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A Straightforward Path Routing in Wireless Ad Hoc Sensor Networks. Junchao Ma, Wei Lou Dept. of Computing The HK Polytechnic University. Zhen Jiang Comp. Sci. Dept. West Chester University. Jie Wu College of Computer & Information Sciences Temple University. Outline . Introduction
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A Straightforward Path Routing in Wireless Ad Hoc Sensor Networks Junchao Ma, Wei Lou Dept. of Computing The HK Polytechnic University Zhen Jiang Comp. Sci. Dept. West Chester University Jie Wu College of Computer & Information Sciences Temple University WWASN'09
Outline • Introduction • Our Approaches • Experimental Results • Conclusion WWASN'09
Goal • A straightforward path in wireless ad-hoc sensor networks (WASNs) • Fewer hops and detours • Faster data delivery • More energy conserved destination source WWASN'09
Problem • Local minimum phenomenon (void) • Sparse deployment • Physical obstacles • Node failures • Communication jamming • Power exhaustion • Animus interference block void stuck node destination source WWASN'09
Idea • Information helps routing to • Predict the ‘void’ ahead • Make a slightturn 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 WWASN'09
Task 1 • Identification of the affected area of a void • Relative to the positions of the source and the destination destination destination source destination source source destination affected area affected area Case 1 Case 2 WWASN'09
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 destination area of mutual impact source WWASN'09
Challenge • Unstructured WASNs • Hard to ensure whether the forwarding still achievable ahead destination ? What kind of information and how to conduct a forecast? source WWASN'09
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) WWASN'09
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) WWASN'09
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 destination destination forwarding candidate LAR 1 LAR 2 request zone current node current node WWASN'09
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. WWASN'09
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 WWASN'09
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 WWASN'09
Type-I Safety Information and the Estimation of Unsafe Area WWASN'09
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 WWASN'09
SLGF2 Routing Cases WWASN'09
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) WWASN'09
Result Summary • # of hops LGF < GF < SLGF < SLGF2 • Length of path LGF < GF < SLGF < SLGF2 WWASN'09
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 WWASN'09
Questions? Thank you! WWASN'09