Out Of Band Emission Research Articles

Filtered OFDM System Improvement Using Hamming Code

Orthogonal Frequency Division Multiplexing (OFDM) technique is widely adopted for broadband Forth Generation (4G) wireless communication systems at present, owing to its ability to combat multi-path interference. Nevertheless, it suffers from a large Peak to Average Power Ratio (PAPR) and Out Of Band Emission (OOBE), making it unsuitable for a high-speed transmission system. On the other hand, the Filtered-OFDM (f-OFDM) system is suggested to overcome the traditional OFDM system's disadvantages and maintain its advantages. Nowadays, the developments and growing communications systems are rapid, especially on their applications such as wireless networks, internet, satellite communications, mobile telephony, etc. This increases the demand for raising the bit rates with decreasing power consumption and the bit error rates (BER). In this paper, Hamming codes are proposed to improve the f-OFDM system performance, while the presence of the subband filter in system architecture could decrease the values of OOBE than the familiar OFDM system. The outcomes showed that utilizing interleaver with Hamming code considerably improves the proposed system performance, while the OOBE values were lower than the conventional OFDM system.

Study and Comparative Analysis of OFDM and UFMC Modulation Schemes

In various areas, wireless systems are used. In order to allocate the available time and frequency resources, these wireless systems require flexible mechanisms. With 5G, transmission rates will be higher, latency will be lower and quality of service and channel capacity will be higher. The physical layer must be able to generate flexible waveforms to meet the above requirements. Currently, Orthogonal Frequency Division Multiplexing (OFDM) transmission does not support 5G communication. In the case of 4G/OFDM, there are many problems in terms of out of band emission, spectral efficiency, and peak to average power ratio (PAPR). An alternative transmission scheme Universal Filtered Multicarrier (UFMC) is introduced to address this problem. The paper compares OFDM with UFMC. The purpose of this paper is to discuss Spectral Density, Spectral Efficiency, Signal to Noise Ratio (SNR) and Bit Error Rate (BER). In comparison to OFDM, UFMC provides better performance.

BER and PSD Improvement of FBMC with Higher Order QAM Using Hermite Filter for 5G Wireless Communication and beyond

Nowadays, multicarrier modulation schemes are being widely used in wireless communication system than single-carrier modulation techniques. Single-carrier modulation schemes are less capable of dealing with multipath fading channels than multicarrier modulation schemes, which results in lower spectral efficiency. Multicarrier modulation schemes have the ability to overcome multipath fading channels. Multicarrier modulation technique currently used in 4G technology in many countries is OFDM and it is easy for implementation, immune to interference, and provide fast data rate. However, the rising users demand on wireless communication resulted in need for further advancement of wireless communication system. The present OFDM transmission does not fulfill the requirements of 5G wireless communication system and beyond due to major limitations such as out of band emission and usage of cyclic prefix. To overcome the challenges of OFDM, different modulation schemes like Filter Bank Multicarrier with Offset-QAM, Filter Bank Multicarrier with QAM, Universal Filter Multicarrier, Filtered-OFDM, and Weighted Overlap and Added-OFDM are proposed. In this study, the Filter Bank Multicarrier with QAM using Hermite prototype filter is proposed to overcome drawbacks of OFDM and all other proposed waveforms. The performances of each multicarrier technique are analyzed based on power spectral density and bit error rate. Simulation result shows that the power spectral density of FBMC with QAM using Hermite filter resulted in 4.7 dB reduction of out of band emission compared to FBMC with QAM using PHYDYAS filter. The bit error rate is also reduced for Vehicular A, Vehicular B, Pedestrian A, and Pedestrian B channel models.

