Binary Pulse Position Modulation Research Articles

Long-range underwater optical wireless communication systems in turbulent conditions.

In this paper, single-photon avalanche diode (SPAD) photodetectors are leveraged across long-range underwater optical wireless communication (UOWC) systems for non-turbid waters, i.e., pure sea and clear ocean, in weak turbulent conditions. We derive the bit error probability of the system using on-off keying (OOK) along with two types of SPADs: ideal, i.e., with zero dead time, and practical, i.e., with non-zero dead time. In our investigations for OOK systems, we study the effect of using both the optimum threshold (OTH) and constant threshold (CTH) at the receiver. Furthermore, we analyze the performance of systems using binary pulse position modulation (B-PPM) and compare them with the ones using OOK. Our results are presented for practical SPADs and both active and passive quenching circuits. We demonstrate that OOK systems with OTH perform slightly better than B-PPM. However, our investigations reveal that in turbulent conditions where using OTH may be challenging, employing B-PPM can be preferable to OOK.

Improved Detection Schemes for Non-coherent Pulse-Position Modulation.

Energy-detection (ED) pulse-position modulation (PPM) receivers exhibit poor performance and low rates. Coherent receivers do not have such problems but their complexity is unacceptable. We propose two detection schemes to increase the performance of non-coherent PPM receivers. Unlike the ED-PPM receiver, the first proposed receiver cubes the absolute value of the received signal before demodulation and achieves a considerable performance gain. This gain is obtained because the absolute-value cubing (AVC) operation reduces the effect of low-SNR samples and increases the effect of high-SNR samples on the decision statistic. To further increase energy efficiency and rate of the non-coherent PPM receivers at almost the same complexity, we use the weighted-transmitted reference (WTR) system instead of the ED-based receiver. The WTR system has adequate robustness to weight coefficients and integration interval variations. To generalize the AVC concept to the WTR-PPM receiver, the reference pulse is first passed through a polarity-invariant squaring (PIS) operation and then is correlated with the data pulses. In this paper, the performance of different receivers employing the binary PPM (BPPM) is investigated at data rates of 2.08 and 9.1 Mbps over in-vehicle channels in the presence of noise, inter-block interference, inter-pulse interference, and inter-symbol interference (ISI). Simulations show that the proposed AVC-BPPM receiver outperforms the ED-based one in the absence of ISI and offers the same performance in the presence of strong ISI, the WTR-BPPM system considerably outperforms the ED-BPPM system (especially at high rates), and the proposed PIS-based WTR-BPPM system considerably outperforms the conventional WTR-BPPM system.

A Power-Domain MST Scheme With BPPM in NLOS Ultraviolet Communications

Due to the high path loss of non-line-of-sight (NLOS) ultraviolet communications (UVC) channel, pulse modulation schemes, such as on-off keying (OOK) and M-ary pulse-position modulation (PPM), and photon-counting receivers are commonly adopted. Although M-ary PPM can be demodulated and decoded without the channel state information, its spectral efficiency is lower than OOK's. To improve the spectral efficiency of M-ary PPM in NLOS UVC, a power-domain multilayer-superposed transmission (MST) scheme with binary PPM (BPPM) is proposed in this work. Based on this scheme, the signal in each layer can be directly decoded without successive interference cancellation, which is necessary for other MST schemes in the power domain. Hence, a low complexity receiver in the NLOS UVC system can be realized. Additionally, the bit-error rate (BER) and achievable data rate (ADR) expressions of the proposed MST scheme are derived. Monte-Carlo simulations are performed to verify the analytical BER expression. The NLOS UVC system performance employing the proposed MST scheme is further demonstrated and compared with pure BPPM. The results indicate that with the optimal power allocation factor for each layer, the overall ADR of the NLOS UVC system with the proposed power-domain MST scheme can surpass that with pure BPPM.

