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(Passive Optical Network) An optical point-to-multipoint access network. There are no optical repeaters or other active devices in a PON, hence the name "passive." PONs are designed for local loop transmission rather than long distance and serve to bring fiber closer to the customer in order to obtain higher speed. PONs began in 1995 when a group of telecom providers organized the Full Service Access Network group (see FSAN).

An optical line terminal (OLT) device resides in the telco central office or cable company head end. It generates or passes on SONET and DWDM signals via fiber to an optical network unit (ONU) in the field. The ONU provides the optical to electrical (O-E) and electrical to optical (E-O) conversion between the fiber and the copper wires that reach homes and offices in a "fiber to the curb" (FTTC) or "fiber to the neighborhood" (FTTN) scenario. When the optical line goes directly into the building for "fiber to the home" (FTTH), an optical network terminal (ONT) is used to terminate the fiber. Fiber to the home is also called "fiber to the premises" (FTTP).

APON (ATM PON) was the first passive optical network and uses ATM for transport. BPON (Broadband PON) includes APON, Ethernet and video transports. GPON (Gigabit PON), which uses the SONET GPF frame, is designed to be efficient for packets as well as TDM. BPON and GPON are the ITU-T G.983 and G.984 standards respectively. EPON is the IEEE Ethernet standard for PONs.

Passive Optical Networks
PONs provide a way to bring high-speed fiber networks closer to the customer in the local loop.

BPON     GPON     EPONITU-T    ITU-T    IEEEG.983    G.984    802.3(Mbps)            (Gbps)ClassesSupported    B,C      A,B,C   PX10/PX20**

 Downstream   155    1.25 Gbps    1.25
 Speeds       622    2.5  Gbps

 Upstream     155     155 Mbps    1.25
 Speeds       622     622 Mbps
                     1.25 Gbps
                     2.5  Gbps

   Maximum Number of ONTsBased on Class and DistanceODN CLASS    7 km    10 km    20 km

   Class A       16      13       6
   Class B       40      32      15
   Class C      101      81      39

  ** PX10 & PX20 are similar to B and C
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References in periodicals archive ?
After embedding in Epon, thin sections were obtained, observed under an electron microscope, and photographed for morphological assessments.
An EPON system composes of an optical line terminal (OLT), multiple optical network units (ONUs), an optical distribution network (ODN) and optical fiber.
Mukherjee, "An SLA-based energy-efficient scheduling scheme for EPON with sleep-mode ONU," in Proceeding of the Optical Fiber Communication Conference and Exposition and the National Fiber Optic Engineers Conference (OFC/NFOEC 11), pp.
In EPON, collision may occur in the upstream transmission when multiple optical network units (ONUs) transmit data to the optical line terminal (OLT) simultaneously.
"Our EPON solutions not only deliver more bandwidth but are also priced significantly lower than the current GPON and GEPON based solutions offered today by Alcatel- Lucent (ALU), Calix (CALX), Ciena (CIEN), and Cisco Systems (CSCO).
Julie Kunstler, telecom components analyst at Ovum, said that the decline was due to maturing EPON network builds in China, Japan and Korea.
Julie Kunstler, telecom components analyst at Ovum, comments: "The decline was due to maturing EPON network builds in China, Japan and Korea.
PMC's 10G-EPON solutions are interoperable with deployed EPON equipment, allowing carriers to gradually upgrade their networks and deploy 10G-EPON ONUs alongside EPON ONUs.
Broadcom Corporation (NASDAQ: BRCM), Irvine, Calif., a global innovation leader in semiconductor solutions for wired and wireless communications, has announced the BCM55524 Quad Port Ethernet Passive Optical Network (EPON) Optical Line Terminal (OLT).
Two standards have been defined for this matter, namely Ethernet Passive Optical Network (EPON) by IEEE (802.3ah) and Gigabit Passive Optical Network (GPON) by ITU-T (G.984).
Infiltration by graded series of Epon resin in propylene oxide was followed by keeping for 30 minutes in 50 percent and 75 percent mixture and for one hour in 100 percent solution.