A Review of Current Routing Protocols for Ad Hoc Mobile Wireless Networks

Author: E. Royer and C.-K. Toh

Source: IEEE Personal Communication April 1999,

vol. 6, no. 2, page. 48~51

Date: 2002/12/12

Outline

Introduction Table-Driven Routing Source-Initiated On-Demand Routing Comparisons Application and Challenges Conclusion

Introduction

Current variations of mobile wireless networks Infrastructured network Infrastructureless mobile network (Ad Hoc)

Existing Ad Hoc routing protocols limitation of these networks

High power consumption Low bandwidth High error rates

Categorized as Table-driven Source-initiated (demand-driven)

Ad Hoc Routing Protocols

Ad hoc routing protocols

Table-drivenSource-initiated

On-demand

DSDV WRP AODV ABRDSR LMR

TORA SSRCGSR

Table-Driven Routing Protocols Destination-Sequenced Distance-Vector

Routing (DSDV) Clusterhead Gateway Switch Routing

(CGSR) The Wireless Routing Protocol (WRP)

Destination-Sequenced Distance-Vector Routing Based on Bellman-Ford algorithm Every mobile station maintains a routing table

that lists all available destinations. The stations periodically transmit their routing

tables to their immediate neighbors.

Movement in DSDV

1

5

6

43

2 8

7

1. update table 2. advertise changes

MH4 forwarding table

1

Destination Next Hop Metric Sequence Number Install Flag Stable_data

MH1 MH6 3 S561_MH1 T810_MH4 M Ptrl_MH1

MH2 MH2 1 S128_MH2 T001_MH4 Ptrl_MH2

MH3 MH2 2 S564_MH3 T001_MH4 Ptrl_MH3

MH4 MH4 0 S710_MH4 T001_MH4 Ptrl_MH4

…

MH4 forwarding table (updated)

Destination Metric Sequence Number

MH4 0 S820_MH4

MH1 3 S516_MH1

MH2 1 S238_MH2

MH3 2 S674_MH3

MH5 2 S502_MH5

MH6 1 S186_MH6

MH7 2 S238_MH7

MH8 3 S160_MH8

MH4 advertised table (updated)

Clusterhead Gateway Switch Routing Cluster member table

Using DSDV algorithm. The mobile nodes are aggregated into

clusters and a cluster-head is elected. Least Cluster Change (LCC) algorithm

A cluster-head control a group of ad hoc nodes.

A gateway is a node that is in the communication range of two or more cluster-heads.

CGSR Example

1

3

6

12

9

2

5

8

11

47

10

Internal node Gateway Cluster-head

The Wireless Routing Protocol A table-based distance-vector routing

protocol Each node maintains

Distance table Routing table Link-Cost table Message Retransmission List (MRL) table

Source-Initiated On-Demand Routing Protocols Ad Hoc On-Demand Distance Vector Routing Dynamic Source Routing Temporally Ordered Routing Algorithm Associativity-Based Routing Signal Stability Routing

Ad Hoc On-Demand Distance Vector Routing Route discovery

Route Request (RREQ) Route Reply (RREP)

Route maintenance Hello messages Failure notification message

Ad Hoc On-Demand Distance Vector Routing (cont.)

N1

N2

N3

N4

N5

N6

N7

N8

Source

Destination

Ad Hoc On-Demand Distance Vector Routing (cont.)

N1

N2

N3

N4

N5

N6

N7

N8

Source

Destination

Dynamic Source Routing

Route discovery Route request Route reply

Route maintenance Route error packets

Dynamic Source Routing

N1

N2

N3

N4

N5

N6

N7

N8

Source

Destination

N1

N1-N2N1-N2-N5

N1-N3-N4

N1

N1-N3

N1-N3-N4

N1-N3-N4-N6

N1-N3-N4-N7

Dynamic Source Routing

N1

N2

N3

N4

N5

N6

N7

N8

Source

DestinationN1-N2-N5-N8

N1-N2-N5-N8

N1-N2-N5-N8

Temporally Ordered Routing Algorithm Route creation

Directed acyclic graph (DAG) Route maintenance

New reference level Route erasure

Clear packet

Temporally Ordered Routing Algorithm (cont.)

