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One of the main disadvantages of multicarrier transmission is the high peak-to-average power ratio (PAPR) of the transmitted signal. If the highest transmitted power is confined by the application restrictions or regulatory, the result is to decrease the average power permitted under multicarrier transmission. Selected mapping (SLM) is a standard P...
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The reduction of the high peak-to-average-power ratio (PAPR) is important to the efficiency of the orthogonal frequency division multiplexing (OFDM) technique. Excessive PAPR contributes to non-linear clipping induced harmonic distortions that reduce system reliability. In this article, a new technique for decreasing the high PAPR in OFDM with mini...
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... The computation involved in modelling these increasingly complex systems has accelerated substantially. A considerable amount of work has been done to model many digital signal processing induced consequences such as by [2], authors utilise the statistical properties of the autocorrelation function to combat autoregressive fading , and adaptive clipping and selective mapping applied to achieve a distortion-less reduction of the average power of transmitted signals [3] . ...
The necessity of the rapid evolution of wireless communications, with continuously increasing demands for higher data rates and capacity Zheng (Big datadriven optimization for mobile networks toward 5g 30:44–51, 2016), is constantly augmenting the complexity of radio frequency (RF) transceiver architecture. A significant component in the configuration of such complex radio transceivers is the power amplifier(PA). Multiple distributed PAs are now common in proposed RF architectures. PAs exhibit non linear behaviour, causing signal distortion in transmission. Behavioural models offer a concise representation of a PAs characteristic performance which is extremely useful in simulating performance of multiple nonlinear power amplifiers. A considerable drawback with using the Recursive Least Squares (RLS) technique is that the instability of the coefficients during the training of the model. This manuscript provides a computationally efficient technique to detect the onset of instability during adaptive RLS training and subsequently to inform the decision to cease training of dynamic memory polynomial based behavioural models, to avoid the onset of instability. The proposed technique does not require modification of the RLS algorithm, merely an observation of the pre-exsisting autocorrelation function based update. This technique is experimentally validated using four different signal modulation schemes, LTE OFDM, 5G-NR, DVBS2X and WCDMA.
... The delay in the system depends upon the number of IFFT processors used, computational complexity of the IFFT, adopted PAPR reduction algorithms, phase sequence optimization methods used, added overheads etc. Several techniques have been proposed in past to overcome this problem, of which selective mapping (SLM) [3][4][5][6][7] and partial transmit sequence (PTS) techniques [8][9][10][11] are most commonly used ones. The major drawback with SLM and PTS technique is that it requires a large number of IFFT processors which results in high computational complexity. ...
... In other techniques, the PAPR is minimized by signal scrambling. There are several techniques which comes under this category such as Selective Mapping (SLM) [3][4][5][6][7], Partial Transmit Sequence (PTS) [8][9][10][11], Tone Reservation (TR) [14], Tone Injection (TI), Detected Peak Sample Combining (DPSC) [15], Hybrid Techniques [6,7,[20][21][22] etc. Of these SLM and PTS are the most popularly used techniques. ...
... In other techniques, the PAPR is minimized by signal scrambling. There are several techniques which comes under this category such as Selective Mapping (SLM) [3][4][5][6][7], Partial Transmit Sequence (PTS) [8][9][10][11], Tone Reservation (TR) [14], Tone Injection (TI), Detected Peak Sample Combining (DPSC) [15], Hybrid Techniques [6,7,[20][21][22] etc. Of these SLM and PTS are the most popularly used techniques. ...
Excessive peak to average power ratio (PAPR) of the communicated signal is a serious problem of the multicarrier-CDMA system. Most popular PAPR minimization techniques such as selective mapping and partial transmit sequence require a larger number of IFFT/FFT processors thereby increasing its computational complexity as well as the processing delay of the system. A novel peaks comparison and subgroups samples scaling technique is proposed which employs only a single IFFT/FFT processor. In this scheme, the PAPR of the MC-CDMA signal is minimized by scaling the samples of some selected subgroups. The subgroups to be selected for scaling are determined by comparing the highest peak sample of each subgroup with a fraction of the overall highest peak among all samples of an MC-CDMA symbol. Side information along with data samples are sent to the receiver end for re-scaling. The results of the simulation indicate that at an appropriate fraction value; the PAPR is decreased by 4.3 dB for a standard value of complementary cumulative distribution function with very minimal effect on BER performance. This approach is considerably simple when compared to the other methods which are currently being used.
... Wireless networks are becoming more complicated, and it is time to move on from the old methods based on outdated models. Likewise, the growing widespread use of deep learning networks has also shifted the focus of efforts to develop new wireless network models [58,149]. An in-depth examination of edge computing and 5G networks was conducted by Niknam et al. [59] using the essential features of FL. ...
