Transcript WCNC03-4.ppt

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 14260
Lafayette, LA 70504
{swadesd,qiao}@cse.buffalo.edu
[email protected]
Presentation Outline
 Introduction
 Motivation for improved routing
 Characteristics of meshed-multipath routing
 Performance studies
 Results
 Summary and conclusion
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
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
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
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
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
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
M-MPR (contd..)
A source-to-destination meshed route
Meshed topology formed
by many-sources-to-adestination routes
M-MPR vs. D-MPR: Throughput Analysis
Idealized meshed routes
Other assumptions:
• All nodes have equiprobable failure rate, pn
• All links (AWGN channel) have equiprobable failure rate, pl
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
Performance Results: M-MPR vs. D-MPR
Throughput plot: Analysis
(6-hop route)
Throughput plot:
Simulation
(avg. hop length 9.06)
Performance Results: M-MPR vs. D-MPR (contd..)
Throughput gain vs. route length (with respect to D-MPR)
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:
Performance Results:
M-MPR vs. Preferred routing (contd..)
Load distribution along multipath:
6
# packets 10
PLR=1 - normalized thpt.
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)
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Thank you !