Dual Header Pulse Interval Modulation Research Articles

BER and outage throughput analysis of DPIM/DHPIM coded QPSK-OFDM based outdoor optical wireless communications

With the growing demand for fast and reliable communication systems, particularly in outdoor environments, it is essential to investigate advanced encoding techniques. Digital Pulse Interval Modulation (DPIM) and Dual Header Pulse Interval Modulation (DHPIM) emerge as promising alternatives to traditional line coding methods, providing enhanced spectral efficiency and resistance to signal disruptions. This paper presents the performance of a Quadrature Phase-Shift Keying (QPSK) Orthogonal Frequency Division Multiplexing (OFDM)-based Optical Wireless Communication (OWC) system using these advanced encoding schemes. The analysis includes simulation results on QPSK-OFDM-based transmitter design, free space optical channel modeling based on Gaussian and log-normal distribution atmospheric turbulence, and recovery of input digital stream using the mentioned line coding techniques. The results demonstrate optimal bit error rate (BER) values for the QPSK-OFDM-based OWC system. The primary innovation of this research lies in the encoding schemes and their performance in outdoor optical wireless communication systems under turbulent conditions. Through extensive simulations and analysis, detailed insights into the bit error rate and outage throughput characteristics of DPIM/DHPIM coded QPSK-OFDM are provided, offering a unique perspective on the performance of these schemes in real-world scenarios. The findings not only highlight the optimal BER values achievable with the QPSK-OFDM-based OWC system but also offer insights into the system's ability to overcome transmission challenges under various atmospheric conditions.

A Comprehensive Comparison and Analysis of Several Intensity Modulations Based on the Underwater Photon-Counting Communication System

Underwater wireless optical communication is facing absorption, scattering problems, which, in principle, can be greatly resolved by underwater photon-counting communication (UPCC) technology that exhibits high-sensitivity communication characteristics in long-range underwater wireless optical communication. Recent studies on UPCC are mainly focused on a single intensity modulation such as on–off keying (OOK) and pulse position modulation (PPM) technologies, and the comprehensive analysis of communication performance combing OOK modulation and digital pulse modulations remains a lack. To this, by using a UPCC system based on a single-photon avalanche diode, we reveal the communication performances of OOK, PPM, differential pulse interval modulation (DPIM), differential pulse position modulation (DPPM), and dual-header pulse interval modulation, and find that (1) the PPM has the longest transmission distance at the same bit error ratio when M > 2, but the lowest communication rate under identical modulation bandwidth and average transmit power; and (2) the DPPM and DPIM perform the optimum communication performance at the fixed communication rate when M = 8. We thus conclude that the DPPM and DPIM have advantages of low modulation bandwidth and long time slot time compared with PPM, indicating the significance of reducing the difficulty of signal synchronization and the complexity of the underwater photon-counting system accordingly.

Comparison study of 8-PPM, 8-DPIM, and 8-RDH-PIM modulator FPGA hardware design in term of bandwidth efficiency and transmission rate

In this paper, a performance study of 8-Pulse-Position Modulation (PPM), 8-Digital Pulse Interval Modulation (DPIM), and 8-Reverse Dual Header-Pulse Interval Modulation (RDH-PIM) implementation in Verilog hardware design language is presented. The hardware design is chosen over software design since it could provide much more flexibility in term of transmission rate and reduce the workload of the processor in the complete system. Using 50 MHz clock as the reference data clock speeds, the transmission rate recorded are 11.11 Msymbol/second or 33.33 Mbps, 9.09 Msymbol/s or 27.27 Mbps, and 6.25 Msymbol/s or 18.75 Mbps for 8-RDH-PIM, 8-DPIM, and 8-PPM respectively. We conclude that 8-RDH-PIM modulator design provides better performance in term of bandwidth utilization and transmission rate as compared to 8-PPM and 8-DPIM.

Secure and Smartphone-Assisted Reprogramming for Wireless Sensor Networks Based on Visible Light Communication

During the period of over-the-air reprogramming, sensor nodes are easy to eavesdrop and even controlled by unauthorized person. That reminds us that security is key issue for over-the-air reprogramming. Most of previous studies discussed this problem from the aspect of data encryption, but give little consideration to the physical level. In this paper, we attempt to improve the security of reprogramming by changing the physical-level communication mode. We apply unidirectional Visible Light Communication (VLC) to the over-the-air reprogramming and use Commercial Off-The-Shelf device such as smartphone and sensor node to improve applicability. However, the unstable light source and low-cost light sensor make the procedure of reprogramming difficult. For this end, we put forward a novel reprogramming approach named ReVLC, which is twofold: firstly, we design a code block mechanism based on function similarity to reduce transmitting code. Secondly, we use compressing representation to optimize the Dual Header-Pulse Interval Modulation (DH-PIM) to save transmission time. The experiment results illustrate the effectiveness of ReVLC at the cost of extra 49.1% energy overhead compared with a traditional reprogramming approach.

