Showing papers on "Pulse-position modulation published in 2020"

Laser measured rate equations with various transmission coders for optimum of data transmission error rates

Abstract: The present study has outlined laser-measured rate equations with various transmission coders for optimum data transmission error rates. Various modulation transmission coders are employed, such as a pulse position modulation coder, a differential pulse intensity modulation coder, and a four band/five band modulation transmission coder, in order to create optimized data rates of up to 40 GB/s for a fiber extension length of up to 100 km. This study has emphasized the important role of pulse position modulation transmission coders, which exhibit superior performance in max. Q parameter and min. data error rates, even for high data rate transmission.

Performance enhancement of hybrid diversity for M-ary modified pulse-position modulation and spatial modulation of MIMO-FSO systems under the atmospheric turbulence effects with geometric spreading

Abstract: In this paper, we propose a novel model for hybrid spatial diversity of M-ary pulse position modulation (M-ary PPM) and spatial modulation (SM) with a multiple-input multiple-output (MIMO) links (i.e., optical receiver diversity) in a free-space optical (FSO) communication system under the atmospheric turbulence (AT) effects with geometric spreading (GS). In the proposed design, the spatial index modulator (SIM) and modified pulse position modulation (MPPM) schemes are combined to improve the system efficiency of the spatial diversity for the M-ary PPM modulated MIMO–FSO communication. In this work, we investigate and enhance the performance of the MIMO-FSO link using a digital pulse position modulation (DPPM) and on–off keying non-return-to-zero (OOK–NRZ). We propose a MIMO-based FSO link using spatial diversity and M-ary PPM modulation technique to compensate for the performance degradation due to geometric losses and atmospheric attenuation. Here, we have combined the N-SM with L-MPPM (N-SM/L-MPPM) and (M × N MIMO) to improve the system performance and provide high bandwidth and a higher throughput under the impact of the AT and GS. We analyze the GS impact on the performance of MIMO–FSO systems using SM over the Gamma–Gamma (GG) model. The performance is achieved by using the PPM technique, so the AT influences and fading are mitigated hence the ability to combat AT and the FSO link systems are enhanced sufficiently. Also, we improve the performance of the proposed link using a novel hybrid of SM/PPM and DPPM over GG to maximize the range and enhance the receiver sensitivity. Simulation results obtained for the bit-error-rate (BER) and average transmitted optical power for the DPPM and OOK modulation against various AT conditions are compared with the spatial diversity techniques and proved that both of the FSO systems based MIMO–SM/MPPM offers better performance in the receiver sensitivity and channel capacity. The obtained results show that the conjunction of the receiver diversity and SM/M-ary MPPM is a magnificent solution for mitigating the strong turbulence (ST) and GS effects. The proposed design provides an excellent optical signal-to-noise ratio (SNR) and high-sensitivity for the SIM/PPM-MIMO in the ST regime and GS. The numerical results report that the DPPM sensitivity improves about 10–11 dB at a distance of 2.5 km and the BER of 10−12 more than an equivalent OOK–NRZ modulation. The SIM/PPM-MIMO offers about 4 dB, 2 dB optical SNR improvements over without SIM/PPM-MIMO for the no turbulence and ST with GS for the FSO link, respectively. This work could be beneficial to the practical implementation of the hybrid spatial diversity for the SM/M-ary MPPM based MIMO-FSO links under the AT effects with GS.

Anti-interference single-photon LiDAR using stochastic pulse position modulation

Abstract: This Letter introduces an anti-interference single-photon light detection and ranging (LiDAR) system with photon-driven stochastic pulse position modulation. A photon arrival sequence with a programmable minimum interval time and trigger rate was proposed to trigger laser pulses, thus providing true nature-based randomness in modulation which is beneficial for achieving better anti-interference capability. In the proposed LiDAR system, two complementary metal–oxide–semiconductor single-photon avalanche diodes (SPADs) are used as an optical receiver and to generate a random trigger pattern of a pulsed laser. To prevent the range ambiguity problem, an interval-time filter capable of controlling the minimum interval time is integrated into the LiDAR system. A trigger rate controller capable of adaptively controlling the driving voltage of a light-emitting diode coupled with the SPAD responsible for the generation of the random trigger sequence is also integrated for achieving a precise control of trigger rate. Finally, a proof-of-concept demonstration was provided through experiments, and the obtained results were consistent with theoretical predictions. At an effective trigger rate of 800 kHz, an excellent suppression ratio of 56.2 dB has been achieved in the presence of a 1 MHz periodic interference.

