High Bit Rate Transmission Research Articles

Optical Add-Drop Multiplexers: Enhancing High Transmission Bit Rates in Next-Generation Communication Networks

The development of optical networks in the telecommunications sector is becoming much closer by considering the help of an Optical Add Drop Multiplexer (OADM) based on a novel technology called Wavelength Division Multiplexing (DWDM). The objective of the current study to examine high transmission bit rates for next-generation optical communication networks using the technology of OADM Based on DWDM. Artificial neural networks (ANNs) were developed via MATLAB software to predict three main parameters in this filed such as transmitted signal power (PT), transmitted signal bandwidth (B.Wsig), and transmission bit rate capacity (Bsh) at different fiber cable lengths, such as L=200, 250, and 300 km. The ANNs results showed that, standard error (SE) for predicting PT as a function of the number of transmitted channels (Nch) was 0.115 mW, 0.095 mW and 0.077 mW, for 200, 250 and 300 km, respectively. Additionally, the SE for predicting B.Wsig was 0.067 GHz, 0.051 GHz and 0.040 GHz for 200, 250 and 300 km, respectively. Lastly, the SE for predicting Bsh was 1.665, 1.311 Gbit/sec and 1.076Gbit/sec for 200, 250 and 300 km, respectively. The SE for predicting PT as a function of the Signal Wavelength (λ) was 0.116, 0.096 and 0.079 mW for 200, 250 and 300 km, respectively. Additionally, the SE for predicting B.Wsig was 0.067, 0.052 and 0.052 GHz for 200, 250 and 300 km, respectively. Lastly, the SE for predicting Bsh was 1.688, 1.417 and 1.110 Gbit/sec for 200, 250 and 300 km, respectively. The low SE in ANNs demonstrated the efficiency, motivating further advancements in optimizing network performance for high-bit-rate transmission.

Collaborative Edge Caching and Transcoding for 360° Video Streaming Based on Deep Reinforcement Learning

360° video streaming provides an immersive viewing experience, but demands high bitrate transmission with low latency. To accommodate the fluctuating network condition and different user requirements, 360° videos are streamed with different quality versions, which makes the bandwidth more demanding. Edge servers with limited resources can be utilized to cache and transcode video contents near users to support 360° video streaming. The edge caching strategy and the transcoding strategy are correlated, as the cached contents limit the transcoding operations, while transcoding extends the use of cached contents at the cost of delay and provides new contents for possible caching. In this article, we consider the problem of collaborative edge transcoding and caching in an edge cluster for tile-based 360° video streaming, which aims to jointly allocate storage and computing resources to reduce quality mismatch level, delay, and transmission cost. The formulated problem is complicated considering dynamic viewers’ Field of View (FoV), video popularity, different quality versions, future user requests, and possible FoV prediction errors. To solve this problem, the process of collaborative transcoding and caching is modeled as a Markov decision process (MDP). Then, a model-free deep reinforcement learning approach, the deep deterministic policy gradient (DDPG), is used to obtain the caching replacement and computing power allocation strategy. Since the action space for caching replacement and power allocation is large, an FoV-guided scheme has been designed to speed the training of the DDPG agent. The simulation results with real viewing traces show that the proposed scheme can increase the cache hit ratio, reduce transmission cost, and improve users’ viewing experience effectively.

Detection of Data over wireless mobile channels based on Maximum Likelihood Technique

Next generation wireless systems are characterized by very high transmission bit rates which gives rise to severe Intersymbol interference (ISI) and this makes the detection process very challenging. Hence, assessment of performance of near-optimal detectors like Near Maximum Likelihood Detectors (NMLD) over such channels assumes great importance. This paper deals with the detection of data in the presence of Noise and ISI with NMLD. Performance improvement of NMLD, as compared to nonlinear equalization, has been assessed in terms of BER versus SNR curves obtained through computer simulation. A number of different cases of mobile radio channels have been simulated in this work. In current world the lot of congestion leads severe fading and interference in the channel which may give the pause in data streaming and call drop in voice calling. These channels have different number of reflected paths with different power distribution in the respective paths. The aim of this paper is to take a ‘worst case’ model of a mobile radio channel in terms of rapidity of fading and ISI, and then to investigate the performance of detectors in the receivers.

