Passive Optical Network

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Passive Optical Networks ( PON ), English Passive Optical Networks are optical access networks that consist of passive components in the area between the exchange and the customer location, i.e. without their own power supply and without switching functionality, in contrast to an active optical network .

Among other things, they are used to implement so-called Fiber To The Home - Access architectures (glass fiber to the customer).

PONs form the basis for modern, high-bandwidth access networks that represent a basis for high-speed Internet and multimedia services (TV broadcast, video-on-demand ). In contrast to copper-based broadband technologies such as xDSL, the optical transmission of signals via optical fibers (glass fiber) makes it possible to achieve considerably higher bandwidths and ranges. The glass fiber as a transmission medium is not only less sensitive to attenuation, it is also resistant to electromagnetic influences, which in a copper cable, caused by a high degree of wiring or the influence of transmission systems, can have a very disruptive effect on the signals to be transmitted.

A distinction: APON ( ATM -based), BPON ( broadband , ATM based), EPON ( Ethernet -based), GEPON ( Gigabit Ethernet-based) and GPON (Gigabit, ATM or GEM -based)

Structure and functionality

Basic structure of a passive optical network

A PON consists of the following components:

  • OLT : Optical Line Termination or "optical line termination " (in the exchange)
  • optical splitter : distribution elements (in switching point, e.g. cable splitter)
  • ONT : Optical Network Termination or "optical network termination " (alternative designation: ONU : Optical Network Unit ) at the customer

The OLT forms the transmission interface between the access network and the backbone network behind it. From the OLT, the individual PONs extend over individual glass fibers to the passive optical splitters located in a switching point or a sleeve , which enable a physical division of the optical signal (optical power division). From the splitters, which can have different splitting factors (e.g. 1:16, 1:32), the fiber optic connections are distributed to the respective customer locations at which the optical transmission link in the ONT is terminated. The ONTs convert the optical signal back into an electrical signal and offer the customer appropriate interfaces (e.g. POTS, 10BT / 100BT) to use the services offered (voice, high-speed Internet, broadcast TV and video on demand). Both the OLT in the exchange and the ONT at the customer's site are active components that require a power supply, only the signal distribution in the distribution network is passive.

Standards

  • ITU-T Study Group 15
    • G.983 (APON and BPON)
    • G.984 (G-PON)
      • G.984.1 (G-PON): General characteristics
      • G.984.2 (G-PON): Physical Media Dependent (PMD) layer specification
      • G.984.3 (G-PON): Transmission convergence (TC) layer specification
      • G.984.4 (G-PON): ONT management and control interface (OMCI) specification
      • G.984.5 (G-PON): Enhancement Band
      • G.984.6 (G-PON): Reach extension
  • IEEE 802.3ah (EPON)

literature

  • Cedric F. Lam (Ed.): Passive Optical Networks. Principles and Practice, Elsevier Inc., Burlington 2007, ISBN 978-0-12-373853-0 .
  • Kevin Roebuck: Passive Optical Network. High-impact Technology - What You Need to Know, Lightning Source Verlag, 2011, ISBN 978-1-74-304360-8 .
  • Laurie G. Cuthbert, Jean-Claude Sapanel. Institution of Electric Engineers, London 1993, ISBN 0-85296-815-9 .

Individual evidence

  1. ↑ http://www.itwissen.info/definition/lexikon/Splitter-splitter.html

Web links