Source

Destination

Ad hoc node

Height metric

Temporally Ordered Routing Algorithm (cont.)

A

B

E

D

C

F

G

(2)

A

B

E

D

C

F

G

(4)

A

B

E

D

C

F

G

(3)

A

B

E

D

C

F

G

(1)

Link reversal Link failure

Associativity-Based Routing

Route discovery Broadcast Query (BQ) Await-Reply (BQ-Reply)

Route reconstruction Route notification (RN) Localized query (LQ)

Route deletion Route delete (RD)

Associativity-Based Routing(cont.)

BQ

RN[1]

SRC

SRC

Route maintenance for a source move

DEST

Associativity-Based Routing(cont.)

RN[0]

SRC

Route maintenance for a destination move

DEST

RN[0]

H=3

LQ[H]

DEST

Signal Stability Routing

Route discovery Beacon to each neighboring node Static Routing Protocol (SRP)

Route maintenance Dynamic Routing Protocol (DRP)

Route failed Error message

Comparisons of Table-driven Protocols

Parameters DSDV CGSR WRP

Time complexity

(link addition/failure)

O(d) O(d) O(h)-routing tree

Routing philosophy Flat Hierarchical Flat*

Loop free Yes Yes Yes

Multicast capability No No**(separate) No

Number of required tables Two Two Four

Frequency of update transmissions

Periodically and as needed

Periodically Periodically and as needed

Updates transmitted to Neighbors Neighbors and cluster head

Neighbors

Utilizes hello messages Yes No Yes

Critical nodes No Yes (cluster head) No

Comparisons of On-Demand ProtocolsPerformance parameters AODV DSR TORA ABR SSR

Time complexity (initialization) O(2d) O(2d) O(2d) O(d+z) O(d+z)

Time complexity (postfailure) O(2d) O(2d) or 0* O(2d) O(l+z) O(l+z)

Communication complexity (initialization)

O(2N) O(2N) O(2N) O(N+y) O(N+y)

Communication complexity (postfailure)

O(2N) O(2N) O(2x) O(x+y) O(x+y)

Routing philosophy Flat Flat Flat Flat Flat

Loop-free Yes Yes Yes Yes Yes

Multicast capability Yes No No**(LAM) No No

Beaconing requirements No No No Yes Yes

Multiple route possibilities No Yes Yes No No

Routes maintained in Route table Route cache Route table Route table Route table

Route reconfiguration methodology

Erase route; notify source

Erase route; notify source

Link reversal; route repair

Localized broadcast query

Erase route; notify source

Routing metric Freshest and shortest path

shortest path shortest path Associativity and shortest path and others***

Associativity and stability

Comparisons (cont.)

ADOV VS. DSR Overhead of DSR is potentially larger than ADOV

(carry information) Symmetric & Asymmetric Single route & Multiple routes DSR is not scalable to large networks

Comparisons (cont.)

TORA (link reversal) Best suited for networks with large dense

populations of nodes Multiple routes Fewer route rebuilding With LAM algorithm to provide multicast capability

(GPS)

Comparisons (cont.)

ABR Aggregated associativity ticks Guarantee to be free of packet duplicate Beacon

SSR Signal strength and location stability not

necessarily shortest in hop count Intermediate can’t reply (long delay)

Applications and Challenges

Application Military (non-fixed) Conference/meeting/lectures Emergency

Challenges Multicast (dynamic multicast-tree ) QoS support (MAC layer) Power-aware routing (handheld devices) Location aided routing (analogous ABR) security, service discovery, internet protocol operability.

Conclusion

Classification Table-driven & On-demand Provide several routing scheme According Advantage & disadvantage to

choose protocol and implement network Many challenge need to be met