1 / 32

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

odette-hardy
Download Presentation

Optical Access and Metro Networks Module 4. xPONs access networks

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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 Davide Careglio, Universitat Politècnica de Catalunya (UPC), careglio@ac.upc.edu

  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

  8. Multi-PON WDM networks Network Controller node EDFA N × N AWG Wavelength Converters Arrays data data control control • Architecture8 • MAC protocol9 • Request-based • Scheduling at NC • Greedy9 • Frame-based10 • QoS mechanism9 • GS • HP and BE 8 N. Caponio et al., “Single layer optical platform based on WDM/TDM multiple access …”, ETT, vol. 11, no. 1, Jan. 20009 A. Bianco et al., “Network controller design for SONATA”, IEEE JSAC, vol. 18, no. 10, Oct. 200010 A. Bianco et al., “Frame-based matching algorithms for input-queued switches”, IEEE HPSR 2002, Kobe, Japan, May 2002

  9. Multi-PON WDM networks PON PON PON PON PON PON PWRN Architecture • Communication between PONs: WDM • PWRN selects the output according to the input wavelength

  10. Multi-PON WDM networks PON PON PON PON PWRN l conv Architecture • Additional capacity: l-converters • When the direct wavelength between PONs is not enough, the pool of wavelength converters provides additional capacity

  11. Multi-PON WDM networks 1 slot (1 ms) DATA-frame/slot structure optical packets 1 frame = 100 - 1000 slots (0.1 - 1 ms) Architecture • DATA-Frame format • The time on each wavelength is divided into slots which are organized into frames

  12. Multi-PON WDM networks NC PON PON PON PON PWRN Architecture • Communication between the terminals and the Network Controller • At least one dedicated wavelength per PON • Static TDMA

  13. Multi-PON WDM networks Y AWG MAC protocol ? Network Controller Node

  14. Multi-PON WDM networks N AWG MAC protocol ? Network Controller Node

  15. Multi-PON WDM networks MAC protocol • Bandwidth demand scheme • The nodes wanting to transmit send a request to the NC asking for a given number of slots in a single frame • A centralised scheduling algorithm assigns the resources to the requests • Greedy algorithm • Frame-based algorithm • QoS scheme • GS: the resources are allocated until a teardown request (connection oriented approach) • HP and BE: distributed scheme

  16. Multi-PON WDM networks Greedy scheduling algorithm • Implementation of the scheduling algorithm is based on a set of matrices, which represents the network available resources: • Matrix W: Each entry points out to a list of records describing the wavelength channels that provide connectivity between corresponding PON-to-PON pair • Matrix S: indicates, for each wavelength channel, which slots of the frame are already assigned (the rest are free) • Matrix Utx: indicates for each transmitter (Tx) which slots of the frame are already assigned • Matrix Urx: indicates for each receiver (Rx) which slots of the frame are already assigned

  17. Multi-PON WDM networks Matrix W linked lists of PON-PON wavelengths Matrix Utx source time slots availability t2 t1 tF PON1 PONP terminal1 1 PON1 0 0 terminal2 PON2 ls PONP Matrix Urx receiver time slots availability Matrix S time slots availability per wavelength t2 t1 tF t2 t1 tF terminal1 l1 0 1 1 terminal2 1 0 1 l2 terminal terminal l2PN 2.107 2.107 Greedy scheduling algorithm Algorithm 1. Select wavelength channel on which request is attempted; scan linked list of wavelength channels associated with the (source PON, destination PON) pair in matrix W 2. Select time slot for use within frame; logically AND the row of matrix S corresponding to the selected channel with the complement of the rows of source and destination matrices Utx and Urx 3. Assign number of requested slots to requesting terminal, using round-robin scan on the vector resulting from the previous step of the algorithm 4. Update matrices S, Utx and Urx and descriptor in matrix W