Performance analysis of various pulse modulation schemes for a FSO link employing gain switched quantum cascade lasers

In this paper, we analyze the performance of an FSO communication link that incorporates gain switched Quantum Cascade Lasers (QCLs) operating at 9 µm and a Quantum-Well based Infrared Photodetector (QWIP). The performance of various modulation techniques like ON-OFF Keying (OOK), Pulse Position Modulation (PPM), Dual-Header Pulse Interval Modulation (DH-PIMα), Differential Pulse Interval Modulation (DPIM) are analyzed for the FSO link with short optical pulses. It is found that DH-PIM2 satisfies most of the properties required for an efficient pulse modulation. It provides highest power efficiency, normalized packet rate (3.8 times that of PPM), possesses the lowest bandwidth requirement of 3.8 GHz and also the lowest average symbol length of 11 bits. DPPM has the highest transmission capacity that is 2 times that of PPM while PPM performs significantly better among all the modulation techniques providing an astounding BER of 10−40 under soft decoding.

Effect of different weather conditions on BER performance of single-channel free space optical links

This paper studies and compares the performance of on-off keying (OOK), pulse position modulation (PPM), digital pulse interval modulation (DPIM) and dual-header pulse interval modulation (DH-PIM) schemes in FSO channels in the presence of different weather conditions. The bit error rate (BER) curves for these modulations are simulated. Moreover, a performance comparison between these modulation techniques is provided. Generally, in the absence of turbulence OOK-NRZ (non-return-to-zero) and PPM is found to achieve a better BER performance as compared to DPIM and DHPIM. In the presence of fog, OOK-NRZ and PPM is better than DPIM and DH-PIM by approximately 1dB at BER 1e-3. While, in case of rain, OOK-NRZ and PPM is better than DPIM and DH-PIM by approximately 1.5dB at BER 1e-3. Moreover, in case of snow, OOK-NRZ and PPM is better than DPIM and DH-PIM by approximately 1.7dB at BER 1e-3. Additionally, in the presence of turbulence, in case of weak turbulence, OOK-NRZ and PPM is better than DPIM and DH-PIM by approximately 8dB and 10dB, respectively at BER 1e-3. Furthermore, in case of moderate turbulence, OOK-NRZ and PPM is better than DPIM and DH-PIM by approximately 6dB and 8dB, respectively at BER 1e-3. Finally, in case of strong turbulence, OOK-NRZ and PPM is better than DPIM and DH-PIM by approximately 3dB and 4dB, respectively at BER 1e-3.

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

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.

Pulse Amplitude and Delay Modulation: Design and performance analysis

Power efficient modulation techniques have previously been proposed to provide the uplink in visible light communication systems. However, such techniques have poor bandwidth utilization as multiple bits are mapped to single narrow pulse. When the bandwidth is limited, it has been found that degradation in optical power becomes very high and data rate poor. In this paper we introduce a new modulation technique called Pulse Amplitude and Delay Modulation (PADM). We compare its performance with Dual Header Pulse Interval Modulation (DH-PIM) that has the best reported bandwidth efficiency. Experiment results show that the data rate could be enhanced from 3.2kps to 4.3kbs using a red link (640nm) under same error rate. This suggests PADM has better bandwidth efficiency than DH-PIM.

A new modulation scheme of visible light communication

In order to use white light emitting diode (LED) as a lighting source and communication part, a new modulation scheme called reverse dual header pulse interval modulation (RDH-PIM) is proposed for indoor visible light communications based on the analyses of the structures of on-off keying (OOK), pulse position modulation (PPM), digital pulse interval modulation (DPIM) and dual header pulse interval modulation (DH-PIM). After analyzing and comparing the symbol structure, bandwidth requirement and average transmission power of different modulation methods, the slot error rate is derived. Simulation results show that OOK has the minimum bandwidth, while RDH-PIM has the highest average transmission power and its bandwidth efficiency is obviously better than those of PPM and DPIM. Hence, RDH-PIM is superior in optical wireless communication systems.

The Performance of a Dual Header Pulse Interval Modulation in the Presence of Artificial Light Interferences in an Indoor Optical Wireless Communications Channel with Wavelet Denoising

Problem statement: Similar to other baseband modulation schemes, the performance of the Dual Header Pulse Interval Modulation (DH-PIM) is adversely affected by Artificial Light Interferences (ALI) in an indoor Optical Wireless Communications (OWC) channel. Approach: The Discrete Wavelet Transform (DWT) based denoising is studied for reducing the effect of the ALI. Computer simulation is carried out to demonstrate the effectiveness of the proposed system. The Baseline Wander (BLW) affects for a range of bit resolutions is also analyzed. Results: The normalized optical power requirement in the presence of ALI is high in the range of 9-15 dB depending upon the bit resolution. A significant reduction in the optical power penalty is observed with the DWT denoising scheme. Conclusion: The DWT based denoising scheme is effective in reducing the consequence of the ALI. The optical power penalty decreases with an increase in the data rate and the bit resolution, which is due to reduction of the DC values and low frequency spectrum.

