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Z. Ghassemlooy, H. Le Minh , Wai Pang Ng Optical Communications Research Group

ALL-OPTICAL PACKET HEADER PROCESSING SCHEME BASED ON PULSE POSITION MODULATION IN PACKET-SWITCHED NETWORKS. Z. Ghassemlooy, H. Le Minh , Wai Pang Ng Optical Communications Research Group Northumbria University, UK http://soe.unn.ac.uk/ocr/. Contents.

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Z. Ghassemlooy, H. Le Minh , Wai Pang Ng Optical Communications Research Group

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  1. ALL-OPTICAL PACKET HEADER PROCESSING SCHEMEBASED ON PULSE POSITION MODULATIONIN PACKET-SWITCHED NETWORKS Z. Ghassemlooy, H. Le Minh, Wai Pang Ng Optical Communications Research Group Northumbria University, UK http://soe.unn.ac.uk/ocr/

  2. Contents • Overview of header processing in optical networks • Header processing based on pulse-position modulation (PPM) • Proposed node architecture • Simulation results • Summary

  3. Demand traffic [bit/s] NEC-2001 1P 100T 10T 1T 100G 10G 1G 100M Total Data Voice 1995 2000 2005 2010 Year Optical Communication Network (OCN) • Future OCNs: faster signal processing and switching to cope with the increase of the demanding network traffic • Existing OCNs: depends on electronic devices for processing the packet address to obtain the routing path. However, the limitation of electronic response will cause the speed bottleneck • Solution: All-optical processing & switching

  4. Optical transparent path Future OCNs • Future OCN will have the processing and switching data packets entirely in optical domain, i.e. generate optical transparent path for routing data packets •  Require: compact and scalable processing scheme

  5. N-bit Port 1 ? Port 2 Port 3 Current All-optical Processing Schemes Example:N = 4, node with M = 3 • All-optical logic gates • All-optical correlators Routing table (RT) • Problems: • Large size routing table  increased processing time • Optical device complexity  poor scalability • Solution: • To reduce the size of the routing table

  6. Data packet payload a0 a1a2a3 Clk Header (packet address) PPM - Operation (a) (b) Address extraction PPM (a) (b)

  7. PPM Based Routing Table Pulse-position routing table (N = 4, M = 3) • Grouping address patterns having the same output ports • Each new pulse-position routing table (PPRT) entry has optical pulses at the positions corresponding to the decimal values of group’s patterns

  8. Processing-time gain: Header Correlation • Single AND operation is required for matching PPM-address and multiple address patterns (PPRT entry)

  9. H SW1 SW2 SWM PPRT Entry 1 Entry 2 ... Entry M Data Data H H C C lk lk & 1 & 2 & M Proposed Node with PPM Processing All-optical switch 1 • Clock extraction: synchronize the arrival of data packet and the node processing • S-P converter: convert the serial address bits to parallel bits • PPM-ACM: (PPM address conversion module): convert binary address to the PPM-converted address • PPRT: store M entries (M PPM frames) • Switch synchronisation: synchronise SW with data packet • All-optical switch: controlled by matching signals to open the correct SW 2 ... M S - P ... PPM - ACM Converter Clock extraction ... Switch Sync. ... Header processing unit

  10. PPRT with Multimode Transmission Pulse-position routing table (N = 4, M = 3) • Same address pattern can appear at multiple PPRT entries • Modes: unicast, multicast, broadcast and deletion

  11. H SW1 SW2 SWM PPRT Entry 1 Entry 2 ... Entry M Data Data Data H H H C C C lk lk lk & 1 & 2 & M Node with Multicast Tx Mode All-optical switch 1 2 ... M S - P ... PPM - ACM Converter Clock extraction ... Switch Sync. ... Header processing unit

  12. Optical PPM Generation Circuit N-bit address-codeword: A = [ai {0,1}], i = 0, …, N–1 PPM-format address: y(t) = x(t + iai2iTs)

  13. PPRT Generation • Is self-initialised with the extracted clock pulse. The M entries are filled by: • Single optical pulse + Array of 2N optical delay lines; Or, • M pattern generators + M optical modulators.

  14. A A×B SOA1 B SOA2 Ultrafast Optical AND Gate Implementation: Using optical interferometer configuration + optical nonlinear devices Symmetric Mach-Zehnder Interferometer (SMZI)

  15. CP1 1 SMZ-1 1 M CP2 2 SMZ-2 … CPM M SMZ-M All-Optical Switch

  16. Simulation Results For an all-optical core network up to 25 = 32 nodes

  17. Simulation Results Demonstrate the PPM processing and Tx modes PPRT with 3 entries:

  18. Input Output 1 Output 2 Output 3 Simulation Results

  19. Simulation Results 0 1 1 1 0 Packet with address 01110 PPM-converted address PPRT entry 1 Synchronized matching pulse

  20. Conclusions • PPM processing scheme • Reduces the required processing time • Provides the scalability: adding/dropping network nodes and node outputs • Applications: • All-optical core/backbone networks (N >> M ~ 3-6) • Optical bypass router (electrical router + optical bypass router) • Challenges: • Optical switch with long and variable switching window • Timing jitter and received pulse dispersion

  21. Publications • H. Le-Minh, Z. Ghassemlooy, and W. P. Ng., “A novel node architecture for all-optical packet switched network”, proceeding of 10th European Conference on Networks and Optical Communications 2005 (NOC2005), pp. 209-216, London, UK, Jul. 2005 • H. Le-Minh, Z. Ghassemlooy, and W. P. Ng., ”Ultrafast header processing in all-optical packet switched-network” proceeding of 7th International Conference on Transparent Optical Networks 2005 (ICTON2005), Vol. 2, pp. 50-53, Barcelona, Spain, Jul. 2005

  22. Acknowledgements • Northumbria University for sponsoring the research work

  23. Thank you!

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