Performance Evaluation of Pulse Position Modulation Scheme in Automatic Dependent Surveillance Broadcast System

this paper presents a new formula for calculating the Bit Error Rate (BER) and the Packet Error Rate (PER) for binary pulse position modulation scheme which had been used in Automatic Dependent Surveillance Broadcast (ADS-B) system, ADS-B system is used in air traffic surveillance and control. ADS-B system uses the Binary Pulse Position Modulation (BPPM) scheme in the link between the aircraft and the ground station. The results show that the simulated bit-error rate and packet error rate are approximately matches the theoretical one; these results have been obtained for both coherent and non-coherent detection. As a result, mathematical formulas to represent the probability of error for BPPM are also derived for both coherent and no-coherent detection scheme.

Performance analysis of PPM FSOC system with APD detector considering atmospheric turbulence channel and fiber coupling

In a free-space optical communication system with an avalanche photodiode (APD) detector, the average bit error rate (ABER) is studied based on pulse position modulation (PPM) considering Gamma–Gamma atmospheric turbulence and fiber coupling efficiency (FCE). By analyzing the shot noise and thermal noise, the approximate analytical expression of the ABER of binary PPM is theoretically derived. Then, the approximate analytical expression of ABER union bound is derived for L-ary PPM. The FCE has a greater impact on the ABER of the APD detection system than it does on the PIN detection system. By adopting the adaptive optics technology, compared with the PIN detection system, the communication performance of the APD detection is greatly improved. Moreover, the optimal average APD gain of the APD detection system is strongly correlated to the detector temperature but weakly dependent on the atmospheric turbulence intensity, FCE, number of wavefront compensation terms, average received photon number, and receiving aperture size. By optimizing the receiving aperture and designing an accurate temperature control system, the communication performance of the APD detection system can be further improved.

Types of modulation in IR ultra-wideband technology

One of the ways to implement the UWB system is the pulse radio IR method, which is based on the transmission of very short (on the order of several nanoseconds and picoseconds) and low – power pulses. The paper considers the types of modulation in short-pulse signals of ultra-wideband communication: binary pulse-position modulation Binary PPM, binary modulation format with two values of the signal amplitude, two-phase modulation Bi-Phase Modulation.

BER Performance Analysis of Non-Coherent Q-Ary Pulse Position Modulation Receivers on AWGN Channel.

This paper introduces the structure of a Q-ary pulse position modulation (PPM) signal and presents a noncoherent suboptimal receiver and a noncoherent optimal receiver. Aiming at addressing the lack of an accurate theoretical formula of the bit error rate (BER) of a Q-ary PPM receiver in the additive white Gaussian noise (AWGN) channel in the existing literature, the theoretical formulas of the BER of a noncoherent suboptimal receiver and noncoherent optimal receiver are derived, respectively. The simulation results verify the correctness of the theoretical formulas. The theoretical formulas can be applied to a Q-ary PPM system including binary PPM. In addition, the analysis shows that the larger the Q, the better the error performance of the receiver and that the error performance of the optimal receiver is about 2 dB better than that of the suboptimal receiver. The relationship between the threshold coefficient of the suboptimal receiver and the error performance is also given.

System Level Simulation of Energy-Detection Based UWB Receivers

The performance of a non-coherent UWB receiver with Binary pulse position modulation is simulated with MATLAB; taking into account the effect of non-linearity, noise, pulse shape and channel effects. This simulation examines the minimum requirements for LNA, AGC, squarer, and operational transconductance amplifier in analog front-end for sensor network application with 100Kb/s data rate and 10-3 BER. The linearity requirement in OTA is achieved using Gilbert cell OTA with the technique of multiple gated transistors. For sensor network applications, analog front-end modules must have 4dB NF (Noise figure), -12dBm IIP3, 50dB gain and -75dBm sensitivity for 100Kb/s data rates. The transceiver power consumption is assumed to be below 50mW. The performance of energy detection non-coherent receiver is simulated in Simulink of MATLAB, it shows that BER of Gaussian pulse is lower than doublet and 4th Gaussian pulse. By increasing the number of transmitted pulse per bit and IIP3, the performance of receiver is improved.

