Title: ALLOPTICAL PACKET HEADER PROCESSING SCHEME BASED ON PULSE POSITION MODULATION IN PACKETSWITCHED NETW
1ALL-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/
2Contents
- Overview of header processing in optical networks
- Header processing based on pulse-position
modulation (PPM) - Proposed node architecture
- Simulation results
- Summary
3Optical 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
4Future 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
5Current 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
6PPM - Operation
(a)
(b)
Address extraction
PPM
(a)
(b)
7PPM 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
8Header Correlation
- Single AND operation is required for matching
PPM-address and multiple address patterns (PPRT
entry)
9Proposed 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
10PPRT 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
11Node with Multicast Tx Mode
All-optical switch
1
2
...
M
S
-
P
PPM
-
ACM
...
Converter
Clock
extraction
...
Switch Sync.
...
Header processing unit
12Optical PPM Generation Circuit
N-bit address-codeword A ai ? 0,1,
i 0, , N1
PPM-format address y(t) x(t ?iai?2i?Ts)
13PPRT 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.
14Ultrafast Optical AND Gate
Implementation Using optical interferometer
configuration optical nonlinear devices
Symmetric Mach-Zehnder Interferometer (SMZI)
15All-Optical Switch
16Simulation Results
For an all-optical core network up to 25 32
nodes
17Simulation Results
- Demonstrate the PPM processing and Tx modes
PPRT with 3 entries
18Simulation Results
19Simulation Results
0 1 1 1 0
Packet with address 01110
PPM-converted address
PPRT entry 1
Synchronized matching pulse
20Conclusions
- 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
21Publications
- 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
22Acknowledgements
- Northumbria University for sponsoring the
research work
23Thank you!