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The theoretical analysis of the Peak-to-Average Power Ratio (PAPR) distribution for an Orthogonal Frequency Division Multiplexing (OFDM) system, depends on the particular waveform considered in the modulation system. In this paper, we generalize this analysis by considering the Generalized Waveforms for Multi-Carrier (GWMC) modulation system based...
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... the number of carriers M is finite, the CCDF of the PAPR is equal to 0 for γ greater than PAPR c,sup . And for γ less than PAPR c,sup , the CCDF depends on the observation duration: when we consider an infinite observation duration, the CCDF is equal to 1, but if we limit the observation duration to a finite number of symbols, the CCDF is defined by Equation 21. Figure 6 presents all the possible cases. ...
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Orthogonal Frequency Division Multiplexing is a multi-carrier system. In this a single carrier is divided into number of sub-carriers. These subcarriers are orthogonal to each other, this helps to reduce ISI effect and full bandwidth is utilized. OFDM is of great interest by researchers and research laboratories all over the world because it gives...
High peak to average power ration (PAPR) in orthogonal frequency division multiplexing (OFDM) is an important problem, which increase the cost and complexity of high power amplifiers. One of the techniques used to reduce the PAPR in OFDM system is the tone reservation method (TR). In our work we propose a modified tone reservation method to decreas...
Pulse blanking is a widely used method to eliminate impulsive interference in an orthogonal frequency division multiplexing (OFDM) receiver. To analyze the effect of the inter-carrier interference caused by pulse blanking on the symbol error rate (SER) performance of OFDM employing maximum ratio combining (MRC) receiver, the analytical expression o...
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Citations
... We use filter at every subband after upsampling by a factor of M . Following [17], [45], [46], the complementary cumulative distribution function (CCDF) of the PAPR corresponding to the m th subband sequence can be approximated as ...
... This shows that the proposed MB-OFDM scheme accomplishes a notable reduction in the PAPR through the THz-specific baseband design that divides the wideband into smaller subbands. It is also evident from (18) and [17], [45], [46] that the front-end filter after upsampling in each subband can increase the PAPR. However, this effect can be offset by the lower number of subcarriers in each subband causing a reduction in peak power [53] and thereby decreasing the likelihood of having peaks in all the subbands at the same time resulting in an overall reduction in PAPR as compared to a single wideband OFDM signal. ...
Terahertz (THz) communication is a highly promising solution for addressing the ultra-high data rate requirements of future sixth-generation (6G) wireless systems. However, the unfavorable frequency-dependent channel characteristics of THz communication pose a significant challenge in realizing this promising technology. In this paper, we present a novel solution to this challenge by proposing a wideband THz system featuring a unique THz-specific digital baseband waveform design tailored to the distinctive channel characteristics of the THz spectrum. To address the frequency-dependent challenges posed by the wideband THz channel and the spectral efficiency loss inherent in conventional orthogonal frequency division multiplexing (OFDM) systems due to cyclic prefix overhead, we propose a THz system with beamforming incorporating a multi-band OFDM (MB-OFDM) based waveform design using a filter-bank based channel model that slices the wideband channel into smaller frequency-independent subbands for ultra-wideband THz communication. Furthermore, this work introduces a novel squint model taking into account the printed-circuit-board (PCB) impairments and circuit imperfections, which have not been considered before. We also propose an all-digital mitigation scheme with this model. We propose a channel estimation algorithm using a three-level adaptive method with an auto-regressive (AR) model for exploiting the frequency dependency among the intra and inter-narrow subbands. Apart from these key contributions, we propose a THz environment-aware precoder to mitigate the wideband effect in the THz channel, specifically the subband-specific path loss and environment-related effect, and balance the overall gains across the band. We have also proposed to optimize the number of subbands and zero-padding in MB-OFDM waveform based on the minimum bit error rate (MBER) criterion. Numerical simulations are carried out to evaluate the performance of the proposed schemes demonstrating their feasibility and effectiveness for wideband THz communication with results showing a lower peak-to-average power ratio (PAPR) for the proposed waveform as compared to conventional OFDM.