A 2.24-pJ/bit 2.5-Gb/s UWB receiver in 28-nm FDSOI CMOS for low-energy chip-to-chip communications

Chip-to-chip communications in high-performance applications such as server racks rely on wireline serial links. In this paper, we present a compact ultra-wideband receiver front-end in 28-nm FDSOI CMOS technology as a wireless interconnect alternative for low-energy and broadcast communications. It is based on binary pulse position modulation without guard interval using two periods of a 10-GHz carrier to reach 2.5-Gb/s datarate over distances >20 cm. The proposed receiver occupies 0.3 mm2 (including decoupling capacitors) and consumes only 5.6 mW which results in an energy of 2.24 pJ/bit.

Performance analysis for a mixed RF and multihop FSO communication system in 5G C-RAN

In this paper, we investigate the performance of a mixed radio frequency (RF) and multihop free space optical (FSO) system in a fifth-generation cloud radio access network (C-RAN) architecture. To cope with the practical channel characteristics, the RF link is assumed to experience the $ \kappa - \mu $ shadowed fading that has recently been proposed to model the small-scale multipath fading as well as line-of-sight shadowing. For FSO links, we adopt the exponentiated Weibull distribution, which can represent irradiance fluctuations at the finite receiving aperture over a wide range of turbulence conditions. Furthermore, we consider the pointing error between the FSO end devices. We first derive a novel probability density function (PDF) expression for the $ \kappa - \mu $ shadowed fading so that the $ \kappa $, $ m $, and $ \mu $ can be equal to the arbitrary positive real value. Then, we study the outage probability and the average symbol error rate (ASER) of the considered system. Our analysis is based on a decode-and-forward (DF) relaying scheme. We choose M-ary quadrature amplitude modulation (M-QAM) for the RF link and binary pulse position modulation (BPPM) for the FSO links. Finally, to provide more insights, we present the asymptotic approximate expressions in high signal-to-noise ratio regimes. Our research shows that the performance of the mixed RF and multihop FSO system can be improved by the large receiving aperture and the increasing number of hops.

Phase‐sampled detection of hybrid modulation impaired by gamma‐gamma turbulence

AbstractThis article presents an alternative, though not innovative detection technique for a hybrid modulation technique based on binary pulse position modulation (PPM). Authors have numerically derived the error performance results of a hybrid modulation called pulse position modulation‐minimum shift keying using phase‐sampled detection technique and aperture averaging (AA). Furthermore, the said hybrid modulation is judged against binary phase shift keying and PPM techniques under weak to strong free space optical environment turbulence channels. For both weak and strong atmospheric turbulence, the error performance is studied using log‐normal channel model and the gamma‐gamma channel model. Furthermore, atmospheric fading probabilities in the form of outage probabilities of all modulation techniques are evaluated for log‐normal turbulence model.

Accurate Evaluation of the Average Probability of Error of Pulse Position Modulation in Amplified Optical Wireless Communications under Turbulence

We present exact and approximate results on the average probability of error (PER) for pulse position modulation (PPM) in pre-amplified optical wireless communication systems with diversity. The approximate results are obtained by combining a new mathematical formula that we derive for binary PPM and an existing formula that associates higher-order PPM PERs with their binary PPM counterpart. The approximate results are compared with the exact in weak, moderate, and strong turbulence, and it is demonstrated that they are in good agreement under all fading conditions. Moreover, the accuracy of the approximation improves with the optical signal-to-noise ratio and the number of diversity branches that are used, which correspond to implementation scenarios that are typically anticipated in practice.

MIMO Underwater Visible Light Communications: Comprehensive Channel Study, Performance Analysis, and Multiple-Symbol Detection

