High Data Rate Systems Research Articles

Integrated photonic encoder for low power and high-speed image processing.

Modern lens designs are capable of resolving greater than 10 gigapixels, while advances in camera frame-rate and hyperspectral imaging have made data acquisition rates of Terapixel/second a real possibility. The main bottlenecks preventing such high data-rate systems are power consumption and data storage. In this work, we show that analog photonic encoders could address this challenge, enabling high-speed image compression using orders-of-magnitude lower power than digital electronics. Our approach relies on a silicon-photonics front-end to compress raw image data, foregoing energy-intensive image conditioning and reducing data storage requirements. The compression scheme uses a passive disordered photonic structure to perform kernel-type random projections of the raw image data with minimal power consumption and low latency. A back-end neural network can then reconstruct the original images with structural similarity exceeding 90%. This scheme has the potential to process data streams exceeding Terapixel/second using less than 100 fJ/pixel, providing a path to ultra-high-resolution data and image acquisition systems.

Verification and Modeling of the Maritime Channel for Maritime Communications and Navigation Networks

This paper presents a geometric stochastic channel model designed for analyzing maritime communication and navigation services between moving ships using the C-band or sub-6 GHz spectrum, which aligns with the focus of emerging 5G networks on land. The channel model is validated through channel measurements conducted both on the sea and land. A software tool has been developed to integrate and analyze these measurements, which is included with this publication. The main challenge in developing the channel model for maritime services lies in the dynamic nature of the sea surface, leading to constantly changing reflection conditions due to varying reflectors and scatterers on the water. Additionally, the motion conditions of the transmitter and receiver on ships change in all three dimensions, depending on the sea state. To address these complexities, data from several measurement campaigns in diverse areas were collected. The analysis involved examining the propagation conditions over the sea with variations in sea surface roughness, antenna heights, and used bandwidths. Moreover, additional propagation conditions over nearby land were also taken into account. The study demonstrates that the changing antenna height on the ship, influenced by sea conditions, significantly affects the reflection and scattering conditions. The research aims to develop reliable, high-data rate, and broadband marine communication systems. Therefore, a measurement bandwidth of 120MHz was employed to derive the propagation model. This model not only offers absolute timing information but can also be used for time-based ranging or positioning systems. The proposed geometric stochastic channel model provides valuable insights into the complex maritime communication and navigation environment. By accounting for the continuously evolving sea surface and its impact on antenna height, the model offers a robust framework for studying and optimizing marine communication systems. The availability of a software tool integrating real-world measurements further enhances the usability and practicality of the channel model for future maritime communication research and deployment.

Design and Build 4G Open Radio Access Network at SmartLab Politeknik Negeri Jakarta

The transition of RAN (Radio Access Network) development from the conventional model to Open RAN is motivated by the fact that Open RAN presents new services by reducing CAPEX (Capital Expenditure) and has the ability to integrate all cellular technologies in one server. One of cellular technology that can be developed using Open RAN is 4G LTE networks. The 4G LTE network produces internet with high data rate and low latency system. Various use case implementations can be carried out, for example to support learning on campus. In this study, the development of Open RAN 4G is implemented as a use case to build the Jakarta State Polytechnic SmartLab which produces its own cellular network. The importance of this research is to be able to ascertain the performance of the Open RAN 4G network using a Centralized RAN scenario. The method used in this research consists of knowing the problem, determining the tools used, determining the implementation scenario, configuring, and testing network performance. Parameters measured to test network performance are uplink downlink speed, RSRP value, and SINR value. Based on the scenarios that have been executed, the results show that the Open RAN 4G network has a maximum downlink speed performance of 13.6 Mbps, a maximum uplink speed of 7.22 Mbps, a maximum SINR of 22 dB, an RSRP of -200 dBm, and a maximum range that can be reached is 5 meters.

