Showing papers on "High-bit-rate digital subscriber line published in 1989"
TL;DR: The attributes of the several line codes considered for a North American standard for ISDN basic access are compared and an intuitive explanation of why the code performs as it does is attempted.
Abstract: The attributes of the several line codes considered for a North American standard for ISDN basic access are compared. Impairments that affect line code performance are examined, and their performance characteristics are discussed. An intuitive explanation of why the code performs as it does is attempted in each case. Some variations of the codes that were considered and that were intended to improve their performance are also discussed. The codes considered are bi-phase, modified duobinary, alternate mark inversion, 3B2T, 2B1Q and 4B3T. >
21 citations
11 Jun 1989
TL;DR: It is shown that the added noise predictor improves the transmission performance in two ways: first, it decorrelates the noise, and second, it decreases the noise power by its prediction gain.
Abstract: The author presents a proposal for solving the problem of reduced performance of coded modulation due to colored channel noise by whitening the noise with an added noise predictor in the decision-feedback equalizer (DFE). This also has the benefit of increasing the nominal SNR. The resulting equalizer has a structure encompassing as a special case the noise-predictive DFE proposed earlier by others. Several numerical examples are provided to illustrate the digital subscriber line transmission performance with the new noise-predictive DFE. It is shown that the added noise predictor improves the transmission performance in two ways: first, it decorrelates the noise, and second, it decreases the noise power by its prediction gain. >
9 citations
11 Jun 1989
TL;DR: Calculations of the reach attainable by simple transmission systems operating over local loop plant at 800 kb/s are presented and the capacity achieved on the limiting length of cable is compared with the Shannon fundamental limit for transmission on that channel.
Abstract: Calculations of the reach attainable by simple transmission systems operating over local loop plant at 800 kb/s are presented. The calculations are based on models of cable gain for pulse and single-frequency signals derived from measurements on real cables, and on a simple model for near-end crosstalk, which is the dominant noise source. The capacity achieved on the limiting length of cable is compared with the Shannon fundamental limit for transmission on that channel. >
7 citations
15 Feb 1989
TL;DR: A transceiver chip set for the ISDN (integrated services digital network) digital subscriber loop using quaternary code (2B1Q) is described which features full-duplex transmission with 144-kb/s net bit rate using the hybrid-balancing principle together with digital adaptive echo cancellation.
Abstract: A transceiver chip set for the ISDN (integrated services digital network) digital subscriber loop using quaternary code (2B1Q) is described which features full-duplex transmission with 144-kb/s net bit rate using the hybrid-balancing principle together with digital adaptive echo cancellation. The two-chip set provides the physical interface between the network termination and the digital exchange according to the T1D1 layer 1 specification for the ISDN basic access interface. A serial multiplexed standard interface allows connection to circuits supporting the layer 2 protocol control at the exchange side of the standard S-bus at the NT. Chip characteristics are listed, and block diagrams are presented. >
6 citations
27 Nov 1989
TL;DR: Numerical results illustrate the nature of the performance trade-offs as a function of channel and system design parameters and are useful in characterizing the parameter choices when there is a clear preference for one system over another.
Abstract: The authors provide a quantitative performance comparison of selected digital transmission schemes proposed for providing reliable communication on two-wire twisted-pair digital subscriber loops in support of ISDN (integrated services digital network) services. More specifically, they consider the bit error probability (BEP) performance of both hybrid adaptive echo cancellation (HAEC) and time compression multiplexing (TCM) schemes employing either AMI or 2B1Q line codes. The modeling assumptions are carefully described and used to develop a quantitative relative-performance evaluation methodology. Numerical results illustrate the nature of the performance trade-offs as a function of channel and system design parameters. These results are useful in characterizing the parameter choices when there is a clear preference for one system over another. >
1 citations
27 Nov 1989
TL;DR: The proposed induction test circuit and the accompanying criteria are intended to ensure reliable performance of ISDN (integrated services digital network) access services in the expected induction environment.
Abstract: A test circuit for analyzing in the laboratory the performance of a digital subscriber line (DSL) under the influence of 60-Hz longitudinal power induction is proposed. The two-wire DSL transmission system, consisting of a nonloaded telephone circuit the line termination (LT) at the central office end, and the first network termination (NT1) at the subscriber end, is subject to the interfering effects of long-term steady-state induction from exposure to electric power systems in the outside plant. Therefore, there is a need for a test circuit to analyze DSL performance in the presence of steady-state induced voltage. The proposed induction test circuit and the accompanying criteria are intended to ensure reliable performance of ISDN (integrated services digital network) access services in the expected induction environment. >
1 citations
01 Jun 1989
TL;DR: A simulation study aimed at improving the use of the subscriber loop plant for digital transmission through adaptive bit rate transceivers for ISDN applications shows that even with transceiver structures as used for basic rate access, operating in the presence of residual echoes, near-end crosstalk, and white noise, bit rates are possible.
Abstract: Selected results are presented from a simulation study aimed at improving the use of the subscriber loop plant for digital transmission through adaptive bit rate transceivers for ISDN applications. The results show that even with transceiver structures as used for basic rate access, operating in the presence of residual echoes, near-end crosstalk, and white noise, it is possible to achieve bit rates up to 1.5 Mb/s over loops up to 1 km long, and that with bit rates reduced to 50 kb/s a reach of 7.5 km is easily achievable. The principle of operation and circuit design of an experimental rate-adaptive hardware implementation are also described. >