Main features of common broadband access technology ADSL

DSL Digital user Line (Digital Subscriber Line) is a combination of transmission technologies using copper telephone lines as transmission media. It includes HDSL, SDSL, VDSL, ADSL, and RADSL, which are generally called xDSL. The main difference between them is the differences in signal transmission speed and distance, and the differences in Uplink speed and downlink speed symmetry.

HDSL and SDSL support symmetric T1/E11.544Mbps/2.048 Mbps) transmission. The valid transmission distance of HDSL is 3-4 kilometers, and two to four pairs of copper twisted pair telephone lines are required. The maximum valid transmission distance of SDSL is 3 kilometers, and only one pair of copper wire is required. In comparison, symmetric DSL is more suitable for enterprise point-to-point connection applications, such as file transmission, video conferencing, and other processes that send and receive data volumes. Compared with asymmetric DSL, the market for symmetric DSL is much smaller.

VDSL, ADSL, and RADSL are asymmetric transmission. Among them, VDSL is the fastest xDSL technology. On a copper pair of twisted pair telephone lines, the uplink data speed is 13 to 52 Mbps, And the downlink data speed is 1.5 to 2.3 Mbps, however, the transmission distance of VDSL is only several hundred meters. VDSL can be a cost-effective alternative to fiber-to-home. Currently, VODVideo on demand in Shenzhen) this access technology is used. ADSL supports the uplink speed of 640Kbps to 1 Mbps on a copper line, and the downlink speed is 1 Mbps to 8 Mbps. The valid transmission distance is within 3-5 kilometers; the speed range provided by RADSL is basically the same as that provided by ADSL, but it can dynamically adjust the user access speed based on the quality of twisted pair copper wires and the distance between transmission. These characteristics make RADSL an ideal technology for high-speed surfing, on-demand video IAV, and remote LAN access, because in these applications, the user downloads much more information than the uploaded information sending command.

The price-performance ratio of the ADSL Access Service is high, which is inseparable from the technical advantages of the ADSL Access Technology over other access technologies.

1. ADSL technology zone-Network Construction
2. Principles and Applications of ADSL Broadband Access Technology-