PAPR Reduction Solutions for 5G and Beyond

The latest fifth generation (5G) wireless technology provides improved communication quality compared to earlier generations. The 5G New Radio (NR), specified by the 3rd Generation Partnership Project (3GPP), addresses the modern requirements of the wireless networks and targets improved communication quality in terms of for example peak data rates, latency and reliability. On the other hand, there are still various crucial issues that impact the implementation and energy-efficiency of 5G NR networks and their different deployments. The power-efficiency of transmitter power amplifiers (PAs) is one of these issues. The PA is an important unit of a communication system, which is responsible from amplifying the transmit signal towards the antenna. Reaching high PA power-efficiency is known to be difficult when the transmit waveform has a high peak-to-average power ratio (PAPR). The cyclic prefix (CP)-orthogonal frequencydivision multiplexing (OFDM) that is the main physical-layer waveform of 5G NR, suffers from such high PAPR challenge. There are generally many PAPR reduction methods proposed in the literature, however, many of these have either very notable computational complexity or impose substantial inband distortion. Moreover, 5G NR has new features that require redesigning the PAPR reduction methods. In line with these, the first contribution of this thesis is the novel frequencyselective PAPR reduction concept, where clipping noise is shaped in a frequencyselective manner over the active passband. This concept is in line with the 5G NR, where aggressive frequency-domain multiplexing is considered as an important feature. Utilizing the frequency-selective PAPR reduction enables the realization of the heterogeneous resource utilization within one passband. The second contribution of this thesis is the frequency-selective single-numerology (SN) and mixed-numerology (MN) PAPR reduction methods. The 5G NR targets utilizing different physical resource blocks (PRBs) and bandwidth parts (BWPs) within one passband flexibly. Yet, existing PAPR reduction methods do not exploit these features. Based on this, novel algorithms utilizing PRB and BWP level control of clipping noise are designed to meet error vector magnitude (EVM) limits of the modulations while reducing the PAPR. TheMNallocation has one critical challenge as inter numerology interference (INI) emerges after aggregation of subband signals. Proposed MN PAPR reduction algorithm overcomes this issue by cancelling INI within the PAPR reduction loop, which has not been considered earlier. The third contribution of this thesis is the proposal of two novel non-iterative PAPR reduction methods. First method utilizes the fast-convolution filteredOFDM (FC-F-OFDM) that has excellent spectral containment, and combines it with clipping. Moreover, clipping noise is also allocated to guard bands by filter passband extension (FPE) and clipping noise in out-of-band (OOB) regions is essentially filtered through FC filtering. The second method is the guard-tone reservation (GTR) which is applied to discrete Fourier transform-spread-OFDM (DFT-s-OFDM). Uniquely, GTR estimates the time domain peaks in data symbol domain before inverse fast Fourier transform (IFFT), and uses guard band tones for PAPR reduction. The fourth contribution of the thesis is the design of two novel machine learning (ML) algorithms that improve the drawbacks of frequency-selective PAPRreduction. The first ML algorithm, PAPRer, models the nonlinear relation between the PAPR target and the realized PAPR value. Then, it auto-tunes the optimal PAPR target and this way minimizes the realized PAPR. The second ML algorithm, one-shot clipping-and-filtering (OSCF), solves the complexity problem of iterative clipping and filtering (ICF)-like methods by generating proper approximated clipping noise signal after running only one iteration, leading to very efficient PAPR reduction. Finally, an over-arching contribution of this thesis is the experimental validation of the performance benefits of the proposed methods by considering realistic 5GNR uplink (UL) and downlink (DL) testbeds that include realistic PAs and associated hardware. It is very important to confirm the practical benefits of the proposed methods and, this is realized with the conducted experimental work

Analysis and Implementation of PAPR reduction algorithms for C-OFDM signals

Nowadays multicarrier modulation has become a key technology for communication systems; for example C-OFDM schemes are used in wireless LAN (802.11a/g/n), terrestrial digital television (DVB-T) and audio broadcaster (DAB) in Europe, and discrete multitone (DMT) in x.DSL systems. The principal difficulty with OFDM is the occurrence of the coherent alignment of the time domain parallel signals at the transmitted side which forces system designer to introduce either additional hard computationally device or a suitable power back-off at the high power amplifier in order to cope with the large magnitude signal fluctuation. This leads to a significant increment in computational cost in the former case whereas in a worse allowable power utilization in the latter case with respect to the original system. However since both allowable power and computational cost are subject to a design as well as regulatory limit others solution must be accomplished. Peak reduction techniques reduce maximum-to-mean amplitude fluctuations nominating as a feasible solution. Peak-to-average power ratio is the key metric to measure this amplitude fluctuations at transmitter and to give a clear figure of merit for comparison among different techniques