Analysis and Demonstration of Quasi Trace Orthogonal Space Time Block Coding for Visible Light Communications

Abstract: In the VLC context, pulse position modulation (PPM) and similar modulations are typically used when the overall complexity of the transmitter is required to be low or the system needs to support dimming, i.e., dynamically control the illumination level of the transmitter. However, despite the power efficiency of PPM, it is known to be bandwidth inefficient. Having known the trade-off between reliability and spectral efficiency, in this paper we propose a PPM-based space-time block coding (STBC) technique named as quasi-trace-orthogonal (QTO), derived from trace-orthogonal, to increase the spectral efficiency of PPM VLC’s by limiting the reliability loss. We provide Monte-Carlo simulations for a $4\times 4$ MIMO-VLC system and validate the results experimentally, and show that for a given signal-to-noise-ratio, the QTO-STBC based 4-PPM VLC system offers higher spectral efficiency at a cost of higher symbol error rate compared to trace-orthogonal STBC.

Molecular Type Permutation Shift Keying for Molecular Communication

Abstract: Molecular communication (MC) via diffusion is envisioned to be a new paradigm for information exchange in the future nanonetworks. However, the strong inter-symbol interference (ISI) caused by the diffusion channel significantly deteriorates the performance of MC systems. To this end, we propose a novel modulation technique to reduce the ISI effect, termed as molecular type permutation shift keying (MTPSK), which encodes information on the permutations of multiple types of molecules. We design a Genie-aided maximum-likelihood detector and a conventional maximum-likelihood detector, and analyze their performance in terms of bit error rate (BER). Aiming at lower computational complexity, we further design a low-complexity maximum-likelihood detector using a Viterbi-like algorithm with compromised error performance. BER simulation results corroborate that the proposed MTPSK can outperform the prevailing modulation schemes for MC, including molecular shift keying (MoSK), concentration shift keying, depleted MoSK, and pulse position modulation.

Error performance analysis of PPM-and FSK-based hybrid modulation scheme for FSO satellite downlink

Abstract: To enhance the error performance of satellite downlink optical wireless communication system, a hybrid modulation scheme called PPM-FSK-SIM is proposed in this study. It is based on the concept of pulse position modulation (PPM), M-ary frequency shift keying (MFSK) and subcarrier intensity modulation (SIM). The analytical bit error rate (BER) of the proposed hybrid scheme is derived, in the presence of atmospheric turbulence with avalanche photodiode (APD) detection by using Meijer-G, which stands out as a reliable and efficient analytical tool that replaces the time-consuming Monte-Carlo simulation method to target a desirable BER. It is analysed over additive white gaussian noise (AWGN), log-normal and gamma–gamma channel models for geostationary satellite to Earth (downlink) communication. As compared to PPM and minimum shift keying (MSK), PPM-MFSK-SIM gives better error rate performance. The scheme is power efficient making it a favourable modulation technique for satellite downlink communication.

Multilevel-Coded Pulse-Position Modulation for Covert Communications Over Binary-Input Discrete Memoryless Channels

Abstract: We consider the problem of coding to ensure covert communication, which involves ensuring reliable communication between two legitimate parties while simultaneously guaranteeing a low probability of detection by an eavesdropper. Specifically, we develop an optimal low-complexity coding scheme that achieves the information-theoretic limits of covert communications over binary-input discrete memoryless channels (BI-DMCs). To justify our design, we first consider a regime in which information theory proves the possibility of covert communication without shared secret key and show the impossibility of achieving information-theoretic limits using linear codes without secret key. We then circumvent this impossibility by introducing non-linearity into the coding scheme through the use of pulse position modulation (PPM) and multilevel coding (MLC). This MLC-PPM scheme exhibits several appealing properties; in particular, for an appropriate decoder, the channel at a given level is independent of the total number of levels and the codeword length. We exploit these properties to show how one can use families of channel capacity- and channel resolvability-achieving codes to concretely instantiate a covert communication scheme.

