Digital Subscriber Line Research Articles

Data Communication Over Power-lines: A Review on Technical, and Applications Challenges

This paper presents a review study on the data communication over power-lines, commonly referred to as power-line carrier, power-line communication (PLC), mains communications, or power-line digital subscriber line (PDSL). This study examines the technical and application advantages and challenges associated with adopting PLC as a preferred alternative technology for wideband or broadband data communication. The broader coverage area of the PLC network gives it a distinct advantage over other communication network technologies. Additionally, implementing a communication system using the existing power-line network is more cost-effective and less time-consuming compared to constructing a new network from scratch. However, the primary challenge lies in the fact that the power-line network is primarily designed for the distribution of electrical power within the frequency range of 50-60 Hz including the harmonics. This poses various obstacles such as electrical noise from appliances, signal distortions caused by the unregulated nature of the wiring, transformer bypassing, interference from high-frequency modulation, and variations in characteristic impedances, among others. Despite these challenges, the emergence of robust modulation techniques like Orthogonal Frequency Division Multiplexing (OFDM) and Direct-Sequence Spread Spectrum (DSSS), along with the development of Application-Specific Integrated Circuit (ASIC) density with improved processing speeds, as well as advancements in signal processing and error control coding techniques, have made the PLC network the most promising telecommunications access network.

The Perspective of Metallic Access Networks Based on MELT Parameter Measurements on Homogeneous Symmetric Lines

In this paper, attention is focused on the perspective of metallic access networks utilizing homogeneous symmetric lines as a transmission medium. This miscellaneous environment has a strong influence on transmitted Digital Subscriber Line (DSL) signals and hence it is necessary to know its specific parameters in the given case. Fast and precise measurements on homogeneous symmetric lines are still essential, meaningful and imperative for many reasons: solving interference problems, designing advanced signal processing techniques and realizing appropriate simulation models. There are various ways of testing measurements with meaningful differences. In this contribution, we are focusing on the importance of measurements on homogeneous symmetric lines by means of metallic ended line testing. Subsequently, possibilities for new evaluation techniques for Metallic Ended Line Testing (MELT) parameters and for analyzing of DSL service provision are presented. Additionally, the realization of a mobile application functionality for facilitating the jobs of technicians is introduced, together with the possible availability of homogeneous symmetric lines for DSL service provision.

Analysis of the Radiation from a Complex Multi-Conductor Transmission Line

The Deployment of Power Line Transmission (PLT) and the development of new broadband services over the telephone network through technology like xDSL (x Digital Subscriber Line), requires higher data rates, consequently higher bandwidths, and operating frequencies. So it is generally accompanied with electromagnetic compatibility (EMC) phenomena, in particular the radiated emissions associated to the deployed system and used cables characteristics. In fact the electrical cable presents variations in their geometry, causing an increase in the electromagnetic radiation. This paper presents a theoretical approach to study a complex transmission line network over ground plane. This approach leads to an analytical expression for the evaluation of P.U.L. parameters of finite length twisted wires lines. These expressions give the capacitances and the inductances values in every point of the cable, the theoretical results are compared to measurements. The formalism is also derived to determine the distribution of the electromagnetic field radiated by Shielded or Unshielded Twisted Pair cables with discontinuity. The obtained results are compared to those provided by a code based on the antenna theory.

Dynamic Spectrum Management in DSL With Asynchronous Crosstalk

In this paper we focus on discrete multitone (DMT) dynamic spectrum management (DSM) in digital subscriber lines (DSL) networks with asynchronous crosstalk. DSM aims to optimally allocate per-user transmit spectra so that the effect of multi-user crosstalk is minimized and the capabilities of the network maximized. Most DSM solutions so far address an idealized situation, one in which all users DMT blocks in the network are perfectly synchronized and crosstalk is dealt with on a per-tone basis. We focus on the case in which the DMT blocks of the various users are offset amongst each other, which leads to inter-carrier interference (ICI). ICI significantly impacts the performance of the system and complicates the DSM optimization problem considerably, as the per-tone decoupling used for the synchronous case is no longer directly applicable. Our contribution is twofold: First, we derive a new and accurate model for the effect of the ICI; Second, we provide a novel DMT DSM algorithm that outperforms the existing state-of-the-art.

