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Optical Access and Metro Networks Module 4. xPONs access networks

Place for logos of authors’ institutions. Optical Access and Metro Networks Module 4. xPONs access networks. Guido Maier, CoreCom, maier@corecom.it Achille Pattavina, Politecnico di Milano, pattavina@elet.polimi.it. Fiber in the loop Passive Optical Network (PON). NT. CO.

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Optical Access and Metro Networks Module 4. xPONs access networks

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  1. Place for logos of authors’ institutions Optical Access and Metro NetworksModule 4. xPONs access networks Guido Maier, CoreCom, maier@corecom.it Achille Pattavina, Politecnico di Milano, pattavina@elet.polimi.it

  2. Fiber in the loopPassive Optical Network (PON) NT CO Primar (WDM) fiber (fiber ring) STB copper ONU HUB Home network Secondary fibers ONT Remote Node (RN) CO switch / POP NT ONU Build./C ONU Primary ODN Secondary ODN • Double-star topology: the Optical Distribution Network is divided into a primary ODN and a secondary ODN by a Remote Node (RN) • It hosts a PASSIVE all-optical splitting/recombining device • Usually located in the cabinet (primary ODN  feeder network) or in the distribution point • Fibers are shared in the primary ODN and less shared (or dedicated) in the secondary ODN

  3. Fiber in the loopPassive Optical Network (PON) NT CO Primar (WDM) fiber (fiber ring) STB copper ONU HUB Home network Secondary fibers ONT Remote Node (RN) CO switch / POP NT ONU Build./C ONU Primary ODN Secondary ODN • Available in all FTTx versions (FTTCab, FTTC/B, FTTH/O) • FTTCab and FTTC/B allow a partial reuse of copper infrastructure • FTTCab and FTTC/B allow a better utilization of the huge fiber capacity, by sharing of the secondary-ODN fibers • The “most optical” network solution • TDM only or TDM+WDM are the most common optical multiplexing techniques adopted in PONs • WDM and other types of multiplexing have also been adopted

  4. Fiber in the loopPassive Optical Network (PON) • Advantages • Very large bandwidth available • A passive RN is cheap and does not require maintenance, power supply and environmental-parameter control (e.g. thermal regulation) • Transparency of the ODN to modulation and information format • Disadvantages • Upstream signals from different ONUs must not collide at the RN • Burst-mode upstream transmission: each ONU transmitter has to switch on and off and the OLT must resynchronize at each burst from a different ONU • ONUs must be synchronized to a common time-reference • A Medium Access Control (MAC) protocol is required • Limited number of ONUs reachable from a primary fiber (few tens) • Cost may be high

  5. Fiber in the loopPON standardization: a brief history • ATM PON (A-PON) • Traffic is carried using ATM raw-cell format and framing • 1982: idea of PON (British Telecom) • 1987 – 1999: PON testbeds by BT, Deutsche Telekom (Eastern Germany), NTT (Japan), BellSouth (Atlanta, USA) • 1995: 622 Mbit/s APON testbed (RACE BAF project) • 1996: beginning of Full Service Access Network (FSAN) works • 1997-’98: ACTS BONAPARTE and EXPERT/VIKING projects • Broadband PON (B-PON) • APON system is standardized by ITU-T with a new name to indicate that the PON can offer full broadband service and not just ATM • Line rates: 155 Mbit/s symmetrical or 622/155 Mbit/s down/upstream; ONU/OLT max distance: 20 km; max. # ONUs: 64 • 1998-’00: ITU-T G.983.1 (physical aspects) and G.983.2 (ONT management and control) • 2001-’02: other ITU-T G.983.x and Q.834.x, e.g. • G.983.4/.7: Dynamic Bandwidth Assignment (DBA), providing statistical multiplexing ( more users per ONU) and Quality of Service (QoS) enforcement • G.983.3: adoption of WDM to increase capacity or to carry video signals

  6. Fiber in the loopPON standardization: a brief history • Ethernet PON (EPON) • Traffic is carried using Ethernet framing • Cheaper user equipment then BPON • Ethernet much more widespread than ATM • Higher subscriber rates (up to 1.25 GbE symmetrical) • 2001: IEEE 802.3ah Study Group “Ethernet in the First Mile (EFM)” • First documents in Sept. 2003) • 2004: final approval of Standard IEEE 802.3ah • Gigabit-capable PON (G-PON) • Traffic is carried by using different possible framings: ATM (G.983 base) or via G-PON Encapsulation Method (GEM), which can interface SHD (G.707 base) or Ethernet (IEEE802.3 base). • Various line rates, up to 2.4 Gbit/s symmetrical, ONU/OLT max distance: 20 km; max. # ONUs: 128 • 2001: activity initiated by the FSAN group • 2003: ITU-T G.984.x

  7. Fiber in the loopCombined PON - HFC Remote node / Fiber node Central Office Fiber Fiber-Coax • Hybrid Fiber To The Building (HFTTB) • An FTTB-PON is deployed in parallel with an HFC: • FTTB: digital upstream and downstream traffic • HFC: analogic downstream broadcast signals and ONU power supply

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