IEEE 802.15.6 WBAN Standard Compliant IR-UWB Time-Hopping PPM Transmitter using SRRC signaling pulse

Abstract: This paper develops the design of an IEEE 802.15.6 Impulse-Radio (IR) Ultra-Wideband (UWB) transmitter for Wireless Body Area Networks (WBAN) in 180-nm CMOS technology. The transmitter operates at the mandatory data rate of 0.487 Mbps and employs a pulse position controller (PPC) to place the Square Root Raised Cosine (SRRC) pulse for a time-hopping pulse position modulation (TH-PPM) scheme. This transmitter features a novel piece-wise linear approximation (PWLA) approach for generation of SRRC signaling pulse. It is found that the generated PWLA SRRC pulse is fully compliant with the WBAN spectral mask. The proposed PWLA approach has the potential to approximate an arbitrary signaling waveform with a high degree of accuracy and hence should be useful in transceiver realizations.

Performance Analysis of Free Space Optical Communication System Using Different Modulation Schemes over Weak to Strong Atmospheric Turbulence Channels

Abstract: In this paper, we have investigated the performance of an optical wireless communication system and reported the achievable BER and average channel capacity using different modulation schemes such as on-off keying (OOK), quadrature phase shift keying (QPSK), and pulse position modulation (PPM). A comparative study based on these three schemes has been studied for free space optics (FSO) system. The atmospheric channel is modeled for weak to strong atmospheric turbulences with combined effect of turbulence and pointing errors. Here, the FSO link is modeled as gamma–gamma (G–G) distribution and lognormal (LN) distribution channel models. A closed-form mathematical expression for average bit error rate (BER) and average channel capacity for various modulation schemes, viz., OOK, QPSK, and PPM, are presented, in order to analyze the performance of the FSO system. The simulated results for BER and channel capacity for different modulation techniques over gamma–gamma and lognormal distribution channel model are reported in this paper.

Time Synchronization in Photon-Limited Deep Space Optical Communications

Abstract: Random jitter or offset between the transmitter/receiver clocks is an important parameter that has to be accurately estimated for optimal detection of pulse position modulation (PPM) symbols for high-data-rate optical communications. This parameter, in general, is modeled as an unknown random quantity that depends on the clock drift between the transmitter/receiver clocks and the random motion between the transmitter and receiver stations. In this paper, we have modeled the time jitter for two scenarios—phase modulation jitter and frequency modulation jitter. The phase modulation jitter is modeled as a Gaussian random variable which is estimated with the help of a maximum a posteriori probability (MAP) estimator. The frequency modulation jitter is characterized as a random walk, and this leads to the modeling of the jitter as a state space variable in the context of a dynamical system. Since the observations are the photon counts in each slot of a PPM symbol (for both MAP estimation and tracking), the resulting dynamical model is highly nonlinear, and particle filters are employed for tracking the frequency modulation jitter. We evaluate the performance of both the maximum a posteriori estimators and the particle filters in terms of the relative mean-square error and probability of error. We conclude that with MAP estimation and particle filters that estimate/track the time offset, we achieve a significant performance gain in terms of probability of error as compared to systems that do not have a time synchronization system in place.

Bit Error Rate performance analysis for Free Space Optic communication

Abstract: This paper discusses the comparison of 4 modulation in Free Space Optic communication namely; Pulse Position Modulation (PPM), Pulse Amplitude Modulation (PAM), and On Off Keying Modulation (OOK). By Utilizing a light source with a length of 1550 nm, a simulation measured by Bit Error-Rate using Signal-to-Noise Ratio (SNR) in several distance. In this research, researchers used a quantitative approach by MATLAB simulation and using correlational studies to compare BER, SNR, distance and visibility. The results show that PPM is the most effective modulation in comparison with others.