  18. Multi-PON WDM networks Frame-based scheduling algorithm Two sub-problems: • F-matching: select a set of cells admissible in the frame (no-overbooking) from input-queues, i.e., Si nij F and Sj nij F • Time Slot Assignment (TSA): find a sequence of F switching configurations to transmit the cells selected by the F-matching

  19. Multi-PON WDM networks Some results: Performance evaluation11 Performance enhancements12,13 QoS mechanism to providepriority service12,13 11 D. Careglio et al., “Performance evaluation of metro optical networks based on …”, WAON 2001, Jun. 200112 D. Careglio et al., “Performance evaluation of interconnected WDM PONs metro networks with QoS provisioning”, ONDM 2003, Feb. 200313 D. Careglio et al., “QoS strategy in an optical packet network with a multi-class frame-based scheduling”, IEEE HPSR 2003, Jun. 2003

  20. Multi-PON WDM networks 4 PONs 1ms slot size 32 nodes / PON 100 slot / frame 32 ls / PON 10 Gbit/s Performance evaluation Power-of-two TM Self-similar model Frame-based better than greedy

  21. Multi-PON WDM networks N AWG Enhancements • Original scheme ? Network Controller Node

  22. Multi-PON WDM networks Y AWG Enhancements • Original scheme ? Network Controller Node

  23. Multi-PON WDM networks N N AWG Enhancements • Original scheme Network Controller Waiting... Node

  24. Multi-PON WDM networks N AWG Enhancements • New scheme • Well-known VOQ • Holding the requests at the NC ? Network Controller Node

  25. Multi-PON WDM networks N Y Y AWG Enhancements • New scheme • Well-known VOQ • Holding the requests at the NC ? Network Controller Node

  26. Multi-PON WDM networks 1 3 original original 0.9 enhanced enhanced 2.5 0.8 end delay (ms) 0.7 2 0.6 - to 0.5 Throughput - 1.5 0.4 Maximum end 0.3 1 0.2 0.1 0.5 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 Offered load Offered load Performance evaluation 4 PONs 1ms slot size 32 nodes / PON 100 slot / frame 32 ls / PON 10 Gbit/s Power-of-two TM Self-similar model The enhancements behave as expected

  27. Multi-PON WDM networks Limited Attempts (LA) mechanism • A limited number of attempts is given to each request • After that, the request is discarded at the NC and the corresponding packet at the node • The number of attempts depends on the priority class • h for Best Effort (BE) • k for High Priority (HP) • Scheduling alternatives to give preference to HP request • Throughput maximisation (TMax): the requests are scheduled all together and then the slots are allocated given precedence to HP requests • High priority maximisation (HMax): HP requests are scheduled firstly, and the BE requests afterwards using the remaining resources

  28. Multi-PON WDM networks 1 TMax H Max 0.9 Total BE 0.8 HP 0.7 40% HP, 60% BE 0.6 Throughput 0.5 0.4 0.3 0.2 0.1 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 Offered load LA mechanism performance 4 PONs 1ms slot size 32 nodes / PON 100 slot / frame 32 ls / PON 10 Gbit/s Power-of-two TM Self-similar model HP priority over BE TMax better than HMax

  29. Multi-PON WDM networks LA mechanism performance 4 PONs 1ms slot size 32 nodes / PON 100 slot / frame 32 ls / PON 10 Gbit/s Power-of-two TM Self-similar model 40% High Priority

  30. Multi-PON WDM networks LA mechanism performance 4 PONs 1ms slot size 32 nodes / PON 100 slot / frame 32 ls / PON 10 Gbit/s Power-of-two TM Self-similar model 40% High Priority LA is compatible with the proposed enhancements

  31. Multi-PON WDM networks Summary • Performance evaluation • Frame-based better than greedy • Performance enhancements • VOQ architecture • Holding the requests at the Network Controller • QoS mechanism • Simple and effective • Robust (max throughput for HP traffic) • Achieves a clear QoS differentiation • Compatible with the proposed enhancements

More Related