Multi-pulse Position Modulation Research Articles

High-capacity MIMO visible light communication integrated into mini-LED LCDs

Visible light communication (VLC) can be integrated into a liquid crystal display (LCD) by modulating its backlight while normally showing pictures. Received by ordinary cameras, such integrated display and communication (IDAC) systems are promising for the Internet of Things and Metaverse. However, in the premise of unaffected display function, the capacity of current IDAC systems is limited, with data rates of very few kbps. This work proposes a new architecture: multiple-input, multiple-output (MIMO) VLC integrated into a mini-LED LCD, whose many backlight segments act as multiple transmitters. A camera utilizes the rolling shutter effect with independent pixel columns to form multiple outputs. The communication capacity is thus significantly multiplied by the backlight column number. In addition, local dimming, which is favorable for an LCD’s contrast and power consumption, is exploited to achieve efficient signal modulation. We built a mini-LED LCD prototype with 8-by-20 backlight segments for experimental verification. The backlight segments multiplex a video-rate signal for local dimming and a high-frequency (∼34 kHz) signal modulated through multi-pulse position modulation (MPPM) for VLC. By taking photographs with a camera 1.1 m away from the screen, a record-high rate of 201.6 kbps (approximately ten times faster than current IDAC systems) was experimentally achieved with a bit error rate satisfying the forward error correction. Improved image contrast due to local dimming was also observed.

Efficient Encoding Method for Combined Codes in the MWD Telemetry System

MPPM (Multipulse Position Modulation) is a pulse code technology that is widely used in optical communication and deep space communication due to its high energy efficiency. Combination code is a variation of MPPM and is widely used in MWD (Measurement While Drilling) telemetry systems. However, whether it is MPPM or combination code, it is difficult to establish a simple mapping relationship between bit symbols and pulse symbols. Therefore, an encoding table is usually used to realize the mapping between bit symbols and pulse symbols. With an increase in bit width, the storage complexity of the encoding table increases exponentially. This is unacceptable for underground transmitters working in harsh environments. This paper maps the code symbols of MPPM to a hyper-triangular region of a high-dimensional tensor and establishes a simple lookup table and lookup algorithm to achieve low-complexity mapping from bit symbols to MPPM code symbols. At the same time, this paper also provides a method for extending from MPPM code symbols to commonly used combination code symbols in MWD, thereby providing an efficient implementation path for large bit width combination code encoding at the underground end of MWD.

FPGA-based PPM Modulation System Design

As a widely used modulation technique in the field of communication, PPM modulation techniques have the advantages of high interference immunity, simple coding and high-power utilization, and are often applied in practical scenarios. PPM modulation techniques can be divided into three categories. single pulse position modulation, differential pulse position modulation and multi pulse position modulation. In different application scenarios, different kinds of pulse position modulation methods should be selected for modulation. In this paper, the frame structures of these three types of pulse position modulation are discussed using the Verilog language based on FPGA, the corresponding mapping relationships for each type of pulse position modulation are given, and the design and performance of these three types of pulse position modulation demodulation systems are compared.

Spectrum analysis of multi-pulse position modulation in optical communication

In this paper, the authors aim to compare the performance of space optical communication and wireless optical communication by analyzing the transmission mechanism, transmission method, and transmission rate of MPPM (Multi-Pulse Pulse Position Modulation). MPPM is a widely used modulation technique in optical communication systems, which has the advantage of reducing the effect of noise and improving the system's error rate. To achieve the objective, the authors will employ mathematical models to compare the performance of space optical communication and wireless optical communication. They will analyze the transmission mechanism, transmission method, and transmission rate of MPPM in both communication systems and draw conclusions based on their findings. The authors hope that the results of this study will positively promote the development of MPPM in the future. By comparing the performance of space optical communication and wireless optical communication, this study will provide insights into the strengths and weaknesses of both systems, which can help in the development of more efficient and reliable optical communication systems.

Asymmetric Dual-Mode Constellation and Protograph LDPC Code Design for Generalized Spatial MPPM Systems

To achieve reliable and efficient transmissions in free-space optical (FSO) communication, this paper designs a new protograph low-density parity-check (PLDPC) coded generalized spatial multipulse position modulation (GSMPPM) system over weak turbulence channels. Specifically, we investigate the PLDPC code, generalized space shift keying (GSSK) modulation, and MPPM constellation. First, we propose a type of novel GSMPPM constellations that intelligently integrates the GSSK into MPPM, referred to as asymmetric dual-mode (ADM) constellations, so as to improve the performance of the PLDPC-coded GSMPPM system. Furthermore, exploiting a protograph extrinsic information transfer (PEXIT) algorithm, we construct a type of improved PLDPC code, referred to as I-PLDPC code, which outperforms the existing PLDPC codes over weak turbulence channels. Analytical and simulation results show that the proposed ADM constellations and the proposed I-PLDPC code can obtain noticeable performance gains over their counterparts. Therefore, the proposed PLDPC-coded GSMPPM system with ADM constellations is competent to satisfy the high-reliability requirement for FSO applications.