Federated learning (FL) is a system in which a central aggregator coordinates the efforts of multiple clients to solve machine learning problems. This setting allows training data to be dispersed in order to protect privacy. The purpose of this paper is to provide an overview of FL systems with a focus on healthcare. FL is evaluated here based on its frameworks, architectures, and applications. It is shown here that FL solves the preceding issues with a shared global deep learning (DL) model via a central aggregator server. This paper examines recent developments and provides a comprehensive list of unresolved issues, inspired by the rapid growth of FL research. In the context of FL, several privacy methods are described, including secure multiparty computation, homomorphic encryption, differential privacy, and stochastic gradient descent. Furthermore, a review of various FL classes, such as horizontal and vertical FL and federated transfer learning, is provided. FL has applications in wireless communication, service recommendation, intelligent medical diagnosis systems, and healthcare, all of which are discussed in this paper. We also present a thorough review of existing FL challenges, such as privacy protection, communication cost, system heterogeneity, and unreliable model upload, followed by future research directions.
... The problem of PAPR reduction has been studied in the literature, and several solutions have been presented for this problem, including clipping and filtering [10], pulse shaping [6,11], coding [12][13][14][15], tone reservation and injection [16,17], partial transmit sequences (PTS) [18], exponential companding transform [19], nonlinear scaling and frequency modulation [20], nonlinear companding transform [21], and conventional selective mapping (C-SLM) [22][23][24][25][26][27][28][29][30]. One of the popular solutions that has been extensively studied in the literature is the C-SLM, in which multiple IFFT operations are implemented on different versions of the input sequence generated through the utilization of different random phase sequences. ...
This paper presents a low-complexity peak-to-average power ratio (PAPR) reduction scheme for single-carrier frequency division multiple access (SC-FDMA) system that is based on all-pass filters (APFs). The basic idea of the APF scheme is that it allows a flat magnitude response with a non-linear phase response. This means that this type of filters passes all frequency content of the input signal, while the phase is severely or intentionally degraded. This idea is well-exploited in this paper for generating random phase sequences that can be treated as multiple versions of an input sequence for the SC-FDMA system. The heart of traditional PAPR reduction techniques such as the conventional selective mapping and blind selective mapping schemes is the generation of multiple random phase sequences for the proper selection of the sequence that achieves the minimum PAPR. This can be accomplished through multiple inverse fast Fourier transform (IFFT) operations, which add more complexity to the system performance. In contrary, with the proposed APF scheme, we generate the signals with different phases through passing the original signal through multiple APFs with different phase responses, which reduces the system complexity.
... Wireless networks are becoming more complicated, and it is time to move on from the old methods based on outdated models. Likewise, the growing widespread use of deep learning networks has also shifted the focus of efforts to develop new wireless network models [58,149]. An in-depth examination of edge computing and 5G networks was conducted by Niknam et al. [59] using the essential features of FL. ...
Federated learning (FL) refers to a system in which a central aggregator coordinates the efforts of several clients to solve the issues of machine learning. This setting allows the training data to be dispersed in order to protect the privacy of each device. This paper provides an overview of federated learning systems, with a focus on healthcare. FL is reviewed in terms of its frameworks, architectures and applications. It is shown here that FL solves the preceding issues with a shared global deep learning (DL) model via a central aggregator server. Inspired by the rapid growth of FL research, this paper examines recent developments and provides a comprehensive list of unresolved issues. Several privacy methods including secure multiparty computation, homomorphic encryption, differential privacy and stochastic gradient descent are described in the context of FL. Moreover, a review is provided for different classes of FL such as horizontal and vertical FL and federated transfer learning. FL has applications in wireless communication, service recommendation, intelligent medical diagnosis system and healthcare, which we review in this paper. We also present a comprehensive review of existing FL challenges for example privacy protection, communication cost, systems heterogeneity, unreliable model upload, followed by future research directions.
... Hence, a trade-off between distortion and power consumption exists. Therefore, PAPR reduction is considerably studied by researchers [10][11] [12][13] [14]. Referring to the PAPR formula; two options can be made in order to minimize the PAPR, either by reducing the maximum peak and/or by increasing the average power (mean value). ...
This paper is concerned with the Orthogonal Frequency Division Multi-plexing (OFDM) system that is adopted by a wireless communication system for transmitting multicarrier modulated signals simultaneously with robustness against interference and noise facing the system. It presents a significant issue related to the OFDM system known as the raise of Peak to Average Power Ratio (PAPR) that is the high peaks of OFDM signals compared to its average power. Increasing the PAPR yields in the component devices of the OFDM system does not cope with the high peaks resulting in distortion and signal losses. Therefore, the objective of this article is to review different approaches of PAPR reduction techniques and compare them to select the best technique for a particular system. The approaches are mainly of three classifications; distortion, probabilistic, and coding schemes with each including several techniques.
