Spread Spectrum Modulation Research Articles

Conducted interference and voltage ripple suppression study in LLC resonant converter based on symmetric chaotic spread spectrum

ABSTRACT Spread-spectrum modulation technique can effectively reduce the peak value of conducted interference in automotive LLC DC/DC converters, but it will bring more serious ripple problems to Class E resonant converters. In this paper, we investigate the voltage ripple trend of LLC resonant converter when applying spread-spectrum modulation, and propose a chaotic signal sampling rule under the minimum output voltage ripple. A symmetric chaotic spreading method is proposed to reduce the output voltage ripple from the source by changing the distribution sequence of the chaotic signal to make it centrosymmetric. The symmetric chaotic spread spectrum is simulated and analysed to be able to suppress the conduction interference while reducing the voltage ripple, and is verified by experiments. This modulation strategy does not require the addition of auxiliary circuits and additional control links, which saves cost and reduces the difficulty of designing control links.

Improving emi performance in automotive data transmission systems using spread spectrum modulation

This paper investigates the enhancement of electromagnetic interference (EMI) performance in automotive data transmission systems through the application of spread spectrum modulation techniques. The significance of this research lies in the growing complexity and density of electronic systems within modern vehicles, which increases the potential for EMI-related issues that can compromise the reliability and safety of automotive communication systems. The primary objective of this study is to evaluate the effectiveness of spread spectrum modulation in mitigating EMI and improving the overall performance of data transmission in automotive environments. To achieve this objective, the research utilizes both theoretical analysis and experimental validation. The methods include a detailed review of current EMI mitigation strategies, the design and implementation of spread spectrum modulation techniques in a controlled environment, and subsequent testing to measure the impact on EMI performance. Key metrics for evaluation include signal integrity, data transmission rate, and EMI reduction levels. The results of the study indicate a significant improvement in EMI performance when spread spectrum modulation is applied. The experimental data demonstrate a notable reduction in EMI levels, leading to enhanced signal integrity and more reliable data transmission. These findings suggest that spread spectrum modulation is a viable solution for addressing EMI challenges in automotive data transmission systems

Is Direct Sequence Spread Spectrum Modulation Promising for AI-Based Design of 6G Networks?

Is Direct Sequence Spread Spectrum Modulation Promising for AI-Based Design of 6G Networks?

Architecting CubeSat constellations for messaging service, Part I

In today’s modern and globalized world, connectivity is a key factor for businesses, production facilities, sensor networks, and ordinary people. However, there are still populated areas which are not covered by ground-based telecommunications infrastructure. This is where telecommunication satellite constellations come in, as they can provide coverage to remote and uninhabited regions and fill existing connectivity gaps to ensure data transfer.LoRa is one of the technologies designed for data transmissions over long distances with low power consumption. Alongside with other technologies of the Low-Power Wide Area Network family, it is widely used for Internet of Things applications. LoRa chirp spread spectrum modulation is robust against the Doppler frequency shifts encountered in low earth orbits, and it has already been used in IoT satellite communications. Due to the low transmitted signal power, the achieved data rate is not high, making it a suitable technology for telecommunications payloads on CubeSat platforms for messaging services. As compared to existing traditional communication satellite systems, CubeSat constellations are low-cost and may offer an affordable connectivity service to developing regions.This study is divided in two parts. In Part I the demand model is built based on the population distribution not covered by cell towers. The LoRa link performance is analyzed, considering the impact of LoRa channel parameters variation, such as spreading factor and channel bandwidth, while satellite orbital height, transmission antenna beamwidth, and transmitter peak power have a direct impact on the payload mass. Among thousands of possible configurations, 73 feasible payload designs have been downselected. In Part II of the study, the satellite mass and the total system cost are estimated based on the payload parameters obtained. Messages transmission simulation via a constellation is conducted in order to identify optimal constellation architectures for messaging service, as well as the main drivers of the system economic profitability.The presented analysis results provide a deeper understanding of LoRa connectivity advantages and limitations together with the performance drivers, which will support the optimization of future LoRa-based satellite communication systems and other IoT satellite constellations.

A Low-Density Parity-Check Coding Scheme for LoRa Networking

This article presents a novel system, LLDPC , 1 which brings Low-Density Parity-Check (LDPC) codes into Long Range (LoRa) networks to improve Forward Error Correction, a task currently managed by less efficient Hamming codes. Three challenges in achieving this are addressed: First, Chirp Spread Spectrum (CSS) modulation used by LoRa produces only hard demodulation outcomes, whereas LDPC decoding requires Log-Likelihood Ratios (LLR) for each bit. We solve this by developing a CSS-specific LLR extractor. Second, we improve LDPC decoding efficiency by using symbol-level information to fine-tune LLRs of error-prone bits. Finally, to minimize the decoding latency caused by the computationally heavy Soft Belief Propagation (SBP) algorithm typically used in LDPC decoding, we apply graph neural networks to accelerate the process. Our results show that LLDPC extends default LoRa’s lifetime by 86.7% and reduces SBP algorithm decoding latency by 58.09×.

