OOK Modulation Research Articles

Pulse position encoded RZ-OOK transmission for free-space optical communications

This paper proposes a pulse position encoded return-to-zero on-off keying (PP-RZ-OOK) transmission for free space optical (FSO) communications. At the transmitter end, PP-RZ-OOK signal is modulated by encoding the pulse position of RZ-OOK in the symbol duration. At the receiver end, PP-RZ-OOK signal is demodulated by symbol-by-symbol signal estimation. First, the existence of pulse is distinguished by adaptive threshold decision using the channel state information (CSI). Then, with respect to the symbol with the pulse, the knowledge of pulse position is estimated by slot-by-slot pulse power comparison. Finally, PP-RZ-OOK signal is effectively demodulated by both pulse existence and pulse position estimation. Therefore, the spectral efficiency of RZ-OOK is increased by the proposed pulse position encoding technique. The performance of the proposed PP-RZ-OOK modulation was verified through simulations under different turbulence channels and pulse durations, and it was compared with non-return-to-zero OOK (NRZ-OOK) and RZ-OOK modulations. The simulation results demonstrated that the capability of scintillation effect compensation was significantly enhanced compared with NRZ-OOK due to the pulse power increasing. Besides, the spectral efficiency was improved compared with RZ-OOK due to the additional pulse position encoding.

Improving FSO Link Performance using PolSK Modulation

Free Space Optical (FSO) communication systems are based on the use of infrared light to transmit information at high speed through the atmospheric channel. Their performance is therefore affected by the characteristics of the atmospheric channel. One of the most widely used methods of compensating for the effects of atmospheric factors is modulation.The main aim of this research is to demonstrate the improvement in FSO link performance using PolSK modulation in a subtropical environment such as Cˆote d’Ivoire. The performance indicators considered are bit error rate, channel capacity, outage probability and energy efficiency. The mathematical expression of the evolution of each of these indicators as a function of the atmospheric parameters of our environment was determined using the gamma-gamma model. A numerical evaluation of the results obtained was carried out using Matlab software. The results show that PolSK modulation offers the best results in terms of BER reduction, with a BER of the order of 10-11 for an SNR of 50dB, compared with BERs of 10-4 and 10-2 for BPSK and OOK modulations respectively. We obtain a probability of interruption of the order of 10-3 for PolSK modulation compared with 10-2 for BPSK modulation and 10-1 for OOK modulation. As for the channel capacity, we obtain the same value (4:1458bit/s) for PolSK and BPSK modulation compared with 3:8181bit/s for OOK modulation. BPSK modulation, on the other hand, stands out for its excellent energy efficiency.

Impact of atmospheric turbulence on OOK and BPSK modulations for satcom optical uplink

Impact of atmospheric turbulence on OOK and BPSK modulations for satcom optical uplink

Enhancing Airport Navigation Using Visible Light Communication

This study introduces an innovative approach to facilitate navigation within crowded multi-terminal airports using Visible Light Communication (VLC) technology. Existing luminaires serve as transmission points, conveying encoded messages through modulated light signals to provide location-specific guidance to users. Equipped with tetrachromatic LEDs and VLC capabilities, these luminaires efficiently transmit data, demonstrated through coverage map analysis and the implementation of the OOK modulation scheme. A novel mesh cellular hybrid structure is proposed, eliminating traditional gateways and enhancing system flexibility. Integrating VLC into an Edge/Fog architecture leverages VLC’s wireless connectivity and secure line-of-sight communication while utilizing existing lighting infrastructure. This integration enables distributed data processing, storage, and communication at the network edge, thereby improving system performance and responsiveness. The paper presents a detailed airport model generation and analyzes two user categories: pedestrians and luggage/passenger carriers. Users are equipped with PINPIN optical sensors to receive and interpret modulated light signals, facilitating localization and positioning calculations. A communication protocol tailored to VLC specifications is discussed, alongside coding and decoding techniques to ensure reliable transmission. This approach demonstrates the potential of VLC to enhance navigation and user experience in high-density environments like airports.

