5G Waveform Research Articles

Continuous-unconstrained and global optimization for PSO-PTS based PAPR reduction of OFDM signals

Orthogonal frequency division multiplexing (OFDM) is a superior technology for the high-speed data rate of wire-line and wireless communication systems. However, one of the major drawbacks of OFDM signals is the high peak-to-average power ratio (PAPR) problem inherent in 5G waveform design. High PAPR causes OFDM signal distortion in the nonlinear region of the high power amplifier (HPA), and signal distortion leads to a decrease in bit error rate (BER). Partial transmit sequence (PTS) technique is a very attractive technique for PAPR reduction. However, to match the optimum condition on PTS for PAPR reduction, the computational unpredictability and cost of traditional PTS strategy are enormous, thus it is urgent to enhance computational efficiency to obtain the optimal PTS. In this paper, an improved scheme called Continuous-Unconstrained Particle Swarm Optimization based PTS (CUPSO-PTS) technique for optimum phase rotation factors searching is presented. A class of continuous-phase PTS schemes has been proposed to obtain the global optimal phase factor, and the theoretical boundaries can be determined in the continuous-unconstrained searching space. Conversely, when the phase factor values in continuous-unconstrained domain, the equivalent unconstrained PTS optimization can drastically accelerate convergence and reduce total calculation cost. In this paper, we compare the performance of Binary PSO based PTS (BPSO-PTS) scheme and Elitist Genetic Algorithm based PTS (EGA-PTS) scheme for 16-QAM modulation scheme. Theoretical analysis and simulations show that the proposed CUPSO-PTS scheme could provide a significant PAPR reduction in the OFDM system, which outperforms the OFDM systems with the traditional PTS scheme by 0.55 dB at CCDF of 10−3 in PAPR reduction. And 84.74% computational complexity is saved.

Acquisition performance of B1I abounding with 5G signals

The widespread 5G base stations can be potential jammers for the vulnerable BeiDou B1I receivers due to its low power. Therefore, a novel analytical model is derived for the 5G signal to evaluate its impact on acquisition performance under three decision methods. The good agreement between the Monte Carlo method (MCM) through software defined receiver (SDR) and the derived expressions validates the effectiveness of the proposed algorithm. It can be found that the receivers exhibit varied responses for different 5G waveforms and decision strategies. The receiver also shows the least endurances for some kind of 5G waveforms, however, this kind of adverse effect can be cancelled by a reduced interference signal ratio (ISR), an increased integration time or a larger accumulation times.

A CR-5G network based on multi-user for various waveforms detection

The 5G network is promised to provide all the requirements surfacing from the speedily rising number of mobile phone users rather than huge amount of data transmission. Many 5G waveforms can be used by 5G network such as Filtered-Orthogonal Frequency Division Multiplexing (F-OFDM), Universal Filtered Multi-Carrier (UFMC), or Filter Bank Multi-Carrier (FBMC) waveform. To effectively capitalize on the spectrum resources, Internet of Thing (IoT), and multimedia transmission, the Cooperative Spectrum Sensing (CSS) system is being extensively utilized by Cognitive Radio (CR). It is able to meet the requisite communication services, however, the conventional CSS systems have been designed to detect only single kind of 5G waveform and poor detection performance for low signal-to-noise ratio (SNR). In this paper, a hybrid filter based CSS system is proposed for detection of various 5G waveforms by multi-user. The proposed filter includes three cascaded stages: cosine filtering, Welch segmentation, and Hamming windowing. The proposed detection system is applied on different data such as various of waveforms and SNRs. The simulation results exhibit a significant detection performance for the parameters of less than zero dB of SNR, greater than 95% global detection probability, less than 1% global system error probability, and less than 1% global false alarm probability. In addition, the detection performance reveals that the proposed system is outperformed related works as shown in the comparison in terms of the previous parameters.

