broadband transmission system

According to a CCITT definition( SG XVIII Draft I.113 Jan. 1990), applications are broadband applications whose transmission requires data rates exceeding the primary multiplex rate.

The primary multiplex rate (primary rate) is that first level of hierarchy created in the early 1970s to allow 64-kbit/s voice channels to be transmitted efficiently. After the analog voice signals have been converted into 64-kbit/s streams, they are combined in bundles of 24 channels each in North America or 30+2 channels in Europe (30 useful channels and two overhead channels) to form a primary multiplex channel. This results in a total transmission rate of 1.544 Mbit/s or 2.048 Mbit/s - the primary multiplex data rate. Systems with data rates below the primary multiplex rate are referred to as narrowband transmission. For the lower end of the broadband range from 2 Mbit/s to 45 Mbit/s, the term wideband transmission is also occasionally used.