Laser based Optical Wireless Communication using Log Normal Distribution and SIM BPSK Modulation

Laser based Optical Wireless Communication(OWC) is emerging as one of the key advancements for the 5G and beyond technologies. This technology provides high bandwidth, extremely high data rate and high speed communication due to the use of optical waves for data transmission in the field of wireless communication. The system performance is limited due to the presence of turbulence in the atmosphere.We have developed system model using log normal channel distribution in the weak to moderate atmospheric turbulence. Closed form of expression is derived which provides the channel capacity in the presence of weak turbulence using log normal distribution. Subcarrier Internsity Modulation (SIM) BPSK modulation technique is used in OWC system which provides bettter performance in terms of received BER as compared to NRZ – OOK modulation.

All-Optical QPSK Pattern Recognition in High-Speed Optoelectronic Firewalls

In the 5G era, more sensitive information will be transmitted on optical networks. Although modern cryptography could support different security mechanisms in different layers, the optical layer has not been paid enough attention but it is also vulnerable to attack by tapping or other methods. The optoelectronic firewall is one of the promising security strategies which can accelerate the operating speed within manageable costs by employing optical signal processing compared with current electronic firewalls. The most significant and challenging component of an optoelectronic firewall is pattern recognition. However, either the latest pattern recognition systems can only process the OOK or BPSK modulation format signals, or the coherent correlators supporting higher order modulation format require advanced components to deal with a higher number of symbols. In this paper, to address the pattern recognition challenges, we propose, analyze and simulate a pattern recognition system of QPSK signals integrated into all-optical high-speed optoelectronic firewalls used for optical layer security. The numerical simulation results first demonstrate the feasibility, and a baud rate of 100GBaud can be achieved. Next, a threshold-setting method is developed which also proves the ability to recognize arbitrary target patterns. Then some noise analysis results demonstrate that the pattern recognition of the I branch can be immune to the noise while the output power of EDFAs in the Q branch needs to be configured carefully. Finally, the matched result of a real Ethernet frame further reveals that our proposed system is promisingly applied in optoelectronic firewalls.

Performance Evaluation of NRZ-OOK and Carrier-Less Amplitude Phase Modulation in Li-Fi Environment

Light Fidelity (Li-Fi) is a wireless technology that utilizes light emitting diodes to convey data. Li-Fi has emerged as a promising alternative to radio frequency communication technology in recent years. This paper examines the performance characterisation between NRZ-OOK and carrier-less amplitude-phase modulation (CAP-2, CAP-4 and CAP-8), within a simulated Li-Fi environment. For the parameters of interest, the eye pattern, bit error rate (BER) and constellation diagram are reported. As no distance is specified in the simulation, the BER for CAP is zero, allowing an ideal transmission to be emulated. The scatter diagram increases as the number of CAP modulations increases. For the eye pattern, CAP modulation provides a better visual representation of how noise might affect system performance compared to OOK modulation.

A peak detection based OOK photoacoustic modulation scheme for air to underwater communication

The popularity of underwater applications has been growing due to the major technological advances in the last few decades. Yet, direct communication from an airborne node to an underwater node remains challenging due to the inability of any known signal which propagates well in both the air and water mediums. Photoacoustic energy transfer is a promising mechanism for enabling such cross-medium communication. Although the use of the photoacoustic mechanism is quite common in medical imaging, little progress has been made on building the communication protocol stack. Most research studies have only focused on characterizing the channel and relating the laser and acoustic signals. Little attention has been given to developing suitable modulation and demodulation schemes. This paper fills such a technical gap and proposes a novel OOK modulation scheme using peak detection technique. We validate the effectiveness of our proposed scheme through simulation and lab experiments.

Mode division multiplexing free space optics system with 3D hybrid modulation under dust and fog

