Routing in Mobile Ad Hoc Networks

Marc HeissenbüttelUniversity of Berne

http://www.iam.unibe.ch/ Bern, 2001-12-19

Table of Contents

Introduction

Proactive Routing Protocols

Reactive Routing Protocols

Further Routing Protocols Hybrid GPSR

NCCR-MICS

Conclusion and Outlook

Introduction

Infrastructured Networks Mobile Host communicates with Base Station

Handoff

Drawbacks• deployment of infrastructure, centralized administration, vulnerable

Ad Hoc Networks autonomous system of mobile routers, connected by wireless links

rapidly deployable, without prior planning or any existing infrastructure

routers are free to move randomly, so topology may change rapidly and unpredictably

Routing Protocols

Ad Hoc Routing Protocol requirements self starting, self organizing

multi-hop, loop free paths

dynamic topology maintenance, rapid convergence

scaleable to large networks, minimal overhead for data transmission

Proactive (table driven) DSDV, OLSR

Reactive (on demand, source initiated) DSR, AODV, TORA, ABR, LAR

ZRP (Hybrid), GPSR

DSDV (Destination Sequenced Distance Vector)

Based on Bellman-Ford

Route with the most recent Seq. Nr. is always used

Factors to alleviate network traffic delay of broadcast through settling time

Packets additionally contain a Seq. Nr. unique to the broadcast

Broken Routes: infinite metric, odd Seq. Nr

MH3 Forwarding Table

Dest. Next Hop Metric Seq. Nr. MH1 MH2 2 S234 MH2 MH2 1 S456 MH3 MH3 0 S478 MH4 MH4 1 S098

MH1 MH2 MH4MH3

OLSR (Optimized Link State Routing)

Build partial topology, connecting all nodes with subset of all links

Multi Point Relays (MPR) subset of neighbors, s.t. every two-hop neighbor can be reached

only MPRs retransmit control messages (only information about MPRs)

other nodes only process packet

DSR (Dynamic Source Routing)

Source route in packet header, sender transmits packet to first hop

Each mobile host maintains route cache

Host wants to send packet checks its route cache

route discovery protocol (Host broadcasts route request packet)

Upon receiving route request packet discard, if already seen, or host’s address listed in the route record

return route (route reply packet), if it is target, or has source route to target

append own address to route record and re-broadcast it

Route reply packet, listing sequence of hops to reach target

AODV (Ad Hoc On Demand Distance Vector)

Combination of DSR and DSDV from DSR: Route discovery, Route maintenance

from DSDV: Hop-by-Hop routing, Seq. Nr.

Route discovery: Route request: creates a reverse route to source

Route reply: creates a forward route to destination

S D

RREQ

RREQ S DRREPRREP

Reverse Route Forward Route

RREQ

AODV (Ad Hoc On Demand Distance Vector)

Combination of DSR and DSDV from DSR: Route discovery, Route maintenance

from DSDV: Hop-by-Hop routing, Seq. Nr.

Route discovery: Route request: creates a reverse route to source

Route reply: creates a forward route to destination

S D

RREQ

RREQ S DRREPRREP

Reverse Route Forward Route

RREQ

Time-out

TORA (Temporally Ordered Routing Algorithm)

Provides multiple routes

Minimizes algorithm’s reaction Localization of control messages (close to topological change)

Uses “height” metric to establish DAG

If node other than destination is local minimum full / partial reversal method

S

D

TORA (Temporally Ordered Routing Algorithm)

Provides multiple routes

Minimizes algorithm’s reaction Localization of control messages (close to topological change)

Uses “height” metric to establish DAG

If node other than destination is local minimum full / partial reversal method

S

D

TORA (Temporally Ordered Routing Algorithm)

Provides multiple routes

Minimizes algorithm’s reaction Localization of control messages (close to topological change)

Uses “height” metric to establish DAG

If node other than destination is local minimum full / partial reversal method

S

D

TORA (Temporally Ordered Routing Algorithm)