PAPR Analysis of OFDM using Selective Mapping Method

A common standard modulation for several high data rate wireless communication systems is Orthogonal Frequency-Division Multiplexing (OFDM). It operates by splitting up large streams of data into several parallel streams with minimal data rates. Compared to single carrier modulation systems, OFDM offers various benefits. Some of these benefits are high transmission bit rates, great spectral efficiency, and sensitivity to frequency fading channels. However, there are drawbacks with OFDM. Among the major issues is the high Peak to Average Power Ratio (PAPR), due to which the system complexity increases. The Selective Mapping approach is used in this study to lower the OFDM PAPR. In this article, simulation has been done using MATLAB, evaluated PSD, spectral efficiency, BER performance and PAPR analysis of OFDM system.

A comprehensive study of large negative dispersion and highly nonlinear perforated core PCF: theoretical insight

A photonic crystal fiber (PCF) containing circularly organized square-shaped air holes in the cladding region is investigated. The fiber core is perforated with four circular air-filled holes to instate high nonlinearity and large negative dispersion. The numerical analysis is done with a finite element method based COMSOL Multiphysics tool to investigate different optical properties of the propounded PCF. The simulation outcome verifies a high nonlinear coefficient value of 85 W−1 Km−1 at telecommunication window 1.55 μm which is, the highest ever achieved value on comparing with the other existing literature without using any nonlinear materials or liquids to the best of the authors’ knowledge. In parallel, the large negative value of dispersion −597 ps nm−1 km−1 is achieved for S/Λ equals 0.70 at the same communication window. However, the highest achieved nonlinearity and negative dispersion are 300 W−1 Km−1 and −1689 ps/nm/km. Moreover, birefringence, numerical aperture, and propagation loss are also measured as 2.40 × 10−3, 0.59, and 4.12 × 10−11 dB m−1 respectively along with an extremely high core power fraction of 99.98%. Hence, the propounded PCF is suitable for residual dispersion compensation, supercontinuum generation, and high bitrate transmission.

A Secure Transmission Method of Network Communication Data Based on Symmetric Key Encryption Algorithm

In order to solve the problems of low transmission efficiency and high transmission bit error rate in traditional transmission methods, a new secure transmission method of network communication data is designed based on symmetric key encryption algorithm. Based on the analysis of the security key theory, the agentless key publishing protocol is adopted to control the access of network communication data, so as to construct the ciphertext protocol. Then the key construction in the encryption process is completed by bilinear mapping method. On this basis, the encryption and decryption algorithm, dynamic key generation module and Shared key update module are combined to realize the secure transmission of network communication data. The experimental results show that the bit error rate of this method was kept below 1%, the time of transmission was below 80 s, and the VIM value exceeded 0.1, indicating that this method has the advantages of high data transmission efficiency, low bit error rate and safer transmission process.

Design and analysis of dispersion-compensating chalcogenide photonic crystal fiber with high birefringence

The photonic crystal fiber (PCF) with a bunch of air holes enclosing the silica core field has momentous and compelling attributes when compared with the ordinary single-mode fibers. In this work, both the birefringence and dispersion properties of a polarization-maintaining chalcogenide (ChG) photonic crystal fiber are numerically investigated by means of the finite element method. Through simulation, it is found that the birefringence of the proposed $${\mathrm{G}\mathrm{e}}_{11.5}{\mathrm{A}\mathrm{s}}_{24}{\mathrm{S}\mathrm{e}}_{64.5}$$ PCF can reach as high as $$0.03$$ when compared with the conventional fiber that has merely $$5\times {10}^{-4}$$ for wavelengths in the 2–10 $$\upmu \mathrm{m}$$ range. The PCF is designed with zero-dispersion wavelengths for x- and y-polarized modes in the 2–10 $$\upmu \mathrm{m}$$ range. It is also observed that over the entire MIR wavelength range, the GVD remains positive and has a maximum value of 30,000 ps2/nm-km. Hence, the proposed $${\mathrm{G}\mathrm{e}}_{11.5}{\mathrm{A}\mathrm{s}}_{24}{\mathrm{S}\mathrm{e}}_{64.5}$$ PCF plays the dual role of acting as a very good polarization-maintaining fiber due to its very high birefringence and an excellent dispersion-compensating fiber due to its large positive GVD. This $${\mathrm{G}\mathrm{e}}_{11.5}{\mathrm{A}\mathrm{s}}_{24}{\mathrm{S}\mathrm{e}}_{64.5}$$ PCF serves as a very good candidate for ultra-broadband high bit-rate transmission. Supercontinuum generation is another important application of PCF. Supercontinuum generation is a generation of coherent and broadband light. SC generation in PCFs has several applications in optical coherence tomography (OCT), optical frequency metrology (OFM), pulse compression, and design of ultrafast femtosecond laser pulses.

