Showing papers on "Pulse-position modulation published in 2017"

Index Modulation Techniques for Next-Generation Wireless Networks

Abstract: What is index modulation (IM)? This is an interesting question that we have started to hear more and more frequently over the past few years. The aim of this paper is to answer this question in a comprehensive manner by covering not only the basic principles and emerging variants of IM, but also reviewing the most recent as well as promising advances in this field toward the application scenarios foreseen in next-generation wireless networks. More specifically, we investigate three forms of IM: spatial modulation, channel modulation and orthogonal frequency division multiplexing (OFDM) with IM, which consider the transmit antennas of a multiple-input multiple-output system, the radio frequency mirrors (parasitic elements) mounted at a transmit antenna and the subcarriers of an OFDM system for IM techniques, respectively. We present the up-to-date advances in these three promising frontiers and discuss possible future research directions for IM-based schemes toward low-complexity, spectrum- and energy-efficient next-generation wireless networks.

Enhanced Orthogonal Frequency Division Multiplexing With Index Modulation

Abstract: Index modulation concept has attracted considerable research interest in the past few years As a realization of index modulation in the frequency domain, orthogonal frequency division multiplexing with index modulation (OFDM-IM) has recently been proposed, which conveys information bits through both the subcarrier activation patterns and the amplitude phase modulation constellation points This paper proposes two enhanced OFDM-IM schemes aimed at achieving higher spectral efficiency and diversity gain, respectively The first one, termed OFDM with hybrid in-phase/quadrature index modulation (OFDM-HIQ-IM), explores the I- and Q- dimensions jointly for index modulation, allowing transmission of more index modulation bits in each subcarrier group The second one, termed linear constellation precoded OFDM-IQ-IM (LP-OFDM-IQ-IM), spreads information symbols across two adjacent active subcarriers through linear constellation precoding to harvest additional diversity gain By maximizing the minimum squared Euclidean distance, two different realizations of LP-OFDM-IQ-IM are derived, which leads to a rotated and a diamond-shaped constellation, respectively The proposed OFDM-HIQ-IM and LP-OFDM-IQ-IM, as revealed by both theoretical analyses and computer simulations, enable low-complexity detection and exhibit superior error rate performance over the existing OFDM-IM schemes

Performance of underwater optical wireless communication with multi-pulse pulse-position modulation receivers and spatial diversity

Abstract: In this study, the performance of underwater optical wireless communication systems employing spatial diversity and multi-pulse position modulation techniques is assessed. The effects of inter-symbol interference, oceanic turbulence and receiver noise are taken into account. Oceanic turbulence is modelled by the log-normal distribution which is regarded as an appropriate model for weak turbulence conditions. For the system under consideration, approximate analytical expressions for the average bit error probability are deduced. The impact of the number of transmitting and receiving apertures, the achievable data rate and the water type on system performance is also investigated. Various numerical results are presented that demonstrate the proposed analysis.

Capacity Analysis of Joint Transmission CoMP With Adaptive Modulation

Abstract: Joint transmission (JT)-based Coordinated Multipoint (CoMP) systems achieve high performance gains by allowing full coordination among multiple cells, transforming unwanted intercell interference into useful signal power. In this paper, we present an analytical model to perform adaptive modulation for a typical JT CoMP system, consisting of three transmission points, under a target bit error rate (BER) constraint. Probability density functions of the signal-to-interference-plus-noise ratio (SINR) are derived for different JT CoMP schemes, and based on them, closed-form expressions for the average spectral efficiency (ASE) are obtained when adopting continuous-rate adaptive modulation. The study of ASE is also extended for the case of discrete-rate modulations, where the performance comparison of different practical quantized modulation schemes is carried out.

Quadrature Channel Modulation

Abstract: In this letter, we propose the concept of quadrature channel modulation (QCM) by combining quadrature spatial modulation (QSM) and media-based modulation (MBM) transmission principles. The proposed QCM schemes exploit not only the in-phase and quadrature components of complex data symbols for antenna indexing but also channel states for the transmission of additional information bits through index modulation by employing a single radio frequency (RF) chain. It is shown via numerical studies that the proposed QCM schemes can outperform the existing emerging schemes such as QSM, plain MBM, and spatial modulation-based MBM, which also employ a single RF chain at their transmitters.

