1.
Meshed Multipath Routing: An Efficient Strategy in Wireless Sensor Networks
Swades DE Chunming QIAO Hongyi WU
EE Dept CSE Dept The Center for Advanced Computer Studies
State Univ of New York at Buffalo Univ of Louisiana at Lafayette
Buffalo, NY Lafayette, LA 70504
CReWMaN

2. Presentation Outline Introduction Motivation for improved routing
Characteristics of meshed-multipath routing
Performance studies
Results
Summary and conclusion

3. Introduction Possible features of wireless sensor networks
Multihop source-destination routes
Limited or no mobility of nodes
Nodes could be imparted with location info during deployment
Small coverage range of a node ~ 20 to 50 meters
Could be unattended for lifetime
High node density
Large network size
Required highly affordable cost of sensors

4. Introduction (contd..) Possible features (…contd.)
Field applications may be associated with high ground wave absorption
High interference from FCC allocated channel users (Likely to use UWB-based communication technology along with CDMA)
Limited memory and processing power
Limited battery resource
Highly failure-prone nodes
Robust and yet energy-efficient routing technique necessary

5. Motivations for Improved Routing
Existing multihop wireless routing techniques
Packet replication (PR) along multiple routes (noted in [Kulik’99, Ganesan’01])
simple but could be energy-intensive
Traffic splitting along multiple disjoint routes (D-MPR) [Lee’01,Tsirigos’01]
End node controlled – no routing flexibility at an intermediate stage
The preferred (primary) route is used, secondary routes are kept standby [Nasipuri’99, Ganesan’01]
Additional energy for route maintenance
Little traffic load balancing – may lead to quicker network partition
End-to-end ACK/NACK [Chen’99], or adjacent node NACK[Ganesan’01,Wan’02], or promiscuous listening [Johnson’96] based retransmission
Involved flow-control mechanism, additional buffer space, transmit/receive changeover delay, and receive power

6. Motivations for Improved Routing (contd..)
Existing multiple-path route searching techniques
Multicast-tree based [Chen’99, Su’99]
Sequential [Ganesan’01] – additional delay and energy requirement

7. Our Approach: Meshed Multipath Routing (M-MPR)
Main characteristics of M-MPR
Uses meshed (non-disjoint) multiple paths
Uses selective forwarding (SF), whereby a packet is forwarded to the best next hop, determined locally and dynamically
Eliminates explicit need for secondary route maintenance
Reduces the risk of making wrong routing decisions at the end node
Multiple paths are utilized automatically
Forward error correction (FEC) coding is used to reduce/ avoid re-transmission

8. M-MPR (contd..) Meshed multipath searching (topology construction)
Acquiring neighborhood information
Uses location information
Route discovery
Meshed (instead of tree-based or sequential)
Route reply
Returns the ACK along the mesh (reverse direction)
Each active node is responsible for maintaining connectivity in the mesh

9. M-MPR (contd..) A source-to-destination meshed route
Meshed topology formed
by many-sources-to-a-destination routes

10. M-MPR vs. D-MPR: Throughput Analysis
Idealized meshed routes
Other assumptions:
All nodes have equiprobable failure rate,
All links (AWGN channel) have equiprobable failure rate,

11. Performance Results Simulation parameters:
500 nodes randomly uniformly distributed in 500 m sq. area
Coverage range of each node 40 m
SNR at the receiver 14 dB
Fixed packet size 50 Byte

12. Performance Results: M-MPR vs. D-MPR
Throughput plot: Analysis
(6-hop route)
Throughput plot: Simulation
(avg. hop length 9.06)

13. Performance Results: M-MPR vs. D-MPR (contd..)
Throughput gain vs. route length (with respect to D-MPR)

14. Performance Results: M-MPR vs. Preferred routing
M-MPR: (M-MPR-SF)
A packet forwarding node is selected dynamically
In case of equally good options, one is chosen by flipping a fair coin
Preferred routing: (Primary/secondary routes)
A packet forwarding node is pre-decided (primary route)
In case of failure (NACK/promiscuous listening), an alternate node is selected
A simulated meshed
multipath:

15. Performance Results: M-MPR vs. Preferred routing (contd..)
Load distribution along multipath:
# packets
PLR=1 - normalized thpt.

16. Summary and Conclusion
Meshed multipath routing provides improved throughput performance over disjoint multipath routing
Selective forwarding along meshed multipath has better load balancing performance than using a preferred route
Performance comparison of FEC based selective forwarding w.r.to packet replication is not studied here (will be presented in upcoming ICC’03)
*******

17. Thank you !