Best candidate integrated technology for low‐noise, high‐speed, and wide bandwidth‐based transimpedance amplifiers in optical computing systems and optical fiber applications

SummaryThis paper presents the best candidate integrated technology for achieving low‐noise, high‐speed, and wide bandwidth transimpedance amplifiers in optical computing and communication systems. Different complementary metal oxide semiconductor (CMOS) technology sizes are employed in addition to high electron mobility transistor (HEMT), bipolar CMOS (BiCMOS), and gallium arsenide technologies‐based transimpedance amplifiers to achieve high‐speed capability with low noise. These different technologies are applied on two proposed models to test the performance parameters. Maximum output signal voltage, maximum RF power spectrum, received output power, maximum Q‐factor, and minimum bit error rate are the tradeoff parameters for two proposed models at high transmission bit rates up to 400 Gb/s. It is observed that 600‐nm CMOS technology has presented the best candidate to deal with high transmission bit rates because of its superior performances in either the first proposed model or the second proposed model compared with other technologies under study. Figure of merit is applied on two proposed models and previous works to show the high‐speed performance operation of transimpedance amplifiers in our proposed models. The signal is tested before and after transimpedance amplifiers in different technologies.

Suitable Optical Fiber Communication Channel for Optical Nonlinearity Signal Processing in High Optical Data Rate Systems

Our research presents best candidate different commercial optical fiber communication channel for optical nonlinearity signal processing in high optical transmission bit rate systems in the presence of traveling wave semiconductor optical amplifier (TW-OSA). These optical fibers that are namely dispersion flattened fiber (DFF), reverse dispersion fiber (RDF), non zero dispersion shifted fiber, dispersion compensated fiber, single mode fiber, and hybrid RDF + DFF. Wavelength division multiplexing (WDM) system is employed to benefit 80 users with the high transmission bit rates up to 160 Gb/s over optical fiber communication channel length up to 200 km with trying to reduce nonlinearity effects by choosing suitable channel spacing and first or second order Bessel, Gaussian WDM Mux./Demux filter. Maximum peak power, optical signal to noise ratio, and signal quality factor can be measured to test the system performance. It is evident that RDF and hybrid RDF + DFF has presented the highest signal quality factor and optical nonlinearity signal processing in compared with other optical fibers communication channel. The obtained results were done using optiwave system software simulation version 7.

Bidirectional Amplification Technique and AcoustoOptic Filter for Upgrading Ultra-High Capacity Optical Transmission Systems

This paper presents high transmission bit rate based on both bidirectional erbium doped fiber amplifiers (EDFAs) and acousto-optic filters using different modulation coding techniques. The performance parameters such as gain flatness, Quality factor, bit error rate, output power, gain with and without acousto-optic filters with EDFA length variation, core radius, pumping power, pumping wavelength, ion density, doping radius, numerical aperture and ambient temperature can be measured. The optimum values for the maximum gain flatness can be obtained with the best modulation format and different number of channels.

Millimeter-Wave Transmission for Small-Cell Backhaul in Dense Urban Environment: a Solution Based on MIMO-OFDM and Space-Time Shift Keying (STSK)

Next generation wireless standards will exploit the wide bandwidth available at the millimeter-wave (mm-Wave) frequencies, in particular the $E$ -band (71–76 and 81–86 GHz). This large available bandwidth may be converted into multi-gigabit capacity, when efficient and computationally affordable transceivers are designed to cope with the constrained power budget, the clustered fading, and the high level of phase noise, which actually characterize mm-wave connections. In this paper, we propose a viable multiple-input multiple-output (MIMO) solution for high bit-rate transmission in the $E$ -band with application to small-cell backhaul based on space-time shift keying (STSK) and orthogonal frequency division multiplexing. STSK provides an efficient tradeoff between diversity and multiplexing without inter-channel interference and without the need for large antenna arrays. These features make STSK theoretically preferable over other throughput-oriented space-time coding techniques, namely, spatial multiplexing and spatial modulation, which were recently considered in the literature for mm-wave MIMO applications. In this paper, we consider the most significant channel impairments related to small-cell backhaul in dense urban environment, namely, the correlated fading with and without the presence the line-of-sight, the phase noise, the rain attenuation, and shadowing. In addition, we consider small-size MIMO systems ( $2 \times 2$ and $4 \times 4$ ), and low-cost base station equipments in the perspective of easily deployable small-cell network components. Comparative results, obtained by intensive simulations targeted at assessing link performance and coverage, have clearly shown the superior performance of STSK against counterpart techniques, although obtained at the cost of a somewhat reduced spectral efficiency.

