High-speed Broadband Communication Research Articles

Performance of HQAM/XQAM Laser Communication System in Anisotropic Non-Kolmogorov Ground–HAP–Satellite Uplink

Satellite laser communication can achieve high-speed, high-precision, and high-security broadband communication without being constrained by the electromagnetic spectrum, which has attracted attention. So, this paper proposes the use of a high-altitude platform (HAP) under anisotropic non-Kolmogorov turbulence to improve the communication performance of the system. Cross quadrature amplitude modulation (XQAM) and hexagon quadrature amplitude modulation (HQAM) are applied to the ground–HAP–satellite (G-H-S) laser communication system. Considering the combined effects of uplink light intensity scintillation, beam wander, and the angle of arrival fluctuation, the G-H-S system’s bit error rate (BER) closure expression is derived under the EW distribution. Simultaneously, the relationship between the G-H-S system’s signal-to-noise ratio (SNR) and BER under different anisotropic factor u values is simulated and compared with the traditional ground–satellite (G-S) system. The results show that the communication performance of the G-H-S system with HQAM modulation is better. In addition, the effects of the zenith angle, receiving aperture, transmitter beam radius, and beam divergence angle on the BER performance of the system are also studied. Finally, the correctness of the analysis results is verified via Monte Carlo simulation. This research will benefit the design and optimization of satellite laser communication systems.

Intensification and Interpretation of Performance in 5G adopting Millimeter Wave: A Survey & Future Research Direction

In context of high speed broadband communication, 5G optical communication has become a most stimulating and motivating domain in research. Recent cellular network LTE (4G) will not be adequate and effective to fulfill the needs of higher data rate, higher bandwidth, low latency and Quality of service.To achieve the above requirements and to address the challenges 5G optical communication have major considerations, the incorporation of Dense Wavelength Division Multiplexing (DWDM), Millimeter wave (mm-wave) communication, eMBB to make efficient decisions.This article summarize the empowering technology for DWDM, mm-wave signal communication and enhanced Mobile Broadband uses 5G optical communication as an evolution from 4G-LTE communication amenities, with fast communications, good throughput and high capacity, it is a successful aspirant for the increasing broadband communications. Such empowering technology, focused mainly on improving the network structure and efficiency, involves producing the mm-wave broadband signal with easy and cost adequate systems. This paper gives a thorough review on developing and empowering advancements identified with optical communication framework that can meet the huge data rate request of broadband. The article further addresses the research gaps and outlines the important future research direction for enhancing communication using DWDM.

Full-space terahertz metasurface based on thermally tunable InSb

Terahertz (THz) metasurfaces have potential research value in high-quality molecular imaging, high-speed broadband communication, biology, etc. In this paper, thermally tunable full space metasurface was proposed and analyzed by using Finite Difference Time Domain method based on Pancharatnam–Berry phase modulation and InSb temperature characteristic. At 220 K, a metasurface composed of InSb elements can simultaneously achieve efficient transmission and reflection of the incident circularly polarized light at 0.8 THz and 1.15 THz, respectively. On the contrary, at 360 K, the metasurface absorbs all of the incident terahertz waves, essentially turning off the incident beam. In addition, dynamically tunable metalenses were proposed and used to generate focused vortex light. The proposed metasurface provides a potential direction for developing an efficiency-tunable PB terahertz device in the future.

Tunable Broadband Mode Converter Based on Long-Period Fiber Gratings at 2-μm Waveband

We demonstrate the fabrication of a broadband mode converter (MC) operating at 2 μm waveband based on long-period fiber gratings (LPFGs) written in the two-mode fiber (TMF) by CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> laser. The proposed MC offers a 10-dB bandwidth of 58 nm, making it suitable for high-speed broad-band optical communication system at 2 μm waveband. The maximum conversion efficiency reaches 98.89% at wavelength of 2 μm. The torsion, strain, bending, and polarization characteristics of the broadband MC were measured experimentally. The torsion sensitivity of the LPFGs was measured to be 1.32 nm/(rad/m) at 2 μm waveband, which was almost three times higher than that of the grating with the same order mode coupling at 1.55 μm waveband. The proposed broadband MC can function as not only a promotion in fiber communication system but also a high sensitivity torsion sensor in fiber sensing system.