Per-Wavelet Equalization for Discrete Wavelet Transform Based Multi-Carrier Modulation Systems

The Discrete Wavelet Transform (DWT) has gained attention in the area of Multi-Carrier Modulation (MCM) because it can overcome some well known limitations of Discrete Fourier Transform (DFT) based MCM systems. Its improved spectral containment removes the need for a cyclic prefix, be it that appropriate equalization then has to be added as the cyclic convolution property no longer holds. Most DWT based MCM systems in the literature use Time-domain EQualizers (TEQs) to mitigate the channel distortion. In this paper, a Per-Wavelet EQualizer (PWEQ) is proposed which directly maximizes the Signal-to-Interference-plus-Noise Ratio (SINR) per symbol and is applicable to any wavelet family. The proposed PWEQ provides a performance upper bound for the TEQs for DWT based MCM systems. The computational complexity of the PWEQ is reduced by modifying the Filter Bank (FB) structure of the DWT. Simulations are performed to compare the PWEQ performance against the TEQs for DWT based MCM systems and the similar Per-Tone EQualizer (PTEQ) for DFT based MCM systems. The simulations are performed using measured Asymmetric Digital Subscriber Line (ADSL) and G.fast channels with Fejér-Korovkin (FK) wavelets. The proposed PWEQ increases the SINR on the received symbols compared to the TEQs at the cost of an increased computational complexity.

EFFICIENCY OF TELECOMMUNICATION SYSTEMS TRANSMISSION OF FIXED BROADBAND ACCESS THROUGH TELEPHONE CABLES

The article provides an assessment of the efficiency of transmission data systems by digital subscriber lines of fixed broadband access over multi-pair telephone cables using the transient interference compensation system “vectoring” between transmission systems. A technique for calculating the signal-to-noise ratio at the receiver input is proposed, which takes into account frequency characteristics and additive interference of lines, uncompensated transient interference between mutually influencing transmission systems, and the limitation of the power of transmitted signals associated with the normalization of the transmitter power, caused by the use of the “vectoring” system. The effectiveness of transmission systems with the help of the transient interference compensation system “vectoring” is evaluated by broadband access network models using G.fast technology when using a multi-pair telephone cable of the TPP type with the number of pairs up to 100 in the frequency range up to 106 MHz and line lengths up to 250 meters. The achievable transmission speed is estimated depending on the characteristics of subscriber lines, the number of parallel operating transmission systems and the limitation of the transmitted signal power. It was determined that the main reason for limiting the achievable speed of information transmission when using the “vectoring” system is the frequency characteristics and additive interference of subscriber lines, uncompensated transient interference and limitation of the power of the transmitted signal. The proposed method of evaluating the signal/noise ratio and the achievable speed of data transmission with vectoring transient interference compensation systems can be applied in the tasks of designing and building fixed broadband access networks that use multi-pair telephone cables and twisted pair cables as a transmission medium.

Technoeconomic assessment of an FTTH network investment in the Greek telecommunications market

Recent years have seen an increasing need for higher broadband connections, fueled by novel applications including fifth generation wireless networks (5G). The European Commission is working on achieving specific milestones regarding the development of next generation networks. Many EU countries have opted to adopt a gradual migration path towards the Fiber-to-the-Home (FTTH) technology in view of the high costs of implementation. The Fiber-to-the-Cabinet (FTTC) architecture, combined with very-high-bit-rate digital subscriber line 2 (VDSL2) and vectoring noise cancellation techniques may therefore provide a viable short-term basis solution. Techno-economic modeling and assessment is vital at the initial stages of the development of a telecommunication network investment project involving high capital expenditures for the infrastructure. The present work provides a techno-economic model in order to assess the prospects of such a network upgrade project from a financial perspective, following a three-way migration path. The three stages are: the implementation of the FTTC architecture with VDSL2 vectoring technology, the upgrade to FTTC with G.Fast and finally the migration to FTTH. The analysis is implemented over a suburb of the city of Athens, Greece. Different scenarios are evaluated, predicting profits even from the first years following the investment. The analysis includes the estimation of the degree of market penetration, analytical cost calculations for the implementation and operation of the network and the evaluation of crucial financial indicators, regarding the prospects of the investment in vectoring services. The study can serve as a complete road-map and can be applied in similar upgrade scenarios. The most important outcome of the analysis is that the profits resulted from each upgrade will finance the next step.