Measurements of polarization mode dispersion on aerial optical cables: Theory and experiments

Higher bit-rate transmission is attractive for improving network resource efficiency and reducing the complexity of network management in future transmission systems. However, chromatic dispersion and Polarization Mode Dispersion (PMD) are one of the most serious impairments. In particular, PMD changes rapidly according to environmental variations such as temperature change and mechanical vibration. This study presents PMD measurements in a mixed aerial and buried optical longhaul network. PMD was measured as a part of a thorough analysis, in order to assess the possibility of deploying, in this actual route, a DWDM network based on 10Gb/s and 40 Gb/s carriers long haul network based on DWDM technology PMD was measured as a part of the previous analysis, in order to assess the possibility of deploying routes based on 10Gb/s carriers and on 40Gb/s carriers. Changes of PMD were mainly introduced by external factors (such as temperature), but also by changes in the wind speed that significantly contributed to changes in Differential Group Delay (DGD), causing side-effects such as bending, transverse pressure or twists on the fiber hauls. In this study we will focus on the effects over PMD caused by the wind speed and its relevant impact on the aerial hauls, where the influence is significant. A quantitative comparison between data obtained from real measurements and data obtained from analytical approaches will be established.

Energy Minimization for Wireless Video Transmissions With Deadline and Reliability Constraints

In wireless video transmissions, encoded video frames are often large in data load and truncated into many transport packets (TPs) for reliable transmissions. These TPs are to be delivered before a deadline at certain reliability that depends on the importance of the video frame. High power and bitrate transmission schemes are often deployed to ensure low loss rate, but at the cost of substantial energy consumption. This paper addresses the energy-minimizing transmission policy for highly reliable transmissions of a group of TP with a common deadline. We jointly adapt the transmission rate, transmission power, and retransmission limit to minimize the transmission energy while ensuring that the video frame is reliably delivered before a deadline. In a slow fading channel, we formulate a deterministic transmission policy that allocates a retransmission limit to the TPs and jointly optimizes with the transmission bitrate and power. Contrary to the intuition that avoids packet loss and retransmission to preserve energy, we demonstrate that allowing some retransmissions in the joint optimization consumes less energy, without compromising the target reliability. In a Rayleigh fading channel, a conventional approach adopts a supportable transmission rate and declares off-channel at deep fading. We generalize the approach to include various transmission schemes at different fading states and propose the probabilistic combination of these schemes. Given the fading statistics and a channel state, our policy determines to pause or to deploy a proper transmission scheme such that the video frame transmission is energy minimized, timely, and highly reliable. Extensive simulations confirm that the proposed transmission policies consume less energy than existing methods. In particular, when the deadline or the target reliability are tightened, the proposed policies yield even higher energy efficiency.

Optical Add Drop Multiplexer (OADM) Based on Dense Wavelength Division Multiplexing Technology in Next Generation Optical Networks

The OADM based on DWDM technology is moving the telecommunications industry significantly closer to the development of optical networks. The OADM can be placed between two end terminals along any route and be substituted for an optical amplifier. Commercially available OADMs allow carriers to drop and/or add up to multi channels between DWDM terminals. By deploying an OADM instead of an optical amplifier, service providers can gain flexibility to distribute revenue–generating traffic and reduce costs associated with deploying end terminals at low traffic areas along a route. The OADM is especially well-suited for meshed or branched network configurations, as well as for ring architectures used to enhance survivability. Moreover, An optical add/drop multiplexer with tunable bandwidth offers several potential advantages, including optical performance monitoring and dynamic bandwidth allocation. This paper has proposed OADM for high transmission bit rates and products in next generation optical communication networks based on dense wavelength division multiplexing for different fiber link lengths at room temperature for best performance efficiency.

Ultra low loss of a thermal arrayed waveguide grating (AWG) module in passive optical networks

In the present paper, high transmission bit rate of a thermal arrayed waveguide grating (AWG) which is composed of lithium niobate (LiNbO3)/polymethyl metha acrylate (PMMA) hybrid materials on a silicon substrate in passive optical networks (PONs) has parametrically analyzed and investigated over wide range of the affecting parameters. We have theoretically investigated the temperature dependent wavelength shift of the arrayed waveguide grating (AWG) depends on the refractive-indices of the materials and the size of the waveguide. A thermalization of the AWG can be realized by selecting proper values of the material and structural parameters of the device. Moreover, we have analyzed the data transmission bit rate of a thermal AWG in passsive optical networks (PONs) based on maximum time division multiplexing (MTDM) technique. Key words: Passive optical networks (PONs), arrayed waveguide gratings (AWGs), integrated optics, optical planar waveguide, optical fiber communications, maximum time division multiplexing (MTDM) technique.