Two‐way decode and forward quadrature media‐based modulation for single‐input multiple‐output scheme

SummaryThe recently proposed quadrature spatial modulation aided single‐input multiple‐output media‐based modulation (QSM aided SIMO‐MBM) improves the spectral efficiency and achieves a high data rate and overall system error performance when compared with conventional SIMO‐MBM and SIMO schemes. Cooperative network (CN) involves collaboration among nodes to improve wireless network reliability, link quality, and spectral efficiency. This paper investigates the performance of QSM aided SIMO‐MBM in CN by employing the decode and forward relaying technique, which utilizes two source nodes that simultaneously transmit a unique message block on the same time slot to the relay node; the relay node decodes the received message block from both transmitting nodes, before re‐encoding and re‐transmitting the decoded message block in the next time slot to the destinations in order to enhance the error performance of the QSM aided SIMO‐MBM further. Each node can decode the data of the other node using network coding (NC) techniques. Algebraic algorithms are applied to the detected message to accumulate the various transmissions. The theoretical average error probability of the proposed scheme was formulated using a lower bound technique, and the Monte Carlo simulation (MCS) results obtained validated the result. The MCS results achieved exhibit a significant improvement of 8 dB at 6 b/s/Hz for a BER of and 12 dB at 8 b/s/Hz for a BER of over the conventional QSM aided SIMO‐MBM scheme. Consequently, the obtained results show that the system configuration with outperforms the system configuration with for the proposed scheme.

High-Frequency Vacuum Electron Devices

Vacuum electron devices at frequencies of millimeter waves and terahertz play highly important roles in the modern high-data rate and broadband communication system, high-resolution detection and imaging, medical diagnostics, magnetically confined nuclear fusion, etc [...]

Enhanced 850-nm SM VCSEL transmission by favorable chirp interaction with fiber dispersion

Single-mode (SM) vertical-cavity surface-emitting lasers (VCSELs), especially those operating around 850 nm, have been studied intensively in recent years for short distance transmission. Despite the demonstrations of increased data rate and system distance, the impact of frequency chirp that is commonly present in directly modulated lasers is an area that needs more detailed studies for 850 nm VCSEL-based systems. In this paper, we explore the interaction between a laser chirp and fiber chromatic dispersion using an 850-nm SM VCSEL over a standard SM fiber that is two-mode at the operating wavelength. Our transmission experiments show that the system can enjoy a benefit from negative fiber dispersion instead of a penalty compared to the back-to-back case, due to the favorable chirp–dispersion interaction, which is also supported by our system bandwidth measurements. Furthermore, we measure the chirp value of the SM VCSEL and conduct modeling using the time-domain pulse concept to illustrate the impact on the chirp–dispersion interaction and explore the optimal chirp parameters for different transmission data rates. Our study indicates a significant system benefit of using 850-nm SM VCSELs with a high bandwidth single-mode fiber around 850 nm due to the favorable chirp–dispersion interaction. Such a benefit can enable high data rate and longer distance system transmission for modern data center applications.

Performance analysis of multilogic all-optical structure based on nonlinear signal processing in SOA

All-optical signal processing in optical technology is the most reliable process that mitigates the limitations of speed and processing power in electronics by replacing the electronic components with the equivalent optical switching components. All-optical switches are very important in communication and computing, as most communication around the globe is carried on optical fibers. Optical switching is effectively performed in high data rate systems through all-optical gates. The nonlinear signal processing in semiconductor optical amplifier (SOA) is the key element for implementing various optical gate logics. In this paper, combination of optical gates such as all-optical AND, OR, NOT, XOR, NOR and XNOR operations are successfully simulated in single structure. The performance analysis of each gate and its cascaded feature is analyzed by varying the structural and functional parameters of SOA’s active region. The simulation results confirm that the proposed design can be implemented at high data rate of more than 10Gbps with good quality factor and extinction ratio of around 12 dB.

Investigation of multiple hop cooperative communication system over time-selective Nakagami-m fading channel

Real-time communication is affected by practical constraints such as node mobility and imperfect channel state information. Most technical contributions in the area of cooperative communication neglect these practical constraints, thus, assumes ideal propagation scenarios. Such approximations make sense in low-rate systems, but can lead to very false results when examining future high data rate systems. In this work, closed-form expression of pairwise error probability (PEP) is derived for dual hop and multiple hop selective decode-and-forward relaying network over time-selective Nakagami-m fading links. Space–time block code is used in combination with multiple-input multiple-output to achieve the diversity gain along with cooperative diversity. To obtain the optimal source-relay power allocation factors, a mathematical framework has been proposed to improve the performance of the system in the power-constraint situation. Simulation results have been presented for various values of fading severity parameter and channel variance. Results for different node-mobility scenarios are also provided. Results show that the system performance improves by increasing the fading severity parameter and relay-to-destination (RD) channel gain. It is noted that the relaying network’s diversity order (DO) is the same as the non-cooperative network’s DO in a scenario when both source node (SN) and destination nodes (DNs) are static, and relay node (RN) is mobile. Also, if the RN and DN are static and the SN is mobile, DO will be equivalent to zero. At high signal-to-noise ratio (SNR), system performance with equal and optimal energy distribution can be seen approaching an asymptotic floor limit, because system performance independent of the power of the noise components. The effect of mobility of the DN on the average per-block PEP output is less important compared to the mobility of the SN. The scheme is restricted by an asymptotic error floor with a greater SNR regime for other node-mobility situations. The analytical results are verified by Monte Carlo simulations for M-ary signaling maximal ratio combiner cooperative system.