... Several methods are proposed, such as clipping with iterative reception and companding transforms, linear precoding techniques are applied to the GFDM system to reduce the PAPR values. The analysis of PAPR analysis is derived using complementary cumulative distribution function (CCDF) for OFDM [10], OQAM [11], FBMC [12] and GFDM [13] for the number of subcarriers and sub symbols. ...
... For example, for an ADC of s = 100 GHz, the power consumption and SNDR are approximately 0.3 Watt (very high) and 35 dB (very low), respectively. The PAPR CCDF of one CP-OFDM symbol ( = 1) is expressed as [61] Pr 1 In this work, we use OTFS with rectangular Tx and Rx windowing and pulse-shaping, and consider one CP per frame ( × symbols), which results in a low-complexity implementation [65]. This setting is different from the OTFS setting in [44] with complexityC (t) /(r) OTFS = 2C FFT ( ) +C FFT ( ) + 4( + CP / ) and the OFDM-based OTFS setting in [46] which adds one CP every blocks (each block is of length ). ...
... for a PAPR threshold th . Furthermore, the closed-form approximation of the PAPR CCDF of OQAM/FBMC in [61] reveals higher PAPR values compared to CP-OFDM due to per-subcarrier filtering. In [69], the PAPR CCDF of discretetime OTFS (no oversampling and rectangular pulse-shaping) is approximated for high values of as ...
The prospects of utilizing single-carrier (SC) and multi-carrier (MC) waveforms in future terahertz (THz)-band communication systems remain unresolved. On the one hand, the limited multi-path components at high frequencies result in frequency-flat channels that favor low-complexity wideband SC systems. On the other hand, frequency-dependent molecular absorption and transceiver characteristics and the existence of multi-path components in indoor sub-THz systems can still result in frequency-selective channels, favoring off-the-shelf MC schemes such as orthogonal frequency-division multiplexing (OFDM). Variations of SC/MC designs result in different THz spectrum utilization, but spectral efficiency is not the primary concern with substantial available bandwidths; baseband complexity, power efficiency, and hardware impairment constraints are predominant. This paper presents a comprehensive study of SC/MC waveforms for THz communications, utilizing an accurate wideband THz channel model and highlighting the various performance and complexity trade-offs of the candidate schemes. Simulations demonstrate that discrete-Fourier-transform spread orthogonal time-frequency space (DFT-s-OTFS) achieves a lower peak-to-average power ratio (PAPR) than OFDM and OTFS and enhances immunity to THz impairments and Doppler spreads, but at an increased complexity cost. Moreover, DFT-s-OFDM is a promising candidate that increases robustness to THz impairments and phase noise (PHN) at a low PAPR and overall complexity.
... For example, for an ADC of s = 100 GHz, the power consumption and SNDR are approximately 0.3 Watt (very high) and 35 dB (very low), respectively. The PAPR CCDF of CP-OFDM is expressed as [51] Pr ...
... for a PAPR threshold th . Furthermore, the closed-form approximation of the PAPR CCDF of OQAM/FBMC in [51] reveals higher PAPR values compared to CP-OFDM due to per-subcarrier filtering. In [56], the PAPR CCDF of OTFS is approximated for high values of as ...
The prospects of utilizing single-carrier (SC) and multi-carrier (MC) waveforms in future terahertz (THz)-band communication systems remain unresolved. On the one hand, the limited multi-path (MP) components at high frequencies result in frequency-flat channels that favor low-complexity wideband SC systems. On the other hand, frequency-dependent molecular absorption and transceiver characteristics and the existence of MP components in indoor sub-THz systems can still result in frequency-selective channels, favoring off-the-shelf MC schemes such as orthogonal frequency-division multiplexing (OFDM). Variations of SC/MC designs result in different THz spectrum utilization, but spectral efficiency is not the primary concern with substantial available bandwidths; baseband complexity, power efficiency, and hardware impairment constraints are predominant. This paper presents a comprehensive study of SC/MC modulations for THz communications, utilizing an accurate wideband THz channel model and highlighting the various performance and complexity trade-offs of the candidate schemes. Simulations demonstrate the robustness of discrete-Fourier-transform spread OFDM (DFT-s-OFDM) to THz impairments and orthogonal time-frequency space (OTFS) to THz Doppler spreads.
