5 February 2003 -- The Geneva-based International Telecommunications Union (ITU) has agreed on two new protocols for Gigabit-capable passive optical networks (G-PONs) - known as Recommendations G.984.1 and G.984.2 - that will allow service providers to offer a raft of new services and represent a further step towards all-optical networks.
In PONs, signals are transmitted optically by lasers to their appropriate destination without the need for active electronics. Eliminating the dependence on expensive active network elements can yield significant savings. PON technology is used in the local loop to connect residential and SME end-user premises in an all-fibre network, offering customers video applications, high-speed Internet access, multimedia and other high-bandwidth capabilities. All-optical networks will allow delivery of applications such as video-on-demand, streamed video, on-line games and voice over IP.
G-PON maintains the same optical distribution network, wavelength plan and full-service network design principles of the existing and widely adopted G.983 series Recommendations relating to broadband PONs, but increases network capacity to Gigabit levels. The new standard also offers more efficient IP and Ethernet handling.
"These new Recommendations represent an evolutionary development of the basic PON standard (G.983.1). They provide a very significant increase in speed while largely maintaining the basic PON-based broadband optical access system requirements of G.983.1 to ensure maximum continuity with existing systems and optical fibre infrastructures," said Peter Wery, chairman of ITU-T Study Group 15.
G.984.1 describes the general characteristics of a Gigabit-capable PON system such as architecture, bit rates, signal transfer delay, split ratio protection and security. G.984.2 describes a flexible optical fibre access network capable of supporting the bandwidth requirements of business and residential services. It covers systems with nominal line rates of 1.25 and 2.5Gbit/s in the downstream (central office to customer) direction and 155Mbit/s, 622Mbit/s, 1.25Gbit/s and 2.5Gbit/s in the upstream (customer to central office) direction. This represents about twice the capacity of the previous release of the standards (G.983.4 and G.983.5). Both standards cover symmetrical and asymmetrical (upstream/downstream) systems.