Intelligent genetic algorithms for next-generation broadband multi-carrier CDMA wireless networks

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.This dissertation proposes a novel intelligent system architecture for next-generation broadband multi-carrier CDMA wireless networks. In our system, two novel and similar intelligent genetic algorithms, namely Minimum Distance guided GAs (MDGAs) are invented for both peak-to-average power ratio (PAPR) reduction at the transmitter side and multi-user detection (MUD) at the receiver side. Meanwhile, we derive a theoretical BER performance analysis for the proposed MC-CDMA system in A WGN channel. Our analytical results show that the theoretical BER performance of synchronized MC-CDMA system is the same as that of the synchronized DS-CDMA system which is also used as a theoretical guidance of our novel MUD receiver design. In contrast to traditional GAs, our MDGAs start with a balanced ratio of exploration and exploitation which is maintained throughout the process. In our algorithms, a new replacement strategy is designed which increases significantly the convergence rate and reduces dramatically computational complexity as compared to the conventional GAs. The simulation results demonstrate that, if compared to those schemes using exhaustive search and traditional GAs, (1) our MDGA-based P APR reduction scheme achieves 99.52% and 50+% reductions in computational complexity, respectively; (2) our MDGA-based MUD scheme achieves 99.54% and 50+% reductions in computational complexity, respectively. The use of one core MDGA solution for both issues can ease the hardware design and dramatically reduce the implementation cost in practice

On the Fast DHT Precoding of OFDM Signals over Frequency-Selective Fading Channels for Wireless Applications

Due to high power consumption and other problems, it is unlikely that orthogonal frequency-division multiplexing (OFDM) would be included in the uplink of the future 6G standard. High power consumption in OFDM systems is motivated by the high peak-to-average power ratio (PAPR) introduced by the inverse Fourier transform (IFFT) processing kernel in the time domain. Linear precoding of the symbols in the frequency domain using discrete Hartley transform (DHT) could be used to minimise the PAPR problem, however, at the cost of increased complexity and power consumption. In this study, we minimise the computation complexity of the DHT precoding on OFDM transceiver schemes and the consequent power consumption. We exploit the involutory properties of the processing kernels to process the DHT and IFFT as a single-processing block, thus reducing the system complexity and power consumption. These also enable a novel power-saving receiver design. We compare the results to three other precoding schemes and the standard OFDM scheme as the baseline; while improving the power consumption efficiency of a Class-A power amplifier from 4.16% to 16.56%, the bit error ratio is also enhanced by up to 5 dB when using a 1/2−rate error-correction coding and 7 dB with interleaving

Analytical Characterization and Optimum Detection of Nonlinear Multicarrier Schemes

It is widely recognized that multicarrier systems such as orthogonal frequency division multiplexing (OFDM) are suitable for severely time-dispersive channels. However, it is also recognized that multicarrier signals have high envelope fluctuations which make them especially sensitive to nonlinear distortion effects. In fact, it is almost unavoidable to have nonlinear distortion effects in the transmission chain. For this reason, it is essential to have a theoretical, accurate characterization of nonlinearly distorted signals not only to evaluate the corresponding impact of these distortion effects on the system’s performance, but also to develop mechanisms to combat them. One of the goals of this thesis is to address these challenges and involves a theoretical characterization of nonlinearly distorted multicarrier signals in a simple, accurate way. The other goal of this thesis is to study the optimum detection of nonlinearly distorted, multicarrier signals. Conventionally, nonlinear distortion is seen as a noise term that degrades the system’s performance, leading even to irreducible error floors. Even receivers that try to estimate and cancel it have a poor performance, comparatively to the performance associated to a linear transmission, even with perfect cancellation of nonlinear distortion effects. It is shown that the nonlinear distortion should not be considered as a noise term, but instead as something that contains useful information for detection purposes. The adequate receiver to take advantage of this information is the optimum receiver, since it makes a block-by-block detection, allowing us to exploit the nonlinear distortion which is spread along the signal’s band. Although the optimum receiver for nonlinear multicarrier schemes is too complex, due to its necessity to compare the received signal with all possible transmitted sequences, it is important to study its potential performance gains. In this thesis, it is shown that the optimum receiver outperforms the conventional detection, presenting gains not only relatively to conventional receivers that deal with nonlinear multicarrier signals, but also relatively to conventional receivers that deal with linear, multicarrier signals. We also present sub-optimum receivers which are able to approach the performance gains associated to the optimum detection and that can even outperform the conventional linear, multicarrier schemes