Optimal covert communications using pulse-position modulation

Abstract: This paper shows the optimality of Pulse-Position Modulation (PPM) for covert communications over discrete-memoryless channels. Specifically, the concatenation of a random m-ary outer code of length O(m) and an inner code consisting of PPM of order m achieves the information-theoretic limits of covert communications. This suggests alternative code constructions for covert communications, in which the sparsity of the PPM symbols ensures covertness and an appropriate choice of the blocklength results in the square root law.

5.12Gbps optical communication link between LEO satellite and ground station

Abstract: A duplex optical communication link has been verified in orbit between a LEO satellite and a optical ground station (OGS), the down link used Differential Phase Shift Keying (DPSK) modulation format and allowed to transmit data with data rate of 5.12Gbps, without error correction coding, the bit error rate (BER) was better than 10−6 with the link distance exceeded 1500 km, and an average BER of 1.9×10−9 was realized in 306s. The uplink used 16-ary PPM (Pulse Position Modulation) technique with a data rate of 20Mbps, and a BER below 10−6 was also realized.

Structured optical receivers for efficient deep-space communication

Abstract: We discuss conceptual designs for structured optical receivers that can alleviate the requirement for high peak-to-average power ratio in photon-starved optical communication. The basic idea is to transmit sequences of suitably modulated coherent light pulses whose energy can be concentrated in a single temporal bin on the receiver side through optical interference. Two examples of scalable architectures for structured receivers are presented. The first one, based on active polarization switching, maps Hadamard codewords composed from the binary phase shift keying (BPSK) constellation onto the standard pulse position modulation (PPM) format. The second receiver, using solely passive optical elements, converts phase-polarization patterns of coherent light pulses into a single pulse preserving a synchronized time of arrival. Such a conversion enables implementation of a communication protocol equivalent to the PPM scheme but with distributed optical power provided that the intersymbol guard-time exceeds the pattern length.

Variable m-CAP for bandlimited Visible Light Communications

Abstract: The multi-band carrier-less amplitude and phase (m-CAP) modulation technique has been demonstrated as a significant candidate for use in visible light communication (VLC) systems, as spectral efficiency becomes ever more important. When employing m-CAP modulation, the signal bandwidth is typically split into m equally distributed subcarriers regardless of the −3 dB bandwidth. Thus, in this paper we investigate the impact of splitting the signal bandwidth into unequally spaced subcarriers on the m-CAP VLC system performance. We demonstrate that by allocating different bandwidths for individual subcarriers, we can achieve up to 36% improvement in data rate for 6-CAP (i.e. 6 subcarriers). We show that the higher the order of the variable m-CAP, the more significant improvement in data rate becomes even for a highly bandlimited VLC system when compared to the conventional m-CAP scheme.

Non-Binary LDPC Code Design for the Poisson PPM Channel

Abstract: This paper investigates the design of non-binary protograph low-density parity-check codes for the Poisson channel with $m$ -ary pulse position modulation. The field order over which the code is constructed is matched to the pulse position modulation order yielding a coded modulation scheme. The optimization of the low-density parity-check code structure is performed via protograph density evolution on a surrogate $m$ -ary erasure channel. The surrogate design is illustrated to be not only accurate, but also robust for a range of practical values of channel background noise and various modulation orders. As a result the proposed codes show excellent performance over the Poisson channel with pulse position modulation outperforming competing schemes. As a side-product of this paper, finite-length benchmarks on the block error probability are provided, together with a union bound to characterize the code performance in the error floor region.

Downlink receiver algorithms for deep space optical communications

Abstract: The goal of the Deep Space Optical Communications project at the Jet Propulsion Laboratory is to demonstrate laser communication links at ranges out to approximately 3 AU. In this paper, we discuss a downlink receiver concept capable of demodulating optical pulse-position modulated (PPM) waveforms with data rates varying from approximately 50 kbps up to 265 Mbps, using a range of PPM orders, slot widths, and code rates. The receiver operates on recorded timestamps corresponding to the times-of-arrival of photons detected by a photon-counting detector array followed by a commercial time-tagger. Algorithms are presented for slot, symbol, and frame synchronization as well as parameter estimation. Estimates of link performance are evaluated through Monte- Carlo simulation for an optical channel that includes optical losses, detector blocking, signal clock dynamics, and pointing-induced downlink fades. Based upon these simulation results, it is expected that link closure may be achieved with at least 3 dB of margin under a variety of relevant conditions.

