04/20/23 WWASN'09

A Straightforward Path Routing in Wireless Ad Hoc Sensor Networks

Zhen JiangComp. Sci. Dept.

West Chester University

Junchao Ma, Wei LouDept. of Computing

The HK Polytechnic University

Jie WuCollege of Computer & Information Sciences

Temple University

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Outline

Introduction Our Approaches Experimental Results Conclusion

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Goal

A straightforward path in wireless ad-hoc sensor networks (WASNs) Fewer hops and detours Faster data delivery More energy conserved

source

destination

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Problem

Local minimum phenomenon (void) Sparse deployment Physical obstacles Node failures Communication jamming Power exhaustion Animus interference

source

destination

voidblock

stuck node

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Idea Information helps routing to

Predict the ‘void’ ahead Make a slight turn early to sufficiently avoid

being blocked Non-detour routing, i.e., greedy forwarding

without perimeter routing Change forwarding direction only if

necessary To keep the optimality of a straight forwarding

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Task 1 Identification of the affected area of

a void Relative to the positions of the source and

the destination

source

destination

destination

source

destination

source

destination

Case 1 Case 2

affected area affected area

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Task 2 Mutual impact of void areas

Global optimization achieved by neighborhood optimizations

No routing table, flooding, or broadcasting Routing decision at each intermediate node Neighbor information collection and distribution

source

destination

area of mutual impact

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Challenge Unstructured WASNs

Hard to ensure whether the forwarding still achievable ahead

destination

source

?

What kind of information and how to conduct a forecast?

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Our Previous Results (Safety Information Model)

Tradeoff between routing adaptivity and structure regularity

Safety information for such a forwarding

Information based forwarding (SLGF routing) to avoid entering detour areas (local minima)

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Our Approaches (Improvement)

Further study the use of safety information

Increase the adaptivity of safety information based routing

Achieve a straightforward path in more routing cases (a new routing algorithm: SLGF2)

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Tradeoff A forwarding with infrastructure in WASNs

LAR2: Forwarding to a neighbor that is closer to the

destination We adopt LAR1

Forwarding limited in the so-called request zone

current node

destination

current node

destination

forwarding candidate

request zone

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Safety Information Inspired by the safety model for 2-D mesh

networks

An unsafe area contains nodes that definitely causing routing detour.

Constructed by information exchanges among neighbors only.

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Estimation of Unsafe Area A local view at each unsafe node of the blocking

effect of local minima (i.e., the topology configuration that makes such a node unsafe)

Ultimate description of all LAR1 forwardings from that unsafe node which are blocked by local minima (in any type)

Simple rectangular shape

Constructed with safety information updates, without extra cost

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Details of the Information Construction Unsafe node

A node without any neighbor in the request zone

A node without any safe neighbor in the request zone

Unsafe area Connected unsafe nodes Estimated as a rectangle at an unsafe node.

4 Different types of unsafe status Due to 4 different types of request zones

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Type-I Safety Information and the Estimation of Unsafe Area

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SLGF2 Routing (new) Three phases conducted in the

order Safe forwarding

Smartly select appropriate safe nodes as forwarding successors to achieve shorter path around unsafe area

Backup path routing Guarantee a successful path by multiple safe-

forwardings to detour around local minima Perimeter routing

Be able to detect the network disconnection and avoid unnecessary detours

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SLGF2 Routing Cases

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Simulation To verify whether

LAR1(-) + Safety Info. (-) + Info. based routing (+) is efficient to achieve straightforward path.

Forwarding routings GF (LAR2 + boundary information) LGF (LAR1) SLGF (LAR1 + safety information) SLGF2 (LAR1 + new use of safety

information)

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Result Summary # of hops

LGF < GF < SLGF < SLGF2

Length of pathLGF < GF < SLGF < SLGF2

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Conclusion

New balance point of the tradeoff between routing adaptivity and information model cost

More accurate safety information Better forwarding routing to

achieve more straight path

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Questions?

Thank you!