High-bit-rate digital subscriber line

About: High-bit-rate digital subscriber line is a research topic. Over the lifetime, 516 publications have been published within this topic receiving 8537 citations. The topic is also known as: HDSL & high-bit-rate DSL.

Combined equalization and alien crosstalk cancellation in ADSL receivers

Abstract: We address the problem of mitigating a dominant alien near-end crosstalker such as HDSL, SDSL or HPNA in DMT-based ADSL and VDSL receivers. Due to the different symbol rates of crosstalker and signal of interest, linear time-invariant filtering is not appropriate. Recently, Zeng et al. presented a method to tackle this problem [4]. In this paper, we present an alternative procedure, which, unlike the solution of [4], does not require any prior knowledge (such as transmission and crosstalk channel, noise characteristics, etc.) other than the crosstalker symbol rate. Moreover, it is fully adaptive, integrates equalization and crosstalk cancellation and optimizes the signal-to-noise ratio for each tone separately. Both algorithms exploit spectral correlation in the received crosstalking signal, thanks to oversampling and excess bandwidth. The method present here is based on the application of so called FREquency-SHift (FRESH) filtering.

Long reach SDSL system spectrally compatible with ADSL systems

Abstract: A method and apparatus for achieving longer data transmission distances in Symmetrical Digital Subscriber Lines (SDSL) systems, while providing spectral compatibility with Asymmetrical Digital Subscriber Lines (ADSL) systems is disclosed. The method and apparatus enables deployment of SDSL and ADSL in any mix in a binder group of twisted pair copper wires without sacrificing performance of either system. The apparatus transmits signals from opposite ends of the twisted pair subscriber loop using first and second discrete frequency bands. The advantages include longer service reach and deployment without regard to ADSL/SDSL services mix in a binder group.

High-speed digital subscriber line (HDSL) wander reduction

Abstract: An apparatus and method are described that allows for improved wander jitter reduction in communication devices and associated communication links, in particular on HDSL communication devices and links. The improved device apparatus and method detects the current data rate offset of the HDSL data rate being utilized and the data rate of the datastream being transmitted through the HDSL communication link and allows for the transmitting HDSL communication device to adjust the HDSL data rate to avoid high wander jitter “sweet spots”. The improved device apparatus and method also allows for the profiling of communication devices for their specific high wander jitter sweet spot maximum points by sweeping the input data rate being transmitted at differing HDSL data rates.

VDSL, from concept to chips

Abstract: Over the previous decades, successive DSL technologies have increased the transmission speeds over the telephone access network from 33.6 Kbit/s for analog modems to about 8 Mbit/s with ADSL. VDSL, or Very high-speed Digital Subscriber Line, puts the copper loop in an even higher gear. VDSL can transport data at tens of Megabits-per-second (Mbit/s) over conventional copper twisted pairs that have been used for more than a century - till the emergence of HDSL and ADSL - to carry only voice calls or low-speed data. Whereas ADSL (Asymmetric DSL) brings you Internet downloads at high speeds and good quality video, VDSL can deliver several films simultaneously. To enable such super-fast traffic, the frequency band over which the system operates has to be increased, from about 1 MHz for ADSL to over 10 MHz for VDSL. This requires faster digital signal processing and analog (integrated) components with higher bandwidths. In addition the system has to withstand loop impairments that were inexistent or less stringent for other DSL variants. Once again (as for ADSL) Discrete MultiTone (DMT) transmission turns out to deliver the required performance. If carefully implemented, DMT can be combined with frequency division duplexing (FDD) without requiring filters for up- and downstream frequency band separation, resulting in extreme flexibility for spectral shaping and band allocation, while simplifying the design. This paper takes you in a couple of pages from the concepts up to the implementation of a system on chip. It shows how a very performant and flexible FDD-DMT system can be integrated while meeting the requirements on power and size.