Error mitigation in LPWAN systems: A study on the efficacy of Hamming-coded RPW.

Rotating Polarization Wave (RPW) is a novel Low Power Wide Area Networks (LPWAN) technology for robust connectivity and extended coverage area as compared to other LPWAN technologies such as LoRa and Sigfox when no error detection and correction is employed. Since, IoT and Machine-to-Machine (M2M) communication demand high reliability, RPW with error correction can significantly enhance the communication reliability for critical IoT and M2M applications. Therefore, this study investigates the performance of RPW with single bit error detection and correction using Hamming codes to avoid substantial overhead. Hamming (7,4) coded RPW shows a remarkable improvement of more than 40% in error performance compared to uncoded RPW thereby making it a suitable candidate for IoT and M2M applications. Error performance of coded RPW outperforms coded Chirp Spread Spectrum (CSS) modulation used in LoRa under multipath conditions by 51%, demonstrating superior adaptability and robustness under dynamic channel conditions. These findings provide valuable insights into the ongoing developments in wireless communication systems whilst reporting Q-RPW model as a new and effective method to address the needs of developing LPWAN and IoT ecosystems.

An Analysis of Electromagnetic Signatures From Triangularly Modulated Spread Spectrum Clocking Signals

An Analysis of Electromagnetic Signatures From Triangularly Modulated Spread Spectrum Clocking Signals

A Spread-Spectrum Modulation Scheme for a 3 × 6 Indirect Matrix Converter Based on a Current Ripple Model

Focused on addressing harmonic suppression in multiphase indirect matrix converters (IMCs), this study explores spread-spectrum modulation technology through ripple analysis calculations. We introduce a current ripple spread-spectrum modulation (CR-SSM) method tailored for multiphase IMC systems. In this approach, a 3 × 6-phase IMC is modeled as a two-port network, and a small-signal model of the output side is established. The transfer function is utilized to analyze the two-port network in the complex frequency domain (s-plane). The time-domain expression of the output current ripple is derived in vector form. Subsequently, the distribution of the output ripple and locus are determined based on specified constraints. The carrier frequency is dynamically adjusted online according to the specified ripple locus. Compared to classical periodic PWM methods, this approach offers a broader range of frequency variations and achieves a more uniform output spectrum. Furthermore, CR-SSM optimizes system efficiency and enhances spread-spectrum modulation. Experimental results demonstrate that this method effectively enhances the quality of input and output waveforms in multiphase IMC systems.

High-Precision Position Detection and Communication Fusion Technology Using Beacon Spread-Spectrum Modulation with Four-Quadrant Detector

In space laser communication, the wide divergence angle of beacon light leads to substantial spatial losses, compounded by background light and detector noise; this results in compromised precision in the detection of the beacon light position. To solve this problem, a high-precision detection technique and communication composite technology employing a four-quadrant detector (QD) with beacon spread-spectrum modulation are proposed. Pseudo-random sequences (PRNs) are employed to spread the beacon communication spectrum, with the spread-spectrum signal utilized to modulate the intensity of the transmitted beacon light at the transmitter end. At the receiver, QD photocurrent signals are cross-correlated with an identical PRN that is used for modulation. The strong auto-correlation properties of PRNs, which are uncorrelated with noise, enhance the output signal-to-noise ratio (SNR), enabling precise position detection and beacon communication under high-SNR conditions. Theoretical analysis is used to explore the effects of spreading gain on the sensitivity of system detection and the precision of position detection. The experimental results demonstrate that the beacon spread-spectrum modulation scheme effectively detects the position of the light spot. At a received optical power of −37 dBm and spreading sequence PRN depths of 1023, 127, and 31, the root-mean-square error (RMSE) values are 0.983 μm, 2.876 μm, and 7.275 μm, respectively. This corresponds to improvements of 14.96 dB, 10.29, dB, and 6.26 dB compared to direct detection precision (30.811 μm). Additionally, under an identical signal bandwidth, the sensitivity improves by 14.6 dB, 10.1 dB, and 6.4 dB, respectively. The proposed beacon spread-spectrum scheme mitigates the limitations of hardware reception sensitivity and position-detection precision, demonstrating its potential application in high-precision detection in long-distance interstellar laser communication.

A sub-μs accuracy GPS alternative using electrical transmission grids as precision timing networks.