A Framed-Pulsewidth Modulation Transceiver for High-Speed Broadband Communication Links

A 20 Gb/s serial link transceiver employing a framed-pulsewidth modulation (FPWM) scheme that overcomes the signal-to-noise (SNR) degradation without a linearity requirement is presented. The FPWM scheme encodes data at the location and the width of the pulses in a frame spanning multiple unit intervals (UI) while maintaining a minimum pulsewidth equal to 1 UI. The test chip achieves a coding gain of 33 %, which allows a total throughput of 20 Gb/s while keeping the baud rate of 15 Gb/s. The equalization core incorporating programmable 3-tap pre-emphasis at the transmitter and a continuous-time linear equalizer (CTLE) at the receiver compensates for the channel insertion loss up to 12 dB at the baud frequency, and achieves $2.2\times0.48$ mm 2 and consumes 90.6 mW from a 0.9 V supply which renders the power efficiency of 4.53 mW/Gb/s.

A tunable self-mixing chaotic laser based on high frequency electro-optic modulation

A tunable self-mixing chaotic laser based on high frequency electro-optical modulation is proposed. A laser dynamics system is designed and tested for tunable chaotic laser generation and provides optical feedback and electro-optic modulation with two degrees of freedom. The chaotic laser is generated by optical feedback, and it becomes tunable by high frequency electro-optic modulation. The frequency is modulated from 10 MHz to 10 GHz to test this system, and an ultra-wide band chaotic laser from 0.8 GHz to 24 GHz is measured by an electrical spectrum analyzer (ESA). The experimental results show the generation of a tunable chaotic laser via electro-optic modulation. At the same time, this tunable chaotic laser has a highly sensitive dynamic response near the 2.0 GHz range of frequency modulation. The system is proved to be suitable for applications in high-speed broadband communication and sensing.

Highly Birefringent Slotted Core Photonic Crystal Fiber for THz Wave Propagation

We propose a novel design of a slotted core photonic crystal fiber (PCF) that offers ultra low-loss and high birefringence attribute for efficient transmission of terahertz (THz) waves. A finite element method has been used to investigate the modal characteristics of the PCF. Our design incorporates an asymmetrical structure of air holes in the core to achieve high birefringence. Moreover, in the cladding region, we have a compact geometry of air holes arranged in five hexagonal layers to obtain lower dispersion. The simulated results show that the PCF exhibits simultaneously a low effective material loss of 0.025 cm–1 and high modal birefringence of 0.0911, a flattened dispersion property of 0.65 ± 0.05 ps THz–1 cm–1 having a frequency range of 0.5 to 1.6 THz, core power fraction of 52% and very negligible confinement loss of about 1.05 × 10–13 cm–1. We believe our proposed PCF will bring about a promising improvement in high-speed broadband communications in the THz regime as well as numerous applications in the near future.

A Design of Input-Decimation Technique for Recursive DFT/IDFT Algorithm

In this paper, an input-decimation technique for the recursive discrete Fourier transform (RDFT)/inverse DFT (RIDFT) algorithm is proposed for the high-speed broadband communication systems. It is worth noting that the input-decimation approach is presented to decrease the number of input sequences for the recursive filter so that the computation cycle of RDFT/RIDFT can be shortened to meet the computing time requirement ( $3.6~{\mu }s$ ) for the high-speed broadband communication systems. Therefore, the input-decimation RDFT/RIDFT algorithm is able to carry out at least 55.5% reduction of the total computation cycles compared with the considered algorithms. Furthermore, holding the advantages of input-decimation technique, the computational complexities of the real-multiplication and -addition are reduced to 41.3% and 22.2%, respectively. The area and the power consumption can be minimized by employing the cost-efficient constant multiplier with the refined signed-digit expression of twiddle factors. Finally, the physical implementation results show that the core area is $0.37\times 0.37$ mm2 with $0.18~\mu \text{m}$ CMOS process. The power consumption is 5.16 mW with the supply voltage of 1.8 V and the operating clock of 40 MHz. The proposed design can achieve 258 million of computational efficiency per unit area (CEUA) and really outperform the previous works.