OFDM 시스템에서의 PAPR 감소를 위한 시간 영역의 큰 샘플을 이용한 저복잡도 PTS 기법

학위논문 (박사)-- 서울대학교 대학원 : 공과대학 전기·컴퓨터공학부, 2018. 2. 노종선.In orthogonal frequency division multiplexing (OFDM) systems, high peak-to-average power ratio (PAPR) of OFDM signals is one of the most important problems. The high PAPR of OFDM signals causes serious nonlinear distortions in process of passing through high power amplifier (HPA). These distortions have a effect on in-band distortion and out-of-band radiation, which result in bit error rate degradation of received OFDM signals and interference in adjacent channel, respectively. In order to solve the PAPR problem of OFDM signals, various PAPR reduction schemes have been proposed. This dissertation includes research results on a kind of the PAPR reduction schemes, called the partial transmit sequence (PTS) for the OFDM systems. As a solution to the PAPR problem in OFDM systems, the PTS scheme is a fairly suitable scheme due to its PAPR reduction performance and distortionless characteristics. The PTS scheme generates several candidate OFDM signals to represent an original OFDM signal and selects one with the lowest PAPR among them for transmission. However, a serious problem in the PTS scheme is high computational complexity, which is mainly required to generate and process the candidate OFDM signals. In this dissertation, in an effort to reduce its computational complexity, new PTS schemes are proposed using dominant time-domain samples of OFDM signals. Dominant time-domain samples is a small number of samples of OFDM signals used to estimate PAPRs of candidate OFDM signals efficiently. In the first part of this dissertation, low-complexity PTS schemes are proposed using new selection methods of dominant time-domain samples. The proposed selection methods of dominant time-domain samples are based on selection methods of candidate samples in candidate OFDM signals. These methods select dominant time-domain samples with reduced computational complexity. The dominant time-domain samples selected by the proposed methods are used to estimate PAPRs of candidate OFDM signals with high accuracy. Therefore, the proposed low-complexity PTS schemes can achieve the optimal PAPR reduction performance with considerably reduced computational complexity. In the second part of this dissertation, improved PTS schemes are proposed to lower the computational complexity of previous PTS schemes further while maintaining high performance of PAPR reduction. Similar with the PTS schemes proposed in the previous part of this dissertation, the improved PTS schemes utilize dominant time-domain samples and candidate samples. However, they use more efficient methods, which select the candidate samples by adaptive method or multi-stage method to select dominant time-domain samples. Therefore, the improved PTS schemes reduce computational complexity further while maintaining the optimal PAPR reduction performance. The proposed PTS schemes in this dissertation use efficient methods to select dominant time-domain samples and thus they reduce the computational complexity considerably compared to previous PTS schemes. In addition, they achieve the optimal PAPR reduction performance, which is equivalent to that of the conventional PTS scheme with the low complexity. Due to the high performance and low complexity, they are fully expected to be used in the practical implementation of OFDM systems.1 INTRODUCTION 1 1.1 Introduction 1 1.2 Overview of Dissertation 4 2 PRELIMINARIES 6 2.1 OFDM and PAPR 6 2.2 High Power Amplifier Models 8 2.3 Analysis of PAPR 11 2.3.1 PAPR of OFDM Signal 11 2.3.2 PAPR and BER 17 2.4 Iterative PAPR Reduction Schemes 18 2.4.1 Clipping and Filtering 19 2.4.2 Tone Reservation 20 2.4.3 Active Constellation Extension 24 2.5 Probabilistic PAPR Reduction Scheme: Selective Mapping 26 2.6 Conventional PTS Scheme 32 2.7 Low-Complexity PTS Schemes Using Dominant Time-Domain Samples 34 2.7.1 Dominant Time-Domain Samples 34 2.7.2 Low-Complexity PTS Schemes Using Dominant Time-Domain Samples 37 3 LOW-COMPLEXITY PTS SCHEMES WITHNEWSELECTION METHODS OF DOMINANT TIME-DOMAIN SAMPLES 40 3.1 Notations 40 3.2 Selection Methods of Candidate Samples for Dominant Time-Domain Samples 41 3.3 Proposed Low-Complexity PTS Schemes 50 4 IMPROVED PTS SCHEMES WITH ADAPTIVE SELECTION METHODS OF DOMINANT TIME-DOMAIN SAMPLES 52 4.1 Adaptive Selection Methods of Candidate Samples for Dominant Time-Domain Samples 52 4.1.1 A1-SM with W = 2 53 4.1.2 A1-SM with W = 4 54 4.1.3 A2-SM with W = 2 55 4.2 Mathematical Representations for Probability Distribution of Cn 66 4.2.1 A1-SM with W = 2 69 4.2.2 A1-SM with W = 4 69 4.2.3 A2-SM with W = 2 69 4.3 Multi-Stage Selection Method of Dominant Time-Domain Samples 70 4.4 Proposed PTS Schemes with Adaptive Selection Methods for Dominant Time-Domain Samples 71 5 PERFORMANCE ANALYSIS 74 5.1 Computational Complexity 74 5.2 Simulation Results 76 6 CONCLUSIONS 85 Abstract (In Korean) 92Docto