Overview and Comparison of Candidate 5G Waveforms: FBMC, UFMC and F-OFDM

The fifth generation (5G) technology standard, utilizing the Internet of Things, promises enhanced communication systems. However, the efficiency expected from such systems entails significant requirements, such as higher data rates and flexibility of the lowest 5G layer. Meeting these requirements in subsequent wireless communication systems is highly dependent on the use of waveforms capable of efficiently enabling multiple access. In other words, proper waveforms determine the effective handling of diverse traffic within a given band. In this study, four candidate multicarrier waveforms, namely filtered orthogonal frequency division multiplexing, filter bank multicarrier, universal filtered multicarrier, and orthogonal frequency division multiplexing, which is currently used in 4G systems, are compared based on multiple parameters. MATLAB simulation results indicate that the waveforms significantly improved spectrum localization and provided appropriate spectrum fragmentation. As these waveforms can mix diverse traffic specifications, they handle the problem of time-frequency synchronization effectively. Therefore, these new waveforms exhibit significant potential in terms of orthogonality and synchronicity and can support numerous users without dropping signals. In addition, they support all applications and scenarios related to multiple-input and multiple-output. The obtained simulation results confirm the suitability of such waveforms for 5G applications and systems.

Performance Evaluation of 5G Waveforms for Joint Radar Communication over 77 GHz and 24 GHz ISM Bands

The V2X environment poses many challenges to emerging wireless communication systems, while it is crucial to ensure the efficiency and safety of road users. Requiring continual localization of the surroundings and accurate obstacle detection while providing high reliability in dense networks and low latency in high-mobility environment communication systems imposes a challenge to the driver-assistance field given that we are overly limited in terms of frequency bands and resources. Hence, pooling of the available frequency resources between different applications can help increase the spectral efficiency. A new collaborative approach multiplexed in the time domain, namely RadCom, which can be described as a joint radar and communication system that performs both vehicle-to-everything communication and detection of the neighboring obstacles in the vehicular environment, has been proposed to overcome the limitations of the existing conventional radar system. Based on orthogonal frequency division multiplexing (OFDM), this RadCom system proved to be suitable up to now for V2X. Moreover, a new RadCom system based on universal frequency multi-carrier (UFMC), an advanced fifth-generation (5G) waveform, has been proposed to enhance the spectral efficiency and surmount the shortcomings induced by the OFDM waveform. This recent RadCom system has been studied in the new frequency range of 76–81 GHz; precisely, 77 GHz. Hence, in this paper, we propose to compare both subsystems of the proposed RadCom system over two different frequency carriers, 24 GHz and 77 GHz, and to adopt the proper system parametrization in order to meet appropriate wireless solutions for automotive RadCom systems.

Fast Convolution Based Complexity Reduction in Universal Filtered Multi-Carrier Systems

The Universal Filtered Multi-Carrier (UFMC) is a derivative of the Orthogonal Frequency Division Multiplexing (OFDM) scheme. It is considered as a candidate waveform for 5G. The considerably high computational complexity restricts the usage of UFMC based systems. This complexity is caused by the filtration process in the system. Since the flexible and efficient use of non-continuous unused spectrum for different network deployment strategies is important in the next generation communication, the selection of UFMC is inevitable because of its improved performance over OFDM and the Filter Bank Multi-Carrier (FBMC) systems. Hence, it is essential to reduce the complexity of a UFMC system. In this paper, we propose a Fast Convolution (FC) based UFMC system. The technique makes use of smaller FFTs and overlapped data frames. The proposed FC-UFMC system achieves a computation minimisation higher than 95% for systems having 64 or more fully utilised sub-channels compared to similar UFMC systems. The Peak to Average Power Ratio (PAPR) for the FC-UFMC system has a 2.27 dB improvement over the UFMC system. The BER performance of the FC-UFMC system in AWGN and ITU-R channels models are superior or similar to the corresponding UFMC system. The paper also presents the relationship of BER dependence on Signal to Noise Ratio (SNR) and Side Lobe Attenuation (SLA) of the sub-band filter.

Acquisition performance of B1I abounding with 5G signals

The widespread 5G base stations can be potential jammers for the vulnerable BeiDou B1I receivers due to its low power. Therefore, a novel analytical model is derived for the 5G signal to evaluate its impact on acquisition performance under three decision methods. The good agreement between the Monte Carlo method (MCM) through software defined receiver (SDR) and the derived expressions validates the effectiveness of the proposed algorithm. It can be found that the receivers exhibit varied responses for different 5G waveforms and decision strategies. The receiver also shows the least endurances for some kind of 5G waveforms, however, this kind of adverse effect can be cancelled by a reduced interference signal ratio (ISR), an increased integration time or a larger accumulation times.