A Modified Design of a Hexagonal Circular Photonic Crystal Fiber with Large Negative Dispersion Properties and Ultrahigh Birefringence for Optical Broadband Communication

In this paper, we propose a modified design of a hexagonal circular photonic crystal fiber (HC-PCF) which obtains a large negative dispersion and ultrahigh birefringence simultaneously. The optical properties of the proposed HC-PCF were investigated using the finite element method (FEM) incorporated with a circular perfectly matched layer at the boundary. The simulation results showed large negative dispersion of −1044 ps/nm.km and ultrahigh birefringence of 4.321 × 10−2 at the operating wavelength of 1550 nm for the optimum geometrical parameters. Our proposed HC-PCF exhibited the desirable optical properties without non-circular air holes in the core and cladding region which facilitates the fabrication process. The large negative dispersion of the proposed microstructure over the wide spectral range, i.e., 1350 nm to 1600 nm, and high birefringence make it a suitable candidate for high-speed optical broadband communication and different sensing applications.

The Design and Implementation of the XWCETT Routing Algorithm in Cognitive Radio Based Wireless Mesh Networks

The Wireless Mesh Networks (WMNs) technology has recently emerged as a promising high-speed wireless technology, which provides the last mile broadband Internet access and delivers integrated wireless communication solutions. Integrating the traditional wireless with new wireless technologies such as cognitive radio (CR) technology creates a platform for high-speed broadband communication. In a multihop ad hoc cognitive radio network (CRN) environment, the performance of the network is degraded by the routing protocols, which are adapted from the traditional wireless networks. In an endeavor to optimize the performance of the CRNs, existing routing protocols can be adapted and optimized. Secondly, new dynamic routing protocols can be designed to meet the requirements of CRNs. This paper investigates the existing routing protocols in WMNs and proposes a new routing protocol called extended Weighted Cumulative Expected Transmission Time (xWCETT). The xWCETT routing protocol was evaluated through network simulations using the NS 2. Its performance was evaluated with respect to the end-to-end average latency, the throughput, jitter, packet delivery ratio, and the normalized routing load. The comparative evaluation results show that the xWCETT achieves superior results in terms of average throughput, latency, and the normalized routing load.

High Power Efficient Quadrature Amplitude Modulation Soft Decision Algorithm

The quadrature amplitude modulation (QAM) is the basic technology on high speed broadband communication physical level symbol mapping. Systems requiring lower signal to noise ratio to achieve the same error probability are more power-efficient. The usage of high order modulation is limited due to its low power efficiency compared to lower order modulation. This paper combines the characteristics of Gray code symbol mapping for QAM constellation to design a soft decision algorithm based on signal diversity (div-log-MAP). The bottle-neck of the low power efficiency is overcome and highest power efficiency can be realized. The performance of div-log-MAP can beyond the performance of log maximum a posteriori probability algorithm. At the same time, the proposed algorithm is a more effective method to utilize high order QAM modulation on high speed broadband communication.

Pilot-Less Time Synchronization for OFDM Systems: Application to Power Line Receivers

Power line networks provide high-speed broadband communications without the need for new wirings. However, these networks present a hostile environment for high-speed data communications. The most common modulation method used in such systems is OFDM, since it copes effectively with noise, multipath, fading selectivity, and attenuation. A potential drawback of OFDM is its sensitivity to receiver synchronization imperfections, such as timing and sampling frequency offsets. Although several approaches have been proposed for estimating the time and frequency offset, they are based on the use of pilot sequences that are not available in power line communication standards. More importantly, they focus on isolated algorithms for compensating either time or frequency offsets without providing a complete, low complexity, OFDM receiver architecture that mitigates jointly time and frequency errors. This paper focuses on providing an OFDM receiver architecture that can be compatible with many power line standards. Extensive simulation studies show under realistic channel and noise conditions that the proposed receiver provides enhanced robustness to synchronization imperfections as compared to conventional approaches.