Filtered OFDM System Improvement Using Hamming Code

Orthogonal Frequency Division Multiplexing (OFDM) technique is widely adopted for broadband Forth Generation (4G) wireless communication systems at present, owing to its ability to combat multi-path interference. Nevertheless, it suffers from a large Peak to Average Power Ratio (PAPR) and Out Of Band Emission (OOBE), making it unsuitable for a high-speed transmission system. On the other hand, the Filtered-OFDM (f-OFDM) system is suggested to overcome the traditional OFDM system's disadvantages and maintain its advantages. Nowadays, the developments and growing communications systems are rapid, especially on their applications such as wireless networks, internet, satellite communications, mobile telephony, etc. This increases the demand for raising the bit rates with decreasing power consumption and the bit error rates (BER). In this paper, Hamming codes are proposed to improve the f-OFDM system performance, while the presence of the subband filter in system architecture could decrease the values of OOBE than the familiar OFDM system. The outcomes showed that utilizing interleaver with Hamming code considerably improves the proposed system performance, while the OOBE values were lower than the conventional OFDM system.

Multi-Carrier Waveforms and Multiple Access Strategies in Wireless Networks: Performance, Applications, and Challenges

Current generation mobile communications require high-quality services. Adopting multiple access (MA) and multi-carrier waveforms potentially enhances the quality of services offered to end-users. However, in the majority of literature, the integration of multi-carrier and multiple-access approaches have not been extensively examined. One possible solution is to review multiple access and multi-carrier waveforms simultaneously to create a favorable foundation for the integration of these schemes. Thus, we consider a comprehensive review of multiple-access systems and multi-carrier waveforms jointly from <inline-formula> <tex-math notation="LaTeX">$1^{st}$ </tex-math></inline-formula> to <inline-formula> <tex-math notation="LaTeX">$5^{th}$ </tex-math></inline-formula>-generation (1G-5G) cellular networks. Initially, we present orthogonal MA (OMA) schemes called: frequency division multiple access (FDMA), time division multiple access (TDMA), code division multiple access (CDMA), and orthogonal frequency division multiple access (OFDMA) that have been utilized in 1G, 2G, 3G, and 4G, respectively. In addition, 5G wireless non-orthogonal multiple access (NOMA) techniques such as power domain NOMA (PD-NOMA), code domain NOMA (CD-NOMA), and other NOMA multiplexing methods are addressed in detail. On the other hand, we glanced at 5G cellular multi-carrier waveforms such as filter bank multi-carrier (FBMC), universal filtered multi-carrier (UFMC), generalized frequency division multiplexing (GFDM), and filtered orthogonal frequency division multiplexing (f-OFDM) waveforms. The assessment and comparison between different OMA, NOMA, and multi-carrier waveforms are carried out with the parameters: modulation schemes, bit error rate (BER), signal to noise ration (SNR), sum rate, peak-to-average power ratio (PAPR), latency, out of band emission (OOBE), and complexity. The analytical formulas of OMA, NOMA, and multi-carrier waveform schemes are also derived and verified using simulation data. Each multiple access strategy&#x2019;s merits, shortcomings, applications, and factors influencing its performance are also addressed. Eventually, possible recommendations for the integration of multiple-access and modulation technologies for next-generation mobile networks are also included.

Impact of peak to average power ratio reduction techniques on Generalized Frequency Division Multiplexing for 5th generation systems

Generalized Frequency Division Multiplexing (GFDM) is the advanced multi-carrier methodology proposed for a reliable operation of the 5th generation (5G) systems. It has been observed that the performance of GFDM is hampered by the elevated peak to power ratio (PAPR). High PAPR leads to the saturation of the transmit power amplifier which degrades the bit error rate (BER) and causes the out of band emissions. The prime objective of this work is to evaluate the PAPR performances of GFDM under the various reduction schemes like precoding, clipping, companding, precoding ＋ clipping and precoding ＋ companding. The results show that the precoding techniques combined with clipping or companding results in less PAPR and BER as compared to the conventional GFDM. The discrete cosine transform (DCT) and discrete sine transform (DST) precoded GFDM provides a signal to noise (SNR) improvement of 2−4 dB and 5−8 dB respectively, in comparison to conventional GFDM systems for a BER of 10−3.