Analysis of Cognitive Radio for LTE and 5G Waveforms

Spectrum sensing is one of the major concerns in reaching an efficient Quality of service (QOS) in the advanced mobile communication system. The advanced engineering sciences such as 5G, device 2 device communications (D2D), Internet of things (IoT), MIMO require a large spectrum for better service. Orthogonal frequency division multiplexing (OFDM) is not a choice in advanced radio due to the Cyclic Prefix (CP), wastage of the spectrum, and so on. Hence, it is important to explore the spectral efficient advanced waveform techniques and combine a cognitive radio (CR) with the 5G waveform to sense the idle spectrum, which overcomes the spectrum issue. The demand for spectrum is ever increasing; however, spectrum is limited and is an acutely scarce resource. To alleviate the issue, techniques like Cognitive Radios (CR) have been devised. However, such techniques are non-standardized, and many variations of CR algorithms have been tried and tested. This paper details the several spectrum sensing methods tailored for CR. We explain the benefits, uniqueness, and drawbacks of the various techniques to provide a comprehensive review of the scene, including all recent and novel techniques of CR. Finally, we provided experimental results for the performance of the CR for key 5G and beyond modulation techniques to elaborate the dependency of the CR techniques for CR applications and provide a competitive review of their performance. Experiments show that the CR integrated with NOMA shows better performance as compared with existing techniques.

STUDY AND ANALYSIS OF PHYSICAL LAYER WAVEFORMS FOR 5G WIRELESS NETWORKS

In the last few decades, telecommunication systems have become an essential tool that profoundly changed the perception of the world and how people interact with it. The fifth generation (5G) envisions the support of a new class of demanding services and requires a paradigm shift in current wireless communication technology. As an example, radio access via alternative waveforms other than orthogonal frequency division multiplexing is feasible and has many advantages. In particular, filter bank multicarrier (FBMC) multiplexing is a promising nonorthogonal waveform due to its high-performance spectrum signature, resilience to time-frequency dispersion, and nonreliance on cyclic prefix. From this perspective, we study FBMC as an enabler of 5G by providing an overview of FBMC systems and proposing new prototype filter designs for such a multiplexing scheme. In this paper, we study FBMC as a means of characterizing and improving the feasibility of FBMC for 5G wireless systems. More specifically, we study promising prototype filters, highlight their importance on the spectrum and their symbol reconstruction qualities of FBMC signals, and propose prototype filter designs to enhance the operation of FBMC systems, throughput, bit error ratio, and bit error probability comparisons of different filters of FBMC systems.

Universal Filtered Multicarrier Receiver Complexity Reduction to Orthogonal Frequency Division Multiplexing Receiver

The Universal Filtered Multicarrier (UFMC) waveform technology is one of the promising waveforms for 5G and beyond 5G networks. Owing 2N-point Fast Fourier Transform (FFT) processor at the UFMC receiver, the computational and implementation complexity is two times more than the conventional Orthogonal Frequency Division Multiplexing (OFDM) receiver system. In this paper, we proposed a simplified UFMC receiver structure to reduce computational complexity as well as hardware requirements. The received UFMC symbol simplified exactly to its equivalent after performing 2N-point FFT and decimation operations. In which, the mathematical model of the frequency-domain UFMC signal is rederived after processing through 2N-point FFT and decimator, and the simplified signal is generated with an N-point FFT. Accordingly, the 2N-point FFT processor and decimator are replaced with a single N-point FFT processor. This approach reduces the 50% computational complexity at the FFT processor level hence the hardware and processing time. The computational complexity of the proposed receiver model is approximately equivalent to the OFDM receiver. Additionally, analyzed the mathematical model for the simplified UFMC receiver and the comparative performance of the UFMC system with the conventional model.

