The c.LINK client modem developed by Matsushita
The c.LINK client modem developed by Matsushita
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Matsushita Electric Industrial Co., Ltd. has developed a c.LINK ultrahigh speed cable modem for network access. c.LINK is a specification for high speed interface utilizing coaxial cable. The modem will be launched in September, 2005.

c.LINK, developed by Entropic Communications, Inc, enables a maximum transmission rate of 250 Mbps at the physical layer. This is more than six times faster than the 40 Mbps speed of DOCSIS 2.0, the latest standard for cable modems. By employing c.LINK, coaxial cable used for TV broadcasts can also be used to connect subscribers' homes when they are grouped together.

The newly developed cable modem system includes three devices; the c.LINK client modem, c.LINK master modem and c.LINK modem management system. The c.LINK client modem and c.LINK master modem are installed in the subscribers' houses and in the shared space of the group housing, respectively. The c.LINK master modem works as a host machine to the client modems. The master modem is connected to the fiber-optic network such as FTTH and HFC (hybrid fiber-coax) laid in the group housing via ONU (optical network unit; the subscriber's terminal unit), and is further connected to the c.LINK modem management system that is installed in the cable Internet service provider.

This arrangement makes the coaxial cable one of the choices for high speed wiring for group housing, and "enables ultrahigh speed Internet service that is equivalent or even faster than the existing VDSL service," according to Matsushita. The transmission rate of c.LINK boasts a maximum of 250 Mbps. However, all the subscribers must share the 250 Mbps-transmission since a coaxial cable is generally wired to each home by splitting one cable. In comparison, in a VDSL setup, a center device installed in the shared space is connected to each home independently by the telephone wire.

Tetsuo Nozawa, Nikkei Electronics