Fundamentals of SD WAN Communication Technologies

Let us take a look at these new high-tech communications and how they shape the industry. Local area-defined software is a software system that manages wide area networks, provides ease of use, single site management and minimizes the cost, and can enhance communication with branch offices and the cloud. There are been some changes in local networks nothing has been more relevant than software-defined WAN or SD-WAN, which changes the way network professionals think about improving multimedia connectivity such as changing the Multi-protocol label. (MPLS), independent transfer and Digital Subscriber Line (DSL). The separation of hardware and control plane is similar to how software-defined networks use visual technology to improve the management and operation of their data centers. In fact, SD-WAN are set up and managed using proprietary protocols such as Cisco iOS. That is less hardware and less control over the hardware. A leading SD-WAN application that enables organizations to build highly efficient WANs with cost-effective turnkey Internet access. This allows organizations to phase out or completely replace low-cost WAN communication technologies such as MPLS. So customers can easily manage their network regardless of the connection provider. SD-WAN is currently one of the hottest topics with a real impact on CC services and WAN environment. SD-WAN it affects the way we think about how we use the web services yet. More importantly, it has great potential to change the way we use Communication Services in future. There are several industries that are interesting SD-WAN deployment conditions.

California’s digital divide and the specter of data uncertainty for evaluating broadband coverage

The digital divide is a persistent feature in the United States. While most Americans have access to some form of broadband internet connection, the bandwidth, quality of service (QoS), and choice of providers remain highly variable throughout the country. For example, while the residents of many urban areas can choose between gigabit fiber, cable, or digital subscriber line connections from multiple providers, residents in rural areas often suffer from limited platform and provider choices. A fundamental problem with developing effective public policy for broadband in the U.S. is the lack of reliable data for estimating the geographic coverage of broadband service. This paper aims to highlight how data uncertainty can negatively impact coverage estimations in subtle and not-so-subtle ways. The state of California serves as our study area. This paper suggests a combination of uncertain broadband data combined with Census data errors co-mingle to create a variable snapshot of local broadband provision and geographic coverage. We provide several strategies for dealing with these uncertainties to improve the evaluation of broadband in California and the United States.

Effects of Market Structure on Broadband Quality in Local U.S. Residential Service Markets

ABSTRACT Does entry and exit of competitors from broadband services markets have large effects on the quality of broadband plans offered to consumers? Answers to this question inform design of subsidies to improved broadband in underserved areas, and antitrust policy. The authors investigate quality effects of entry (or exit) in 2014 legacy (cable and digital subscriber line) duopoly residential markets. Entry or exit by legacy technology providers had large impacts on 2018 service quality, though impacts diminished rapidly with continued entry. Entry by a single fiber Internet service provider (ISP) had no impact on available quality; entry by more fiber ISPs had modest but statistically significant effects.

