An efficient void resolution method for geographic routing ...osnet.cs.nchu.edu.tw/powpoint/seminar/2013/An... · sensor networks because of lightweight and scalable characteristics

An efficient void resolution method for geographic routing

in wireless sensor networks

The Journal of Systems and Software 82 (2009) 963–973

Young Il Ko a,*, Chang-Sup Park b, In Chul Song a, Myoung Ho Kim a a Division of Computer Science, Korea Advanced Institute of Science and Technology,

373-1, Guseong-Dong, Yuseong-Gu, Daejeon 305-701, Republic of Korea b Department of Computer Science, Dongduk Women’s University, Republic of Korea

Speaker : TSUNG-JU LEE Data : 2013.5.21

Outline

Motivation Introduction Basic proposed method Other considerations Experimental results Conclusion

The Journal of Systems and Software

Motivation


• Geographic routing is an attractive choice for routing data in wireless sensor networks because of lightweight and scalable characteristics

• Conventional geographic routing methods commonly use the right-hand rule for void resolution

• However, the detour path produced by the right-hand rule is not energy-efficient in many cases

• The right-hand rule often produces a path containing many redundant nodes

3

Fig. 1. A routing path reduction

Introduction(1/3)

• Wireless sensor networks consist of many sensor nodes which have sensing, computing, and wireless communication capabilities

• Energy efficiency should be considered a primary factor in developing sensor network applications

• An efficient technique is required to transport data across a sensor network because energy consumption in data communication is much greater than that of local computation

The Journal of Systems and Software 4

Introduction(2/3)

• Geographic routing is a promising approach for message transmission in large-scale location-aware sensor networks

• Most of the previous geographic routing approaches use a combination of greedy forwarding and a certain variation of face routing

• However, greedy forwarding may route a message to a stuck node – Stuck node

• A node that has no neighbor whose distance to the destination is shorter than that of the current node

• When greedy forwarding is not possible due to a void area, we need a void resolution mechanism


Introduction(3/3)

• When a message gets stuck at a node in the course of greedy forwarding, the routing mode of GPSR is changed into perimeter forwarding

• In the perimeter forwarding, a message is routed by the right-hand rule along the faces in the planar graph of the sensor network until either it can be routed by greedy forwarding again or it returns to the node where it entered the perimeter mode

• However, the methods based on the right-hand rule may produce inefficient routing paths


Outline




Basic proposed method(1/10) • Azimuth angle and distance

– In this paper, It uses the 2D polar coordinate system to locate the sensor nodes in a sensor network

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Basic proposed method(2/10)

• Quadrant division – Quadrant 1 is the area that has a shorter distance and a larger azimuth angle than the node n – Quadrant 2 is the area that has a longer distance and a larger azimuth angle than the node n – Quadrant 3 is the area that has a longer distance and a smaller azimuth angle than the node n – Quadrant 4 is the area that has a shorter distance and a smaller azimuth angle than the node n



• Overall message transmission policy – Greedy forwarding

(1) If there are neighbors whose distances to the destination are shorter than that of the current node, forward a message to the neighbor whose distance is the shortest among them (2) If the destination is reached, stop (3) If a stuck node is reached, start void resolution-forwarding

– Void resolution (VR)-forwarding (1) Determine a quadrant of the current node to send a message from the current node based on the quadrant selection scheme (2) Select a successor node ns among the nodes in the quadrant determined in step 1, based on the node selection heuristics, and send the routing message to it .Now ns becomes the current node



• Overall message transmission policy(cont.) – Choose one of the following cases

(1) If ns satisfies the condition of greedy forwarding, i.e., the distance of ns to the destination is shorter than that of the stuck node, resume greedy forwarding at ns (2) Otherwise, go to step 1(Determine a quadrant of the current node)



• Void resolution-forwarding – Determination of the routing quadrant



• Void resolution-forwarding(cont.) – Selection of the successor node

• The underlying motivation of all the heuristics is to select a node that can result in a routing path going out of the quadrant more quickly and thus having a smaller number of hops to the destination than a path generated by the conventional right-hand rule


Basic proposed method(7/10) • Void resolution-forwarding(cont.)