... In view of the problem of PAPR in CO-OFDM system, various PAPR reduction technologies have been proposed in the past decade, which are mainly divided into two types: signal distortion technology and distortionless technology. The most famous signal distortion techniques are clipping and filtering (CF) [6][7][8] and companding [9,10]. These methods significantly reduce the PAPR of the signal using nonlinear operation that limits the peak envelope of the transmitting signals to a desired value. ...
In this paper, a hybrid technique using a low complexity selective mapping (LCSLM) cascading an improved μ law companding scheme (LCSLM-μ) is proposed to reduce the peak-to-average power ratio (PAPR) and complexity in coherent optical orthogonal frequency division multiplexing system. The simulation results show that at the complementary cumulative distribution function of \({10}^{{ - 4}}\), the PAPRs of the scheme LCSLM-μ(D = 4,m = 3,\(\mu { = 1}\)) are optimized by 1.488 dB and 1.166 dB compared those of LCSLM (D = 4) and companding(\(\mu { = 1}\)) schemes, respectively. Meanwhile, when the bit error rate (BER) is 10–3, the optical signal to noise ratios (OSNRs) of the LCSLM-μ(D = 4,m = 3,\(\mu { = 1}\)) scheme are optimized by 6.61 dB and 7.31 dB compared with those of companding (\(\mu { = 1}\)) and improved \(\mu\) law companding (m = 3, μ = 1) schemes, respectively. The computational complexity and PAPR reduction performance of various schemes, such as traditional SLM, LCSLM, improved law companding and LCSLM-μ schemes are analyzed respectively. The simulation results show that the LCSLM-\(\mu\) (D = 4, m = 3, μ = 1)provides better PAPR reduction performance. When the alternative signal is 16, compared with the traditional SLM algorithm, the LCSLM-\(\mu\)(D = 4, m = 3, \(\mu { = 1}\)) scheme reduces the computational complexity of complex addition and complex multiplication by 53.1% and 45%, respectively. This paper provides a choice for a trade-off among PAPR reduction, BER and reduced complexity.
... Bharati and Podder [18] proposed a hybrid method combining clipping and SLM. The author has compared both the techniques for OFDM scheme and found that the fusion technique performs better compared to conventional SLM, which has relatively more energy efficiency compared to single method. ...
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
... Light fidelity (LiFi) [11][12][13][14][15][16] is also an emerging technology for the Internet. OFDM, MIMO systems are playing a vital role in order to establish upgraded wireless communication systems [17][18]. However, there are many forms of security issues in IoT/IoMT communication environment. ...
Internet of Things (IoT) is being considered as the growth engine for industrial revolution 4.0. The combination of IoT, cloud computing and healthcare can contribute in ensuring well-being of people. One important challenge of IoT network is maintaining privacy and to overcome security threats. This paper provides a systematic review of the security aspects of IoT. Firstly, the application of IoT in industrial and medical service scenarios are described, and the security threats are discussed for the different layers of IoT healthcare architecture. Secondly, different types of existing malware including spyware, viruses, worms, keyloggers, and trojan horses are described in the context of IoT. Thirdly, some of the recent malware attacks such as Mirai, echobot and reaper are discussed. Next, a comparative discussion is presented on the effectiveness of different machine learning algorithms in mitigating the security threats. It is found that the k-nearest neighbor (kNN) machine learning algorithm exhibits excellent accuracy in detecting malware. This paper also reviews different tools for ransomware detection, classification and analysis. Finally, a discussion is presented on the existing security issues, open challenges and possible future scopes in ensuring IoT security.
... Several improvements and variants of information [85], [86]. Also the SLM is combined with clipping in [87]. ...
Orthogonal Frequency Division Multiplexing (OFDM) is the key technology used in
high-speed communication systems. One of the major drawbacks of OFDM systems
is the high Peak to Average Power Ratio Peak to Average Power Ratio (PAPR) of the
transmitted signal. A signal with a high PAPR requires a very large linear range of
Power Amplifier (PA) at the transmitter side. To propose a PAPR reduction algorithms
is a big challenge, several methods are proposed such as coding, clipping and filtering,
companding, Selective Mapping Technique (SLM), Partial Transmit Sequences (PTS), and
Peak Insertion. To solve this problem, we propose and study three new algorithms in
OFDM systems with Solid State Power Amplifier (SSPA) as a High Power Amplifer (HPA)
type. To evaluate and analyze its performances in terms of the PAPR and Bit Error Rate
(BER), we performed some computer simulations by varying the modulation schemes,
Coding rate and Clipping Ratio (CR). The obtained results show that it is possible to
achieve a good gain in terms of PAPR reduction and BER peformances depending on
the type of modulation. In addition, the comparison with several techniques in terms
of PAPR and BER shows that our methods are a strong alternative that can be adopted
as a PAPR reduction technique for OFDM’s bases communication systems.
