Alternative Waveform Research Articles

Exploring Universal Filtered Multi Carrier Waveform for Last Meter Connectivity in 6G: A Street-Lighting-Driven Approach with Enhanced Simulator for IoT Application Dimensioning

In the dynamic landscape of 6G and smart cities, visible light communication (VLC) assumes critical significance for Internet of Things (IoT) applications spanning diverse sectors. The escalating demand for bandwidth and data underscores the need for innovative solutions, positioning VLC as a complementary technology within the electromagnetic spectrum. This paper focuses on the relevance of VLC in the 6G paradigm, shedding light on its applicability across smart cities and industries. The paper highlights the growing efficiency of lighting LEDs in infrastructure, facilitating the seamless integration of VLC. The study then emphasizes VLC’s robustness in outdoor settings, demonstrating effective communication up to 10 m. This resilience positions VLC as a key player in addressing the very last meter of wireless communication, offering a seamless solution for IoT connectivity. By introducing a freely available open-source simulator combined with an alternative waveform, UFMC, the study empowers researchers to dimension applications effectively, showcasing VLC’s potential to improve wireless communication in the evolving landscape of 6G and smart cities.

Adaptive threshold for discrete fourier transform‐based channel estimation in generalized frequency division multiplexing system

AbstractEven though generalized frequency division multiplexing is an alternative waveform method expected to replace the orthogonal frequency division multiplexing in the future, its implementation must alleviate channel effects. Least‐squares (LS), a low‐complexity channel estimation technique, could be improved by using the discrete Fourier transform (DFT) without increasing complexity. Unlike the usage of the LS method, the DFT‐based method requires the receiver to know the channel impulse response (CIR) length, which is unknown. This study introduces a simple, yet effective, CIR length estimator by utilizing LS estimation. As the cyclic prefix (CP) length is commonly set to be longer than the CIR length, it is possible to search through the first samples if CP is larger than a threshold set using the remaining samples. An adaptive scale is also designed to lower the error probability of the estimation, and a simple signal‐to‐interference‐noise ratio estimation is also proposed by utilizing a sparse preamble to support the use of the scale. A software simulation is used to show the ability of the proposed system to estimate the CIR length. Due to shorter CIR length of rural area, the performance is slightly poorer compared to urban environment. Nevertheless, satisfactory performance is shown for both environments.

ID: 212641 Salvage Therapy With Bilateral T12 and S1 DRG Stimulation for Post-Laminectomy Syndrome: A Case Report

Neuromodulation with tonic spinal cord stimulation (t-SCS) is well evidenced to manage chronic pain syndromes. However, for patients with post-laminectomy syndrome refractory to t-SCS, salvage therapies such as alternative waveforms of SCS (burst, high frequency, or multiple waveform) or dorsal root ganglion (DRG) stimulation have been studied. DRG stimulation is an emerging option for salvage therapy and was shown to be non-inferior and superior to t-SCS in treating lower extremity neuropathic pain for CRPS in the ACCURATE study. DRG stimulation’s use as salvage therapy for post-laminectomy syndrome is poorly reported. In this case, we present the treatment approach with DRG stimulation as salvage treatment for post-laminectomy syndrome refractory to t-SCS.

O076 / #774 IMPROVED LONG-TERM SPINAL CORD STIMULATION OUTCOMES UPON INTRODUCING ALTERNATIVE WAVEFORMS IN REAL-WORLD PRACTICE: EXPERIENCE WITH OVER 300 CONSECUTIVE PADDLE IMPLANTS OVER 14 YEARS: TRACK 4: CLINICAL USE OF SCS / DRG

Spinal cord stimulation has been shown to be efficacious and cost-effective for various forms of chronic pain. Historically, standard paresthesia-based waveforms have been successful in the short-term (< 1 year), but associated with limited longer-term outcomes. Over the last 5-7 years, various alternative waveforms have been introduced based upon compelling data from, vendor-funded controlled studies. Longer-term real world data assessing the impact of adopting these new waveforms has been lacking.

PO027 / #1009 ANODIC VERSUS CATHODIC GENERATION OF SUBTHALAMIC NUCLEUS AND CORTICAL EVOKED POTENTIALS USING NON-SYMMETRICAL MONOPOLAR STIMULATION IN PARKINSON'S DISEASE PATIENTS: E-POSTER VIEWING

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is standard of care treatment for moderate to severe Parkinson’s disease. However, optimizing the therapeutic benefit of DBS can, in some cases, be complicated by the occurrence of side effects that are attributed to current spread outside of the target region. Modeling studies have suggested non-symmetric waveforms may result in preferential activation of neural elements and potentially increase DBS’ therapeutic window [1]. To date, however, data demonstrating the physiological effects of alternative waveform morphologies in human patients has been limited.