... Theoretical analysis of the PAPR can be much helpful for understanding the PAPR properties of multicarrier signals, as well as for designs of PAPR reduction schemes (e.g., for nonlinear companding transforms [14]- [16]) and optimizations of various nonlinear devices [9]- [18]. The well-known approximated expressions for the complementary cumulative distribution function (CCDF) of PAPR have been derived in Orthogonal Frequency Division Multiplexing (OFDM) systems [9]- [11] and Filter-Bank based Multi-Carrier with Offset Quadrature Amplitude Modulation (FBMC/OQAM) systems [12], [13]. Theoretical results in OFDM systems indicated that the CCDF of PAPR was mainly determined by the number of subchannels, and have been employed for PAPR reduction designs [14]- [16]. ...
... According to (6), (13) and (17), there will be ...
... From (6), (13) and (14), we can find that σ 2 n (n ∈ S) also has a periodicity of K, i.e., σ 2 n = σ 2 n+iK (n ∈ S P ) Thus we havē ...
... The CCDF of the PAPR for GFDM signals can be calculated as [13] ( ) ( ...
... And a raised cosine (RC) filter with a roll-off factor a rf =0.1 is adopted to assess PAPR reduction and BER performance. Note that the average power of the RC filter is normalized, as mentioned in (13). Besides, a solid-state power amplifier (SSPA) with parameter p=2 and the saturation point x sat =E{|x c [n]| 2 } is considered. 1 We compare the proposed method with other PAPR reduction schemes, e.g., the clipping method (clipping ratio (CR)=1, iteration number n iteration =1) [6], the polynomial companding method (polynomial order (P)=15, iteration number n iteration =1) [7], and the DFT-precoding method [8]. ...
Abstract:
Similar to the widely used orthogonal frequency division multiplexing (OFDM) scheme, Generalized Frequency Division Multiplexing (GFDM) system suffers from the problem of the high peak-to-average power ratio (PAPR). In this paper, we propose an efficient piecewise nonlinear companding transform for PAPR reduction of GFDM signals and a novel iterative receiver of GFDM to improve the bit error rate (BER) performance. By carefully adjusting transform parameters and the number of iterations of the receiver, more flexibility in the companding form and a better trade-off between PAPR reduction and BER performance can be achieved to satisfy various system requirements. Compared with existing PAPR reduction schemes in GFDM, simulation results show that the proposed technique can substantially offer the better performance of GFDM system in terms of PAPR reduction and BER performance.
... The CCDF of the PAPR for GFDM is then calculated as [16] ( Fig. 1 Amplitude of the transmit matrix A for GFDM system with M=5, K=32, and a raised cosine filter with roll-off factor of 0.1. ...
... (20) According to (16), parameter a can be calculated by b. Hence, by properly adjusting the parameter b, we can achieve different levels of PAPR reduction. ...
Abstract:
Generalized Frequency Division Multiplexing (GFDM) has been regarded as one of the most promising multicarrier modulation schemes for the upcoming fifth generation (5G) mobile communication system. However, similar to other multicarrier schemes, GFDM still suffers from the problem of high Peak-to-Average Power Ratio (PAPR). To reduce the PAPR effectively, we propose an efficient nonlinear companding scheme to transform the statistics of GFDM signals into a half-sine distribution form along with remaining an unchanged average signal power in GFDM blocks. Additionally, a new iterative reception method for the receiver of GFDM is also proposed to obtain a better bit error rate (BER) performance. This scheme can achieve a significant reduction in PAPR and an improved BER performance simultaneously. By properly adjusting system parameters, more design flexibility in companding form and an effective trade-off between PAPR reduction and BER performance can be obtained. Compared with existing solutions for PAPR reduction in GFDM, simulation results illustrate that the proposed technique can achieve a better overall performance in terms of PAPR reduction and BER performance.