Ultra‐wideband GCPW‐MS‐GCPW driven electrode for low‐cost and wide range application electro‐optic modulators

AbstractElectro‐optic modulators are key components in high bit‐rate optical transmissions. Decreasing the manufacturing cost without damage on performances is one of the most challenging issues for such components. We demonstrate that the electro‐optic modulators based on polymer are compatible with high bandwidth requirements. Indeed, according to the results obtained by numerical simulation and partly validated by experiments, with the via‐free GCPW‐MS‐GCPW electrodes proposed and analyzed in this article, the (400 MHz–67 GHz) bandwidth is achievable with electro‐optic modulators based on suitable polymers. These encouraging results are very useful for low‐cost mass production of polymer‐based electro‐optic modulators for a wide range of applications: digital and analogue high bit‐rate transmissions.© 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1078–1082, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25112

Technologies and standards forTD-SCDMA evolutions to IMT-advanced

The current TD-SCDMA commercialization in China brings about many issues concerning the implementation of TD-SCDMA technology, the market, and its applications. In order to make TD-SCDMA successful, evolution from the current TD-SCDMA standards to international mobile telecommunications-advanced are anticipated. TD-SCDMA standards and technologies will take a home-made evolution path in China, aiming at a smooth migration to the next-generation mobile communication system. This article provides a brief description of the evolution strategies of both the standards and key technologies, in which the evolution is divided into three phases. The state of the art of TD-SCDMA evolution is surveyed, and its technologies and standards in different evolution phases are characterized. Single- and multi-carrier high-speed packet access is specified in the first evolution phase for guaranteeing the high transmission bit rate of packet services. Meanwhile, broadcast services are supported, and the HSPA evolution is also incorporated in this phase. Long term evolution is defined in the second evolution phase for approaching similar performance as mobile WiMAX, where channel-reciprocity- based multiple antenna techniques are utilized. The last phase is the revolution to the IMT-Advanced system and becoming one alternative standard in beyond 3G systems, which is based on the evolution of TD-LTE. The difference of standardizations between 3GPP and local standard releases are introduced. Some challenging work and open issues in different evolution phases are discussed as well.

High performance InP-based quantum dash semiconductor mode-locked lasers for optical communications

Several applications are pushing the development of high performance mode-locked lasers: generation of short pulses for extremely high bit rate transmission at 100 Gb-s and beyond, all-optical cloc...

160 Gb/s-Based Field Transmission Experiments Using Polarizer-Based PMD Compensator With Optical Power Monitor

Higher bit-rate transmission is attractive for improving network resource efficiency and reducing the complexity of network management in future transmission systems. However, chromatic dispersion and polarization mode dispersion (PMD) are one of the most serious impairments. In particular, PMD should be compensated for dynamically because it changes rapidly according to environmental variations such as temperature change and mechanical vibration. Therefore, an adaptive PMD compensator is indispensable for higher bit-rate transmission systems. In this paper, we employed a simple and bit-rate independent PMD compensator based on a polarizer with an optical power monitoring scheme in 160 Gb/s-based field experiments. By using the PMD compensator, the single channel transmission of a 160 Gb/s return-to-zero differential phase-shift-keying modulation signal over an installed fiber link with buried and aerial cable routes was successfully achieved. Approximately 1 dB of Q-factor was improved by using the PMD compensator when PMD impairment was maximized. Through these experiments, the effectiveness of the PMD compensator in the higher bit-rate transmission systems was confirmed in the field environment. Furthermore, single-polarization 8times160 Gb/s wavelength division multiplexing transmission over the installed 200 km standard single mode fiber without polarization demultiplexing was successfully achieved by using the simple PMD compensator.

SUPPRESSION OF SOLITON TIMING JITTERS BY PERIODIC OPTICAL PHASE CONJUGATIONS AND OPTICAL FILTERS

We propose a new method for suppressing the timing jitters of soliton pulses by using periodic phase conjugations and optical spectral filters in a high bit-rate transmission system. It is proven that the tolerable transmission distance limited by timing jitters can be increased through modulating frequency shifts by optical phase conjugators and eliminating the interaction between dispersive waves and the central pulses by optical filters. Our results also show that the optical-phase-conjugated soliton with spectral filters is superior to the common soliton in suppressing polarization mode dispersion induced by random birefringence. The physical mechanisms of soliton timing jitters are analyzed.