Showing papers on "High-bit-rate digital subscriber line published in 1992"

Very high-speed digital transport capability of passband ADSL

Abstract: The loop length coverage of an asymmetrical digital subscriber line (ADSL) passband system operating at very high bit rates is determined. The ADSL is implemented using the quadrature amplitude modulation (QAM) scheme, and transmits information on the high-rate channel from the networking end to the customer end. Simulation results are presented for ADSL impairments arising from various combinations of self-far-end crosstalk (FEXT), background receiver and cable noise (excluding impulse noise), and near-end crosstalk (NEXT) from basic rate DSL and high-bit-rate DSL (HDSL). It is shown that the 16-QAM constellation generally achieves the best performance. Depending on the types of ADSL impairment, coverage of the extreme carrier serving area (CSA) is possible at bit rates that are well above 1.6 Mb/s. >

Device for the multiple use of subscriber lines

Abstract: Analog telephone sets (TA) are connected as shared connection via a connecting device (RWD) and a common subscriber line (TL) to an ISDN exchange. The connecting device (RWD) contains an echo cancellation module (IEC), a communication controller (ICC) with a microcomputer ( mu C) for signalling evaluation, a digital/analog converter group (SICOFI) and one subscriber line module (SLIC) for each telephone set (TA). Due to the digital/analog conversion at the subscriber end, utilisation of the ISDN standard saves subscriber lines (TL) and a later conversion to digital subscriber connections can take place without problems. In operation, the connecting device (RWD) and the telephone sets (TA) are supplied with power by remote power feeding.

The range of baseband ADSLs as a function of bit rate

Abstract: Computer simulation results that found the range, in kilofeet, of reliable asymmetric digital subscriber line (ADSL) transmission for forward bit rates between 1.6 Mb/s and 9.2 Mb/s and reverse bit rates between 160 kb/s and 1.6 Mb/s are presented. The range is found for homogeneous 24 and 26 gauge loops. Simple, high-performance, baseband pulse amplitude modulation (PAM) is used for both directions of transmission. It is shown that the optimum number of signal levels for the forward channel is always four, if the reverse channel carries basic rate access ISDN. The range is determined for symmetric dual-duplex digital subscriber lines, which transmit the same bit rate in both directions. The range is also determined in the presence of crosstalk from high rate digital subscriber lines (HDSL). >

Bandpass line codes

Abstract: In the letter we present block codes and finite-state-machine codes with higher-order spectral zeros at DC for applications where a speech channel and a baseband digital signal are simultaneously transmitted on the same twisted pair, as in the asymmetrical digital subscriber line (ADSL)

Performance evaluation study of signal design and equalization options for high-bit-rate digital subscriber line transceivers

Abstract: This paper analyses different equalization, coding and signal constellation alternatives for the proposed high-bit-rate (800 kb/s) digital subscriber loop transmission interface. The simulation results presented in the paper demonstrate that bit rates above 1000 kb/s at acceptably low bit-error rates (≤ 10−7) are feasible, if baseband transceivers with appropriate equalization and simple trellis coding are used. It is also shown that baseband transmission and Tomlinson precoding provide a significant performance advantage over bandpass transmission and decision-feedback equalization, respectively.

Potential for new digital subscriber loop technologies in selected African situations

Abstract: The author reviews modern developments in telecommunications transmission and services offered over the digital subscriber loop. Issues in provision of telecommunications in African low-income urban situations are discussed. Two particular services, the High Density Subscriber Loop (HDSL) and the Asymmetric Digital Subscriber Loop (ADSL), are examined. Their appropriateness for the African urban situation is examined. The HDSL is seen as offering significant pair-gain opportunities and a new approach to planning subscriber cable installations in areas with little or no telephone service penetration. ADSL is argued to have significant potential for delivery of educational material to urban schools.

Universal subscriber line connection unit for a digital switching exchange.

Abstract: Different subscriber line connection units have hitherto been used for analog subscriber lines and ISDN subscriber lines. This requires development and production effort for both types of assemblies. To avoid this effort, only one universal subscriber line connection unit is now developed, the operating mode of which is adjusted by software in dependence on the type of subscriber connected in each case.

HDSL transceiver performance optimization

Abstract: The receiver filter optimization problem is re-examined in the context of the high-bit-rate digital subscriber line (HDSL) application. The performance gap between an ideal decision feedback equalizer (DFE) and a baud-rate DFE is derived. An alternative matched filter implementation that does not introduce additional low-frequency phase distortion is introduced as a practical suboptimal receiver front end filter in conjunction with a baud-rate finite-length DFE. >

Subscriber loop optical distribution architecture: a cost-effective TDM/TDMA subscriber loop system

Abstract: While it is clear that the development of the laser and low loss optical fiber has had an unmistakable impact on the field of telecommunications, the deployment of optical fiber in the subscriber (local) loop is an especially challenging task. It requires development of low cost equipment that will initially be used at low bit rates (< few tens of Mb/s) due to the fact that basic telephone service does not require more than 64 kb/s per subscriber. Transmission of TV data, in either analog or digital form, will make more efficient use of the fiber bandwidth and generate additional revenues. But as seen from the perspective of the telephony industry, basic telephone services are the principal source of revenue and economic justification for the installation of subscriber loop fiber systems. For large scale deployment in the subscriber loop, the fiber optic system must provide basic telephone services with equal or better performance at a cost that is competitive with that of existing copper pair technology. In this paper we examine a number of possible fiber-to-the-home (FTTH) and fiber-to-the-curb (FTTC) architectures, and present an architecture for urban areas that is best classified as fiber-to-the-building (FTTB). We examine the costs and performance characteristics of the various networks. We show how demographic information can be used to optimize the capacity of the remote terminals. It is shown that for the demography of Spain (where in urban areas the majority of the population resides in apartment buildings with 10 or more dwellings) a remote terminal with a variable subscriber capacity presents a cost savings over remote terminals with a fixed number of subscriber channels.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.