Cardiac cells stimulated with an axial current-like waveform reproduce electrophysiological properties of tissue fibers

Background and objective: In silico electrophysiological models are generally validated by comparing simulated results with experimental data. When dealing with single-cell and tissue scales simultaneously, as occurs frequently during model development and calibration, the effects of inter-cellular coupling should be considered to ensure the trustworthiness of model predictions. The hypothesis of this paper is that the cell-tissue mismatch can be reduced by incorporating the effects of conduction into the single-cell stimulation current. Methods: Five different stimulation waveforms were applied to the human ventricular O’Hara-Rudy cell model. The waveforms included the commonly used monophasic and biphasic (symmetric and asymmetric) pulses, a triangular waveform and a newly proposed asymmetric waveform (stimulation A) that resembles the transmembrane current associated with AP conduction in tissue. A comparison between single-cell and fiber simulated results was established by computing the relative difference between the values of AP-derived properties at different scales, and by evaluating the differences in the contributions of ionic conductances to each evaluated property. As a proof of the benefit, we investigated multi-scale differences in the simulation of the effects induced by dofetilide, a selective IKr blocker with high torsadogenic risk, on ventricular repolarization at different pacing rates. Results: Out of the five tested stimulation waveforms, stimulation A produced the closest correspondence between cell and tissue simulations in terms of AP properties at steady-state and under dynamic pacing and of ionic contributors to those AP properties. Also, stimulation A reproduced the effects of dofetilide better than the other alternative waveforms, mirroring the ’beat-skipping’ behavior observed at fast pacing rates in experiments with human tissue. Conclusions: The proposed stimulation current waveform accounts for inter-cellular coupling effects by mimicking cell excitation during AP conduction. The proposed waveform improves the correspondence between simulation scales, which could improve the trustworthiness of single-cell simulations without adding computational cost.

Joint CFO and highly frequency selective channel estimation in FBMC/OQAM systems

Filter Bank-based Multicarrier with Offset Quadrature Amplitude Modulation (FBMC/OQAM) has been considered as an alternative waveform to the conventional Cyclic Prefix (CP)-based Orthogonal Frequency Division Multiplexing (OFDM). Despite the adoption of variants of the latter in 5G NR, FBMC/OQAM is still at the top of the promising multicarrier modulation waveforms for future generation communication systems. Although it enjoys a number of unique advantages over CP-OFDM, most importantly maximum spectral efficiency and good time-frequency localization, it is also sensitive to Carrier Frequency Offset (CFO), which can cause inter-carrier interference that degrades system performance if left uncompensated. Besides, the presence of CFO prevents accurate channel estimation. In this paper, our goal is to propose joint estimators for the channel impulse response (CIR) and CFO via an approximate Maximum Likelihood (ML) approach. No simplifying assumption is made about the channel delay spread so our results also apply to highly frequency selective channels. One of the novelties is that the estimation procedure is aided by so choosing the pilots as to result in zero intrinsic interference in the absence of impairments. Moreover, to reduce the complexity of CFO estimation, a lighter implementation, based on the truncation of the Taylor series expansion of the exponential term containing the CFO, is proposed. Simulation results demonstrate the superiority of the proposed estimators over existing methods, in terms of both mean squared estimation errors and bit error rate.

The visual cortical responses to sinusoidal transcorneal electrical stimulation

Retinal stimulation has become a widely utilized approach to restore visual function for individuals with retinal degenerative diseases. Although the rectangular electrical pulse is the primary stimulus waveform used in retinal neuromodulation, it remains unclear whether alternate waveforms may be more effective. Here, we used the optical intrinsic signal imaging system to assess the responses of cats’ visual cortex to sinusoidal electrical stimulation through contact lens electrode, analyzing the response to various stimulus parameters (frequency, intensity, pulse width). A comparison between sinusoidal and rectangular stimulus waveform was also investigated. The results indicated that the optimal stimulation frequency for sinusoidal electrical stimulation was approximately 20 Hz, supporting the hypothesis that low-frequency electrostimulation induces more responsiveness in retinal neurons than high-frequency electrostimulation in case of sinusoidal stimulation. We also demonstrated that for low-frequency retinal neuromodulation, sinusoidal pulses are more effective than rectangular ones. In addition, we found that compared to current intensity, the effect of the sinusoidal pulse width on cortical responses was more prominent. These results suggested that sinusoidal electrical stimulation may provide a promising strategy for improved retinal neuromodulation in clinical settings.

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.