Deep Q-Network Learning Based Downlink Resource Allocation for Hybrid RF/VLC Systems

Developing high data rate systems to meet the requirements of fifth generation mobile systems has become crucial. Hybrid radio frequency/visible light communication (RF/VLC) has appeared as a promising mechanism for achieving this objective. In hybrid RF/VLC, data rate maximization is subject to constraints on bandwidth, power and the user association. The joint optimization problem of bandwidth, power and user association to maximize the data rate is non-concave and obtaining an optimal solution is difficult with conventional optimization algorithms. The existing solutions are based on a presumption of at least one optimization variable. In this article, this issue has been overcome by solving the joint optimization problem in hybrid RF/VLC with a deep Q-network (DQN) learning based algorithm, which has been recognized as an efficient learning based mechanism for optimization. Our system model considers one RF and multiple VLC access points (APs). The idle APs are also incorporated in the system model. The application of DQN learning based algorithm is carried out by finding an optimal policy with the help of an action-value function. As the data sets for the considered system are large, a multi-layered network is used for approximating the action-value function estimator. Finally, a transfer learning based algorithm has been proposed for maximizing the total data rate of the system for the case of a newly entering user equipment (UE) that uses the information of the environment before the arrival of the new UE. Through simulations, it is found that our proposed algorithms can lead to an improvement of more than 10% and 54% in the achievable sum-rate and number of iterations for convergence respectively as compared to that obtained with existing conventional optimization algorithms.

Performance Examination of OFDM Modulation Techniques in LTE 4G

The digital modulation methods are being chosen in high data rate systems as Long Term Evolution (LTE) and LTE-A. Quadrature Phase Shift Keying (QPSK) and Binary Phase Shift Keying (BPSK) is the simplest form of the PSK with double carrying capacity when compare to the other traditional techniques in modulation. In conventional method the performance was analyzed in MIMO .In this paper proposed the performance analysis of BPSK and QPSK modulator and demodulator in LTE 4G system models under the Additive white Gaussian Noise (AWGN) and Rayleigh fading by comparing the Bit Error Rate (BER). From the analysis, compare to BPSK QPSK has good BER. Using the MATLAB Simulink tool Implementation is performed.

An Efficient Method for Offset Mitigation in Free-Space Optical Systems

Channel estimation is a key feature for free space optical (FSO) wireless communication systems which are required for a high QoS and high data rate system. Aiming at the problem of FSO wireless channel estimation, this paper proposes an implicit sequence channel estimation scheme to eliminate dc offset, and studies the key factors affecting the system performance. The optimal power allocation factor is derived based on the maximum SNR criterion. The system performance parameters such as the bit error rate (BER), mean square error (MSE), and computational complexity are evaluated. The results show that under the same dc bias condition, the MSE is estimated to decrease significantly after using the method of this paper. With the increase of dc offset d , the system error rate is significantly reduced and more approaching d = 0 (i.e., no dc offset). The proposed algorithm effectively mitigates the dc offset impact on the system and the BER is significantly improved while the MSE is reduced to 50% of the traditional state-of-the-art method. The proposed work can provide a technical solution to the FSO system and give support to technological development.