A Novel Peak-to-Average Power Ratio Reduction for 5G Advanced Waveforms

Multi and single carrier waveforms are utilized in cellular systems for high-speed data transmission. In The Fifth Generation (5G) system, several waveform techniques based on multi carrier waveforms are proposed. However, the Peak to Average Power Ratio (PAPR) is seen as one of the significant concerns in advanced waveforms as it degrades the efficiency of the framework. The proposed article documents the study, progress, and implementation of PAPR reduction algorithms for the 5G radio framework. We compare the PAPR algorithm performance for advanced and conventional waveforms. The simulation results reveal that the advanced Partial Transmission Sequence (PTS) and Selective Mapping (SLM) methods enhanced the throughput and gain of the 5G waveforms. Furthermore, we have also analyzed the performance of Orthogonal Time Frequency Space Modulation (OTFSM) based on a single carrier system and found that PAPR is significantly low and is best suited to fading environments. It is seen that the conventional algorithms lower the PAPR but increase the complexity. The proposed PTS and SLM have shown good performance with low computational complexity.

PAPR Reduction of NOMA Using Vandermonde Matrix-Particle Transmission Sequence

Non-Orthogonal Multiple Access (NOMA) is an ideal choice for 5G waveforms due to their characteristics such as high data rate, massive device connectivity, high spectral access, and effective frequency selective fading. Thus, it permits gigantic connectivity. The spectrum overlaps with NOMA, which consents several operators to segment the spectrum at the same frequency. These features make NOMA more suitable for use beyond 5G. Peak to Average Power (PAPR) is a major problem in Multi-Carrier Techniques (MCT) like NOMA and it also degrades the performance of the amplifier. The Partial Transmission Sequence (PTS) is a superior algorithm for moderating the PAPR. However, it also increases the complexity of the structure. The PAPR is reduced in NOMA by multiplying the NOMA signal with optimised phase vectors (P). The phase vectors are generated by using the Vandermonde Matrix (VM). In this work, we proposed a VM-PTS algorithm for the NOMA system, and the number of computations to search the optimal phase vectors for NOMA high PAPR signal is less as compared with existing PTS. The outcomes demonstrate that the performance of the recommended PTS in terms of PAPR, Bit Error Rate (BER), and complexity is better than the conventional PTS (C-PTS).

PAPR Reduction Using Advanced Partial Transmission Scheme for 5G Waveforms

The implementation of Peak Average to Power Ratio (PAPR) reduction technologies will play an important role in the regularization of Fifth Generation (5G) radio communication. PAPR reduction in the advanced waveform will be the key part of designing a 5G network for different applications. This work introduces the simulation of an Advanced Partial Transmission Sequence (A-PTS) reduction techniques for Orthogonal Frequency Division Multiplexing (OFDM) and Filter Bank Multi-Carrier (FBMC) transmission schemes. In the projected A-PTS, the FBMC signals are mapped into the number of sub-blocks and Inverse Fast Fourier transform (IFFT) is performed to estimate the high peak power in the time domain. The FBMC sub-blocks are multiplied with the phase elements to achieve an optimal PAPR value. A MATLAB 2014v simulation is used to estimate the PAPR, Bit Error Rate (BER), Error Vector Magnitude (EVM), and Modulation Error Rate (MER) performance of the proposed reduction schemes. The simulated result reveals that the performance of the projected algorithm is better than the conventional algorithms.

Optimized Waveforms for 5G–6G Communication With Sensing: Theory, Simulations and Experiments

Joint communication and sensing (JCAS) is an emerging technology for managing efficiently the scarce radio frequency (RF) spectrum, and is expected to be a key ingredient in beyond fifth-generation (5G) networks. We consider a JCAS system, where the full-duplex radar transceiver and the communication transmitter are the same device, and pursue orthogonal frequency-division multiplexing (OFDM) waveform optimization by jointly minimizing the lower bounds of delay and Doppler estimation. This is attained by filling the empty subcarriers within the OFDM frame with optimized samples while reallocating a proportion of the communication subcarriers’ power, which essentially controls the fairness between the two functionalities. Both communication and filled <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">radar subcarriers</i> are used for radar processing. The optimized sample values are found analytically, and a computationally feasible algorithm is presented for this task. We also address how the peak-to-average power ratio of the waveform can be controlled and minimized along the optimization process. The results are then numerically evaluated in 5G New Radio (NR) network context, which indicate a trade-off between the minimization of the lower bounds. The main-lobe width and the peak side-lobe level (PSL) of the range and velocity profiles of the radar image are also analyzed. An inverse relation between the lower bounds and the PSLs is observed, while the main-lobe width can be minimized simultaneously. The trade-off between communication and sensing is investigated, which indicates that the lower bounds can be improved at the cost of the communication capacity. Moreover, over-the-air RF measurements are carried out with unoptimized and optimized 5G NR waveforms at the 28 GHz mm-wave band, to validate the range profile’s PSL improvement in an outdoor mapping scenario, depicting considerable performance gain.