– Selection of the successor node(cont.) • Example

– Node R is selected by the proposed heuristic for quadrant 1, which has the shortest distance in quadrant 1


Fig. 6. Node selection in quadrant 1.


• Void resolution-forwarding(cont.) – Selection of the successor node(cont.)

• In any quadrant, multiple nodes can tie on the node selection criterion for each quadrant

• It uses additional heuristics to break the tie based on the values of the other polar coordinate of the nodes

• This strategy can make a routing path which is more close to the faces of the void



• Void resolution-forwarding(cont.) – Routing termination during

VR-forwarding • First, It aims to detect a

ring-type void surrounding the destination

• It sums up the amount of differences between the azimuth angles of a receiver and a sender at every message hop starting from the stuck node



• Void resolution-forwarding(cont.) – Routing termination during

VR -forwarding(cont.) • As another case, Fig. (b)

shows a ring-type void surrounding the source node

• It measures and accumulate the size of the angle between two rays originating from the source


Outline




Other considerations(1/4) • The quadrant-level right-hand rule first examines the Quadrant 1 of the

current node, it can miss a routing path passing through a node in the backward quadrant

19

Other considerations(2/4)

• To find a direct node, the current node needs to investigate its backward quadrant first prior other quadrants by the quadrant-level right hand rule

• The qualification for a direct node satisfied the condition that depends on the current direction as described in Table 3



• Void resolution using direct nodes


Fig. 18. An efficient detour path through a direct node (when the current routing direction is F-direction)


• Switchover to GPSR – The proposed VR-forwarding void resolution scheme has a possibility

to fail to find a routing path from the source to the destination by entering into a loop even when there exists a path in a given sensor network

– It suggests a strategy to exploit the GPSR method when VR-forwarding cannot find a detour path

– It changes the routing method from VR-forwarding to GPSR when the following condition is satisfied:

– The right-hand side of the above inequality formula means the number of message hops in a routing path along the boundary of the entire sensor network


Where w and h denote the width and height of the given sensor network area and r is the radius of the radio range of the sensor nodes

Outline



Experimental results(1/6)

• Simulation setting – In the experiments, It has generated sensor networks having 1500 to 5000

nodes which are randomly scattered over the flat area of 600 by 600 square meters

– It uses a T-shape void whose aspect ratio (i.e. the ratio of width to height) is 5:4

– It selects a source and destination node near the lower left corner and upper right corner of the sensor network, respectively


Experimental results(2/6) • Energy efficiency

– Fig. 11 presents the results of experiments with various numbers of fixed-size voids in sensor networks

– Average hop stretches • The ratio of the number of hops in a routing path to the number of hops in the shortest path

from the source to the destination



• Energy efficiency(cont.)


Experimental results(5/6) • Message delivery success rate


Fig. 14. Delivery success rate of the proposed method


• Effect of the hybrid approach


Conclusion • In this paper, It has proposed a new geographic routing scheme called VR-

forwarding which can efficiently detour void areas

• Based on the polar coordinate system to locate sensor nodes

• It provides the quadrant-level right-hand rule and node selection heuristics to generate an energy-efficient routing path when the greedy forwarding fails due to various types of voids

• The experimental results also present that it can produce more efficient routing paths than the previous GPSR geographic routing protocol based on the conventional right-hand rule


THANK YOU FOR LISTENING

An efficient void resolution method for geographic routing in wireless sensor networksOutlineMotivationIntroduction(1/3)Introduction(2/3)Introduction(3/3)OutlineBasic proposed method(1/10)Basic proposed method(2/10)Basic proposed method(3/10)Basic proposed method(4/10)Basic proposed method(5/10)Basic proposed method(6/10)Basic proposed method(7/10)Basic proposed method(8/10)Basic proposed method(9/10)Basic proposed method(10/10)OutlineOther considerations(1/4)Other considerations(2/4)Other considerations(3/4)Other considerations(4/4)OutlineExperimental results(1/6)Experimental results(2/6)Experimental results(3/6)Experimental results(4/6)Experimental results(5/6)Experimental results(6/6)ConclusionThank you for listening

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An efficient void resolution method for geographic routing ...osnet.cs.nchu.edu.tw/powpoint/seminar/2013/An... · sensor networks because of lightweight and scalable characteristics