This paper presents a comprehensive study of underwater visible light communications (UVLC), from channel characterization, performance analysis, and effective transmission and reception methods. To this end, we first simulate the fading-free impulse response (FFIR) of UVLC channels using Monte Carlo numerical procedure to take into account the absorption and scattering effects; and then to characterize turbulence effects, we multiply the aforementioned FFIR by a fading coefficient modeled as a lognormal random variable (RV) for weak oceanic turbulence. Based on this general channel model, we analytically study the bit error rate (BER) performance of UVLC systems with binary pulse position modulation (BPPM). In the next step, to mitigate turbulence effects, we employ multiple transmitters and/or receivers, i.e., we apply spatial diversity technique over UVLC links. Closed-form expressions for the system BER are provided, when an equal gain combiner is employed at the receiver side, thanks to the Gauss-Hermite quadrature formula as well as approximation to the sum of lognormal RVs. We further apply saddle-point approximation, an accurate photon-counting method, to evaluate the system BER in the presence of shot noise. Both laser-based collimated and light emitting diode based diffusive links are investigated. Additionally, in order to reduce the intersymbol interference (ISI), introduced by the multiple-scattering effect of UVLC channels on the propagating photons, we also obtain the optimal multiple-symbol detection (MSD) algorithm, as well as the suboptimal generalized MSD (GMSD) algorithm. Our numerical analysis indicate good matches between the analytical and photon-counting results implying the negligibility of signal-dependent shot noise, and also between the analytical results and numerical simulations confirming the accuracy of our derived closed-form expressions for the system BER. Besides, our results show that spatial diversity significantly mitigates fading impairments while (G)MSD considerably alleviates ISI deterioration.

Statistical Modeling of Single-Photon Avalanche Diode Receivers for Optical Wireless Communications

In this paper, a comprehensive analytical approach is presented for modeling the counting statistics of active quenching and passive quenching single-photon avalanche diode (SPAD) detectors. It is shown that, unlike ideal photon counting receiver for which the detection process is described by a Poisson arrival process, photon counts in practical SPAD receivers do not follow a Poisson distribution and are highly affected by the dead time caused by the quenching circuit. Using the concepts of renewal theory, the exact expressions for the probability distribution and moments (mean and variance) of photocounts in the presence of dead time are derived for both active quenching and passive quenching SPADs. The derived probability distributions are validated through Monte Carlo simulations and it is demonstrated that the moments match with the existing empirical models for the moments of SPAD photocounts. Furthermore, an optical communication system with on–off keying and binary pulse position modulation is considered and the bit error performance of the system for different dead time values and background count levels is evaluated.

Two-by-two user grouping for enhanced multipoint-to-multipoint Free-Space Optical communications with Pulse Position Modulation

In this paper, we consider the scenario of N collocated users communicating over Free-Space Optical (FSO) channels. We propose a novel cooperation scheme where the users are grouped together in groups of two for the sake of achieving enhanced diversity orders in a simple manner. In this context, instead of communicating independent binary Pulse Position Modulation (PPM) symbols over each of the N available links in a non-cooperative manner, the information from the different users will be combined and encoded in a joint manner. We propose a method for performing the joint encoding and we propose the structure of the 4-ary augmented constellation to be associated with the proposed cooperation scheme. A performance analysis is conducted over gamma-gamma channels reflecting the capability of the proposed scheme in enhancing the diversity order for all levels of background radiation. In particular, we prove that the diversity order is enhanced by the factor ⌊N2⌋+1.

Performance analysis of a PPM-FSO communication system with an avalanche photodiode receiver over atmospheric turbulence channels with aperture averaging.

The average bit error rate (ABER) performance of an avalanche-photodiode (APD)-based pulse-position modulation (PPM) free-space optical (FSO) communication system is investigated considering the aperture averaging effect. The approximate ABER expression is theoretically derived in terms of M and exponentiated Weibull (EW) distributions under weak-to-strong turbulent atmosphere conditions with a binary PPM (BPPM) scheme. Union-bound and Hermite polynomials are then considered to estimate the performance of M-ary PPM FSO systems. The system performance is analyzed with the aperture sizes, turbulence strengths, receiver temperatures, and average photon counts taken into account. The results show that an optimal average APD gain, which is affected by receiver temperature, can be chosen to minimize the ABER value. And the impact of aperture averaging on the system performance over M distribution is not so apparent as that over EW distribution for different temperatures, turbulent strengths, and average photon counts. In addition, the present APD-based system can offer better ABER performance than that of a P-i-N-based PPM system over both EW and M fading channels at 300 and 500 K. This work is beneficial to the FSO system design.