Mode division multiplexing (MDM) is an emerging information transmission technique in which multiple data signals can be transmitted simultaneously on different modes of a single wavelength laser beam over a free-space channel. MDM is a potential technique for the realization of high-speed spectral efficient communication links for future generations of wireless networks. We present a novel MDM-based free-space optics (FSO) system. The system integrates a 3D hybrid modulation scheme produced by combining carrier suppressed-non-return-to-zero (CSNRZ), differential quadrature phase-shift keying (DQPSK), and polarization shift keying (PolSK) modulation schemes for beyond 100 Gbps applications. Three unrelated 40 Gbps data signals are modulated and transmitted on one optical carrier utilizing three distinct signal properties: amplitude (CSNRZ), phase (DQPSK), and polarization state (PolSK). The proposed 3D modulation scheme offers a high-capacity system, where each channel transmits 4 Gbps as compared to 1 Gbps in the case of OOK modulation. MDM using distinct Hermite Gaussian modes: (HG00 and HG01) of a laser beam is incorporated to boost the spectral efficiency and information rates of the FSO link. The proposed 120 Gbps single-channel MDM-FSO link performance is examined under the impact of different levels of dust and fog environmental conditions using quality factors and received eye diagrams as the performance metrics. This system achieved optimal performances up to 1250 m (very light dust), 540 m (light dust), 170 m (moderate dust), 750 m (low fog), and 425 m (medium fog). In the worst-case scenario, the system manages to work up to a 67 m range in dense dust with a maximum attenuation of 297.38 dB/km and a 200 m distance in heavy fog with only 90 dB/km attenuation which is less than 1/3rd of the attenuation measured for dense dust event. In addition, our results and the case studies confirm that dust introduces greater signal attenuation than fog. Therefore, an encounter with a dust environment should be considered as the bottleneck issue for FSO links. The creative contribution of this paper is to put forward a bandwidth-efficient MDM-FSO-enabled B5G system that could be deployed in harsh and challenging locations at reduced visibility. This is expected to be further technically sustainable owing to the use of advanced 3D hybrid optical orthogonal modulation and therefore find use in implementing 5G and 6G cellular and data networks.

Adaptive threshold setting for OOK modulation with a prefix code in THz band

Adaptive threshold setting for OOK modulation with a prefix code in THz band

O2O: An Underwater VLC Approach in Baltic and North Sea

Recently, underwater visible light communication (UVLC) has become a potential wireless carrier candidate in the acrimonious mingled ocean straits. The combined strait of the North and Baltic ocean is a harsh and strongly turbid aqueous zone that contributes signal fading at a large scale. Due to this, we are proposing a UVLC system within the Baltic–North ocean mingled water under strong turbulence channel conditions. In this study, the Gamma–Gamma distribution is used to model UVLC link under an OOK modulation scheme. Subsequently, the reason for the unavailability of the latest North–Baltic oceanographic data within this bayou, we investigate the BER and outage probability performance of the proposed system within the mingled strait for the whole year during 1996s. Throughout, this work, the performance is obtained individually in both of the oceans and then compared with the heterogeneous state. It is noteworthy that the analytical work has been considered of the following distinct physio-chemical properties and the data provided for each ocean. Additionally, the simulation results are verified the analytical work of the proposed system model.

Simultaneous monitoring of the values of CD, Crosstalk and OSNR phenomena in the physical layer of the optical network using CNN

The aim of the research was to explore the possibilities of using the Asynchronous Delay Tap Sampling (ADTS) and Convolutional Neural Network (CNN) methods to monitor the simultaneously occurring phenomena in the physical layer of the optical network. The ADTS method was used to create a data sets showing the combination of Chromatic Dispersion (CD), Crosstalk and Optical to Signal Noise Ratio (OSNR) as optical disturbances in graphic form. Data were generated for 10 GB/s, Non-return-to-zero On–off keying (NRZ-OOK) and Differential Phase Shift Keying (DPSK) modulation and bit delays: 1 bit, 0.5 bit and 0.25 bit. A total of 6 data sets of 62,000 images each were obtained. The learning process was carried out for the number of epochs 50 and 1000. From the obtained learning results of the network, models with the best R^{2} matching factor were selected. The learned models were further used to study the recognition of three phenomena simultaneously. The tests were carried out on sets of 2500 images in a combination of interference in the following ranges: 400–1600 ps/nm for CD and 10–30 dB for Crosstalk and OSNR. Very good results were obtained for recognizing simultaneously occurring phenomena using models learned up to 1000 epoch. Accuracy of over 99% was obtained for CD and Crosstalk for both modulations. In the case of the OSNR phenomenon, slightly weaker results were obtained above 96% in most cases. For models taught up to 50 epoch, very good results were obtained for the CD phenomenon (over 99%). For Crosstalk weaker results for OOK modulation were obtained. Poor results were obtained for the OSNR phenomenon, where recognition accuracy ranged from 50 to 80%, depending on the type of modulation and bit delay. Based on the conducted research, it was established that the use of ADTS and CNN methods enables monitoring of simultaneously occurring CD, Crosstalk and OSNR interference in the physical layer of the optical network, while maintaining the requirements for Optical Performance Monitoring systems. These requirements are met for network models learned up to 1000 epoch.