An IR-UWB CMOS Transceiver With Extended Pulse Position Modulation

An impulse radio ultra-wideband (IR-UWB) transceiver is implemented with low power, high data rate communication techniques, such as extended multipulse position modulation (E-MPPM), cross-coupled (CC) envelope detection, and digital frequency hopping (DFH). The use of the E-MPPM helps increase the modulation efficiency. The capacitive-CC technique helps improve the sensitivity by increasing the conversion gain of an envelope detector. DFH increases the pulse energy of a transmitted impulse without sacrificing the power spectral density (PSD) requirement. The proposed CMOS transceiver achieves a data rate of 1.125 Gbps and a radio range of 2 m with a power consumption of 28 mW and energy efficiency of 24.9 pJ/b.

Average spectral efficiency of multi-pulse position with adaptive transmissions and aperture averaging over atmospheric turbulence

Abstract The analysis of average spectral efficiency (ASE) of multi-pulse position modulation (MPPM) scheme with optimal rate adaptation (ORA) and channel inversion with fixed rate (CIFR) adaptation schemes over the gamma–gamma free space optical (FSO) channel has been carried out in this paper. The performance of the adaptation schemes has been analyzed in terms of the average channel capacity and has been further scrutinized under the aperture averaging effects in moderate and strong atmospheric turbulence. For the first time, closed form expressions for MPPM with ORA and CIFR transmitter adaptation schemes have been derived in terms of Meijer’s G functions. Using the derived expressions, the performance of the two adaptation policies have been compared for different transmitter power and varying FSO length, MPPM modulation order and aperture averaging. The analysis results revealed that generally, ORA performs better than CIFR under the considered turbulence strength, modulation order and aperture averaging. However, aperture averaging offers more gain in ASE in strong turbulence than moderate turbulence for both ORA and CIFR. Furthermore, the results revealed that aperture averaging effects offers much more gain in ASE when used with CIFR than ORA.

Wireless Control Combining Myoelectric Signal and Human Body Communication for Wearable Robots.

In this study, a communication module based on human body communication was developed to wirelessly control a wearable robot hand based on myoelectric signals. The communication module adopts 10–60 MHz band and an impulse radio multi-pulse position modulation method to achieve low transmission loss and high data rate. A technique to reduce the module size was developed by sharing the myoelectric signal detection electrode and transmitting electrode, and three receiving electrode structures were investigated to improve signal transmission performance. As a result, the developed communication module provides a packet detection rate of 100% and a bit error rate of less than 10 up to at least 110 cm along the arm, and a wearable robot hand was demonstrated to be properly controlled based on a human subject’s myoelectric signals.

Implementation of dimming controlled visible light communication using Raspberry Pi

Visible light communication (VLC) is a technology of wireless optical communication, which combines lighting and communication simultaneously. In indoor VLC system, both data communication and lighting quality plays an important role and must be considered. Thus, to achieve the desired levels of illumination, dimming control in VLC is an efficient technology. In this paper, the authors have designed and implemented a dimming control VLC system employing multi header-hybrid pulse position modulation (MH-HPPM) to achieve dimming functionality. MH-HPPM supports various dimming levels and also doesn’t have flicker problems. In this paper, the authors present the implementation of MH-HPPM based VLC system using Raspberry Pi. The prototype is designed using low-cost commodity hardware. Comprehensive experiments are carried out to evaluate the performance of MH-HPPM based VLC under dimming levels 0.25, 0.5 and 0.75. The results demonstrate that designed prototype supports a communication distance up to 3 m for dimming level 0.25 and 3.5 m for dimming level 0.5 and 0.75. It is also observed that MH-HPPM based VLC system also achieves and maintains better throughput for different incidence angle.

Spectral Analysis of (Multi-) Pulse-Position Modulation

Nowadays, laser communication has received great achievements owing to its advantages, e.g., large channel capacity, easy miniaturization of communication system and strong anti-interference ability in different conditions. Pulse position modulation (PPM), as an important modulation technology in laser communication system that transmit signal with lower power, is attracting much attention. However, the performance of the modulation scheme highly depends on the bandwidth of transmission. To remedy this defect of PPM, the multipulse position modulation (MPPM) scheme is proposed to increase the accuracy and bandwidth limit. This modulation scheme has stronger anti-interference ability than PPM. Therefore, there has been rising interest in studying the characteristics of the multi-PPM. In this article, we developed an appropriate mathematical model to represent a PPM transmission, analyzed the spectrum of the transmission and characterized the bandwidth of this transmission. Compared with benchmarks of MPPM scheme, its performance has been discussed. According to the analysis, MPPM strongly increases band-utilization efficiency, however PPM has a better bit error rate (BER) performance than MPPM.