On the Interference Immunity of Visible Light Communication (VLC)

Abstract: Visible Light Communication (VLC) relies on the dual use of existing light infrastructure for wirelessly send data. VLC is regarded as a “green”, cost-effective and secure communication technology. Moreover, VLC has been always considered immune to Radio Frequency (RF) waves. The only type of interference that has always been included in the channel model is the optical interference. Nevertheless, all the interference components potentially impacting on the performance of the system should be integrated in the transmitting model in order to improve the performance of the communication system. In this paper, we investigate on the interference and immunity of the VLC systems in respect of frequencies spanning the spectrum up to 1 GHz. We provide a detailed evaluation of the immunity of a VLC system by the means of experiments realized in “controlled” environment, i.e. an anechoic chamber, by considering interference at different power levels. Results are very interesting, since at specific frequency values, the VL transmitted signal results too “interfered” and noisy to be correctly recovered. In order to evaluate the impact of this interference, we have estimated the Bit Error Rate (BER) for different index modulations of Pulse-Position Modulation (mPPM).

Average Error Probability of an Optically Pre-Amplified Pulse-Position Modulation Multichannel Receiver under Malaga-ℳ Fading

Abstract: We present analytical results on the average probability of error (PER) performance of an optically pre-amplified pulse-position modulation (PPM) receiver under Malaga- M fading. The results are in the form of a finite sum whose number of terms depends on the PPM modulation order and the noise modes of the amplifier, enabling the efficient calculation of the average PER. In addition, we utilized the presented analysis to evaluate the performance of a equal-gain-combining (EGC) diversity receiver that operates in conjunction with optical amplification and PPM. The results show that the utilization of diverse and relatively low PPM orders achieves a drastic reduction in the average PER.

Single-photon counting detector scalability for high photon efficiency optical communications links

Abstract: For high photon-efficiency deep space or low power optical communications links, such as the Orion Artemis-2 Optical Communications System (O2O) project, the received optical signal is attenuated to the extent that single- photon detectors are required. For direct-detection receivers operating at 1.55 µm wavelength, single-photon detectors including Geiger-mode InGaAs avalanche photon diodes (APDs), and in particular superconducting nanowire single-photon detectors (SNSPDs) offer the highest sensitivity and fastest detection speeds. However, these photon detectors exhibit a recovery time between registered input pulses, effectively reducing the detection efficiency over the recovery interval, resulting in missed photon detections, reduced count rate, and ultimately limiting the achievable data rate. A method to overcome this limitation is to divide the received optical signal into multiple detectors in parallel. Here we analyze this approach for a receiver designed to receive a high photon efficiency serially concatenated pulse position modulation (SCPPM) input waveform. From measured count rate and efficiency data using commercial SNSPDs, we apply a model from which we determine the effective detection efficiency, or blocking loss, for different input signal rates. We analyze the scalability of adding detectors in parallel for different modulation orders and background levels to achieve desired data rates. Finally we show tradeoffs between the number of detectors and the required received optical power, useful for real link design considerations.

Low-Power Wireless Transceiver With 67-nW Differential Pulse-Position Modulation Transmitter

Abstract: This article presents a low-power wireless narrowband (NB) transceiver consisting of a 434-MHz NB transmitter (NBTX) and a 434-MHz NB receiver (NBRX) implemented in 0.18 $\mu \text{m}$ CMOS. The NBTX utilizes differential pulse-position modulation (DPPM) to decrease consumed energy per bit (EPB) by up to 67% compared to on-off keying (OOK). The packet error performance of DPPM with a soft-decision decoding scheme is analyzed. According to the results, the packet error ratio (PER) does not deteriorate compared to OOK except at very low signal-to-noise levels. The lowest power consumption of the NBTX is 8.3 $\mu \text{W}$ when DPPM data is transmitted continuously. Utilizing packet-mode transmission, the average power consumption is 67 nW at a data rate of 4.8 kbps. The transmitted data was received with a PER of 0.1% by a receiver placed at a 30-meter distance from the NBTX. With a higher power consumption of 2.5 $\mu \text{W}$ at the same data rate, the estimated line-of-sight (LOS) uplink range is up to 200 meters. The NBRX is a mixer-first uncertain-IF receiver. A temperature-compensated ring oscillator (TCRO) is utilized as a local oscillator. Its measured deviation of frequency is from +0.1% to −1.2% over a temperature range from −40 to +85 °C. The NBRX utilizes Manchester encoding and the sensitivity is −87 to −82 dBm over the temperature range at a data rate of 40 kbps. The NBRX consumes 85 $\mu \text{W}$ .