It is widely recognised that over-reliance on GNSS (e.g GPS) for time synchronisation represents an acute threat to modern society, and a diversity of alternatives are required to mitigate the threat of an outage. This paper proposes a GNSS alternative using time dissemination over national scale transmission or distribution networks. The method utilises the same frequency bandwidth and coupling technology as established power line carrier technology in conjunction with modern chirp Spread Spectrum modulation. The basis of the method is the transmission of a time synchronised chirp from a central substation, coupled into the aerial modes of the transmission line. During GNSS operation, all substations can estimate the time of flight by correlating the received chirp with a time-synchronised local copy. During GNSS outage, time sychronisation to the central substation is maintained by correcting for the precalculated time of flight. It is shown that recent advances in chirp spread spectrum allow for a computationally efficient algorithm with the capacity to compute hundreds of thousand of chirp correlations every second, facilitating timing accuracy which satisfies the majority of smart grid applications. ATP-EMTP simulations of the method on large transmission networks demonstrate sub-μs timing accuracy even in the presence of low SNR and impulsive noise. An FPGA prototype demonstrates experimentally sub-μs accuracy for time dissemination over a distance of 700 m. Averaging over time is shown to facilitate satisfactory performance down to , which could extend the range of the system to a national scale and a time dissemination network invulnerable to wireless spoofing and jamming attack vectors.

Chaotic Spread-Spectrum Communication: A Comparative Study between Chaotic Synchronization and Matched Filtering

This publication investigates the performance of demodulation methods utilized in spread spectrum chaotic communication systems in order to understand conditions at which advanced demodulation methods, such as chaotic synchronization, provide tangible benefits over classical, matched filtering-based approaches. We conduct simulations and comparisons of three different communication systems: classic direct sequence spread spectrum (DSSS), chaotic signal fragment-based pseudo-chaotic spread spectrum (PCSS), and chaotic synchronization-based antipodal chaos shift keying (ACSK). These systems possess similar spectral and time domain characteristics, allowing us to shed light on their fundamental differences and limitations in chaos-based communication. Additionally, we assess the impact of frequency modulation (FM) on these modulation methods, as FM allows the creation of simplified non-coherent modulation schemes. Our findings, based on the analysis of bit error ratio (BER) curves, demonstrate that in the case of a non-dispersive communication channel, the utilization of chaotic synchronization does not allow to achieve performance of correlation-based receivers. Additionally, the utilization of chaotic synchronization for multiple access poses certain challenges due to malicious synchronization between users. As a supplementary finding, we show that in systems with matched filter-based demodulation, discrete-time quantized spreading sequences confer an advantage over analogous, continuous-time spreading waveforms.

Predictive Modeling of Environmental Impact on Drone Datalink Communication System

In this study, we introduce an innovative model for evaluating the impact of environmental factors on drone-to-ground control station datalink communications. Our approach integrates both deterministic and stochastic processes to account for small-scale and large-scale fading effects, encompassing propagation attenuation, the Rician fading model, and Gaussian noise to accurately reflect real-world conditions. The model is implemented on signals transmitted using spread spectrum modulation. Through a comparative analysis of the model’s predictions against actual signals received in three distinct environments, the model’s efficacy in diverse scenarios is affirmed. Error metrics obtained from Monte Carlo simulations are employed to validate the theoretical results against experimental data. The proposed approach is pivotal for predicting the transmission range and understanding the electromagnetic susceptibility of the datalink, offering a substantial contribution to the optimization of remote drone control.

Performance Analysis of a Wildlife Tracking CubeSat Mission Extension to Drones and Stratospheric Vehicles

This study presents a performance analysis for an Internet-of-Things wildlife radio-tracking mission using drones, satellites and stratospheric platforms for data relay with Spread Spectrum Modulation devices. The performance analysis is presented with link and data budgets, calculations of the area coverage, an estimation of the time resolution and allowable data amount of each collar, a power and energy budget and consequent battery pack and collar weight estimations, cost budgets, and considerations on synergetic approaches to incorporate more mission segments together. The paper results are detailed with example species to target with each collar weight range, and with design drivers and guidelines to implement improved mission segments.

A tactical data link model based on CCSK-FMSK

In collaborative combat operations, the challenges brought by the communication adversities of tactical data links are becoming increasingly prominent. Ensuring the reliable connection of tactical data links has always been a key issue, especially considering the increasing impact of external interference on the signal at the receiving end of the system, which in turn affects the bit error rate (BER) of the tactical data link system. To address this challenge, this paper proposes a tactical data link anti-interference scheme based on cyclic code shift keying (CCSK) spread spectrum and minimum shift keying (MSK) modulation fusion frequency hopping technology, named CCSK-FMSK, and introduces turbo code and cyclic redundancy check (CRC) coding to construct a tactical data link model based on CCSK-FMSK. Specifically, CCSK-FMSK disperses interference power by expanding the signal spectrum, enhancing the anti-interference ability of tactical data links. CRC coding and Turbo coding achieve error detection and correction by introducing supervised symbols. In addition, this paper proposes a soft despreading and a soft demodulation algorithm corresponding to CCSK spread spectrum and MSK modulation to achieve cascade with Turbo decoder and improve the error rate performance and robustness of the model. Compared with existing models, the tactical data link based on CCSK-FMSK has better BER performance.