Filtered orthogonal frequency division multiplexing for improved 5G systems

Wireless communications became an integrated part of the human life. Fifth generation (5G) is the modern communication which provides enhanced mobile broadband (eMBB), ultra reliable low latency communications (URLLC), and massive machine type communication (mMTC). Thus, 5G have to provide coverage to multi-numerology devices, therefore, modulation and access schemes are suggested in the literature such as cyclic prefix orthogonal frequency division multiplexing (CP-OFDM) and filtered OFDM (f-OFDM). CP-OFDM suffers from the high out of band emission which limited the multi-numerology applications. In f-OFDM, the out of band emission can be suppressed to an accepted extent such that different numerologies can be coexisting. On the other hand, f-OFDM can be more improved by using a proper filtering approach. In this paper three different filters are suggested based windowed-sinc function; Hanning, Hamming, and Blackman. Simulation results show that the proposed filters are promising for high spectral efficiency and out of band emission rejection. Furthermore, the bit error rate, error vector magnitude, and power spectral density are further improved with respect to CP-OFDM scheme but some trade-off is present. Overall, the suggested windowed-sinc filters are outperforming the traditional CP-OFDM. As a conclusion, the suggested windnowed-sinc filters have no limitations on the modulation order or the number of subcarriers utilized in the system.

Prototype filter design for filter bank multicarrier modulation

The use of the cyclic prefix in the orthogonal frequency division multiplexing (CP-OFDM) system recently it is the technique widely used method in many wireless communication systems, which depends on the use of the rectangular pulse shape for the transmission. However, the use of the rectangular pulse shape in the filter leads to appearance of many problems such as out of band emission and also the necessary need to use what is known as the cyclic prefix for the purpose of preventing interference, which leads to decrease the spectral efficiency due to the exploitation of part of the spectrum for the purpose of protection from interference. For the purpose of getting rid of these problems, the filter bank multicarrier (FBMC)system has been proposed who uses filters to construct the typical pulse that can be used in this system. The main idea in this system is how to choose the appropriate filter system for the FBMC/OQAM because this filter plays a fundamental role in the system. In this research, we will be focused on presenting a new prototype pulse shape that can be used in the fifth-generation networks(5G) of communications and also for the purpose of improving the performance of this system and overcoming the previously mentioned obstacles. During this research we will present two models to form the used pulse model, and then we compare these shapes with the most common pulse shape like (Rectangular, RC, PHYDYAS, Hermite). Through this comparison, the efficiency of these pulses can be determined by studying several different parameters that have a direct impact on performance, such as (BER, SIR, PAPR).

A new FWHT‐CMF‐DFE based approach for channel equalization in CP‐free OFDM systems

Orthogonal frequency division multiplexing (OFDM) has been widely used in wireless communication systems due to its robustness against the frequency selectivity of fading channels. It provides optimal performance and it also meets the requirements of the next generation communication systems. Although OFDM has these advantages, its spectrum efficiency is usually degraded significantly due to the use of cyclic prefix (CP). In this paper, motivated to deal with this issue, the combined structure of Fast Walsh-Hadamard Transform (FWHT) and Time Domain Equalizer (TDE) is proposed to use in CP-free OFDM systems. The results validated by Monte Carlo simulations decipher the improved performances in terms of spectral efficiencies, bit error rate, peak to average power ratio and out of band emission for using this structure over frequency selective multipath fading channels in CP-free OFDM systems. The acquired simulation results have illustrated that the proposed method provides 20% spectral efficiency without compromising the BER performance.

UFMC System Performance Analysis for 5G Cellular Networks

Orthogonal frequency division multiplexing (OFDM) is a multicarrier modulation technique, which is used as a dominant waveform for the 4G communication systems. But OFDM cannot meet the demands in 5G. Universal filtered multicarrier (UFMC) has been paid more attention in the 5G communication system because of its low out of band emission (OOBE) and compatibility for multiple input multiple output (MIMO) communication. In this paper performance of UFMC is analyzed in terms of power spectral density (PSD), Bit error rate (BER) and peak to average power ratio (PAPR). Extensive comparison of UFMC and OFDM is included to illustrate the advantages of UFMC. PAPR performance of UFMC is evaluated for various design parameters including FFT size and side lobe attenuation.