Intelligent genetic algorithms for next-generation broadband multi-carrier CDMA wireless networks

This dissertation proposes a novel intelligent system architecture for next-generation broadband multi-carrier CDMA wireless networks. In our system, two novel and similar intelligent genetic algorithms, namely Minimum Distance guided GAs (MDGAs) are invented for both peak-to-average power ratio (PAPR) reduction at the transmitter side and multi-user detection (MUD) at the receiver side. Meanwhile, we derive a theoretical BER performance analysis for the proposed MC-CDMA system in A WGN channel. Our analytical results show that the theoretical BER performance of synchronized MC-CDMA system is the same as that of the synchronized DS-CDMA system which is also used as a theoretical guidance of our novel MUD receiver design. In contrast to traditional GAs, our MDGAs start with a balanced ratio of exploration and exploitation which is maintained throughout the process. In our algorithms, a new replacement strategy is designed which increases significantly the convergence rate and reduces dramatically computational complexity as compared to the conventional GAs. The simulation results demonstrate that, if compared to those schemes using exhaustive search and traditional GAs, (1) our MDGA-based P APR reduction scheme achieves 99.52% and 50+% reductions in computational complexity, respectively; (2) our MDGA-based MUD scheme achieves 99.54% and 50+% reductions in computational complexity, respectively. The use of one core MDGA solution for both issues can ease the hardware design and dramatically reduce the implementation cost in practice.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Design and implementation of low complexity adaptive optical OFDM systems for software-defined transmission in elastic optical networks