Parallel relay-assisted free-space optical communication using multi-pulse position modulation over the generalized turbulence channel model

Parallel relay-assisted free-space optical communication using multi-pulse position modulation over the generalized turbulence channel model

Analysis of multi-pulse position modulation free space optical communication system employing wavelength and time diversity over Malaga turbulence channel

Free space optics (FSO) communication has proved to be a useful technology both in the scientific and commercial domains in response to exponential growth in demand for ultrahigh bandwidth for applications such as urban broadband services, cellular backhaul and earth to satellite links among others. However, atmospheric turbulence, prevailing adverse weather conditions and pointing errors between the transmitter and receiver affect significantly this technology. To mitigate these challenges, different approaches have been considered in literature such as error control coding, spatial diversity, the use of relays and so on alongside different modulation techniques. Therefore in this paper, we have considered the use of multipulse position modulation (MPPM) modulation technique first with wavelength diversity and then with time diversity techniques over the Malaga (M) distribution as a way of mitigating against turbulence fading and pointing error effects. Closed form expressions for the average bit error rate (BER) and outage probability have been derived and later on used to analyze the system performance. The effect of diversity order, normalized jitter and beam width has been scrutinized, all as functions of the transmitted power. Beside the fact that the increase in diversity order improves both the BER and outage probability, it has been noted that the system performance is highly degraded when the normalized jitter is increased beyond 4 for any given diversity order. The BER decreases while the receiver beam width, Wz increases for all diversity orders, reaching to an optimum value of 0.5 m and 1.2 m for normalized jitter of 2 and 5 respectively. Ultimately, the conclusion drawn from the analytical results of this paper support the application of wavelength as well as time diversity as means of enhancing the FSO communication system performance

Experimental Validation of Inverse M-PPM Modulation for Dimming Control and Data Transmission in Visible Light Communications

A hybrid-coding scheme based on Multi-Pulse Position Modulation (M-PPM) and Pulse Width Modulation (PWM) is proposed and experimentally validated for simultaneous control of illumination and data transmission in a visible light communication system VLC (Visible Light Communications). The implemented VLC system complies with the dual functionality of indoor lighting and data transmission using low cost components. The codification implemented allows data transmission at a constant speed despite the lighting levels supported by the VLC system. The proposed and experimentally validated coding solves the problem of the interdependence between the data transmission rate and the variation of the lighting levels. Such interdependence is caused by the variation of the useful cycle available for data transmission after the lighting control performed by PWM.In this work, the feasibility of the implementation of the proposed scheme is demonstrated using low cost elements and commercial photodetectors. A constant transmission speed of 30 kbit/s was obtained with two 10W RGB LEDs at 0.9 meters from the OPT101 photodetector from Texas Instruments, with a range of illumination ranging from 25\% to 85\% of the possible luminous power of the LED sources.

A Spatial Time-Frequency Hopping Index Modulated Scheme in Turbulence-free Optical Wireless Communication Channels

In this article, we propose an index modulation system suitable for optical communications, where the intensity of the light is modulated along the time, space and frequency dimensions, building a Frequency-Hopping Spatial Multi-Pulse Position Modulation (FH-SMPPM). We analyze its performance from the point of view of its efficiency in power and spectrum, and its implementation complexity and required receiver latency. We analyze its error probability in the case of the non-turbulent free-space optical (FSO) channel. We derive formulas for the average symbol and bit error probabilities, and the simulation results show that they are tight enough for a wide range of signal-to-noise ratios and system parameters. We compare FH-SMPPM with other proposed index modulated systems of the same nature, and we highlight its distinctive advantages, like the flexibility to build an appropriate waveform under different constraints and objectives. Moreover, FH-SMPPM shows to be better performing in BER/SER and/or offer advantages in efficiency with respect to those alternatives, thus offering the possibility to be adopted for a variety of contexts.

Performance analysis of multipulse position modulation free space optical communication system under generalized atmospheric turbulence conditions including pointing errors

The free space optical communication system has become remarkably important nowadays due to huge benefits associated with it. However, atmospheric induced laser beam scintillation remains a challenge that has been addressed using different techniques over the years. Multipulse position modulation has been analyzed over the generalized atmospheric turbulence model ( M distribution) using bit error rate (BER), ergodic channel capacity, and outage probability as performance metric measures. Using Meijer’s G functions closed form expressions for the said performance metrics have been derived. Next, using the derived closed form expressions, a thorough investigation of how the BER, ergodic channel capacity, and the outage probability are affected by the atmospheric turbulence conditions and other parameters, such as operational wavelength, has been carried out. It has been observed that increasing the modulation level cannot significantly reduce the transmitted power required for a targeted BER in strong atmospheric turbulence channels. Also the outage probability increases with increasing threshold signal-to-noise ratio.