Twisted Pair Cable Fault Diagnosis via Random Forest Machine Learning

Applying the fault diagnosis techniques to twisted pair copper cable is beneficial to improve the stability and reliability of internet access in Digital Subscriber Line (DSL) Access Network System. The network performance depends on the occurrence of cable fault along the copper cable. Currently, most of the telecommunication providers monitor the network performance degradation hence troubleshoot the present of the fault by using commercial test gear on-site, which may be resolved using data analytics and machine learning algorithm. This paper presents a fault diagnosis method for twisted pair cable fault detection based on knowledge-based and data-driven machine learning methods. The DSL Access Network is emulated in the laboratory to accommodate VDSL2 Technology with various types of cable fault along the cable distance between 100 m to 1200 m. Firstly, the line operation parameters and loop line testing parameters are collected and used to analyze. Secondly, the feature transformation, a knowledge-based method, is utilized to pre-process the fault data. Then, the random forests algorithms (RFs), a data-driven method, are adopted to train the fault diagnosis classifier and regression algorithm with the processed fault data. Finally, the proposed fault diagnosis method is used to detect and locate the cable fault in the DSL Access Network System. The results show that the cable fault detection has an accuracy of more than 97%, with less minimum absolute error in cable fault localization of less than 11%. The proposed algorithm may assist the telecommunication service provider to initiate automated cable faults identification and troubleshooting in the DSL Access Network System.

Broadband Speeds in Fibered us Markets: An Empirical Analysis

ABSTRACT Broadband deployment policies have directly subsidized fiber providers because fiber broadband delivers fast download speeds. This article examines whether recent fiber buildout has increased competition for Asymmetric Digital Subscriber Lines (aDSL) and cable incumbents and whether entry by a fiber competitor predicts faster incumbent download speeds. Despite significant growth in fiber broadband service in the United States between 2014 and 2019, the number of fiber competitors in census blocks with aDSL or cable incumbents remains low. Further, our econometric results, while not interpretable as causal relationships, suggest that the entry of a rival fiber operator does not explain recent increases in cable and aDSL speeds.

Cable fault classification in ADSL copper access network using machine learning

Asymmetrical Digital Subscriber Line (ADSL) is the technology widely deployed worldwide, but its performance may be limited with respect to its intrinsic. The nature of the copper cable causes it to be more susceptible to signal degradation and faulty line. Common ADSL line faults are short-wired fault, open-wired fault, bridge taps, and uneven pair. However, ADSL technology is still one of the most established networks, and users in the suburban area still depend on the technology to access the internet service. This paper discussed and compared a machine learning algorithm based on Decision Trees (J48), K-Nearest Neighbor, Multi-level Perceptron, Naïve Bayes, Random Forest, and Sequential Minimal Optimization (SMO) for ADSL line impairment that affects the line operation performance concerning their percentage of accuracy. Resulting from classifications done using algorithms as mentioned above, the random forest algorithm gives the highest overall accuracy for the ADSL line impairment dataset. The best algorithm for classifying DSL line impairment is chosen based on the highest accuracy percentage. The accomplishment classification of fault type in the ADSL copper access network project may benefit the telecommunication network provider by remotely assessing the network condition rather than on-site.

On impropriety for a large-sized discrete fourier transform of a real-valued stationary process

It is known that a finite-sized discrete Fourier transform (DFT) of a real-valued colored stationary random process results in improperly distributed complex random variables in the frequency domain. It is also well-known that a large-sized DFT of a colored random process approximates the behavior of the Karhunen–Loève (KL) transform, in terms of achieving approximate decorrelation between the frequency domain terms. We show that this decorrelating behavior also manifests itself in terms of the approximate complex circular (proper) nature of the majority of the transform domain terms, except near the band edges, where the nature of the complex distribution may be non-circular. We derive an analytical result relating the DFT size with the degree of impropriety, and also demonstrate the same via simulations. The result is important in the context of wideband xDSL (Digital Subscriber Line) discrete multi-tone (DMT) receivers affected by extraneous spectrally colored noise sources, besides being of general interest.

Comparative Examination of CO-OFDM Formats for Varied Fiber-Length and Bit Rate

The use of multiple carriers in Orthogonal Frequency Division Modulation (OFDM) makes it bandwidth-efficient and suitable for modern communication such as Long-Term Evolution (LTE), Digital Subscriber Line (DSL) internet access, optical fiber communication, digital television, audio broadcasting, etc. In this paper, four modulation formats by using Coherent Optical Orthogonal Frequency Division Modulations (CO-OFDM) have been analyzed. These are Single Port Dual Polarization (SP DP) 16 QAM, Single-Port Single Polarization (SP SP) 16 QAM, Dual Port Single Polarization (DP SP) QPSK 16-QAM, and Single Port Dual Polarization (SP DP) QPSK. Operation characteristics such as Bit Error Rate (BER) versus fiber-length and BER versus bit-rate have been examined. The range of fiber length used for this investigation is from 0 Km to 1000 Km with loop count equal to 2 and the range of bit rate of operation is from 20 Gbps to 200 Gbps. The present investigation helps in determining the relative suitability of CO-OFDM formats at various bit-rates of operation for different fiber lengths.