Field Programmable Gate Arrays (FPGA) Based Computational Complexity Analysis of Multicarrier Waveforms

Multicarrier waveforms with enhanced spectral efficiency, low latency, and high throughput are required for 5G wireless networks. The Orthogonal Frequency Division Multiplexing (OFDM) method is well-known in research, but due to its limited spectral efficiency, various alternative waveforms are being considered for 5G systems. In the recent communication world, NOMA (non-orthogonal multiple access) plays a significant part due to its wider transmission of data with less bandwidth allocation. Even if a high data rate can be attained, the transmission problem will arise due to the spread of multiple paths. In order to reduce complexity and area utilization, a novel PL-based FWFT (Fast walsh hadamard fourier transform) technique is proposed and implemented in the VLSI architecture. To achieve a high-performance system, the main concept of pass transistor logic (PL) with VLSI implementation is to diminish the size and power consumption. Finally, the performance of the proposed FWFT/ IFWFT implementation has been evaluated. For FPGA’s 16-point FWFT, the number of transistors decreased by 21% and the total power required was reduced by 5.5%. The same implementation for 34 transistor-pass-logic customs and power consumption is 2.764 mW with a latency of 78.256 ns. As a consequence, the proposed system achieves low power, area and low complexity system that can enhance the function of the multicarrier waveform systems.

Present and Future of Reconfigurable Intelligent Surface-Empowered Communications [Perspectives

Signal processing and communication communities have witnessed the rise of many exciting communication technologies in recent years. Notable examples include alternative waveforms, massive multiple-input multiple-output (MIMO) signaling, non-orthogonal multiple access (NOMA), joint communications and sensing, sparse vector coding, index modulation, and so on. It is inevitable that 6G wireless networks will require a rethinking of wireless communication systems and technologies, particularly at the physical layer (PHY), considering the fact that the cellular industry reached another important milestone with the development of 5G wireless networks with diverse applications. Within this perspective, this article aims to shed light on the rising concept of reconfigurable intelligent surface (RIS)-empowered communications towards 6G wireless networks. Software-defined RISs can manipulate their impinging signals in an effective way to boost certain key performance indicators. We discuss the recent developments in the field and put forward promising candidates for future research and development. Specifically, we put our emphasis on active, transmitter-type, transmissive-reflective, and standalone RISs, by discussing their advantages and disadvantages compared to reflective RIS designs. Finally, we also envision an ultimate RIS architecture, which is able to adjust its operation modes dynamically, and introduce the new concept of PHY slicing over RISs towards 6G wireless networks.

Optimal Signal Design for a New Physically Motivated Clutter Model With Applications to Ultrasonic Testing.

In this article, we will explore the optimal signal design problem for a new physically motivated clutter model. The reason to pursue the optimal signal design is that the model, even though it was simple, led to a robust detector that worked well on real ultrasonic data. Moreover, by using the model, an analytical solution for the optimal signal is obtained. In addition, the optimal waveform gives a new insight into the signal design problem that can be valuable for many applications. New proof has been provided for a finite data record that is lacking in the literature. We have found that the optimal signal is an impulse, and as a result, it has an impulsive autocorrelation sequence (ACS). Since an impulsive ACS signal is not realizable, in practice, a study for an alternative waveform is conducted. Waveforms from four different categories have been explored: linear frequency-modulated (LFM), nonlinear frequency-modulated (NLFM), phase-coded modulated (PCM) signals, and, finally, what we called other signals. Comparison analysis between these waveforms themselves and the most commonly used transmitted pulse in practice, which is the Gaussian amplitude-modulated sinusoid (GAMS) pulse, has been implemented. We show that the LFM pulse has a large advantage over the GAMS pulse in terms of detectability. In addition, a comparison between the LFM and the GAMS signals under a deviation from the single scatterer assumption, indicating a more complex target, using simulated noise is performed.

Joint Channel Estimation and Equalization Using New AFB Output Signal Models for FBMC/OQAM Systems

Filter bank multicarrier with offset quadrature amplitude modulation (FBMC/OQAM) has been studied as an alternative waveform for post-orthogonal frequency division multiplexing (OFDM) wireless communications. However, due to the intrinsic imaginary inter-carrier/inter-symbol interference of FBMC/OQAM signals, accurate channel estimation and equalization remain open issues for FBMC/OQAM systems in dispersive channels. In this article, two new signal models of the analysis filter bank (AFB) output are first derived in the absence of any channel assumption and in the presence of a relaxed channel assumption, respectively. Based on the new-built models, initial channel estimation with least squares (LS) (IniCE-LS) is presented and its output is used as the initial condition of recursive weighted LS (RWLS) estimation; moreover, non-iterative and iterative channel equalization combined with RWLS channel estimation (i.e., N-ICE-RWLS and ICE-RWLS) are proposed by using the real-time reconstructed FBMC/OQAM data symbols as pilots. The proposed N-ICE-RWLS and ICE-RWLS schemes not only allow to improve channel estimation and equalization performance, but also achieve high transmission efficiency. Considering the requirements of practical application, we further develop the low-complexity implementation methods of N-ICE-RWLS and ICE-RWLS. All these schemes are validated by analyzing the channel estimation accuracy and bit error rate (BER) over various frequency selective channels.