Asymmetrical clipping optical filter bank multi-carrier modulation scheme

Filter bank multi-carrier (FBMC) is considered a promising alternative to the Orthogonal Frequency Division Multiplexing (OFDM) scheme. It improves spectral efficiency by eliminating the need for cyclic prefix while attenuating interference due to the robustness of the out-of-band emission. In this work, we present a framework, and the performance evaluation of FBMC is a multi-carrier modulation scheme for the direct detection of optical communications. As the proposed model has higher spectral efficiency than the classical ACO-OFDM, as removing the guard interval enhances the spectral efficiency. Furthermore, the perfect rectangular pulse shaping and eliminating the out of band emission of the filter bank enhances the ACO-FBMC the BER performance of the ACO-OFDM. We propose a transceiver model for Asymmetrical Clipped Optical FBMC (ACO-FBMC) based on Fast Fourier Transform (FFT) operations, analyze inter-frame interference, and offer an iterative receptive method to eliminate it. Finally, we compared the bit error rate (BER) performance of the ACO-FBMC using different overlapping factors with the ACO-OFDM.

A Survey of Candidate Waveforms for beyond 5G Systems

The 5G and beyond future wireless networks aim to support a large variety of services with increasing demand in terms of data rate and throughput while providing a higher degree of reliability, keeping the overall system complexity affordable. One of the key aspects regarding the physical layer architecture of such systems is the definition of the waveform to be used in the air interface. Such waveforms must be studied and compared in order to choose the most suitable and capable of providing the 5G and beyond services requirements, with flexible resource allocation in time and frequency domains, while providing high spectral and power efficiencies. In this paper, several beyond 5G waveforms candidates are presented, along with their transceiver architectures. Additionally, the associated advantages and disadvantages regarding the use of these transmission techniques are discussed. They are compared in a similar downlink transmission scenario where three main key performance indicators (KPIs) are evaluated. They are the peak-to-average power ratio, the overall system spectral efficiency (wherein the out of band emissions are measured, along with the spectral confinement of the power spectral density of the transmitted signals) and the bit error rate performance. Additionally, other KPIs are discussed.

UFMC and f-OFDM: Contender Waveforms of 5G Wireless Communication System

Because of the increased demand for high data rates, looking for using new technologies that meet these requirements are considered a necessary. Hence, Fifth Generation (5G) is expected to be impressive in offering these requirements and implement around 2020. Orthogonal Frequency Division Multiplexing (OFDM) is considered a main technology of LTE wireless communication standards. Due to its suffering from high Bit Error Rate (BER) and Peak Average Power Ratio (PAPR), OFDM doesn't consider as charming solution for future wireless communications and several emerging applications of 5G. Moreover, high Out of Band Emission (OOBE) and inability of supporting the flexible numerology are other demerits of OFDM systems. Thus, looking for alternative waveforms which have the ability of solving OFDM disadvantages are necessary to introduce it as contender candidate for 5G wireless communication systems. In this paper, both of Filtered-OFDM (f-OFDM) and Universal Filtered Multi carrier (UFMC) systems have been discussed for 5G wireless communication systems and compared to OFDM system. The results showed that f-OFDM system is better than both OFDM and UFMC systems and could be introducing as competitive candidate for 5G wireless communication systems because of its ability of reducing OOBE and enhancing BER performance.