Влияние нестационарных помех в анализе информационных моделей с модуляцией с одной и несколькими несущими

The aim of the study is to try to analyze the most common mechanisms of impulse noise impact on data transmitted in the symbols of single-carrier and multi-carrier modulation systems. The paper solves the problem of a qualitative analysis of the destructive effect of impulse noise on the possibility of restoring symbols of digital modulation systems operating on the basis of a copper cable infrastructure. The performed analysis uses induction as research methods, which allows extending isolated special cases of symbol distortion to the generalized procedures for degrading the transmitted information quality; an analogy involving the consideration of similar mechanisms for modifying data in a stream of modulated signals with one carrier and multiple ones. The novelty of the findings obtained consists in generalizing the process of decoding errors due to noise bursts to the systems with one carrier and several ones, as well as in differentiating the influence of the noise pulse duration and power on the transmitted symbols. As the main findings of the work, we can note the identification of the impact ambiguity of impulse noise on the transmission systems of digital subscriber lines, expressed in the necessity to take into account while analyzing both the parameters of the noise itself and the type of modulation, and the energy and time relationships between the useful signal and noise. Thus, the work shows that the destructiveness degree of the impulse noise impact on the transmission system of a digital subscriber line is determined by several characteristics that should be taken into account when developing mechanisms for the protection against interference, or, conversely, to justify the inappropriateness of their use.

Wi-Fi for Affordable Broadband & 5G in Rural Areas

The importance of Internet in our lives today cannot be overemphasized. So much so that access to Internet has been declared a fundamental right of citizens in several countries such as Finland, Spain, and Greece [1]. In most of the developed countries, high-speed Internet connectivity is enabled through wired communication infrastructure such as Fiber-to-the-Home (FTTH) and Very high bit-rate Digital Subscriber Line (VDSL). Unfortunately, the situation is not particularly encouraging in developing countries due to non-availability of such a pervasive communication infrastructure. The difference in the fiber-deployed-to-population ratio across developed and developing countries further underscores this disparity; while this ratio is 1.2 in USA, it is barely 0.1 in India [2]. Owing to this inadequacy of fiber/DSL availability, cellular access technology has emerged as the primary broadband access mechanism in developing countries.
 However, the penetration of cellular network is limited in rural areas as its deployment becomes unviable due to challenges such as low average revenue per user, sparse population density, and intermittent availability of electricity. This situation leaves majority of the rural people unconnected thereby creating a massive rural urban digital divide. The next generation cellular system along with the use of unlicensed Wi-Fi Technology can bridge this divide if we overcome the above-mentioned challenges. However, since the Fifth Generation (5G) cellular technology has focus on requirements such as 10 Gbps data rate, 1 ms latency, and very high speed mobility, the problems of coverage and affordability are likely to persist, further widening the digital divide [3]. This article explains how Wi-Fi is being used for affordable high speed broadband in rural areas. A successfully implemented case study of Jharkhand state is also presented, and it can be adopted as reliable business model for 5G or 5G type services in rural areas [4].

