regimes that would yield having CCI favourable are characterized in terms of spectrum
conditions and CR parameters

11. [24] Tragos et al. (2013), analyzed that Cognitive radio (CR) has emerged as a promising technology to exploit the unused portions of spectrum in an
opportunistic manner. The fixed spectrum allocation of governmental agencies results in unused portions of spectrum, which are called “spectrum holes” or
“white spaces”. CR technology overcomes this issue, allowing devices to sense the spectrum for unused portions and use the most suitable ones, according
to some pre-defined criteria. Spectrum assignment is a key mechanism that limits the interference between CR devices and licensed users, enabling a more
efficient usage of the wireless spectrum. Interference is a key factor that limits the performance in wireless networks. The scope of this work is to give an
overview of the problem of spectrum assignment in cognitive radio networks, presenting the state-of-the-art proposals that have appeared in the literature,
analyzing the criteria for selecting the most suitable portion of the spectrum and showing the most common approaches and techniques used to solve the
spectrum assignment problem.
[25] Sun et al. (2013), analyzed that Cognitive radio has emerged as one of the most promising candidate solutions to improve spectrum utilization in next
generation cellular networks. A crucial requirement for future cognitive radio networks is wideband spectrum sensing: secondary users reliably detect
spectral opportunities across a wide frequency range. In this article, various wideband spectrum sensing algorithms are presented, together with a discussion
of the pros and cons of each algorithm and the challenging issues. Special attention is paid to the use of sub-Nyquist techniques, including compressive
sensing and multichannel sub Nyquist sampling techniques.
[26] Masonta et al. (2013), focussed on Spectrum decision is the ability of a cognitive radio (CR) to select the best available spectrum band to satisfy
secondary users’ (SUs’) quality of service (QoS) requirements, without causing harmful interference to licensed or primary users (PUs). Each CR performs
After the available spectrum has been identified, the first step is to characterize it based not only on the current radio environment conditions, but also on the
PU activities. The second step involves spectrum selection, whereby the most appropriate spectrum band is selected to satisfy SUs’ QoS requirements.
Finally, the CR should be able to reconfigure its transmission parameters to allow communication on the selected band. Key to spectrum characterization is
PU activity modelling, which is commonly based on historical data to provide the means for predicting future traffic patterns in a given spectrum band. This
paper provides an up-to-date survey of spectrum decision in CR networks (CRNs) and addresses issues of spectrum characterization (including PU activity
modelling), spectrum selection and CR reconfiguration. For each of these issues, we highlight key open research challenges.
[27] Lee et al. (2013), focussed on spectrum sharing transmission capacity. In this paper breaks down huge scale networks that share the spectrum with
interference cancellation (IC). The efficiency of spectrum sharing is determined primarily by interference, which in turn depends on the spatial densities, the
interference cancellation method, and the spectrum sharing method, i.e., underlay or overlay. By assuming the Poisson distribution for transmitters, equal
transmission power in the same system, and an interference-limited environment, this paper finds the performance gain from IC in terms of spectrum-
sharing transmission capacity (S-TC), defined as the number of successful transmissions per unit area while guaranteeing the target outage probabilities of
all coexisting systems. The effectiveness of IC is characterized by the coefficient of cancellation (CoC), and specific CoC values are derived for two simple
IC scenarios, the strong interferer and the close interferer cancellation, with the assumption of having perfect information for channel states of interfering
links and interferer locations. The sum S-TC optimal spatial densities of the two systems are given. Finally, CoC conditions to determine the superiority of
an underlay or overlay method are presented. verify that the underlay method could be preferred depending on the CoCs of coexisting systems; that is
starkly different from the case without IC, in which the overlay method is always better.