Provides multiple routes

Minimizes algorithm’s reaction Localization of control messages (close to topological change)

Uses “height” metric to establish DAG

If node other than destination is local minimum full / partial reversal method

S

D

ABR (Associativity Based Routing)

New routing metric: Degree of association stability

Nodes periodically generate beacons

Increments associativity tick of current node for beaconing node

Route discovery similar to DSR, broadcast a BQ (Broadcast Query)

Node receiving BQ, appends its address and its associativity ticks from neighbors

successor node erases associativity tick entries for all nodes, except for itself

Destination select best route

Nodes propagating reply packet mark their routes as valid

LAR (Location Aided Routing)

Nodes know their current locations

Source knows Dest. was at location L at time t0

Expected Zone: Circular region with radius v(t1-t0) centered at L

Request Zone includes expected zone

Node within request zone forward route request

1. Rectangle

2. Distance• Includes distance d to dest.• Next Node only forwards req. ,

if its distance < d +δ• replaces d with its distance

S

Lr

Expected Zone

Request Zone

IJ

ZRP (Zone Routing Protocol)

Proactive within routing zone (IARP: IntrAzone Routing Protocol)

Routing zone: min. distance in hops <= zone radius

Reactive for dest. located beyond

routing zone (IERP: IntErzone RP)

Bordercast Resolution Protocol (BRP)

Central Node

Zone RadiusPeripheral Node

IARP

IERP

Routing Zone

SDBRP

BRP

IARP

BRP

GPSR (Greedy Perimeter Stateless Routing)

No route discovery prior to data transmission

Nodes only know local topology (Beaconing) Beaconing mechanism to know neighbors’ position

Packet marked with destination’s location

Greedy forwarding select closest-to-destination neighbor as next hop

Perimeter forwarding if node is local maximum in proximity

Right-Hand Rule

X

zy

D

y’z’

NCCR-MICS

Terminodes

Different viewpoint wide area

replacing (extending) conventional mobile communication systems

scalability to large numbers (one million nodes!)

incentive to cooperation

Covering different research areas

mathematical aspects

information theoretical question and physical layer

networking

security

applications

...

Packet Forwarding

Two Routing Methods Terminode Local Routing (TLR)

• limited in distance and number of hops (similar to IARP)

Terminode Remote Routing (TRR)• Anchored Geodesic Packet Forwarding (AGPF, similar to LAR)• Friend Assisted Path Discovery (FAPD)

• based on small world graphs

SD

AP1

AP2

Mobility Management: Virtual Home Region

Distribute location information of the nodes in the network may not be exact, only inside the TLR-Area

in a dynamic, scalable way

Node advertises its position (LDA) to a geographical region (VHR)

fixed center, variable radius

Nodes inside VHRD store location information of D

DS

VHRD

LDAD

Mobility Management: Virtual Home Region

Distribute location information of the nodes in the network may not be exact, only inside the TLR-Area

in a dynamic, scalable way

Node advertises its position (LDA) to a geographical region (VHR)

fixed center, variable radius

Nodes inside VHRD store location information of D

DS

VHRD

LDAD

LDAD ?

Mobility Management: Virtual Home Region

Distribute location information of the nodes in the network may not be exact, only inside the TLR-Area

in a dynamic, scalable way

Node advertises its position (LDA) to a geographical region (VHR)

fixed center, variable radius

Nodes inside VHRD store location information of D

DS

VHRD

LDAD

LDAD

Conclusions and Outlook

DSDV OLSR DSR AODV TORA ZRP ABR LAR

GPSR Terminode

Loop-free Y Y Y Y

No, short lived loops

Y N Y

Multiple routes N N Y N Y N Y Y

Unidirectional links

supported N N Y N N N N N

Periodic Broadcast

Y Y N Y Y Y N Y

Conclusions and Outlook

Nodes are willing to forward packets

Diameter of the network is small

Multi-path forwarding -> improving reliability, stability

Load Balancing

Symmetrical Links are not required

Support of real-time applications

“Ant-Algorithms”?