Mixed-Numerology Signals Transmission and Interference Cancellation for Radio Access Network Slicing

A clear understanding of mixed-numerology signals multiplexing and isolation in the physical layer is of importance to enable spectrum efficient radio access network (RAN) slicing, where the available access resource is divided into slices to cater to services/users with optimal individual design. In this paper, a RAN slicing framework is proposed and systematically analyzed from the physical layer perspective. According to the baseband and radio frequency (RF) configurations imparities among slices, we categorize four scenarios and elaborate on the numerology relationships of slices configurations. By considering the most generic scenario, system models are established for both uplink and downlink transmissions. Besides, a low out of band emission (OoBE) waveform is implemented in the system for the sake of signal isolation and inter-service/slice-band-interference (ISBI) mitigation. We propose two theorems as the basis of algorithms design in the established system, which generalize the original circular convolution property of discrete Fourier transform (DFT). Moreover, ISBI cancellation algorithms are proposed based on a collaboration detection scheme, where joint slices signal models are implemented. The framework proposed in the paper establishes a foundation to underpin extremely diverse use cases in 5G that implement on a common infrastructure.

Performance of Filtered OFDM Over Different Fading Channels

Orthogonal frequency division multiplexing (OFDM) schemes are used extensively nowadays in large number of practical systems, but OFDM may not be the ideal solution for 5G scenarios because OFDM has high Out of band emission (OOBE) due to high spectral leakage and high peak to average power ratio (PAPR). Therefore Filtered OFDM (F-OFDM), which uses sub band filtering, is proposed as the most flexible waveform for 5G. However there is no work listed in the literature so far that compares the bit error rate (BER) performance of F-OFDM and conventional OFDM in AWGN, Rayleigh and Rician channel. This paper presents the simulation results on the BER performance of F-OFDM and OFDM in presence of AWGN, Rayleigh and Rician channel. The comparison is also done in terms of OOBE and PAPR factor. Results indicate that F-OFDM shows significantly less spectral leakage with same performance in terms of BER compared to conventional OFDM. However for the cases considered, OFDM performance is slightly better than F-OFDM in terms of PAPR factor.

BCH codes for 5G wireless communication systems over multipath fading channel

&lt;span&gt;Due to its large peak to average power ratio (PAPR) and high out of band emission (OOBE), OFDM doesn't meet the requirements of 5G services. Additionally, it supports only one type of waveform parameters in entire bandwidth. In contrast, f-OFDM is dividing the system's bandwidth into a number of subbands to support several waveform parameters based on various service scenarios. So, Filtered-OFDM (f-OFDM) is considered as a modern enabler of the flexible waveform to overcome the OFDM drawbacks while remaining its advantages as well as, to encounter the new challenges that faced 5G. Nonetheless, there is a trade-off among OOBE, PAPR and SNR performance. Meanwhile, channel coding technology is one of the most important issue in physical layer which is playing an essential role in order to achieve the reliability and latency. So, BCH code has been suggested in this paper for f-OFDM system to achieve the reliability of transmission information and thus improving BER performance over multipath fading channel. Whilst, BCH-LTE system is introduced as a baseline in this paper that using for comparison purpose with proposed system. Simulation results showed that the proposed BCH-f-OFDM system was significantly better than BCH-LTE system in terms of decreasing OOBE and achieving improving in BER performance. Although, PAPR levels was stilling high in proposed system due to the trade-off among OOBE, PAPR and SNR performance. However, the proposed system is considered a promising candidate to meet the requirements of 5G services because of its ability to solve two important issues in between three trade-offs'.&lt;/span&gt;

The impact of out of band emissions: A measurement based performance comparison of UF-OFDM and CP-OFDM

Long Term Evolution (LTE) networks, along with their recent releases, rely on the cyclic prefix orthogonal frequency division multiplexing (CP-OFDM) waveform as the foundation. However, high side lobes, synchronization problems and spectral efficiency constraints of CP-OFDM cannot meet future requirements of cellular network design targets. At this point, universal filtered orthogonal frequency division multiplexing (UF-OFDM) emerges as a strong candidate. Equipped with the advantages of using filters, UF-OFDM provides additional design flexibility to address the fundamental problems of CP-OFDM. In this study, the effect of adjacent channels that causes interference between different frequency channels because of out-of-band (OoB) emissions on UF-OFDM performance is investigated by performing real-time tests on software defined radio (SDR) nodes with multiple reception paths. Frequency domain carrier frequency offset (CFO) and symbol timing offset (STO) correction techniques are used. By the application of the same correction approaches to CP-OFDM, these two waveforms are evaluated in terms of signal to noise ratio (SNR), bit/symbol error rate (BER/SER) and error vector magnitude (EVM). Test results indicate that, based on lower OoB emissions, UF-OFDM uses the spectrum more efficiently and provides better results than CP-OFDM in congested environments.

