High-speed networks
Gurdeep S. Hura, Mukesh Singhal · 2001
The idea of introducing a single network became evident when integration of voice and data was provided by a digital network known as an integrated services digital network (ISDN). In most countries, the existing public switched telephone networks are being converted or replaced for full digital operations. This means that new networks will be based on all-digital transmission and switching, which is expected to offer fast connection setup for voice communication across the network anywhere around the world. This new interface will handle data communications, offering both data and voice communications simultaneously. The ISDN became the first network to transmit both voice and data over the same medium or channel. Although N-ISDN allows the integration of voice and data outside the network and offers two types of interfaces ( basic rate interface (popular in the U.S.) and primary rate interface (popular in Europe), inside the N-ISDN we can see two types of networks being defined. These networks are based on different switching techniques and are known as the circuit-switched network (CSN) and packet-switched network (PSN) . ISDN switches are available for voice channel communication (based on circuit switch- ing), but recent hardware technologies in different areas have introduced a number of lower-bit-rate chips, e.g., adaptive differential PCM chips of 32 Kbps, chips of 13 Kbps to be used with mobile networks, etc. This concept of defining a single service-independent network is picking up the market, and it is expected that in the future, this type of single, unified, and universal network must provide the existing services and also must support future services of both voice and data communication efficiently.