Implementation of different randomized PWM schemes using Atmega328p microcontroller for EMI reduction in boost converter

Abstract: The randomized pulse width modulation techniques are used to reduce electromagnetic interference in power converters by spreading the harmonic energy. Thus, a wider spectrum with lower amplitudes is obtained. Based on the pulse width modulation signal parameters, three main randomized techniques are achieved: the random carrier frequency modulation, the random pulse width modulation and the random pulse position modulation. This paper presents a short review of the different implementation methods. Then, a detailed implementation of the three considered random techniques using Atmega328p microcontroller is detailed. Finally, an analysis of the experimental conducted electromagnetic noise taken from a boost converter is discussed. These results prove that the random carrier frequency modulation approach is completely better than other techniques in terms of electromagnetic noise reduction.

Design of macroscopic air-based molecular communication concept using fluorescein

Abstract: A proof of concept for a macroscopic air-based molecular communication testbed is presented using fluorescein. The compound in solution state when excited by ultra-violet light, acts as information carrier between a sprayer (transmitter) and a camera (receiver). Relatively higher data rates can be achieved compared to traditional air-based testbeds using alcohol. Implemented modulation schemes include on-off keying, pulse position modulation and differential pulse position modulation, which showcase the efficacy of the system in terms of achievable data transmission rates.

Performance enhancement of hybrid-SIM for optical wireless downlink communication with aperture averaging and receiver diversity

Abstract: Error performance of hybrid subcarrier intensity modulation (hybrid-SIM) in optical free-space satellite downlink has been studied in this work. Bit error rate (BER) is improved by aperture averaging and spatial receiver diversity and it is found out be effective in strong turbulence regime. Subsequently, the reduction in scintillation index has been investigated by implementing a single large receiver and an array of point receivers of length n R with the same effective aperture area. Moreover, the BER at different turbulence conditions is compared with minimum shift keying and multiple levels of pulse position modulation pertaining to aperture averaging. Upon analysing the single input multiple outputs (SIMO) system, the desired response is obtained above a certain threshold in average received irradiance. At different zenith angles and turbulence strengths for n R = 4 , the threshold is 4.59 and 3.35 dB, respectively, and it rises by 13.6 and 26.43 dB when n R is increased to 9. This constraint can be exploited to optimise the number of receivers concerning system requirement and availability. Further, the pointing error effects are also investigated for SISO and SIMO systems, which takes into account both atmospheric turbulence and misalignment induced fading.

M-ary pulse position modulation performance with adaptive optics corrections in atmospheric turbulence

Abstract: The performance of M-ary pulse position modulated (PPM) optical wireless communication (OWC) systems in atmospheric weak turbulence medium is evaluated by using adaptive optics corrections. Piston,...

An Adaptive DPPM for Efficient and Robust Visible Light Communication Across the Air-Water Interface

Abstract: The scarcity of the optical power is the main challenge for underwater visible light communication. It becomes worst for communication across the air-water interface because of the reflection of light from the air-water interface. Differential pulse position modulation (DPPM) is one of the power efficient modulation techniques. In L-DPPM a block of $M=log_{2}L$ input data is mapped into one of the L distinct waveforms containing only one on’ chip. The size of the DPPM packet is variable and depends on the value of input data and L, which makes error detection quite challenging. In this paper, we propose a frame structure that efficiently enables error detection within a packet for various symbol length, L, of DPPM. We also propose an algorithm using such a frame structure to enable effective detection of packet errors and for adaptively changing the value of L for optimal power efficiency while meeting a certain bound on the packet error rate (PER). We have named our proposed protocol as adaptive differential pulse position modulation (ADPPM). The Bit rate and PER have been studied for different signal-to-noise ratio (SNR) through simulation. A comparison between ADPPM and OOK, DPPM with fixed L is provided.