... High PAPR causes nonlinear distortion in HPA because it saturates HPA. Similarly, UFMC and FBMC have high PAPR because these systems are based on multi-carrier [10][11]. In UFMC and FBMC system, if nonlinear distortion is caused by high PAPR, OOB power of these systems is increased. ...
... Les symboles numériques d'entrée, représentant les données à transmettre et issus d'une constellation de modulation numérique, sont décomposés en plusieurs blocs. Chaque bloc de symboles numériques est inséré en parallèle dans la modulation du système multiporteuses, générant à la sortie un symbole multiporteuses temporel comme montré dans la Figure 5. 1. Après la modulation, un signal GWMC peut être exprimé par [144] : ...
... . Le comportement du PAPR pour différents scénarios et conditions de transmissions est également étudié.Les travaux présentés dans ce chapitre ont fait l'objet de deux articles de conférence internationale[143,144] et de leur extension en un article de revue[145]. ...
L’OFDM est une technique de modulation multiporteuses largement utilisée dans des applications de communications filaires et sans-fils comme le DVB-T/T2, le Wifi, et la 4G, grâce à sa robustesse contre les canaux sélectifs en fréquence en comparaison avec la modulation monoporteuse. Cependant, le signal OFDM souffre de grandes variations d’amplitude. Les fluctuations de l’enveloppe du signal OFDM génèrent des distorsions non-linéaires quand on introduit le signal dans un équipement non-linéaire comme l’amplificateur de puissance. Réduire les variations du signal améliore le rendement de l’amplificateur, réduit la consommation énergétique et diminue les émissions de CO2 des transmissions numériques. Le PAPR (rapport de la puissance crête sur la puissance moyenne) est une variable aléatoire qui a été introduite pour mesurer les variations du signal. Il existe plusieurs systèmes multiporteuses basés sur différentes bases de modulation et filtres de mise en forme. Nous prouvons d’abord dans ces travaux que le PAPR dépend de cette structure de modulation. Ensuite, nous étudions le comportement du PAPR vis-à-vis des formes d’ondes utilisées dans la modulation. Le problème de réduction du PAPR est ainsi formulé en un problème d’optimisation. Par ailleurs, une condition nécessaire pour construire des formes d’ondes avec un meilleur PAPR que l’OFDM est développée. Cette condition est notamment satisfaite par des bases en ondelettes. Enfin, une nouvelle forme d’onde en paquets d’ondelettes adaptative est proposée, permettant des gains significatifs en PAPR, tout en maintenant les avantages des modulations multiporteuses.
... OFDM, UFMC 그리고 FBMC는 모두 다중 반송파를 사 용하는 변조 기술이다[9]～[11]. OFDM은 OOB의 전력이 높 지만, UFMC와 FBMC 변조 기술의 경우 필터링 기술을 결합하며, OOB 전력을 효과적으로 억압하여 스펙트럼을 보다 효율적으로 사용할 수 있다. 그림 1, 그림 2 그리고 그림 3은 각각 OFDM, UFMC, FBMC의 송수신기 시스템 모델을 보여준다. ...
In this paper, we propose and design a SSD(Simultaneous Single band Duplex) system using 5G(Generation) candidate modulations. Especially, we consider HPA(High Power Amplifier) nonlinearity in the proposed system. And then, we evaluate and analyze performance of the proposed system. As simulation results, performance of SSD-OFDM(Orthogonal Frequency Division Multiplexing), SSD-FMC (Universal Filtered Multi-Carrier), and SSD-FBMC(Filter Bank Multi-Carrier) is severely degraded by HPA nonlinearity. However, performance of SSD-OFDM, SSD-UFMC, and SSD-FBMC is similar in the same condition. That is, OFDM, UFMC, and FBMC have a similar PAPR(Peak to Average Power Ratio) characteristic. Finally, we can confirm that the proposed SSD system can not cancel(SI) self-interference effectively by strong HPA nonlinearity. That is, Reducing PAPR is important in order to avoid effect of HPA nonlinearity in the proposed SSD system.
