SUNY@Buffalo 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 wu@cacs.louisiana.edu CReWMaN

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-a-destination routes

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,

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: # packets 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) *******

Thank you !