Due to the increasing global IP traffic and the exponential growing demand for broadband services, optical networks are experimenting significant changes. Advanced modulation formats are being implemented at the Digital Signal Processing (DSP) level as key enablers for high data rate transmission. Whereas in the network layer, flexi Dense Wavelength-Division Multiplexing (DWDM) grids are being investigated in order to efficiently use the optical spectrum according to the traffic demand. Enabling these capabilities makes high data rate transmission more feasible. Hence, introducing flexibility in the system is one of the main goals of this thesis. Furthermore, minimizing the cost and enhancing the Spectral Efficiency (SE) of the system are two crucial issues to consider in the transceiver design. This dissertation investigates the use of Optical Orthogonal Frequency Division Multiplexing (O-OFDM) based either on the Fast Fourier Transform (FFT) or the Fast Hartley Transform (FHT) and flexi-grid technology to allow high data rate transmission over the fiber. Different cost-effective solutions for Elastic Optical Networks (EON) are provided. On the one hand, Direct Detection (DD) systems are investigated and proposed to cope with present and future traffic demand. After an introduction to the principles of OFDM and its application in optical systems, the main problems of such modulation is introduced. In particular, Peak-to-Average Power Ratio (PAPR) is presented as a limitation in OFDM systems, as well as clipping and quantization noise. Hence, PAPR reduction techniques are proposed to mitigate these impairments. Additionally, Low Complexity (LC) PAPR reduction techniques based on the FHT have also been presented with a simplified DSP. On the other hand, loading schemes have also been introduced in the analyzed system to combat Chromatic Dispersion (CD) when transmitting over the optical link. Moreover, thanks to Bit Loading (BL) and Power Loading (PL), flexible and software-defined transceivers can be implemented maximizing the spectral efficiency by adapting the data rate to the current demand and the actual network conditions. Specifically, OFDM symbols are created by mapping the different subcarriers with different modulation formats according to the channel profile. Experimental validation of the proposed flexible transceivers is also provided in this dissertation. The benefits of including loading capabilities in the design, such as enabling high data rate and software-defined transmission, are highlighted.Degut al creixement del tràfic IP i de la demanda de serveis de banda ampla, les xarxes òptiques estan experimentant canvis significatius. Els formats avançats de modulació, implementats a nivell de processat del senyal digital, habiliten la transmissió a alta velocitat. Mentre que a la capa de xarxa, l'espectre òptic es dividit en ranures flexibles ocupant l'ample de banda necessari segons la demanda de tràfic. La transmissió a alta velocitat és fa més tangible un cop habilitades totes aquestes funcionalitats. D'aquesta manera un dels principals objectius d'aquesta tesis es introduir flexibilitat al sistema. A demés, minimitzar el cost i maximitzar l'eficiència espectral del sistema són també dos aspectes crucials a considerar en el disseny del transmissor i receptor. Aquesta tesis investiga l'ús de la tecnologia Optical Orthogonal Frequency Division Multiplexing (OFDM) basada en la transformada de Fourier (FFT) i la de Hartley (FHT) per tal de dissenyar un sistema flexible i capaç de transmetre a alta velocitat a través de la fibra òptica. Per tant, es proposen diferent solucions de baix cost vàlides per a utilitzar en xarxes òptiques elàstiques. En primer lloc, s'investiguen i es proposen sistemes basats en detecció directa per tal de suportar la present i futura demanda. Després d'una introducció dels principis d' OFDM i la seva aplicació als sistemes òptics, s'introdueixen alguns dels problemes d'aquesta modulació. En particular, es presenten el Peak-to-Average Power Ratio (PAPR) i els sorolls de clipping i de quantizació com a limitació dels sistemes OFDM. S'analitzen tècniques de reducció de PAPR per tal de reduir l'impacte d'aquests impediments. També es proposen tècniques de baixa complexitat per a reduir el PAPR basades en la FHT. Finalment, s'utilitzen algoritmes d'assignació de bits i de potència, Bit Loading (BL) i Power Loading (PL), per tal de combatre la dispersió cromàtica quan es transmet pel canal òptic. Amb la implementació dels algoritmes de BL i PL, es poden dissenyar transmissors i receptors flexibles adaptant la velocitat a la demanda del moment i a les actuals condicions de la xarxa. En particular, els símbols OFDM es creen mapejant cada portadora amb un format de modulació diferent segons el perfil del canal. El sistema és validat experimentalment mostrant les prestacions i els beneficis d'incloure flexibilitat per tal de facilitar la transmissió a alta velocitat i cobrir les necessitats de l'Internet del futurDebido al crecimiento del tráfico IP y de la demanda de servicios de banda ancha, las redes ópticas están experimentando cambios significativos. Los formatos avanzados de modulación, implementados a nivel de procesado de la señal digital, habilitan la transmisión a alta velocidad. Mientras que en la capa de red, el espectro óptico se divide en ranuras flexibles ocupando el ancho de banda necesario según la demanda de tráfico. La transmisión a alta velocidad es más tangible una vez habilitadas todas estas funcionalidades. De este modo uno de los principales objetivos de esta tesis es introducir flexibilidad en el sistema. Además, minimizar el coste y maximizar la eficiencia espectral del sistema son también dos aspectos cruciales a considerar en el diseño del transmisor y receptor. Esta tesis investiga el uso de la tecnologia Optical Orthogonal Frequency Division Multiplexing (OFDM) basada en la transformada de Fourier (FFT) y en la de Hartley (FHT) con tal de diseñar un sistema flexible y capaz de transmitir a alta velocidad a través de la fibra óptica. Por lo tanto, se proponen distintas soluciones de bajo coste válidas para utilizar en redes ópticas elásticas. En primer lugar, se investigan y se proponen sistemas basados en detección directa con tal de soportar la presente y futura demanda. Después de una introducción de los principios de OFDM y su aplicación en los sistemas ópticos, se introduce el principal problema de esta modulación. En particular se presentan el Peak-to-Average Power Ratio (PAPR) y los ruidos de clipping y cuantización como limitaciones de los sistemas OFDM. Se analizan técnicas de reducción de PAPR con tal de reducir el impacto de estos impedimentos. También se proponen técnicas de baja complejidad para reducir el PAPR basadas en la FHT. Finalmente, se utilizan algoritmos de asignación de bits y potencia, Bit Loading (BL) y Power Loading (PL), con tal de combatir la dispersión cromática cuando se transmite por el canal óptico. Con la implementación de los algoritmos de BL y PL, se pueden diseñar transmisores y receptores flexibles adaptando la velocidad a la demanda del momento y a las actuales condiciones de la red. En particular, los símbolos OFDM se crean mapeando cada portadora con un formato de modulaci_on distinto según el perfil del canal. El sistema se valida experimentalmente mostrando las prestaciones y los beneficios de incluir flexibilidad con tal de facilitar la transmisión a alta velocidad y cubrir las necesidades de Internet del futuro