Smart Fault Location for Smart Grid Operation Using RTUs and Computational Intelligence Techniques

The smart grid aims to improve the quality and reliability of power at the generation, transmission, and distribution levels. The transmission lines can be considered the arteries of the power system, as they carry power over long distances and are exposed to difficult terrain. Transmission line protection philosophy is undergoing a change of paradigm with the advent of digital relays and high-speed broadband communication with the global positioning system (GPS). This paper explores the possibility of transmission line protection for a multigenerator system using wavelet multiresolution analysis (MRA) and computational intelligence techniques in conjunction with GPS. The inputs for the wavelet transform are the synchronized currents measured from remote telemetry units (RTUs) using GPS technology on different buses. The smart location technique uses a wavelet MRA technique to extract the features of the transient current signals based on the harmonics generated at the instant of occurrence of faults due to the abrupt changes of currents in a three-phase transmission line. These extracted features, with such computational intelligence techniques as an adaptive neuro-fuzzy inference system (ANFIS) and artificial neural network (ANN), lead the grid toward smarter strategies for locating the fault distance. A comparative study establishes the superiority of ANFIS over ANNs for more accurate and reliable smart fault location. Furthermore, the efficacy of the proposed method is validated through a Monte Carlo simulation to incorporate the stochastic (random) nature of fault occurrence in a real-time transmission line. The most significant contribution of this paper is that the proposed smart location technique is immune to the effects of the fault inception angle (FIA), fault impedance, fault distance, and power angle. The results contained in this paper validate the use of the proposed algorithm for the real-time smart grid operation of transmission lines.

Detecting on Forward Error Correction Codes

Under the development of society, the dissemination of information plays an increasingly significant role. How to achieve the goal of continually reducing the error rate and enhance the quality of communication and construct a highly reliable, efficient and high-speed Broadband Communication System is really a tough task. Here comes the FEC that is one particular type of error correction codes which is introduced to protect the process of data transmitting. In addition to a brief introduction to FEC, this article covers the categories of FEC and their applications along with comparisons and also describes the latest development of these error correction algorithms.

Distribution of Broadband Services Over 1-mm Core Diameter Plastic Optical Fiber for Point-to-Multipoint In-Home Networks

This paper presents a point-to-multipoint (P2MP) in-home optical network infrastructure based on 1-mm core diameter plastic optical fiber (POF). By employing passive POF splitters, converged broadband wired and wireless service transmission over a P2MP POF infrastructure is demonstrated. A gross 2.2 Gb/s fractional discrete multitone (DMT) and a 528-MHz ultra wideband (UWB) wireless signal distribution simultaneously to four end-users are successfully achieved with BER <; 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> and EVM <; 15.5% , respectively. Up to 50 m transmission distance is achieved using off-the-shelf optical components. This feasibility study on all-optical P2MP infrastructures presents a promising low-cost solution for high-speed in-home broadband communication.

Time-Reversal Division Multiple Access over Multi-Path Channels

The multi-path effect makes high speed broadband communications a very challenging task due to the severe inter-symbol interference (ISI). By concentrating energy in both the spatial and temporal domains, time-reversal (TR) transmission technique provides a great potential of low-complexity energy-efficient communications. In this paper, a novel concept of time-reversal division multiple access (TRDMA) is proposed as a wireless channel access method based on its high-resolution spatial focusing effect. It is proposed to use TR structure in multi-user downlink systems over multi-path channels, where signals of different users are separated solely by TRDMA. Both the single-transmit-antenna scheme and its enhanced version with multiple transmit antennas are developed and evaluated in this paper. The system performance is investigated in terms of its effective signal-to-interference-plus-noise ratio (SINR), the achievable sum rate and the achievable rates with outage. And some further discussions regarding its advantage over conventional rake receivers and the impact of spatial correlations between users are given at the end of this paper. It is shown in both analytical and simulation results that desirable properties and satisfying performances can be achieved in the proposed TRDMA multi-user downlink system, which makes TRDMA a promising candidate for future energy-efficient low-complexity broadband wireless communications.

