ITU-T Asymmetric digital subscriber line transceivers 2 (ADSL2

EURASIP Journal on Advances in Signal Processing, 2006

The recent deployment of digital subscriber line (DSL) technology around the world is rapidly making broadband access for the mass consumer market a reality. The ever-growing customer demand for higher data rates has been fueled by the popularity of applications like peer-to-peer (P2P) filesharing networks and video-streaming and high-definition television (HDTV). DSL technology allows telephone operators to get maximum leverage out of their existing infrastructure by delivering broadband access over existing twistedpair telephone lines. At the heart of DSL lies a plethora of signal processing techniques which enable such high-speed transmission to be achieved over a medium originally designed with only voice-band transmission in mind. These advanced signal processing techniques address many challenges that exist in DSL networks today, such as the near-end and far-end crosstalk (NEXT/FEXT), impulse noise, peak-toaverage-power ratio (PAR), intersymbol and intercarrier interference (ISI/ICI), radio-frequency interference (RFI), and so forth. The goal of this special issue is to discuss the stateof-the-art and recent advances in signal processing techniques for DSL.

Automatika : časopis za automatiku, mjerenje, elektroniku, računarstvo i komunikacije, 2006

In this paper the Asymmetric Digital Subscriber Line (ADSL) analog front end (AFE) designs are described and compared. AFE is the part of ADSL modems most responsible for quality signal transmission over phone wires. It can be divided into the transmitting path (TX) circuitry, the receiving path (RX) circuitry and the hybrid network and transformer. The operations and realizations of each functional block are presented. There are the D/A converter, the filter and the line driver in the TX path and the voltage gain amplifier, the filter and the A/D converter in the RX path. The hybrid network and transformer process signals in both directions. Different fabrication technologies are used for the practical realizations of the AFE chip. The directions of the further developing are notified.

Bell System Technical Journal, 61: 6. July-August 1982 pp 1003-1077.

To investigate the feasibility of transmitting data bidirectionally between 56 and 144 kb/s, an extensive simulation and experimental study was undertaken. The computational techniques for the study have been developed and coupled to a large data base, which contains the individual loop configurations of a statistically significant population of the Bell System loop plant. Two modes of transmission (the hybrid and the time-compression multiplexing) are investigated thoroughly by computational techniques, and the simulated plots are compared with experimentally generated oscillograms. These results are displayed graphically by eye diagrams for individual loops and by scatter plots for all the loops in the data base. Different varieties of scatter plots display different attributes of eye diagram. Broad spectrums of such results are cross-compared to choose optimal systems and circuit configurations for a particular mode of transmission at a particular bit rate. Effects of varying terminating networks are also studied and the extent of echo cancellation necessary is investigated by studying the amplitude and the shape of near-end reflections. Various codes are investigated even though the primary emphasis has been on the bipolar code. Major conclusions are summarized in the concluding remarks.

2002 IEEE International Symposium on Circuits and Systems. Proceedings (Cat. No.02CH37353), 2002

The practical implementation of communication over power lines (PLC) using an Asymmetric Digital Subscriber Line (ADSL) front-end is discussed. Both PLC and ADSL modems are based on the same principle of using their respective transmission medium in a frequency range they were never originally designed for. One property both technologies share is the large power that is required when transmitting signals onto the communication medium. The frequency ranges are also comparable. Therefore, ADSL front-ends are evaluated as a power line interface. This paper presents the front-end topology and discusses the signal-to noise measurements that were performed to determine, using Shannon's theorem, the theoretical data throughput.

Communications Engineer, 2004

IEEE Transactions on Communications, 2009

This paper presents the use of the common-mode signal in digital-subscriber-line (DSL) transmission. The DSL binder's metallic sheath is used as a common reference to obtain reliable channels for the common-mode signals. The direct and crosstalk channels for the common-mode signal are obtained using multi-conductor transmission line theory, and the data-rate improvement by exploiting these extra dimensions is presented. The lines in the binder are coordinated to cancel differential-mode crosstalk and also to avoid interference caused by radiation from the common-mode within the binder. The high level of common-mode noise is countered by exploiting the correlation between the differential-and common-mode noises. Numerical results based on the derived models show data-rate improvements of up to 100% compared to using only differentialmode transmission.

This paper analyses qualitative and quantitative impact of large number twisted pairs transmitting ADSL signal, on one specific pair in the same cable. Change of pair capability to establish ADSL signal in respect to number of near active ADSL signals is observed. Downlink transmission rate is chosen as parameter of observed pair quality. At the beginning of this paper, simplified mathematical model of treated case is presented. After that, one pair during exploitation is analysed.

IEEE Journal on Selected Areas in Communications, 1995

The fundamental limits of the outside loop pIant to carry high-speed digital (bi-directional HDSL and ADSL) data are reported. The paper focuses on the copper wire pairs, drop lengths, and interconnects that convey data over the 'last mile" to almost all businesses and residences in the US. The two major customers, businesses and households, are class%&, characterized, and categorized by the distance to the central oEce or the remote terminal. Their spectral capabilities are computed and their ultimate digital capabilities are reported. The crosstalk limitations inherent in the plant are also computed and verified against the loss of signal due the distance and spectral constraints. The signal to noise ratio can thus be estimated to ascertah the transmission quality through the plant. Accordingly, the paper reports on losses, bandwidths, and bit rates in the first half, and discusses the major bottlenecks in the second half.