Evaluation of Waveform Profiles for Traveling Wave Ion Mobility Separations in Structures for Lossless Ion Manipulations.

Structures for lossless ion manipulations (SLIM) have recently enabled a powerful implementation of traveling wave ion mobility spectrometry (TWIMS) for ultrahigh resolution separations; however, experimental parameters have not been optimized, and potential significant gains may be feasible. Most TWIMS separations have utilized square-shaped waveforms applied by time-dependent voltage stepping across repeating sets of electrodes, but alternative waveforms may provide further improvements to resolution. Here, we characterize five waveforms (including square and sine) in terms of their transmission efficiency, IMS resolution, and resolving power, and explore the effects of TW amplitude and speed on the performance of each. We found, consistent with previous work, separations were generally improved with higher TW amplitudes, moderately improved by lower speeds (limited by ion "surfing" with the waves), and found decreases in signal intensity at the extremes of operating conditions. The triangle and asymmetric "ramp forward" shaped profiles were found to provide modestly greater resolution and resolving power, an observation we tentatively attribute to their relatively uniform fields and minimal low-field regions.

A novel discrete cuckoo search algorithm‐based selective mapping technique to minimize the peak‐to‐average power ratio of universal filtered multicarrier signal

SummaryThe universal filtered multicarrier (UFMC), which has emerged as a product of the intensive studies carried out for developing alternative waveforms compatible with the oncoming fifth generation (5G) technology, has rapidly become one of the few waveforms considered seriously to be utilized in the next generation telecommunication systems due to its exclusive features. However, high peak‐to‐average power ratio (PAPR) problem specific to the multicarrier waveforms is waiting for researchers as the primary issue to be tackled in the UFMC waveform. To address this issue, an efficient PAPR reduction scheme called discrete cuckoo search algorithm‐based selective mapping (DCS‐SLM) is suggested in this paper. While creating the proposed DCS‐SLM scheme, in order to make the original CS algorithm suitable to be integrated into the conventional SLM method, a novel DCS algorithm was developed. Thanks to the related DCS algorithm, it becomes possible in the SLM technique to perform phase sequence optimization, which is a combinatorial optimization process that can be carried out in discrete space. It is clearly observed from the simulation results that the integration of our novel DCS algorithm to create a new PAPR reduction technique called DCS‐SLM leads to a remarkable performance improvement in the conventional SLM method due to the DCS‐based phase optimization through which the PAPR of UFMC signals are reduced to minimum levels.

Systematic Evaluation of DBS Parameters in the Hemi-Parkinsonian Rat Model.

Electrical stimulation of the subthalamic nucleus (STN) is clinically employed to ameliorate several symptoms of manifest Parkinson’s Disease (PD). Stimulation parameters utilized by chronically implanted pulse generators comprise biphasic rectangular short (60–100 μs) pulses with a repetition frequency between 130 and 180 Hz. A better insight into the effect of electrical stimulation parameters could potentially reveal new possibilities for the improvement of deep brain stimulation (DBS) as a treatment. To this end, we employed single-sided 6-hydroxidopamine (6-OHDA) lesioning of the medial forebrain bundle (MFB) in rats to systematically investigate alternative stimulation parameters. These hemi-parkinsonian (hemi-PD) rats underwent individualized, ipsilateral electrical stimulation to the STN of the lesioned hemisphere, while the transiently induced contralateral rotational behavior was quantified to assess the effect of DBS parameter variations. The number of induced rotations during 30 s of stimulation was strongly correlated with the amplitude of the stimulation pulses. Despite a general linear relation between DBS frequency and rotational characteristics, a plateau effect was observed in the rotation count throughout the clinically used frequency range. Alternative waveforms to the conventional biphasic rectangular (Rect) pulse shapes [Triangular (Tri), Sinusoidal (Sine), and Sawtooth (Lin.Dec.)] required higher charges per phase to display similar behavior in rats as compared to the conventional pulse shape. The Euclidean Distance (ED) was used to quantify similarities between different angular trajectories. Overall, our study confirmed that the effect of different amplitude and frequency parameters of STN-DBS in the hemi-PD rat model was similar to those in human PD patients. This shows that induced contralateral rotation is a valuable readout in testing stimulation parameters. Our study supports the call for more pre-clinical studies using this measurement to assess the effect of other DBS parameters such as pulse-width and interphase intervals.