Receiver design for pulse position modulation technique in diffusion-based molecular communication

Abstract: Molecular Communication via Diffusion (MCvD) is one of the most prominent approaches to interconnect the nanomachines which can do some simple communication functions. In this paper, Pulse Position Modulation is studied. We proposed two techniques in order to design the receiver for this modulation. These detection methods called ML and MAX detector. The performances of the proposed detection algorithms are discussed in the different ISI values. It is seen that two detection methods can achieve the same performance in bit error probability for some practical cases. While the MAX detector is simpler than ML detector.

Joint Estimation of TOA and PPM Symbols Using Sub-Nyquist Sampled IR-UWB Signal

Abstract: Impulse radio ultra wideband (UWB) signals are used in various applications which require joint localization and communication. Due to the large bandwidth of the UWB signal, the estimation of time of arrival (TOA) and data symbols requires high sampling rates. This letter describes a sub-Nyquist rate receiver, which can jointly estimate TOA and data symbols. We first represent the received UWB signal in a new domain in which it is sparse. Then, we design physical layer waveforms and estimation algorithms to exploit this sparsity for joint estimation of TOA and pulse position modulation data symbols. The performance of the receiver is compared against the maximum likelihood (ML)-based receiver using an IEEE 802.15.4a CM1 line of sight UWB channel model. The proposed algorithm yields performance similar to the ML-based algorithms with only a fraction of sampling rate at high SNRs (> 25 dB).

Visible light communication based on offset pulse position modulation (Offset-PPM) using high power LED

Abstract: In this paper, the performance of a visible light communication (VLC) system based on offset pulse position modulation (Offset-PPM) has been demonstrated using a commercial high power white single LED (30 W) and the new coding scheme. Data at a speed of 11 Mbps has been successfully transmitted over a distance of 1 m with zero bit error rate (BER), and 18 Mbps with 1.15 × 10−6 of BER through the simplest transceiver circuits.

Timing jitter’s influence on the symbol error rate performance of the L-ary pulse position modulation free-space optical link in atmospheric turbulent channels with pointing errors

Abstract: An analytical approach is proposed to evaluate the impact of timing jitter on the error performance of the L-ary pulse position modulation (L-PPM) free-space optical (FSO) link, under the gamma–gamma (ΓΓ) turbulence with pointing errors. The expression of the conditional symbol error rate (SER) for a certain timing jitter is developed while the Gaussian–Hermite polynomial approximation is utilized to derive the closed-form expression of the average SER by the jitter’s variance. It is discovered that the timing jitter contributes to an error floor on the SER in both Monte–Carlo simulations and the theoretical results. Also, the jitter with small variance could be tolerable. What is more, the PPM system with lower order is more sensitive to the timing jitter than the higher ones.

Frequency-Hopping Pulse Position Modulation Ultrawideband Receiver

Abstract: Pulse position modulation (PPM) has been used in the radio-frequency (RF) domain to achieve both low-dissipation requirements and provide precision ranging. In ultrawideband (UWB) architectures, it underpins an asynchronous receiver, multiple access environments, and interference-resistant transmission. When combined with frequency hopping (FH), it allows for an additional level of immunity to jamming and low probability of intercept. Realization of a FH-PPM transceiver poses a practical challenge, particularly in the UWB RF range. With UWB pulses reaching the multi-gigahertz range, FH adds to the effective bandwidth at which the receiver must be operated, exceeding the performance of a modern quantizer and digital demodulation backplane. This study describes a new photonics-assisted FH-PPM receiver architecture that rests on mutually coherent frequency combs. The performance of the new receiver was characterized by receiving and decoding an 80–Mb/s rate FH-PPM UWB signal.

Comparative Study and Packet Error Rate Analysis of Advance Modulation Schemes for Optical Wireless Communication Networks

Abstract: The selection of modulation schemes is an essential stage for every communication network. In optical wireless communication, the analysis of modulation schemes is needed to improve the transmitters and receivers to reinforce the received signal energy. In this work, comparative investigation of key attributes of various modulation schemes used in optical communication systems. Conventional schemes, including on off keying and pulse position modulation, are used as reference to analyze the advanced modulation schemes such as digital pulse interval modulation (DPIM)/dual header pulse interval modulation (DH-PIM) in terms of some benchmark parameters such as transmission power, bandwidth requirement, capacity of system, symbol length, packet correction rate and frequency of transmissions and retransmissions. DH-PIM shows the potential benefit of reduced transmission power, minimum bandwidth and shortest possible symbol length while DPIM offers quick transmission rates with least error rates. The overall complexity involved in modulation schemes is also found to be dependent of network types which are being implemented. In this work, recommendations are made based upon the types of network and capacity of information.

