1. OLSR + FSR for Scalability in Mesh Networks
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Maniezzo et al. UCLA

2. Outline Optimize Link State Routing (OLSR) Protocol Overview
Pros and Cons
Fisheye State Routing (FSR)
Merging OLSR and FSR
Simulation Results
Conclusions
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3. Optimized Link State Routing (OLSR): Protocol Overview
Proactive link-state routing protocol
Periodic topology information exchange.
Optimization of Link State algorithm
Defines a subset of one-hop neighbors (MPR, MultiPoint Relay) that cover all the nodes that are two hops away.
MPR:
Minimize the amount of link-state information
Reduce the number of nodes that mast transmit the broadcast packets such as the Topology Control (TC) packets.
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4. OLSR: Protocol Architecture
Periodic Hello messages exchange (broadcast packets with TTL=1)
Exchange neighbor list
Check the status of the link with 1-hop neighbors
Acquire topology information of 2-hops neighbors
Periodic Topology-Control Messages exchange (broadcast packet with TTL=max)
Source address
Address of each node in the MPR selector set
Compute the MPR i.e. the one hop relay required to reach the 2-hops neighbors
1-hop neighbors
2-hops neighbors
MPR of central node
Only the node on the MPR of the sender retransmit the TC packets
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5. OLSR: Pros and Cons Perfect Network Topology at every node
Minimization of the routing overhead using MPR
Flooding of topology information in all the network
Not suitable for large networks
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6. Fisheye State Routing (FSR): Protocol Overview
Proactive link-state routing protocol.
Similar to LS as it maintains a full topology map at each node
Periodic exchange of Hello packet.
Periodic exchange of topology tables within the local neighbors only (instead of flooding the entire network) .
Topology tables update frequency decreases with distance to destination
Updates for a near destination are propagated more frequently then updates for a remote destination
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7. FSR: Protocol Overview (cont’d)
Central Node
1-hop neighbor
2-hops or more neighbor
Scope 1
Scope 2
The link state updates are sent every 2kT to all the node in scope k where
K is the hop distance
T is the minimum link state updates transmission period
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8. FSR: Protocol Overview (cont’d)
Highly accurate routing information about the immediate neighborhood of a node; progressively less detail for areas further away from the node
FSR achieve potential scalability by limiting the scope of link state update dissemination
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9. FSR: Pros and Cons
Minimization of the flooding using the “scope” concept
Suitable for dense network
Not perfect Network topology knowledge
Multiple Routing Packets received at the same node
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10. Merging OLSR and FSR
Final protocol based on OLSR with the addition of “scope” concept
Every node divides the network in “scope” and maintains information about nodes in a “scope” depending of the distance.
With the new protocol, a node reports the TC packets to “far-away” nodes less frequent.
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11. Simulation Scenario
100 nodes, uniformly placed in a 1600mX1600m field.
IEEE MAC
DCF
channel rate = 2Mbps
radio range = 367 meters.
Node mobility model
randomly waypoint mobility model
pause time = 10 seconds.
maximum mobility speed = minimum mobility speed variable.
10 random CBR/UDP flows
packet size = 1000 bytes
packet interval = 5 packets per second
Simulation time = 450 seconds.
The OLSR+FSR scheme use scope width as 2 hops and totally 4 scopes.
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12. Simulation Results
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13. Simulation Results (cont’d)
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14. Simulation Results (cont’d)
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15. Simulation Results (cont’d)
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16. Conclusions
From above comparison figures, clearly we observe the advantages of the OLSR + FSR routing.
Good performance is observed even when update interval of hello message is 1 second. And when mobility is high, the performance improvement is significant.
The average data packet end-to-end delay is also significantly reduced.
Overhead reduction is also clearly demonstrated.
From the comparison, we conclude that OLSR + FSR is a good way to improve the routing scalability to node mobility.
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17. Any idea or other suggestions?
Maniezzo et al. UCLA