LoRa Based IoT Enabled Sensor Networks for Plantations

The integration of Wireless Sensor Network (WSN) technology with the Internet of Things (IoT) in agriculture plays a pivotal role in addressing a range of challenges and constraints faced by the sector, encompassing issues such as labour shortages, suboptimal farm management practises, and unpredictable weather conditions. In response to these pressing concerns, this study focuses on the development of WSN with IoT for agriculture, employing a spread spectrum modulation technique named the Long Range (LoRa) module. By leveraging LoRa devices and wireless radio frequencies, this technology serves as a versatile platform for delivering wireless, long-range, and energy-efficient communication to support small and medium-sized agricultural operations. These operations often lack adequate technological assistance due to factors such as limited expertise and the high costs associated with cutting-edge agricultural technology. The research undertakes a comprehensive exploration, involving LoRa parameter testing, Line-of-Sight evaluations, Non-Line-Of-Sight (NLOS) simulations, and sensor calibration, to assess the efficacy of LoRa-based IoT-enabled sensor networks within plantation environments. The overarching objective of this research endeavour is to provide valuable insights that contribute to the optimisation of agricultural practises through streamlined IoT solutions. By implementing practical and cost-effective strategies, the local agricultural sector stands poised to achieve seamless strides in both sustainable and efficient food production.

Implementation of Underwater Electric Field Communication Based on Direct Sequence Spread Spectrum (DSSS) and Binary Phase Shift Keying (BPSK) Modulation.

Stable communication technologies in complex waters are a prerequisite for underwater operations. Underwater acoustic communication is susceptible to multipath interference, while underwater optical communication is susceptible to environmental impact. The underwater electric field communication established based on the weak electric fish perception mechanism is not susceptible to environmental interference, and the communication is stable. It is a new type of underwater communication technology. To address issues like short communication distances and high bit error rates in existing underwater electric field communication systems, this study focuses on underwater electric field communication systems based on direct sequence spread spectrum (DSSS) and binary phase shift keying (BPSK) modulation techniques. To verify the feasibility of the established spread spectrum electric field communication system, static communication experiments were carried out in a swimming pool using the DSSS-based system. The experimental results show that in fresh water with a conductivity of 739 μS/cm, the system can achieve underwater current electric field communication within a 11.2 m range with 10-6 bit errors. This paper validates the feasibility of DSSS BPSK in short-range underwater communication, and compact communication devices are expected to be deployed on underwater robots for underwater operations.

Spread spectrum OFDM-IM with X-transform

This paper proposes a developed index modulated spread spectrum orthogonal frequency division multiplexing (OFDM) that is based on X-transform (IM-XOFDM-SS). The presented OFDM sends information not only by M-ary data symbols but also by indexes bits that used to select the spreading code from a known set, and applies the X-transform for baseband processing. A theoretical analysis for upper bound bit-error rate (BER) over Rayleigh fading channels is derived for the proposed scheme. Simulations results show that our proposed scheme outperforms the competitive benchmark systems in terms of BER, peak-to-average power ratio (PAPR) and computational complexity. It achieves, at 10−4 BER, about 22 dB and 21 dB SNR gain when spectral efficiency is SE=1 bps/Hz. Additionally, it gains about 5.5 dB PAPR reduction in comparison to IM-OFDM-SS scheme that is based on FFT for baseband processing.

Spread Spectrum Modulation to Reduce EM Noise for LLC Resonant Converter Using Partial Power Processing Concept

Spread Spectrum Modulation to Reduce EM Noise for <i>LLC</i> Resonant Converter Using Partial Power Processing Concept

EMI Reduction at the Source in WBG Inverters: A Comparative Study of Spread-Spectrum Modulation and Auxiliary Switching Leg Techniques

EMI Reduction at the Source in WBG Inverters: A Comparative Study of Spread-Spectrum Modulation and Auxiliary Switching Leg Techniques

Potenciando el Desarrollo de IoT con Tecnología LPWAN: Caso de Estudio en la Universidad Nacional de Misiones

This document underscores the vital role of Low Power Wide Area Network (LPWAN) technology in advancing the Internet of Things (IoT) and enabling connectivity for low-power devices, prioritizing factors like range, durability, and cost-efficiency. It explores the influences on LPWAN performance, including Ultra Narrow Band (UNB) and Spread Spectrum (SS) modulations, offering in-depth insights into their technical characteristics, pros, and cons across licensed and unlicensed operational spectrums. Notable challenges encompass battery life, quality of service, coverage, and expenditure. The city of Posadas, Argentina, is showcased as a successful LoRaWAN testbed, illustrating the system’s commendable performance and functionality.