LPTV-Aware Bit Loading and Channel Estimation in Broadband PLC for Smart Grid

Power line communication (PLC) has received steady interest over recent decades because of its economic use of existing power lines, and is one of the communication technologies envisaged for Smart Grid (SG) infrastructure. However, power lines are not designed for data communication, and this brings unique challenges for data communication over power lines. In particular for broadband (BB) PLC, the channel exhibits linear periodically time varying (LPTV) behavior synchronous to the AC mains cycle. This is due to the time varying impedances of electrical devices that are connected to the power grid. Another challenge is the impulsive noise in addition to power line background noise, which is due to switching events in the power line network. In this work, we focus on two major aspects of an orthogonal frequency division multiplexing (OFDM) system for BB PLC LPTV channels; bit and power allocation, and channel estimation (CE). First, we investigate the problem of optimal bit and power allocation, in order to increase bit rates and improve energy efficiency. We present that the application of a power constraint that is averaged over many microslots can be exploited for further performance improvements through bit loading. Due to the matroid structure of the optimization problem, greedy-type algorithms are proven to be optimal for the new LPTV-aware bit and power loading. Significant gains are attained especially for poor (i.e. high attenuation) channel conditions, and at reduced transmit-power levels, where the energy per bit-transmission is also low. Next, two mechanisms are utilized to reduce the complexity of the optimal LPTV-aware bit loading and peak microslot power levels: (i) employing representative values from microslot transfer functions, and (ii) power clipping. The ideas of LPTV-aware bit loading, complexity reduction mechanism, and power clipping are also applicable to non-optimal bit loading schemes. We apply these ideas to two additional sub-optimal bit loading algorithms that are based on even-like power distribution for a portion of the available spectrum, and demonstrate that similar gains in bit rates are achieved. Second, we tackle the problem of CE for BB PLC LPTV channels. We first investigate pilot based CE with different pilot geometry in order to reduce interpolation error. Block-type, comb-type, and incline type pilot arrangements are considered and a performance comparison has been made. Next we develop a robust CE scheme with low overhead that addresses the drawbacks of block-type pilot arrangement and decision directed CE schemes such as large estimation overhead for block-type pilot geometry, and difficulty in channel tracking in the case of sudden changes in the channel for decision directed approaches. In order to overcome these drawbacks, we develop a transform domain (TD) analysis approach to determine the cause of changes in the channel estimates, which are due to changes in the channel response or the presence of impulsive noise. We then propose a robust CE scheme with low estimation overhead, which utilizes pilot symbols placed widely apart and exploits the information obtained from TD analysis as a basis for switching between various CE schemes. The overhead of the proposed scheme for CE is low, and sudden changes in the channel are tracked affectively. Therefore, the effects of the LPTV channel and the impulsive noise on CE are mitigated. Our results indicate that for bit and power allocation, the proposed reduced complexity LPTV-aware bit loading with power clipping algorithm performs very close to the optimal LPTV-aware bit loading, and is an attractive solution to bit loading in a practical setting. Finally, for the CE problem, the proposed CE scheme based on TD analysis has low estimation overhead, performs well compared to block-type pilot arrangement and decision directed CE schemes, and is robust to changes in the channel and the presence of impulsive noise. Therefore, it is a good alternative for CE in BB PLC