Concentration and Position-Based Hybrid Modulation Scheme for Molecular Communications

Abstract: Modulation design is a particularly interesting problem in the context of molecular communication via diffusion (MCvD), due to the heavy and signal dependent inter-symbol interference (ISI) imposed on the communication link. To tackle the modulation design issue in MCvD, a hybrid modulation family is proposed in this study. The proposed scheme operates by combining conventional concentration constellations with pulse position modulation symbols, and is able to encode more bits into a single joint symbol than traditional concentration or position-based schemes. Called molecular concentration-position modulation (MCPM), it is shown through theoretical and numerical results that the proposed scheme yields promising error performances, especially in the regime with high ISI and low transmission power. Furthermore, MCPM only utilizes a single type of molecule, which suggests an easier implementability for micro- or nano-scale machinery.

Performance of free space optical communication system based on M-ary PPM modulation over double generalized gamma channel

Abstract: In this paper, we provide analytical results on average Symbol Error Probability (SEP) of a Free Space Optics (FSO) link employing M-ary Pulse Position Modulation (PPM), subjected to turbulent atmosphere modeled with Double Generalized Gamma (DGG) distribution. FSO link is generally impaired by turbulent atmosphere and pointing errors. As far as we know, results are presented in previous works by considering the atmosphere turbulence modeled with a Gamma-Gamma distribution. In our work, we also give asymptotic results on average SEP in order to approximate its evolution at high Signal-to-Noise-Ratio (SNR). Numerical results showed that FSO link performance is enhanced when PPM-modulation index is increased, for both strong and moderate turbulence regimes, and for both strong and weak pointing error jitter. Monte-Carlo simulations were presented to corroborate our analytical expressions.

Beam Tracking with Photon-Counting Detector Arrays in Free-Space Optical Communications

Abstract: Optical beam center position on an array of detectors is an important (hidden) parameter that is essential not only from a tracking perspective, but is also important for optimal detection of Pulse Position Modulation symbols in free-space optical communications. In this paper, we have examined the beam position estimation problem for photon-counting detector arrays, and to this end, we have proposed and analyzed a number of non-Bayesian beam position estimators. These estimators are compared in terms of their mean-square error, bias and the probability of error performance. Additionally, the Cramer-Rao Lower Bounds (CRLB) of the tracking error is also derived, and the CRLB curves give us additional insights concerning the effect of number of detectors and the beam radius on mean-square error performance. Finally, the effect of beam position estimation on the probability of error performance is investigated, and our study concludes that the probability of error of the system is minimized when the beam position on the array is estimated as accurately as possible.

Analysis of Modulation Performance of Underwater Visible Light Communication with Variable Wavelength

Abstract: This paper evaluates the performance of Underwater Visible Light Communication (UVLC) with various modulation and wavelength. The first scenario will analyze the Signalto-Noise Ratio (SNR) of the UVLC with 450, 480, and 500 nm wavelength. The second scenario will compare the performance of Bit Error Rate (BER) with various modulation from Onoff Keying No-Return Zero (OOK-NRZ), On-Off Keying Return Zero (OOK-RZ), 8 Pulse Position Modulation (8-PPM), and 8 Pulse Amplitude Modulation (8-PAM). Same as the first scenario the comparison of BER use 450, 480, and 500 nm wavelength. From the simulation of the first scenario, the used of 500 nm wavelength get the result 13.1147, which is the best result of SNR in this simulation. Meanwhile, in the second scenario, the combination of 8-PPM with 500 nm wavelength get the result 1.8922 $\times 10^{-10}$, which is the best result and the value is smaller from Optical Wireless Communication (OWC) BER which is $10^{-9}$