A 5-pJ/Bit OOK Transmitter Using MEMS-Based RF Oscillator for IoT Application in 180-nm CMOS

An 800-MHz OOK transmitter for short-range Internet-of-Things (IoT) applications is presented in this letter. The OOK transmitter utilizes a microelectromechanical system (MEMS)-based RF oscillator for carrier frequency generation, leading to a hardware- and power-efficient architecture. The transmitter is implemented in a 180-nm CMOS process and delivers −12.4-dBm output power. The power consumption of the MEMS oscillator is only 0.24-mW with 126.3-dBc/Hz phase noise at 100-kHz offset and a figure-of-merit (FoM) of 210.5 dB due to the optimized high- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Q$ </tex-math></inline-formula> aluminum nitride (AlN) piezoelectric MEMS resonator. The transmitter can provide a 120-Mb/s data rate of OOK modulation with an energy efficiency of 5 pJ/bit by directly switching ON/OFF the power amplifier (PA). The 175-ns startup time of the MEMS-based oscillator can support very heavy duty-cycle transmitter operation, leading to ultralow average power consumption of 50 nW.

Adaptive Receiver Control for Reliable High-Speed Underwater Wireless Optical Communication With Photomultiplier Tube Receiver

Photomultiplier tube (PMT) receiver is a promising solution for long-distance underwater wireless optical communication (UWOC) due to its characteristics of high gain, low noise, and large receiver area. However, the complex underwater environment leads to the dynamic change of the received optical intensity and impacts the stability and reliability of UWOC system using PMT. In this work, the bandwidth limitation and performance degradation of UWOC system caused by PMT saturation is experimentally observed and characterized for various optical intensity and PMT gain. A low-cost, high-integrated, and small-volume receiver control system and relevant adaptive control strategy are proposed to improve the stability and reliability of UWOC system by dynamically adjusting the received optical power and PMT gain according to the detected optical signal. The experiment results show that the dynamic range of UWOC received optical power can be extended to 68 dB (-63 dBm~5 dBm) for 100 Mbit/s OOK modulation based UWOC system.

Enhancement and performance analysis of channel access mechanisms in Terahertz band

With Terahertz band (0.1–10 THz) technology, several nanoscale ad hoc applications could be developed, such as intrabody health monitoring, programmable material, etc. The fundamental element to ensure the functionality of these applications is the way to access the radio communication channel. The main challenge with nanocommunication is the need to efficiently share the terahertz radio spectrum to optimize data transmission in nanonetworks. In this context, Spread in Time On-Off Keying (TS-OOK) protocol was proposed as a channel access mechanism that uses Femtosecond-Long pulse-based OOK modulation. Furthermore, different new improvements of TS-OOK were introduced, such as RD-TSOOK and SRH-TSOOK approaches.In this paper, we review and compare the proposed OOK-based channel access techniques with our new approach called SDMA-TSOOK. The design of the proposed scheme takes into account the weaknesses of these mechanisms in terms of channel access balancing, co-channel collision, and networking capacity that pose a problem for concurrent channel access. We evaluate the performance of our proposed protocol using the BitSimulator. The obtained results showed that SDMA-TSOOK ensures 100% equitable access between nanodevices, as well as a better success rate with an insignificant number of collisions as compared to the published reference protocols.