Methods and apparatus for LIDAR operation with pulse position modulation

Abstract: Described examples include an integrated circuit that includes an encoder configured to modulate a driving signal for an optical transmitter with a plurality of encoded pulses corresponding to a code, in which the driving signal is transmitted to the optical transmitter periodically. The integrated circuit also includes a demodulator configured to receive a received signal from an optical receiver that is configured to receive a reflection of light transmitted by the optical transmitter off an object, the demodulator configured to discriminate the plurality of encoded pulses in the received signal and estimate a distance of the object.

Adaptive polar coding with high order modulation for block fading channels

Abstract: We consider the design of polar codes for block fading channels. The key idea is to combine modulation, fading, and coding in a single entity. This design is based on two facts: (i) for each fading block, symbols with different fading coefficient has different reliability; (ii) for each symbol, different bit levels of a high order modulation observe different noise levels. In other words, the bit channels are partially polarized by modulation and fading. This new viewpoint inspires us to construct polar codes by matching code polarization perfectly with modulation polarization and fading polarization. The resulting codes adapt to the channel quality fluctuation, thus provide better performance than conventional polar BICM schemes and LDPC codes.

Investigations on suitable modulation techniques for visible light communications

Abstract: Optical Wireless Communication (OWC) is widely used in current broadband access markets. This is due to the usage of optical radiation through free space for transmission. OWC employs Intensity Modulation with Direct Detection (IMDD) to modulate the intensity of the signal in order to transmit information. This offers a flexible networking solution. OWC systems that operate in the visible band region (390–750 nm) are referred to as Visible Light Communication. VLC has a dual purpose of illumination and communication system. VLC uses On-Off Keying (OOK) and Pulse Position Modulation (PPM). But recently, a noticeable increase in the use of a number of other modulation techniques such as Digital Pulse Interval Modulation (DPIM) and Dual-header Pulse Interval Modulation (DH-PIM) to improve the efficiency in terms of both the bandwidth and power has been observed. This paper concentrates on baseband pulse time modulation techniques that are used to modulate data for OWC and compares OOK, PPM, DH-PIM and DPIM techniques with respect to their spectral efficiency, optical power, bandwidth, transmission capacity, packet transmission rates and peak average power ratio (PAPR).

Characterization of Impulse Radio Intrabody Communication System for Wireless Body Area Networks

Abstract: Intrabody communication (IBC) is a promising data communication technique for body area networks. This short-distance communication approach uses human body tissue as the medium of signal propagation. IBC is defined as one of the physical layers for the new IEEE 802.15.6 or wireless body area network (WBAN) standard, which can provide a suitable data rate for real-time physiological data communication while consuming lower power compared to that of radio-frequency protocols such as Bluetooth. In this paper, impulse radio (IR) IBC (IR-IBC) is examined using a field-programmable gate array (FPGA) implementation of an IBC system. A carrier-free pulse position modulation (PPM) scheme is implemented using an IBC transmitter in an FPGA board. PPM is a modulation technique that uses time-based pulse characteristics to encode data based on IR concepts. The transmission performance of the scheme was evaluated through signal propagation measurements of the human arm using 4- and 8-PPM transmitters, respectively. 4 or 8 is the number of symbols during modulations. It was found that the received signal-to-noise ratio (SNR) decreases approximately 8.0 dB for a range of arm distances (5–50 cm) between the transmitter and receiver electrodes with constant noise power and various signal amplitudes. The SNR for the 4-PPM scheme is approximately 2 dB higher than that for the 8-PPM one. In addition, the bit error rate (BER) is theoretically analyzed for the human body channel with additive white Gaussian noise. The 4- and 8-PPM IBC systems have average BER values of 10−5 and 10−10, respectively. The results indicate the superiority of the 8-PPM scheme compared to the 4-PPM one when implementing the IBC system. The performance evaluation of the proposed IBC system will improve further IBC transceiver design.

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

Abstract: 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.

Performance analysis of adaptive modulation in underwater visible light communications

Abstract: In optical wireless communication systems, the underwater visible light communication (UVLC) systems is becoming more and more popular. However, due to intrinsic properties of water body, the propagating optical channel can suffer from severe degrading effects, namely absorption, scattering, and turbulence. Here, we aim to improve the UVLC system performance. For this, we propose to utilize an adaptive modulation scheme at the optical transmitter based on the channel conditions. The performance of such system using different modulation schemes such as the pulse position modulation (PPM), the digital pulse interval modulation (DPIM) and the dual-header pulse interval modulation (DH-PIM), are demonstrated to prove the effectiveness of our adaptive UVLC systems.