12. [10] Yoshizawa et al. (2015), one of the major drawbacks of orthogonal frequency division multiplexing (OFDM) systems is their high peak-to-
average power ratio (PAPR) signals, and trellis shaping (TS) is a promising approach for reducing both peak power and average power of
OFDM signals. In practice, OFDM should be employed with coded modulation for improving reliability, and bitinterleaved coded modulation
(BICM) has been often combined with OFDM to gain robustness against severe fading channels. In this work, we propose a new BICM-OFDM
system concatenated with TS for achieving good error performance. To this end, a novel soft-in–soft-out decoder for TS is developed.
Optimization of the shaping convolutional code in terms of transmitter performance is also discussed. The effectiveness of our system is
demonstrated through the analysis in terms of average mutual information as well as frame error rate (FER) over an additive white Gaussian
noise channel. Furthermore, the FER is evaluated over a frequency-selective Rayleigh fading channel and compared with the theoretical
outage probability. The simulation results reveal that our system can achieve good frequency diversity effect over such a fading channel while
enjoying much lower PAPR.
[11] Wu,et al.(2015), one challenge of employing high-order modulations in single carrier frequency division multiple access (SC-FDMA) systems
is the resultant high peak-to-average power ratio (PAPR). Proposed a novel PAPR reduction scheme by jointly considering the PAPR reduction
and the incurred bit error rate (BER) degradation for SC-FDMA systems with high-order modulations. In the proposed scheme, an additive
pre-distortion vector is introduced to modify the few modulated symbols causing the peak of the SC-FDMA signal. This pre-distortion vector
is optimized to minimize the in-band distortion under the expected PAPR constraint. Simulation results demonstrate that our proposed
scheme can achieve the desired PAPR reduction with negligible BER performance degradation.
[12]Estevez, et al. (2015), made a clear trend shows that cells are smaller, more homogeneously distributed, higher frequency oriented, and
more energy conscious. This points toward wireless systems that implement millimeter-wave modulation; therefore, improving its usability is
essential for the communication systems evolution. The proposed bottom-layer solutions are (1) a variable slot time multiplexing access
technique with an energy-conservation feature that supports self-sustainability, and (2) SC-FDMA as the technology implemented at the
physical layer to minimize the peak-to-average-power ratio (PAPR) of the system. It is shown that the multiplexing protocol has advantages
over TDMA, self sustainability is feasible, and SC-FDMA reduces the PAPR of the modulated signal.
[13] Feng, et al. (2015), a novel Nyquist filter was proposed to reducethe peak-to-average power ratio (PAPR) in the interleavedsingle carrier
orthogonal frequency division multiple access (SC-IFDMA) system based on pulse shaping. The proposed filter hasa piece-wise rectangular
frequency characteristic composed of sixnonzero linear segments with variable-length projections onto thefrequency axis, which are used as
a set of independent designparameters from roll-off factor α.Simulation results show thatthe novel filter has a better PAPR reduction
performance andlower symbol error rate compared to some recently proposedfilters, and it has lower computational complexity.