A Modified SLM Scheme for PAPR Reduction of UFMC Systems

One of the most promising 5G waveform candidates is the universal-filtered multicarrier system (UFMC). The UFMC system reduces the out-of-band (OoB) emission, bringing about higher spectral efficiency. This is assumed to reach robustness against frequency offset and low latency. Although, as aforementioned, the UFMC system offers many advantages, it lacks high peak-to-average power ratio (PAPR) as a multicarrier transmission technique. This research paper tackles two approaches; firstly, RCS, by developing a simulated conventional SLM system, with modifications to generate the same number of waveforms, while using fewer UFMC modulators. Secondly, by developing a simulated conventional SLM system, with modifications using the same number of modulators to generate more waveforms that would be generated in the conventional scheme. The two sets of results from the proposed M-SLM scheme are compared to each other, and to other PAPR reduction schemes using OFDM and UFMC. To reduce PAPR in UFMC systems, (M-SLM) scheme with low complexity is proposed. The essence of the proposed M-SLM scheme is represented in making use of the cyclically shifting process and FMC modulator’s linearity property. The proposed M-SLM scheme uses Um UFMC modulators to produce Uw alternative UFMC waveforms, where Uw = Um (2Um − 1). As a result, drawing a comparison with existing SLM based PAPR reduction schemes for UFMC systems; the proposed M-SLM scheme's computational complexity is reduced. Finally, there is a comparison between the proposed M-SLM scheme and the schemes there in the literature according to PAPR reduction ability.

UFMC Waveform and Multiple-Access Techniques for 5G RadCom

In recent years, multiple functions traditionally realized by hardware components have been replaced by digital-signal processing, making radar and wireless communication technologies more similar. A joint radar and communication system, referred to as a RadCom system, was proposed to overcome the drawbacks of the conventional existent radar techniques while using the same system for intervehicular communication. Consequently, this system enhances used spectral resources. Conventional orthogonal frequency division multiplexing (OFDM) was proposed as a RadCom waveform. However, due to OFDM’s multiple shortcomings, we propose universal filtered multicarrier (UFMC), a new 5G waveform candidate, as a RadCom waveform that offers a good trade-off between performance and complexity. In addition to that, we propose multicarrier code division multiple access (MC-CDMA) as a multiple-access (MA) technique that can offer great performance in terms of multiuser detection and power efficiency. Moreover, we study how UFMC filter length and MC-CDMA spreading sequences can impact overall performance on both radar and communication separately under a multipath channel. Analysis of the bit error rate (BER) of the UFMC waveform was performed in order to confirm the experiment results.

A novel discrete elephant herding optimization-based PTS scheme to reduce the PAPR of universal filtered multicarrier signal

The recently proposed waveform called universal filtered multicarrier (UFMC) has already managed to get the attention of science world due to its superior features and it has been accepted as one of the foremost fifth generation (5G) waveform contenders. However, due to being a type of multicarrier waveform, the UFMC suffers from the problem of high peak-to-average power ratio (PAPR). In this paper, a new discrete elephant herding optimization-based partial transmit sequence (DEHO-PTS) scheme is suggested to reduce the PAPR of UFMC signals to minimum levels. Due to the fact that the optimization of phase rotation factors multiplied by the sub-blocks in the conventional partial transmit sequence (PTS) technique is a combinatorial optimization problem to be solved in discrete space, in order to integrate the elephant herding optimization (EHO) algorithm into the PTS scheme, we developed its discrete version (DEHO) in this paper. In the simulations, the capability of the suggested DEHO-PTS procedure to minimize the PAPR, suppress the out-of-band emission and decrease the bit error rate of the UFMC signal amplified via a nonlinear high power amplifier was analyzed. Simulation results clearly indicate that our proposed DEHO-PTS procedure can be a serious option for UFMC waveform to minimize the PAPR values of transmission signals due to its significant PAPR reduction, side lobe suppression and bit error rate performances with low computational complexity.