Average Bit Error Rate at Signal Transmission with OOK Modulation Scheme in Different FSO Channels

Average Bit Error Rate at Signal Transmission with OOK Modulation Scheme in Different FSO Channels

Optimal sub‐harmonic injection‐locked MICS band transmitter for wireless CW‐fNIRS systems

AbstractPortable and wireless functional near‐infrared spectroscopy is a growing field of research for real‐time monitoring of brain functions. The most critical challenges in this field are the use of low‐power and calibrated circuits. A novel transmitter architecture is proposed to overcome these barriers. This transmitter is low power, capable of being calibrated against process variation, and has a better phase noise and spurious‐free dynamic range (SFDR) at the antenna. Besides that, the transmitter can be calibrated, which is not seen in similar research. In this transmitter, injection locking and frequency calibration lead to having an optimal and low‐power circuit. The circuit is capable of transmitting data with BFSK and OOK modulations in the frequency band of the medical implant communication service (MICS). The transmitter is designed and simulated in a typical CMOS 0.18‐μm technology with a 1‐V power supply. The transmitter's power consumption is around 146 and 123 μW, equal to 5.92 nJ/bit and 246–630 pJ/bit for BFSK and OOK modulations, respectively. The signal's phase noise at the antenna is almost −109 dBc/Hz at 1‐MHz frequency offset.

Design and Performance Analysis of THz Wireless Communication Systems for Chip-to-Chip and Personal Area Networks Applications

Terahertz (THz) communication is a promising technique for chip-to-chip communication and wireless personal area networks. In this paper, we present an experimental study and design to realize such THz communication systems. We develop two different chip sets for on-off-keying (OOK) modulation based THz transceivers which include carrier generators, modulators, THz amplifiers, and baseband amplifiers. Specifically, the first chip set integrates the circuit blocks for the OOK modulation without the THz amplifier for short-range communication. In addition, the second chip set design includes the THz amplifier modules to extend the coverage of transmission. For these two chip sets, we experimentally demonstrate the feasibility of the wireless communication at THz frequency bands and assess performance using the bit error rate (BER) analysis. We estimate the BER by calculating the signal-to-noise ratio (SNR) based on the eye diagram and compare with actual BER measurements and Monte Carlo simulations. We also address the impact of the distance, the transmit power, and the data rate for the proposed THz transceivers based on the link budget analysis, and confirm the accuracy of the derived BER expression.

A 35 Gb/s junction-less dual parallel Mach-Zehnder modulator for short reach interconnects

An electrostatic doping (ED) based 35 Gb/s dual-parallel Mach-Zehnder modulator (DP-MZM) for photonic integrated circuits (PICs) is proposed and analyzed. Theoretical formulation of the transfer function and linearity analysis of the proposed modulator is also presented here. The proposed modulator contains two ED-aided sub-MZMs and an ED-aided optical phase shifter (PS) in a MZI structure. Numerical simulations are performed using commercially available tools and the simulation results are presented here. From the results we estimate that the proposed DP-MZM with 400 μm long sub-MZMs can offer peak dynamic extinction ratio (ER) of 14 dB with maximum 8.7 dB of insertion loss (IL) at 10 Gb/s data rate. Using dual-tone test method, the predicted spurious free dynamic range (SFDR) of the modulator are 62.74 dB·Hz1/2 and 99.35 dB·Hz $$^{2/3}$$ for second and third harmonic intermodulation distortions (IMD2 and IMD3), respectively. From the transient analysis, the estimated maximum operating frequency and 3-dB EO bandwidth of the modulator are approximately 35.5 GHz and 32.37 GHz, respectively. At maximum data rate, 5.89 dB of dynamic ER is offered by the proposed DP-MZM for OOK modulation. Simulation verifies successful transmission of 25 Gb/s OOK modulated PRBS data stream over a 10 km standard single mode fiber (SSMF) link. Furthermore, we have shown that the proposed DP-MZM is capable of generating 50 Gb/s PAM-4 signal, which makes the modulator suitable for next-generation short-reach interconnects.

A 3.5-GHz 0.24-nJ/b 100-Mb/s Fully Balanced FSK Receiver With Sideband Energy Detection

This letter presents a sub-6-GHz 100-Mb/s receiver that employs a fully balanced FSK, namely, a binary frequency-domain OOK (BFOOK) modulation. Demodulation is done based on a delay-line FM demodulator and a sideband energy detection (SB-ED) circuit with reduced noise bandwidth by leveraging a fully balanced BFOOK feature. A prototype 3.5-GHz receiver based on the proposed architecture is implemented in 65-nm CMOS. The receiver performs 100-Mb/s BFOOK demodulation and consumes 24.3 mW with the sensitivity of -62 dBm, achieving high energy efficiency of 243 pJ/b.