Introduction to network access technology VDSL line access technology

I. Overview

In short, VDSL is a fast version of ADSL. With VDSL, the maximum downloading rate within a short distance can reach 55 Mbps, And the upload speed can reach 2.3 Mbps (19.2 Mbps or higher in the future ). Both the upload and download data channels can be frequently divided on existing POTS or ISDN services, making VDSL a good choice for high-speed and low-cost networks. Future upgrades may require switching to Echo Cancellation or other technologies to manage the line. Like ADSL, VDSL is mainly used for real-time video transmission and high-speed data access.

Distance (feet) rate (Mbps)

> 1000 51.84

> 1000 to <= 3000 25.82

> 3000 to <= 4500 12.96

Ii. Principles

The architecture of VDSL is like high-speed ADSL. VDSL reuses the upload and download pipelines to get a higher transmission rate. It also uses the built-in error correction function to make up for noise and other interference. VDSL is suitable for short-distance transmission.

Currently, we recommend that you use four types of VDSL encoding: CAP, DMT (see ADSL), DWMT, and SLC. DWMT (Discrete Wavelet Multitone) is a multi-carrier modulation system that uses a single-carrier Wavelet transform. SLC (Simple Line Code) is a baseband signaling version that filters the baseband and restores it at the transceiver.

VDSL uses frequency division multiplexing (OFDM) to separate channels. In the future, VDSL will support symmetric data rates, which may need to be switched to feedback suppression. Generally, the downstream channel is configured on the upload channel, but the DAVIC specification is vice versa so that VDSL can be used for coaxial cable.

Forwarding error control is another feature of VDSL. Like ADSL (T1.413), it uses Reed Solomon encoding and interleaving to correct line noise.

Iii. Current situation

VDSL technology is still in its infancy, and long-distance applications still need to be tested. Data of many of its line features is only speculation, which may damage its overall performance. It also takes time to popularize its endpoint devices.

ADSL has a good product Foundation. Using VDSL and ADSL together is a good strategy. using ADSL for distance and VDSL for near distance can provide better services for future data.