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.

UFMC system performance improvement using RS codes for 5G communication system

Fifth generation (5G) mobile communication is expected to be deployed in several countries by 2020. Where, the data consumptions are expected to be increased to 30% thus, it cannot be supported by the present technologies 3G and 4G. In contrast, looking for new alternative modulation techniques of orthogonal frequency division modulation (OFDM) system which is suffering from high Peak to Average Power Ratio (PAPR) and out of band (OOB) side lobes are needed to use in 5G communication system. Hence, Universal Filtered Multi-Carrier (UFMC) is considered as alternative waveform to overcome of OFDM disadvantages. In communication systems, channel coding is considered vital part, where error correction codes (ECC) are used to detect and correct the errors which is occurring in channel noise. In this paper, RS codes are suggested with UFMC system to achieve the reliability of information transmission over noisy channels. The results showed that although, the values of PAPR levels for using RS codes in UFMC increased to 8.8653dB against 6.9735 dB for OFDM system. However, there are significant improvements in BER performance owing to use RS codes against uncoded-UFMC system. Furthermore, the values of OOB in UFMC system was lower than OFDM system.

Concepção de um sistema de automação e monitoramento para equipamento utilizado em ensaios de trilhamento elétrico e erosão

&lt;p&gt;This paper aimed at the design and development of a data acquisition and control system using the Arduino open-source platform to automate equipment responsible for the IEC 60587 electrical tracking and erosion test. The developed system allows the selection of protection resistors specified by the standard from the voltage value informed by the operator, monitoring of the leakage current flowing over five samples simultaneously tested and automatically interrupts the samples if the leakage current exceeds 60 mA for more than two seconds. The leakage current values are measured indirectly from the voltage drop across 50 Ω shunt resistors installed in series with each sample. The voltage values on the shunt resistors are conditioned by a measuring circuit that allows the voltage level to be adjusted to the analog inputs of the microcontroller, ie, between 0 V and 5 V. The microcontroller treatment performs the voltage signal obtained by the measuring circuit, the calculation of the RMS value of the current and stop criterion monitoring the leakage current. The calibration of the leakage current measurement circuit was performed by comparing voltage values measured by a digital oscilloscope for four different alternate waveforms and values up to 5 Vrms, corresponding to currents up to 100 mA. The results showed that the circuit provided measurements close to the values measured by the oscilloscope, with errors below 11%. For current values between 30 mA and 80 mA, the errors were less than 6%.&lt;/p&gt;

Design and Convergence Analysis of an IIC-based BICM-ID Receiver for FBMC-QAM Systems

Next generation cellular networks are expected to connect billions of devices through its massive machine-type communication (mMTC) use case. To achieve this, waveforms with improved spectral confinement and high spectral efficiency compared to cyclic-prefix orthogonal division multiplexing (CP-OFDM) are required. In this paper, filter-bank muilticarrier with quadrature amplitude modulation (FBMC-QAM) is studied as an alternative to CP-OFDM for such applications. However, FBMC-QAM presents the challenge of high intrinsic interference due to the loss of complex orthogonality in time-frequency domain. Bit-interleaved coded modulation with iterative decoding (BICM-ID) has been shown to exhibit capacity-approaching decoding performance. Therefore, in this paper, an iterative interference cancellation (IIC) based BICM-ID receiver is designed to cancel the intrinsic interference in FBMC-QAM systems. The proposed receiver consist of an inner decoder, which combines iterative demodulation and interference cancellation, and an outer decoder which is a low density parity check (LDPC) channel decoder. To evaluate the convergence behaviour of the proposed receiver, extrinsic information transfer (EXIT) chart analysis is employed, where EXIT curves for the components of the iterative decoder are derived. Numerical results show that the intrinsic interference in FBMC-QAM systems can be removed by adopting the proposed IIC-based BICM-ID receiver. With a receiver that is able to successfully cancel intrinsic interference, FBMC-QAM becomes an interesting alternative waveform for asynchronous mMTC applications due to its superior frequency localization compared to CP-OFDM. Furthermore, it has been shown that FBMC-QAM with the IIC-based receiver can achieve similar bit-error-rate (BER) performance as a CP-OFDM benchmark under different fading channels. Finally, the complexity of the proposed receiver for FBMC-QAM is analysed and compared to the complexity of the CP-OFDM benchmark.