Numerical assessment and optimization of discrete-variable time-frequency quantum key distribution

The discrete variables (DV) time-frequency (TF) quantum key distribution (QKD) protocol is a BB84 like protocol, which utilizes time and frequency as complementary bases. As orthogonal modulations, pulse position modulation (PPM) and frequency shift keying (FSK) are capable of transmitting several bits per symbol, i.e. per photon. However, unlike traditional binary polarization shift keying, PPM and FSK do not allow perfectly complementary bases. So information is not completely deleted when the wrong-basis filters are applied. Since a general security proof does not yet exist, we numerically assess DV-TF-QKD. We show that the secret key rate increases with a higher number of symbols per basis. Further we identify the optimal pulse relations in the two bases in terms of key rate and resistance against eavesdropping attacks.

Received response based heuristic LDPC code for short-range non-line-of-sight ultraviolet communication.

Through slight modification on typical photon multiplier tube (PMT) receiver output statistics, a generalized received response model considering both scattered propagation and random detection is presented to investigate the impact of inter-symbol interference (ISI) on link data rate of short-range non-line-of-sight (NLOS) ultraviolet communication. Good agreement with the experimental results by numerical simulation is shown. Based on the received response characteristics, a heuristic check matrix construction algorithm of low-density-parity-check (LDPC) code is further proposed to approach the data rate bound derived in a delayed sampling (DS) binary pulse position modulation (PPM) system. Compared to conventional LDPC coding methods, better bit error ratio (BER) below 1E-05 is achieved for short-range NLOS UVC systems operating at data rate of 2Mbps.

Error performance of optically preamplified hybrid BPSK-PPM systems with transmitter and receiver imperfections

In this paper, we investigate the impact of the transmitter finite extinction ratio and the receiver carrier recovery phase offset on the error performance of two optically preamplified hybrid M-ary pulse position modulation (PPM) systems with coherent detection. The first system, referred to as PB-mPPM, combines polarization division multiplexing (PDM) with binary phase-shift keying and M-ary PPM, and the other system, referred to as PQ-mPPM, combines PDM with quadrature phase-shift keying and M-ary PPM. We provide new expressions for the probability of bit error for PB-mPPM and PQ-mPPM under finite extinction ratios and phase offset. The extinction ratio study indicates that the coherent systems PB-mPPM and PQ-mPPM outperform the direct-detection ones. It also shows that at $$P_b=10^{-9}$$Pb=10-9 PB-mPPM has a slight advantage over PQ-mPPM. For example, for a symbol size $$M=16$$M=16 and extinction ratio $$r=30$$r=30 dB, PB-mPPM requires 0.6 dB less SNR per bit than PQ-mPPM to achieve $$P_b=10^{-9}$$Pb=10-9. This investigation demonstrates that PB-mPPM is less complex and less sensitive to the variations of the offset angle $$\theta $$? than PQ-mPPM. For instance, for $$M=16$$M=16, $$r=30$$r=30 dB, and $$\theta =10^{\circ }$$?=10? PB-mPPM requires 1.6 dB less than PQ-mPPM to achieve $$P_b=10^{-9}$$Pb=10-9. However, PB-mPPM enhanced robustness to phase offset comes at the expense of a reduced bandwidth efficiency when compared to PQ-mPPM. For example, for $$M=2$$M=2 its bandwidth efficiency is 60 % that of PQ-mPPM and $$\approx 86\,\%$$?86% for $$M=1024$$M=1024. For these reasons, PB-mPPM can be considered a reasonable design trade-off for M-ary PPM systems.

A Low-Complexity Detector for BPPM Systems Under Additive Gaussian Mixture Noise

We analyze the performance of the single-threshold detector (STD) for binary pulse position modulation in the presence of symmetric Gaussian mixture noise (GMN). We first derive a general closed-form expression for the average error probability that is later used to investigate the optimality of the STD with zero threshold, which is the simplest form of STD. We also establish conditions sufficient to guarantee minimum error rates with the low-complexity STD for a wide range of signal-to-noise ratio. The theoretical results are verified through simulations of GMN with various noise parameters.