Low‐complexity receivers for massive MIMO‐GFDM communications

AbstractThe orthogonal frequency division multiplexing (OFDM)‐based modulation scheme is widely utilized in asymmetric digital subscriber lines (ADSL), wireless local area networks (WLAN), and the fourth generation (4G) of mobile communication systems due to its ability to cope with severe channel conditions without complex equalization processes. However, the drawbacks of OFDM such as: requirement of a high peak to average power ratio (PAPR) radio frequency (RF) power amplifier, sensitive to carrier frequency offset, high out‐of‐band (OOB) emissions cause the OFDM is not applicable for the fifth generation (5G) mobile communication application scenarios such as machine‐type communications (MTC), Internet of things (IoT), and cognitive radio (CR). Generalized Frequency Division Multiplexing (GFDM) modulation scheme has regarded as one of the promising candidates for 5G waveforms due to its properties, such as low latency, low OOB emission, robust against carrier frequency offset (CFO), and time offset (TO). The GFDM is also combined with massive multiple‐input multiple‐output (MIMO) technology that equipping each base station (BS) with an array of many active antennas, which are used to spatially multiplex many user equipment (UE) to improve spectrum efficiency (SE). However, as the modulation order and the number of antennas increases, the complexity of the maximum likelihood (ML) detector and the minimum‐mean‐square‐error (MMSE) detector causes an impediment for real‐world applications. This paper proposes a low‐complexity detector configuration which utilizes quadratic programming principle. The simulations show that the computation complexity of the proposed detector is lower than the ML detector and the bit‐error‐rate performance of the proposed detector is better than that of the MMSE detector.

Spatial Interference Reduction by Subarray Stacking in Large Two-Dimensional Antenna Arrays

This article proposes a systematic approach for stacking uniform linear arrays (ULAs) of different sizes to reduce sidelobes and form nulls to the radiated beam pattern. In sidelobe reduction, the nulls and sidelobes of the vertically stacked ULAs are aligned to reduce the overall sidelobe level (SLL). In nulling, the nulls of varying length ULAs are aligned to configure the null direction and simultaneously reduce the sidelobes. Both approaches are relaxed to ensure the feasibility of the implementation. The stacking methods are studied by an extensive set of simulations together with azimuth and elevation beamforming. A sidelobe reduction method showed potential for better than 30 dB SLL and more than 20 dB relative null depth with less than 100 antenna elements. Finally, the concepts are validated by beam pattern measurements of a 28 GHz 64-element, 16-chain phased-array transceiver using a 100 MHz wide 5G waveform.

PAPR reduction using selective mapping scheme in universal filtered multicarrier waveform

In this paper, the selective mapping (SLM) technique possessing the powerful and distortionless peak to average power ratio (PAPR) reduction capability was employed in universal filtered multicarrier (UFMC) waveform that is considered as one of the most promising fifth generation (5G) waveform candidates in order to provide a solution to the PAPR issue encountered in the related waveform. Owing to our SLM-based PAPR reduction implementation performed by employing the SLM scheme between the quadrate amplitude modulation (QAM) mapping and bandwidth-subdivision operations at the transmitter side, successful PAPR reduction results were achieved in a straightforward and effective manner. In the simulations, the effect of the related way of SLM application on alleviating the PAPR and spectral leakages of the UFMC signal amplified via the solid state power amplifier (SSPA) was investigated for various number of phase factor combinations. Besides, the impact of SLM on the bit error rate (BER) of the UFMC waveform was analyzed for varied values of SSPA parameters called smoothness (p) and input back off (IBO) controlling the linearity and operation point of the SSPA, respectively.