13. [14] Song, et al. (2016), peak cancellation (PC) is known as one of the simplest peak-to-average power ratio (PAPR) reduction techniques those are applicable to
various communications standards. The salient advantage of PC is its ease of hardware implementation, but it induces in-band distortion and out-of-band radiation.
In order to restrict the amount of distortion within an acceptable level, it is critical to carefully design the cancelling pulses as well as the envelope threshold over
which PC is applied. In most studies however, they are determined empirically through computer simulations. This paper thus focuses on a rigorous theoretical
analysis of PC applied to band-limited orthogonal frequency division multiplexing (OFDM) signals, and discusses its validity and limitation for practical applications.
Based on the level-crossing rate approximation of the peak distribution, we derive a closed-form expression for the achievable signal-to-distortion power ratio
(SDR). We also analyze the adjacent channel leakage ratio (ACLR) as well as error vector magnitude (EVM), with which the symbol error rate (SER) over an additive
white Gaussian noise (AWGN) channel is obtained. All the theoretical results developed in this work are compared with those based on the corresponding
computer simulations to justify our analytical approach. It thus serves as a useful and accurate tool for designing cancelling pulses as well as the threshold level, for
given specific system requirements such as SDR (or EVM) and ACLR.
[15] Preenu Ann P. (2016), proposed that Orthogonal Frequency Division Multiplexing (OFDM) is a spectrally efficient multicarrier modulation technique for
high speed data transmission over multipath fading channels. OFDM modulation schemes offer many advantages for multicarrier transmission at high
data rates. One of the main issues of OFDM is high Peak-to-Average Power Ratio (PAPR) of the transmitted signal which adversely affects the complexity of
power amplifiers. A number ofpromising techniques have been proposed and implemented to reduce PAPR of OFDM signal with expense of
transmitted signal power, Bit error rate (BER), complexity etc. In this paper,clipping and filtering, selective mapping (SLM), partial transmit sequence (PTS),
linear block coding (LBC), peak insertion (PI) techniques are implemented for PAPR reduction of OFDM signal attransmitter. Comparison of these PAPR
reduction techniques is done based on CCDF and BER performance of the system.
[16] Chao, (2016), indicated that Golay complementary sequences and complementary sets have been proposed to deal with the high peak-to-average power ratio
(PAPR) problem in orthogonal frequency division multiplexing (OFDM) system. The existing constructions of complementary sets based on generalized Boolean
functions are limited to lengths which are powers of two. In this pa- per, we propose novel constructions of binary and non binary complementary sets of non-
power-of-two length. Regardless of whether or not the length of the complementary set is a power of two, its PAPR is still upper bounded by the size of the
complementary set. Therefore, the constructed complementary sets can be applied in practical OFDM systems where the number of used subcarriers is not a
power of two. In addition, while the binary Golay complementary pairs exist only for limited lengths, the constructed binary complementary sets of size 4 exist
formore lengths with PAPR at most 4.
[17] Feng, et al. (2017), made a crystal clear that A novel Nyquist filter was proposed to reduce the peak-to-average power ratio (PAPR) in the interleaved single carrier
orthogonal frequency division multiple access (SC-IFDMA) system based on pulse shaping. The proposed filter has a piece-wise rectangular frequency characteristic
composed of six nonzero linear segments with variable-length projections onto the frequency axis, which are used as a set of independent design parameters from
roll-off factor α. Simulation results show that the novel filter has a better PAPR reduction performance and lower symbol error rate compared to some recently
proposed filters, and it has lower computational complexity.

14. Methodology
Partial transmit sequence is one of the most important technique for reducing the
peak to average power ratio (PAPR) in OFDM system.
The basic idea of partial transmit sequence algorithm is dividing the signal into
several subsequence, multiplied by different weight until an optimum value is
chosen.

15. Discrete Cosine Transform
In particular, a Discrete Cosine Transform (DCT) is a Fourier-related
transform similar to the discrete Fourier transform (DFT) which uses only
real numbers. The autocorrelation of peak signals is used to find the PSD of
the signals.
 DCT extends the original N-point data sequence to 2N-point sequence by
doing mirror – extension of the N-point data sequence. Since the both ends
of the data is always continuous in the DCT, the lower order of components
will be dominated in the transformed domain signal after converted by
DCT.
 The main properties of DCT are signal energy compaction, reduce
autocorrelation among data sequences and have good boundary property.

17. Simulation Results and Discussion
Fig 1: PTS/DCT Reduction Technique with 64 carriers Fig 2 : PTS/DCT Reduction Technique with 128
carriers

18. Fig 3 : PTS/DCT Reduction Technique with 256
carriers
Fig 4 : PTS/DCT Reduction Technique with
1024 carriers

19. Table : Final Results
64 Carriers 128 Carriers 256 Carriers 1024 Carriers
Original OFDM signal 10.9 11 11.4 12
PTS 6.5 7.2 7.6 8.7
PTS+DCT 6.4 7 7.5 8.3

20. Conclusion and Future Scope
In this presentation we have investigated the PAPR problem in the
OFDM system, especially in the downlink. A new hybrid technique of
partial transmit sequence and DCT are used to reduce the PAPR at
different carriers.
Different carriers are used to the dependency of PAPR on the number
of subcarriers. It can be concluded that PAPR increases with the
number of carriers and shows the significant decrement using the
proposed techniques.

21. Analysis of the proposed techniques and find out its impact on the
PAPR mathematically.
Proposed PTS/DCT technique by using the proposed method.
Study the impact of these proposed technique on bandwidth, noise,
distortion and the ratio of power saving.
Study the impact of this proposed technique on statistical distribution.
The proposed PAPR reduction methods can be used with MIMO
OFDM system

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