Nonlinear L2-by-3 transform for PAPR reduction in OFDM systems

Orthogonal frequency division multiplexing (OFDM), the multicarrier modulation technique with high bandwidth efficiency and robustness against multipath fading, is used in several high-speed broadband communication systems including digital video broadcasting (DVB), digital audio broadcasting (DAB), asymmetric digital subscriber line (ADSL), wireless local area network (WLAN IEEE 802.11a,g), high performance radio local area network (HIPERLAN 2), and worldwide interoperability for microwave access (WiMAX IEEE 802.16). However, the transmit signal in OFDM system has a high peak-to-average power ratio (PAPR), one of the major drawbacks of multicarrier transmission, and therefore high dynamic range is required in both the digital to analog converter (DAC) and the power amplifier (PA) for proper operation. Otherwise, the nonlinearities of PA cause out-of-band distortion and increase in bit error rate (BER). Therefore, the reduction in PAPR in OFDM system is desirable in order to obtain power efficiency and increase BER performance. In this paper, a new parametric PAPR reduction technique, L 2-by-3 transform from sliding norm transform (SNT) family is proposed. Based on its parameter, a significant PAPR reduction is obtained. This paper presents the analysis of power saving and computational complexity of the proposed method L 2-by-3 and comparison to two other methods; selected mapping and partial transmit sequence.

Analysis of electromagnetic field emitted from home plug power line used for indoor high-speed broadband communication

High-speed broadband power line communication (BPL) is a novel and practicable technique for Net-atHome or home area local area networking (LAN). Because of the characteristics of BPL, the electromagnetic wave emitted from the BPL transmission media will influence the indoor electromagnetic environment, which would also affect the performance of other wireless communications. Based on the analysis of the communication channel characteristic, network impedance and attenuation characteristic of the BPL, this paper proposes a novel model for calculating the BPL radiation and the computer simulation model, which are proved by the coherence of the simulation and the test data. The interferences from the high-speed BPL to indoor wireless communications are analyzed to stipulate the standards of high-speed BPL in the future.

Broadband PLC Radiation from a Power Line with Sag

This paper presents a computational model for the analysis of broadband PLC radiation by a practical power line with sag. The numerical results show that the sag may have a signiflcant in∞uence on the magnetic vector potential generated by the power line. DOI: 10.2529/PIERS060830095053 Power line carrier (PLC) is a communication technique that uses existing power lines to carry information, traditionally using frequencies in the KHz range. Lately, there has been an interest in high-speed broadband communication on power lines. The broadband power line carrier commu- nication uses frequencies in the MHz range, which is a challenge, concerning the signal attenuation and its electromagnetic compatibility with other communication systems. Wave propagation in a straight transmission line above ground has been studied in the past. But an overhead power line is actually of catenary shape due to its sag. The goal of this paper is to investigate the difierence between the electromagnetic (EM) fleld radiated by a broadband PLC line of catenary shape and that radiated by a straight line. z

Performance evaluation of multicast routing methods in optical switching networks with multiple wavebands

The linear lightwave network (LLN) is proposed as an optical switching communication system that can realize high-speed broadband communication. The authors have previously proposed a multicast routing method in LLN, in which a dynamically expanding/contract tree is introduced in the network, and call connection is realized within that tree. The effectiveness of the method was shown by simulation. This article extends the result and discusses the case of multiple wavebands in an LLN. When there exist multiple wavebands, the selection of the waveband and of the wavelength are the keys to realizing an effective multicast communication system. This article presents and evaluates several selection methods that seem suited to LLN. The following result is obtained. By using the wavelength selection method, in which the calls are connected successively from high-use wavelengths or wavebands, a newly generated call can be accepted by concentrating the calls at a particular wavelength, which improves the performance. It is also shown that the number of unintended signals generated due to linear processing in the LLN is reduced with an increasing number of wavebands, which further improves performance. © 1999 Scripta Technica, Electron Comm Jpn Pt 1, 83(2): 84–96, 2000