An Efficient Data Transmission with GSM-MPAPM Modulation for an Indoor VLC System

As an emerging wireless communication technique, visible light communication is experiencing a boom in the global communication field, and the dream of accessing to the Internet with light is fast becoming a reality. The objective of this study was to put forward an efficient and theoretical scheme that is based on generalized spatial modulation to reduce the bit error ratio in indoor short-distance visible light communication. The scheme was implemented while using two steps in parallel: (1) The multi-pulse amplitude and the position modulation signal were generated by combining multi-pulse amplitude modulation with multi-pulse position modulation using transmitted information, and (2) certain light-emitting diodes were activated by employing the idea of generalized spatial modulation to convey the generated multi-pulse amplitude and position modulation optical signals. Furthermore, pulse width modulation was introduced to achieve dimming control in order to improve anti-interference ability to the ambient light of the system. The two steps above involved the information theory of communication. An embedded hardware system, which was based on the C8051F330 microcomputer and included a transmitter and a receiver, was designed to verify the performance of this new scheme. Subsequently, the verifiability experiment was carried out. The results of this experiment demonstrated that the proposed theoretical scheme of transmission was feasible and could lower the bit error ratio (BER) in indoor short-distance visible light communication while guaranteeing indoor light quality.

An IR-UWB CMOS Transceiver for High-Data-Rate, Low-Power, and Short-Range Communication

An impulse radio ultra-wideband (IR-UWB) transceiver with digitalized multipulse position modulation (D-MPPM) is proposed for high-data-rate, low-power, and short-range communication. The D-MPPM overcomes the data-rate dependence on the system clock frequency by modulating data with the time difference between the two pulses and also allows fully digital circuit-based modulation and demodulation. With this technique, the data rate is improved by a factor of 5 compared to conventional IR-UWB modulation schemes at the same clock frequency, which results in 4.28-dB link margin enhancement compared to bi-pulse position modulation (BPPM). Also, the technique makes it possible to design a clockless receiver, which allows more compact and power efficient design. Thus, it can achieve 500 Mb/s with 27.7-mW power consumption for Rx and 7 mW for Tx and the radio range of 1–5 m.

瞄准误差对多脉冲位置调制星间激光通信系统误符号率的影响

瞄准误差对多脉冲位置调制星间激光通信系统误符号率的影响

Development and In Vivo Performance Evaluation of 10–60-MHz Band Impulse-Radio-Based Transceiver for Deep Implantation Having 10 Mbps

In view of the requirements for high-speed, highly reliable wireless implant communication, we have developed an implant transceiver working at a 10–60-MHz band. The developed transceiver is based on an impulse radio technology with multipulse position modulation to increase the communication speed and reliability, and utilizes the automatic equalization technique to suppress waveform distortion and intersymbol interference due to frequency-dependent tissue properties. The transmit antenna has a dimension of $2.6\,\,\text {cm} \times 1.6\,\,\text {cm} \times 1.6$ cm and a relative bandwidth of 16% by forming the radiation elements on a flexible magnetic sheet for miniaturization. Through an in vivo experiment on a living swine, we have shown the feasibility of implant communication in a depth up to 26 cm with a minimum data rate of 10 Mbps. These results demonstrate the superiority of this new technology over all others reported so far in the literature.

A novel serial link transceiver, using a new combination of MPPM and PAM schemes

In this paper, an efficient modulation technique, which was a new combination of multi-pulse position modulation (MPPM) and pulse amplitude modulation methods, was introduced. Using the proposed modulation, 8-bit per symbol data rate was achieved. Applying this method increased the data rate value and reduced the power consumption value. In addition, due to the use of MPPM method in the proposed modulation, the generated signal was of the return-to-zero nature. This means that the clock signal was embedded inside the modulated signal. Therefore, there was no need to apply a complicated clock recovery circuit in the receiver side. Moreover, by sending the 8-bit data and clock signal through a single channel, the value of pin count was reduced considerably. To implement this new scheme, a new transceiver was proposed in this paper. Further, a very simple slot selector circuit was proposed to create 5-time slots per symbol. In addition, a new structure of absolute comparator circuit was designed to reduce the number of comparators at the receiver side. The whole power dissipation of the proposed transceiver was only 101 mW.