Performance of FSO system using PPM and MSK sub-carrier intensity modulation scheme

Abstract: Performance analysis of FSO system using pulse position modulation (PPM) and minimum shift keying (MSK) subcarrier intensity modulation (PPM-MSK-SIM) is done in this paper. Performance of system has been analyzed for different values of APD gain over varying turbulence strength and link ranges. Noise sources considered are shot noise, thermal noise and back ground noise. Results reveal that by selecting proper average APD gain, the channel capacity and bit error rate (BER) of system improves considerably.

Inverse pulse position modulation schemes for simultaneous visible light wireless information and power transfer

Abstract: In this paper, for constructing flexible underwater wireless sensor network, we discussed an underwater visible light communication system with simultaneous power transfer. For realizing the system, the received optical power is used for both data communication and power transfer, and it is necessary to design the receiver for separating the signal to alternate current (AC) and direct current (DC). We employ the receiver circuit based on low pass filter for DC signal and high pass fileter for AC signal. Moreover, we analyzed the BER performance and power supply performance when the designed AC/DC separation filter is based solar panel is used as the receiver. As a modulation scheme, we consider inverse pulse position modulation (IPPM) which would achieve stable supply of power. As a result, in the BER performances, IPPM show the higher performances compared to OOK. Compared to PPM, the performances for IPPM deteriorated by about 4.78 dB due to the high transmitted power per bit. However, the high transmitted power per bit is important for power supply, and PPM and IPPM show similar BER performances when the same pulse amplitudes of these modulation schemes. In the CV performances, CV of IPPM is improved by 20% compared to OOK and 1.1% compared to PPM with the bit rate of 200 kbps. From these results, IPPM can achieve stable supply of power.

Index Weber and APD based error rate calculating method of PPM wireless optical communication system

Abstract: The invention discloses an index Weber and APD based error code calculating method of a PPM wireless optical communication system. The method comprises that 1) an atmospheric channel mathematical model of free space optical communication is established; 2) an accurate statistical model in which an APD outputs the electron number is used to calculate a probability density function and an accumulative distribution function of the electron number output by the APD when each time slot of a PPM signal has light pulses; 3) according to the a conditioned error code formula and an equivalent signal to noise ratio formula of the free space optical communication, and a theoretical average error rate of the system in an index Weber fading channel is calculated; and 4) a Hermite polynomial is used for simplification to obtain average error rate formulas in the BPPM system and an M element pulse position modulated MPPM system. According to the method, each time slot of a PPM block is detected in the reception end, the complexity degree is reduced, and the performance of the error rate system is higher than that of a PIN algorithm or other turbulent flow models.

Efficiency of optimized pulse position modulation with noisy direct detection

Abstract: We analyze theoretically the impact of background counts on the efficiency of optical communication in the photon-starved regime using the pulse position modulation (PPM) format with direct detection. Degradation of the photon information efficiency is studied in the case when the background count rate is at most comparable with the rate of photodetection events generated by the incoming optical signal. The PPM symbol length is optimized under the constraint of a fixed average spectral power density using an analytical approximation. The results are compared with generalized on-off keying (OOK) optimized over the a priori probability distribution for the input binary alphabet. The generalized OOK scheme can be viewed as a relaxation of the PPM scheme by removing the requirement that a light pulse must occur exactly once in each fixed-length frame of time bins that constitute the PPM symbol. It is shown that the asymptotic scaling of the photon information efficiency does not change qualitatively in this scenario.

Improving the capacity of MQAM technique using adaptive modulation

Abstract: Dynamic link adaptation techniques or adaptive modulation technique, where the modulation signal transmission is adjusted dynamically in accordance with the changing channel conditions that ultimately helps in improving the capacity of a channel. The Symbol Error Rate (SER) curves and capacity performance of different modulation schemes are analyzed using adaptive modulation. Adaptive modulation is a useful technique to improve the capacity of a fading channel. SER performance of different modulation schemes of M-Level Quadrature Amplitude Modulation (MQAM) are analyzed using adaptive modulation technique. The paper introduces the implementation of adaptive modulation scheme using MQAM. Improvement in capacity of MQAM using adaptive modulation has been discussed.