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Passive Optical Networks

Passive Optical Networks. Communication Networks. ( Transmit Optical Sub-Assembly ). access. core. LAN. Access network bottleneck. hard for end users to get high data rates because of the access bottleneck local area networks use copper cable get high data rates over short distances

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Passive Optical Networks

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  1. Passive Optical Networks

  2. Communication Networks (Transmit Optical Sub-Assembly)

  3. access core LAN Access network bottleneck hard for end users to get high data rates because of the access bottleneck local area networks • use copper cable • get high data rates over short distances core networks • use fiber optics • get high data rate over long distances • small number of active network elements access networks (first/last mile) • long distances • so fiber would be the best choice • many network elements and large number of endpoints • if fiber is used then need multiple optical transceivers • so copper is the best choice • this severely limits the data rates

  4. Fiber to the x • FTTN - Fiber-to-the-node - fiber is terminated in a street cabinet up to several kilometers away from the customer premises, with the final connection being copper. • FTTC- Fiber-to-the-cabinet or fiber-to-the-curb - this is very similar to FTTN, but the street cabinet is closer to the user's premises; typically within 300 m. • FTTB - Fiber-to-the-building or Fiber-to-the-basement - fiber reaches the boundary of the building, such as the basement in a multi-dwelling unit, with the final connection to the individual living space being made via alternative means. • FTTH - Fiber-to-the-home - fiber reaches the boundary of the living space, such as a box on the outside wall of a home. • FTTP - Fiber-to-the premises – the term is used for both FTTH and FTTB, or where the fiber network includes both homes and small businesses.

  5. Fiber to the x

  6. Fiber To The Curb Hybrid Fiber Coax • switch/transceiver located at curb or in basement • need only 2 optical transceivers but not pure optical solution • lower BW from transceiver to end users • need complex converter in constrained environment core N end users feeder fiber copper access network

  7. core N end users access network Fiber To The Premises we can implement point-to-multipoint topology purely in optics • but we need a fiber (pair) to each end user • requires 2 N optical transceivers • complex and costly to maintain

  8. An obvious solution deploy intermediate switches • (active) switch located at curb or in basement • saves space at central office • need 2 N + 2 optical transceivers core N end users feeder fiber fiber access network

  9. access network 1:2 passive splitter core N end users typically N=32 max defined 128 feeder fiber 1:4 passive splitter The PON solution another alternative - implement point-to-multipoint topology purely in optics • avoid costly optic-electronic conversions • use passive splitters – no power needed, unlimited MTBF(renewal process) • only N+1 optical transceivers (minimum possible) ! (MTBF)Mean Time Between Failures

  10. PON advantages shared infrastructure translates to lower cost per customer • minimal number of optical transceivers • feeder fiber and transceiver costs divided by N customers • Greenfield per-customer cost similar to UTP(unshielded twisted-pair) passive splitters translate to lower cost • can be installed anywhere • no power needed • essentially unlimited MTBF fiber data-rates can be upgraded as technology improves • initially 155 Mbps • then 622 Mbps • now 1.25 Gbps • soon 2.5 Gbps and higher

  11. PONarchitecture

  12. downstream upstream NNI Optical Distribution Network Optical Network Units core splitter Optical Line Terminal UNI Optical Access Network Terminal Equipment Terminology like every other field, PON technology has its own terminology • the CO head-end is called an OLT • ONUs are the (Customer Premises Equipment (CPE)) devices (sometimes called ONTs in ITU) • the entire fiber tree (incl. feeder, splitters, distribution fibers) is an ODN • all trees emanating from the same OLT form an OAN • downstream is from OLT to ONU (upstream is the opposite direction)

  13. PON types APON-ATM PON. It was used primarily for business applications, and was based on ATM BPON-Broadband PON. It is a standard based on APON. It adds support for WDM, dynamic and higher upstream bandwidth allocation, and survivability. GPON-Gigabit PON. Evolution of the BPON standard. It supports higher rates, enhanced security, and choice of Layer 2 protocol EPON-Ethernet PON/ GEPON-Gigabit Ethernet PON. It is an IEEE standard for using Ethernet for packet data. CPON-CDMA PON WPON-WDM PON

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