ALLOPTICAL PACKET HEADER PROCESSING SCHEME BASED ON PULSE POSITION MODULATION IN PACKETSWITCHED NETW

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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/

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Contents

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

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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

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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

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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

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PPM - Operation
(a)
(b)
Address extraction
PPM
(a)
(b)
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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 groups
  patterns

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Header Correlation

• Single AND operation is required for matching
  PPM-address and multiple address patterns (PPRT
  entry)

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Proposed Node with PPM Processing
All-optical switch
1

2
...

M
S
-
P

PPM
-
ACM

...

Converter




Clock
extraction

...
Switch Sync.
...
Header processing unit

• 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

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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

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Node with Multicast Tx Mode
All-optical switch
1

2
...

M
S
-
P

PPM
-
ACM

...

Converter




Clock
extraction

...
Switch Sync.
...
Header processing unit
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Optical PPM Generation Circuit
N-bit address-codeword A ai ? 0,1,
i 0, , N1
PPM-format address y(t) x(t ?iai?2i?Ts)
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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.

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Ultrafast Optical AND Gate
Implementation Using optical interferometer
configuration optical nonlinear devices
Symmetric Mach-Zehnder Interferometer (SMZI)
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All-Optical Switch
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Simulation Results
For an all-optical core network up to 25 32
nodes
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Simulation Results

• Demonstrate the PPM processing and Tx modes

PPRT with 3 entries
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Simulation Results
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Simulation Results
0 1 1 1 0
Packet with address 01110
PPM-converted address
PPRT entry 1
Synchronized matching pulse
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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 gtgt 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

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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

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Acknowledgements

• Northumbria University for sponsoring the
  research work

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Thank you!