Space Time Regularized Zero Forcing in Downlink Code Division Multiple Access Systems with Complementary Codes

Complementary coded code-division multiple access (CC-CDMA) has been originated as one of the extremely robust multiuser access technique in designing high data rate systems with frequency diversity for futuristic wireless communication. The integration of multiple-input multiple-output (MIMO) systems with CC-CDMA offers space diversity gain in addition to the achievable frequency diversity in CC-CDMA systems. However, the performance of conventional chip level space–time receiver in MIMO CC-CDMA is deteriorated due to multiple access interference (MAI) and spatial interference under frequency selective fading channels. A zero-forcing receiver used for minimizing MAI provides unsatisfactory performance in interference limited environments due to amplification of noise and hence the use of regularized zero-forcing (RZF) receiver is proposed and investigated in this study to achieve a space–time interference cancellation (STIC) system. Simulation results are performed to reveal the significance of RZF-STIC in achieving performance gain than conventional equalization schemes, and at the same time enhancing frequency diversity and spatial diversity gain with less complexity at all system loads.

High-Rate Regular APSK Constellations

The majority of modern communication systems adopt quadrature amplitude modulation (QAM) constellations as transmission schemes. Due to their square structure, however, QAM do not provide satisfying protection to phase noise effects, as the number of constellation points grows, increasing at the same time their peak-to-average-power ratio. This requires an expensive power amplifier and an oscillator at the transmitter to guarantee low distortion, complicating the adoption of dense transmission schemes in practical high-data rate systems. In this paper, we construct a coded modulation scheme based on regular amplitude and phase shift keying modulations. We propose a novel multilevel coding labeling for the constellation points separating the amplitude and phase domains. We provide a novel multistage decoding scheme allowing for a low-complexity log-likelihood ratio calculation for soft-input decoding of component codes, along with a suitable rate design. Finally, we compare the proposed scheme with the state-of-the-art QAM constellations and optimize the constellations in the presence of phase noise.

A Fully Digital Phase Modulator With a Highly Linear Phase Calibration Loop for Wideband Polar Transmitters

This brief presents a digital phase modulator for wideband polar transmitters. It adopts a digital-to-time converter (DTC) and a highly linear phase calibration loop that improves phase resolution for high data-rate systems. The proposed 10-bit DTC consists of a coarse 5-bit cascaded delay line and a fine 5-bit digitally controlled delay line. This DTC achieves a fine delay resolution with digitally controlled varactors and is capable of introducing incremental delays as small as 2.49 ps. A phase calibration loop based on an advanced successive approximation register (SAR) time-to-digital converter (TDC) is nested inside the phase modulator and sets the DTC output phase accurately across the range of input digital codes. The SAR TDC also compensates for any process, voltage, and temperature variations. By using the proposed SAR TDC-based calibration loop, the phase modulator can achieve a high sampling rate and a fine phase resolution. This was possible because the number of phase comparisons of the SAR TDC has been significantly reduced. The phase modulator achieves 0.61 degrees root-mean-square phase error and a 30 MS/s sampling rate at the carrier frequency of 600 MHz while consuming 9.4 mW. This phase modulator is implemented in a 180-nm CMOS technology and occupies 0.19 mm2.

High speed and low area decision feed-back equalizer with novel memory less distributed arithmetic filter

In this paper an efficient implementation of decision feed back equalizer (DFE) is carried out using novel memory less distributed arithmetic (NMLDA) filter. In wireless transmission systems, DFEs are used to mitigate the inter-symbol interference (ISI). The ISI is occurred due to multi-path propagation of the transmitted signal. High data rate systems demand higher order filters in DFE architectures which increase complexity in hardware design. In our proposed NMLDA design, we have used multiplexers and enhanced compressor adders in place of memory unit and conventional adders. The proposed design occupies lower area and gives higher throughput, when compared to MAC based filter and all other memory based DA filter architectures. By using proposed NMLDA based DFE, the ISI errors in transmission signal, will be minimized and the performance of the transmission system will be enhanced. We have synthesized the NMLDA of 32-tap, 16-tap, 8-tap and 4-tap filters and implemented them on FPGA device. The proposed design has nearly 70% less number of logical elements than OBC DA and 50% less than MDA and offers better throughput than the existing designs when implemented on Altera Cyclone III EP3C55F484C6.

Interference Mitigation for 5G Millimeter-Wave Communications

We present a novel ultra-wideband low-cost transmit/receive architecture with reduced power and hardware requirements, which includes interference mitigation capabilities and accommodates multiple users. Specifically, a novel encoding approach is introduced to multiplex signals across large bandwidths and achieve secure communication and interference mitigation through spread signals. In this paper, a detailed description of the proposed high data rate system architecture is presented. Simulations are also provided in the presence of high-power interferers with eight concurrent users. To assess the performance and impact of the encoding/decoding process, a noise analysis was conducted for the transmitter and receiver chains. Specifically, bit error rate curves are generated at different stages of the system. The measurements show interference margin ratios improvement by at least 16 dB.