Determining of Optimal Telemedicine Communication Technologies with Regards to Network Interactive Modes: A Delphi Survey

Introduction: Different communication services with varying bandwidth are used to send information in the form of telemedicine technology. Bandwidth management, as defined in telemedicine technology, refers to using the desirable communication services according to the type of transaction and the information size to be transferred. Selection of communication services must be in such a way to result in minimum latency in the process of sending information and maintaining maximum cost-effectiveness.Material and Methods: This is an applied research which was conducted in 2019 by questionnaire survey amongst 60 participants, specialized in health information technology and medical informatics, who are working in hospitals and educational institutions of Tehran. Likert rating scale was used to quantify the research questions. Finally, by analyzing each weighted average, this study revealed the desirable communication services that correspond to the required transactions for deployment of telemedicine.Results: Transfer of multimedia information, using synchronized teleconferencing via primary low bandwidth technologies, had the lowest number average (0.96) and transmission of hybrid data (combination of picture, text, multimedia templates in synchronized or asynchronized modes) via Asymmetric Digital Subscriber Line (ADSL) technology had the highest average (4.96).Conclusion: Selection of communication services, with regard to its convergence with the information size and the type of their application, plays a significant role in controlling network traffic and preventing latency in the process of sending information in the context of telemedicine technology. High bandwidth communication services should be used for those telemedicine systems, which are offering services to many users, as well as those in which real-time transmission of information is essential. It needs to be pointed out that with regard to the cost-effectiveness of sending information, it is necessary to use low-cost services with low bandwidth for transfer of light weight information as well as for asynchronous applications in which latency in the process of information transfer is not detrimental.

Low‐complexity receivers for massive MIMO‐GFDM communications

AbstractThe orthogonal frequency division multiplexing (OFDM)‐based modulation scheme is widely utilized in asymmetric digital subscriber lines (ADSL), wireless local area networks (WLAN), and the fourth generation (4G) of mobile communication systems due to its ability to cope with severe channel conditions without complex equalization processes. However, the drawbacks of OFDM such as: requirement of a high peak to average power ratio (PAPR) radio frequency (RF) power amplifier, sensitive to carrier frequency offset, high out‐of‐band (OOB) emissions cause the OFDM is not applicable for the fifth generation (5G) mobile communication application scenarios such as machine‐type communications (MTC), Internet of things (IoT), and cognitive radio (CR). Generalized Frequency Division Multiplexing (GFDM) modulation scheme has regarded as one of the promising candidates for 5G waveforms due to its properties, such as low latency, low OOB emission, robust against carrier frequency offset (CFO), and time offset (TO). The GFDM is also combined with massive multiple‐input multiple‐output (MIMO) technology that equipping each base station (BS) with an array of many active antennas, which are used to spatially multiplex many user equipment (UE) to improve spectrum efficiency (SE). However, as the modulation order and the number of antennas increases, the complexity of the maximum likelihood (ML) detector and the minimum‐mean‐square‐error (MMSE) detector causes an impediment for real‐world applications. This paper proposes a low‐complexity detector configuration which utilizes quadratic programming principle. The simulations show that the computation complexity of the proposed detector is lower than the ML detector and the bit‐error‐rate performance of the proposed detector is better than that of the MMSE detector.

Price of Fairness in Digital Subscriber Line Systems Using Dynamic Spectrum Management

Bit rate fairness is an important concern in current G.fast and the forthcoming fifth generation DSL systems where the frequency is extended to hundreds of MHz and crosstalk couplings reach unprecedented levels. In this paper, we study the price of fairness (PoF) in dynamic spectrum management (DSM) enabled DSL systems. We propose optimal low complexity PoF-constrained max-min fairness (MMF), weighted max-min fairness (WMMF), proportional fairness (PF), and (p,α)-PF algorithms. The proposed algorithms inherently provide weight factors which can be used to reduce the computational complexity of user encoding or decoding order optimizing algorithms used in nonlinear vectoring. Our simulation results show that although PoF grows exponentially with the minimum bit rate, fairness can be improved considerably with a relatively small price in DSM level 2 spectrum balancing and particularly in DSM level 3 using minimum mean square error (MMSE) generalized decision feedback equalizer (GDFE). It is also seen that the proposed optimal PoF-constrained MMF algorithm can reach the solutions of PF and (p,α)-PF measures for some PoF. That is, the PoF-constrained MMF or WMMF algorithms can be used instead of the non-linear PF and (p,α)-PF measures, which often result in computationally intensive solutions.