Convolutional coded dual header pulse interval modulation for line of sight photonic wireless links

The analysis and simulation for convolutional coded dual header pulse interval modulation (CC-DH-PIM) scheme using a rate ½ convolutional code with the constraint length of 3 is presented. Decoding is implemented using the Viterbi algorithm with a hard decision. Mathematical analysis for the slot error rate (SER) upper bounds is presented and results are compared with the simulated data for a number of different modulation techniques. The authors show that the coded DH-PIM outperforms the pulse position modulation (PPM) scheme and offers >4 dB code gain at the SER of 10−4 compared to the standard DH-PIM. Results presented show that the CC-DH-PIM with a higher constraint length of 7 offers a code gain of 2 dB at SER of 10−5 compared to the CC-DH-PIM with a constraint length of 3. However, in CC-DH-PIM the improvement in the error performance is achieved at the cost of reduced transmission throughput compared to the standard DH-PIM.

Slot error rate performance of DH‐PIM with symbol retransmission for optical wireless links

AbstractIn this paper we introduce the dual‐header pulse interval modulation (DH‐PIM) technique employing a simple retransmission coupled with a majority decision detection scheme at the receiver. We analytically investigate the slot error rate (SER) performance and compare results with simulated data for the symbol retransmissions rates of three, four and five, showing a good agreement. We demonstrate that the proposed scheme significantly reduces the SER compared with the standard single symbol transmission system, with retransmission rate of five offering the highest code gain of ∼5 dB. Copyright © 2007 John Wiley & Sons, Ltd.

Artificial-light-interference effects on indoor optical wireless links employing DH-PIM

We study the effects of artificial (fluorescent) light interference on a dual-header pulse interval modulation (DH-PIM) modulation scheme for an indoor optical wireless environment. Artificial-light-induced interference can be reduced using high-pass filtering (HPF), but it results in a new interference known as the baseline wander. We examine the effects of changing the HPF cut-on frequency in the absence and presence of multipath propagation. The results show that depending on the value of the HPF cut-on frequency, the severity of baseline wander will vary; thus there is a trade-off between the extent of artificial-light-interference rejection and the severity of baseline wander. We show that for DH-PIM, the power requirements are almost constant for HPF with cut-on frequency less than 1% of the bit rate and increase exponentially beyond this value.

Indoor optical wireless systems employing dual header pulse interval modulation (DH‐PIM)

AbstractThis paper assesses the performance of dual header pulse interval modulation (DH‐PIM) over indoor optical wireless systems. DH‐PIM being anisochronous scheme offers a built‐in symbol synchronization capability. Theoretical and simulation results demonstrate that DH‐PIM offers shorter symbol length, improved transmission rate and bandwidth requirement and a comparable power spectral density profile compared with digital pulse interval modulation (DPIM) and pulse position modulation (PPM) schemes.It is shown that DH‐PIM2, with wider pulse duration is the preferred option when the available channel bandwidth is limited and higher optical power is tolerable. Whereas DH‐PIM1, with narrower pulse width, exhibits comparable power requirements but a marginally higher bandwidth compared with DPIM, and is also more bandwidth efficient than PPM at the cost of increased power requirement. However, at higher bit resolutions, i.e. M⩾7, DH‐PIM1 is both bandwidth and power efficient compared with PPM. Error rate analysis show that DH‐PIM offers improved packet error rate compared with on‐off‐keying (OOK) and DPIM, but marginally inferior as compared with PPM. The power requirement and penalty due to intersymbol interference for non‐dispersive and dispersive channels is analysed and the results show that for given parameters, DH‐PIM requires marginally higher optical power compared with PPM and DPIM, but it supports the same bit rate at much less bandwidth requirement. Copyright © 2005 John Wiley & Sons, Ltd.

Dual header pulse interval modulation for dispersive indoor optical wireless communication systems

The performance of the dual header pulse interval modulation (DH-PIM) scheme in indoor diffuse optical wireless environments is examined. The power requirement and penalty due to intersymbol interference is analysed using the ceiling-bounce model and results are compared with other modulation schemes such as PPM and DPIM. It is shown that for given parameters, DH-PIM requires marginally higher optical power compared with PPM and DPIM, but it supports the same bit rate with much lower bandwidth requirement.

Error performance of dual header pulse interval modulation (DH-PIM) in optical wireless communications

The performance of dual header pulse interval modulation in distortion-free optical wireless channels is examined in terms of error performance, power requirement and achievable bit rate. Complete derivations of the slot and packet error rates, optical power and bandwidth requirements are presented. The calculated results are confirmed by computer simulation of the proposed scheme. The performance of DH-PIM is compared with PPM, PIM and OOK modulation schemes. It is shown that DH-PIM offers improved error performance compared with OOK and PIM, but is marginally inferior to PPM.