Incorporating SDC Module for ISI Compensation for a Long-Haul Co-OFDM System

Abstract With the increase in demand of bandwidth hungry applications, it is recommended to develop a high data rate system for long-haul coherent optical orthogonal frequency division multiplexing (CO-OFDM). At a very high data rate, CO-OFDM signal experiences deterioration. At 50 Gbps, the signal experiences ISI effect and in order to overcome this ISI effect, a prolonged system has been developed to reach optimal ISI compensation technique. One of the prominent and competent techniques to enhance system performance is (SDCM) symmetrical dispersion compensation module. In order to make system more bandwidth efficient 4-QAM (Quadrature Amplitude Modulation) with gray coding is applied and manual adjustments are done at receiver phase to decrease error vector magnitude (EVM). OFDM data stream is successfully transmitted over a distance of 4,000 km to compete the demand of long-haul CO-OFDM system. With different launch powers and laser linewidths, the performance of the system is enhanced in terms of Q-factor, SNR and EVM.

Design of realisable optimum post‐detection filters for high data‐rate m ‐PAM systems with clock jitter tolerance

The continual increase in demand for extremely high data-rate systems spans the full range of network systems from local area networks to long-haul systems. While coherent optical systems dominate the long-haul market, there is significant interest in using simpler direct detection systems for application areas, where simplicity and lower-cost is a key driver. Pulse-amplitude modulation (PAM) is appropriate to consider as it enables the reduction of the channel symbol rate for a given data rate, without unduly increasing the complexity of the system. A route to the design of optimum post-detection filter for PAM systems is presented that offers significantly improved robustness to timing jitter, which is an impairment of increasing import as symbol rates are increased.

Aggregate Hardware Impairments Over Mixed RF/FSO Relaying Systems With Outdated CSI

In this paper, we propose a dual-hop radio-frequency (RF)/free-space optical system with multiple relays employing the decode-and-forward and amplify-and-forward with a fixed gain relaying scheme. The RF channels are subject to a Rayleigh distribution while the optical links experience a unified fading model emcopassing the atmospheric turbulence that follows the Malaga distribution (or also called the $\mathcal {M}$ -distribution), the atmospheric path loss, and the pointing error. Partial relay selection with outdated channel state information is proposed to select the candidate relay to forward the signal to the destination. At the reception, the detection of the signal can be achieved following either heterodyne or intensity modulation and direct detection. Many previous attempts neglected the impact of the hardware impairments and assumed ideal hardware. This assumption makes sense for low data rate systems but it would no longer be valid for high data rate systems. In this paper, we propose a general model of hardware impairment to get insight into quantifying its effects on the system performance. We will demonstrate that the hardware impairments have small impact on the system performance for low signal-to-noise ratio (SNR), but it can be destructive at high SNR values. Furthermore, analytical expressions and upper bounds are derived for the outage probability and ergodic capacity while the symbol error probability is obtained through the numerical integration method. Capitalizing on these metrics, we also derive the high SNR asymptotes to get valuable insight into the system gains, such as the diversity and the coding gains. Finally, analytical and numerical results are presented and validated by the Monte Carlo simulation.

Performance evaluation of FSO system using wavelength and time diversity over malaga turbulence channel with pointing errors

There is an immense demand for high bandwidth and high data rate systems, which is fulfilled by wireless optical communication or free space optics (FSO). Hence FSO gained a pivotal role in research which has a added advantage of both cost-effective and licence free huge bandwidth. Unfortunately the optical signal in free space suffers from irradiance and phase fluctuations due to atmospheric turbulence and pointing errors which deteriorates the signal and degrades the performance of communication system over longer distance which is undesirable. In this paper, we have considered polarization shift keying (POLSK) system applied with wavelength and time diversity technique over Malaga(M)distribution to mitigate turbulence induced fading. We derived closed form mathematical expressions for estimating the systems outage probability and average bit error rate (BER). Ultimately from the results we can infer that wavelength and time diversity schemes enhances these systems performance.