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A Region-Based Routing Protocol for Wireless

Mobile Ad Hoc Networks

Speaker: Chen-Nien Tsai

Adviser: Kai-Wei Ke

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Outline

Introduction Region-Based Routing (REGR) Protocol Route Creation Protocol Route Update Protocol Simulation Results Conclusions

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Introduction

Routing Protocols for mobile ad hoc networks are responsible for establishing low-cost, high quality routes.

To avoid huge route maintenance cost, various on-demand routing protocols have been proposed.

Flooding-based route discovery is widely assumed in existing on-demand routing protocols.

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Flooding-based Route Discovery

Source Destination

(a) (b)

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Flooding-based Route Discovery (cont.)

It enables the discovery of optimal routes from sources to destinations.

All nodes are required to relay the route request (RREQ) packets.

Therefore, substantial control overhead is inevitable. Nodes located outside the region between sourc

e-destination pair waste their power to rebroadcast the RREQs. how to improve it?

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Region-based Routing (REGR)

Dynamically establish a prerouting region between source and destination pair.

Limit the propagations of RREQ packets only within the prerouting region.

Can find the optimal or near-optimal routes. Consequently

Route construction overhead reduced. Route optimality is also guaranteed.

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REGR (cont.)

Region-based route creation protocol to handle new route formation cases.

Region-based route update protocol to handle route reconstruction cases.

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Route Creation Protocol

Route creation process consists of 3 stages: Destination Discovery

build a preliminary route (shortest route) from source to destination.

Formation of the Prerouting Region Prerouting region is formed in the neighborhood of the

preliminary route. In-Region Route Discovery

The optimal route within the region can always be detected.

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Route Creation Protocol

Destination Discovery

The source first broadcasting a destination location (DLOC) packet.

It utilize the distance-based backoff scheme to define the rebroadcast defer time.

Ideally, only the border nodes of the DLOC sender need to rebroadcast the DLOC packet.

All nodes relaying the DLOC have to create a backward routing entry for the source.

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Route Creation Protocol

Destination Discovery (cont.)

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Route Creation Protocol

Prerouting Region Formation

The destination selects the shortest route and names it preliminary route.

In this stage, it establish a prerouting region in the neighborhood of the preliminary route.

In wireless networks the shortest route in many cases is no longer the optimal one.

Although the preliminary route may not be the optimal route, it is a good direction indicator.

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Route Creation ProtocolPrerouting Region Formation (cont.)

The optimal route or near-optimal routes very likely lie in the prerouting region.

After choosing a preliminary route, the destination broadcasts a region definition (RDEF) packet.

All nodes receiving the RDEF mark themselves as in-region nodes.

REGION-WIDTH is a value to name the size of the prerouting region.

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Route Creation Protocol Prerouting Region Formation (cont.)

REGION_WIDTH = 1

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Route Creation Protocol

In-Region Route Discovery

The destination broadcasts an RREQ a short period after it releases the RDEF.

Only nodes with in-region marks participate in rebroadcast of the RREQ.

REGR makes intermediate nodes relay the duplicated RREQs if they are transmitted from better routes. (unlike AODV)

The optimal route within the region can always be detected.

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Route Creation Protocol

In-Region Route Discovery (cont.)

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Route Update Protocol

Node mobility and power depletion may lead to breakage of existing routes.

A route update process is needed for these cases to repair problematic routes.

This process can skip the destination discovery stage since the old route is a good preliminary route.

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Route Update Protocol

Prerouting Region Formation

Route-update source (RU-SRC) initiates the process by broadcasting an RDEF.

The broken points of the route may block propagation of the RDEF.

An efficient solution is to enlarge the prerouting region only at problematic spots. Route-clear timer RDEF_ACK

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Route Update ProtocolPrerouting Region Formation (cont.)

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Route Update Protocol

In-Region Route Discovery

The RU-SRC sends an RREQ a short period after it releases the RDEF.

Upon receiving the RREQs, the route update destination (RU-DEST) selects the best route and return a route confirmation packet.

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Simulation Results Simulation environment

IEEE 802.11 model. Nodes are randomly placed in the network. Nodes have the same transmission range: 250m. Initial power of each node: 25J. Node transmitting power: 0.66W. Node receiving power: 0.395W. Node idling power: 0.035W. Each source sends out 5 packets per second. Data packet size: 2048 bits RREQ and DLOC share the same size: 192 bits RDEF packet size: 160 bits Channel capacity: 1 MB/s

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Performance of the REGR Route Creation Protocol

Routing overhead MBCR (Minimum Battery

Cost Routing) AODV (Ad hoc On-

demand Distance Vector routing)

REGR (Region-Based Routing)

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Performance of the REGR Route Creation Protocol (cont.)

Residual power variance is calculated among all

nodes every 20s to measure the network-wide energy balancing.

MBCR always searches the whole network for the optimal routes.

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Performance of the REGR Route Update Protocol

QL (Query Localization) Very small routing overhead, but nodes

quickly deplete their batteries.

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Conclusions

Introduce a region-based routing protocol. It limit route discovery activities within a

predefined region. Not only routing overhead is low, but good

route quality is also ensured. Simulation results show that REGR is

extremely efficient in large, dense, highly dynamic networks.

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Reference

Yong Lin, Xuhui Hu, Myung J. Lee and Tarek N. Saadawi, “A Region-Based Routing Protocol for Wireless Mobile Ad Hoc Networks,” IEEE Network, vol. 18, no. 4, Jul 2004, pp. 12 – 17.

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The End