Filter bank SCFDMA: an efficient uplink strategy for future communication systems

This paper develops a generalized system model for the precoded multicarrier communication system, using basic multirate building blocks. Mathematical analysis of the proposed model is carried out, and the results are utilized in developing an efficient uplink wireless communication standard filter bank single carrier frequency division multiple access. The proposed system combines the low peak to average power ratio (PAPR) advantage of a single carrier communication system with the reduced out of band emission (OBE) of filter bank multicarrier (FBMC) scheme. The sensitivity of the proposed system to carrier frequency offset (CFO) is analyzed, and the results are utilized in developing a CFO compensation scheme with reduced complexity. A Nyquist filter design approach, which strikes a balance between OBE and tail size, is developed and is incorporated into the proposed system to enhance the OBE and PAPR characteristics. The instantaneous power of the proposed system is theoretically analyzed using characteristic function based approach, and the effectiveness of modifications is substantiated. A detailed simulation study is carried out to validate the performance of the proposals.

Zadoff-chu sequence based preamble design of fbmc/oqam for 5g

The Spectrum effectiveness for 5G networks can be accomplished by Filter Bank Multi Carrier / Orthogonal Quadrature Amplitude Modulation (FBMC / OQAM) that avoids the benefit of guard band. FBMC is very considerate to Carrier Frequency Offset (CFO) and Timing Offset (TO). This paper suggests Zadoff-chu (ZC) sequence based preamble or pilot is accustomed to design the FBMC frame for synchronize more with receiver to achieve sufficient channel inference and phase tracking which reduces the carrier frequency and timing synchronization. This method helps to influence the out of band emissions and conceive non-orthogonal waveforms to investigate the overall system performance such as Bit Error Rate (BER) over AWGN channels. The performance measuresbeing Complementary Cumulative Distribution Curve (CCDF) for FBMC signal with different multicarrier to evaluate the Peak to Average Power Ratio (PAPR) has been achieved by simulation. The simulation outcomeshows that FBMC outperforms well when analyzed with other multicarrier systems.

Wired-Wireless Converged Passive Optical Network with 4-PAM and Multi-sub-bands FBMC

Future 5G based passive optical networks (PON) are expected as capable of the simultaneous provision of wired and wireless services for multi-users. In this paper, for the first time, we propose and demonstrate the simultaneous delivery of wired 4-pulse amplitude modulation (4-PAM) and wireless multi-sub-bands filter bank multicarrier (FBMC) signals in one wavelength using one laser source for the future 5G PON. The 4-PAM can be used in cost-efficient intensity modulation direct detection (IM/DD) systems and it provides the double bandwidth efficiency compared to conventional on-off keying (OOK). FBMC is considered as a potential candidate for future wireless 5G due to its high suppression for out of band emissions, which allows combining multiple sub-bands with very narrow band-gaps. Using multi-sub-bands with a narrow band gap, the overall transmission capacity can be increased. In the designed system, the composite wired 4-PAM and wireless multi-sub-bands FBMC signal is generated and transmitted with intensity modulation in optical line terminal (OLT). In the optical network unit (ONU) the wired and wireless signals from the received composite signal are extracted using an electrical square band-pass filter and separately demodulated using digital signal processing techniques. The designed 4-PAM has baseband bandwidth of 4.8 GHz and multi-subbands FBMC consists of 4 sub-bands of 500 MHz each, having very narrow inter-sub-bands gap of 488.28 kHz and the aggregate bandwidth of 2.0015 GHz. The bit error rate (BER) has been evaluated for the performance analysis of the 4-PAM and multi-sub-bands FBMC for two cases (a) separate transmission and (b) composite transmission.