Self Organization in Ad Hoc Networks

BASIL SAEED, ATTA ZAINALDIN

Professor: ABDULMOTALEB EL SADDIK Course: ELG 5121November 26, 2010

Outline

Overview of Ad Hoc Networks Self organization Ad hoc Networks Problems with self organizing ad hoc networks ZRP Protocol Small World graph phenomenon

Terminode Routing Grid Routing

Comparison Conclusion References

Ad hoc Networks Overview

Local area network (LAN) that is built spontaneously as devices connect.

Instead of relying on a base station to coordinate the flow of messages to

each node in the network, the individual network nodes forward packets to

and from each other (act as routers).

A network can be integrated with existing infrastructure.

Self Organization Ad hoc Networks

Decentralized and Non-authorized networks unlike internet that has specific characteristics:– Self-healing - mechanisms that allow to detect, localize, and repair failures

automatically; primarily distinguished by the cause of the failure

– Self-configuration - methods for (re-)generating adequate configurations depending on the current situation in terms of environmental circumstances, e.g. connectivity, quality of service parameters

– Self-management - capability to maintain devices or networks depending on the current parameters of the system

– Self-optimization - similar to self-management but focuses on the optimal choice of methods and their parameters based on the system behaviour

– Adaptation - adaptation to changing environmental conditions, e.g. the changing number of neighbouring nodes

Advantages:

– Scalability

Problems with Self Organization Ad hoc Networks

There are some problems that may occur when designing a self

organized ad hoc network;

Configuration Discovery Routing Cooperation incentive Security

Configuration

DHCP is used in the internet

DHCP cannot be used in self organizing networks

Using Mobile IP: Designed to allow mobile device users to move from one network to

another while maintaining a permanent IP address.

Adding care of address capability to DHCP An IP address associated with mobile node that is visiting a foreign

link.

Discovery

A node has to be discovered and located in the network

Solution:

1) Global Positioning system (GPS) Bad Signal

2) A Self Positioning Algorithm (SPA) using the distance between nodes to form a coordinate system

which is then used to locate and discover the node. Uses time of arrival to obtain the distance between neighbors

Cooperation

Ad hoc networks are highly cooperative

Nodes are selfish Nodes tend to use services provided by other nodes, but not to provide

services for free to the community

There should be a way to: Encourage users to provide services Discourage users to from overloading the network

Cooperation incentives, i.e. Nuglet Nuglet: Virtual Currency

Security

In self organized networks, the nodes are easy to be attack; The channel is wireless The network is decentralized

Solution Node 1 asks for secure communication by send Cipher Suites Node 2 chooses the strongest Cipher and notifies node 1 Node 2 send digital certificate Node 1 uses random number to encrypted the public key of node 2 Node 2 decrypted the message using its private key From the random number, both node can encrypt and decrypt the data

Routing Protocols

There are two routing protocol categories for ad hoc networks:

Proactive Routing Protocols: maintain routing information

independently of need for communication i.e. OLSR

Reactive Routing Protocol: discover route only when you

need it researchers chose i.e. AODV

Cont.

OLSR Protocol:

a HELLO message which is used to discover the information about the link status and the host’s neighbours

Topology Control message which is used to send information all over the network about the node’s neighbours

Cont.

Pros. Low latency, suitable for real-time traffic

Cons.Bandwidth might get wasted due to periodic updates

13

Cont. AODV protocol contains 3 type of messages;

Route Request message (RREQ) Route Reply message (RREP) Route Error message (RERR)

Source node uses an expanding ring search technique to establish a route to the destination node.

14

Cont.

Pros. Saves energy and bandwidth during inactivity

Less overheads which are needed to track the route from the source to destination nodes.

It responds fast in the topological changes, and updates only the nodes that are involved in this change using RRER.

Cons.

Significant delays may occur as a result of route discovery

Zone Routing Protocol

• Hybrid routing protocol uses both combination of proactive and reactive routing protocols

• Uses reactive (inter-zone) and proactive (intra-zone) routing protocols to maintain routes

• Nodes use intra-zone routing protocol to maintain local routing tables to neighbours

• Nodes use inter-zone routing protocol to communicate with nodes outside of their zone

Cont.

Zone Radius = 2

Intra Zone Routing

Inter Zone Routing

How ZRP works

If destination is in same zone, the data is delivered directly

If in different zone, source broadcasts Route Request to all nodes of its zone

If destination is in border node’s zone, border node responds with Route Reply

Source forwards data to appropriate border node to reach destination

Cont.

S

G

H

C

E

BAD

Advantages and Disadvantages

Advantages: The amount of the data stored in each node is smaller than using a pure

table-driven routing resulting in a faster protocol than using a pure reactive routing protocol.

Can use single and multipath

Disadvantages: Large overhead than proactive and reactive protocols If there are many zone overlaps, redundant Route Request messages are

flooded through the network (waste of Bandwidth) Large delay due to the procedure of discovering the route from source to

destination (reactive/inter-zone)

– Not applicable for multimedia applications

Regular Graph vs. Random Graph

- High characteristic path length- High degree of clustering.

- Low characteristic path length- Low degree of clustering.

Small World Graph

Low characteristic path length

High degree of clustering.

Two types of routing protocolswhich use Small World Graph:

1) Terminode Routing

2) GRID Routing

Terminode Routing

Every Terminode uses two Addresses for Identification:

1) End System Unique Identifier (EUI): Permanent Address.

2) Location Dependent Address (LDA): Temporary Address.

- LDA address is obtained either by:

a) GPS (Global Positioning System).

b) No GPS (Self Positioning Algorithm SPA)

Cont.

Packet forwarding is done using two routing categories: Terminode Local Routing (TLR):

Uses to reach the destination Distance Vector Intra Zone Routing (Proactive) in ZRP via EUI permanent addresses without using location information

Terminode Remote Routing (TRR): Uses to reach the destination the geographical location (LDA), which consists of

Friend Assisted Path Discovery (FAPD)Anchored Geodesic Packet Forwarding (AGPF)Path Maintenance Multipath Routing

TRR is perform until some node finds destination to be between 2 hops, from there on, only TLR is used

Anchored Geodesic Packet Forwarding (AGPF)

Allow data to be sent to remote terminode based on locations of node Data be sent along the Anchored path

– Anchored path is the route from source to destination and provided with a list of Anchore

– Anchore point describe the geographical coordinates (LDA)– Good Anchore: Path that avoids obstacles and un-useful terminodes from source to destination

S D

Other elements

Friend assisted path discovery This method is used to obtain the Anchore paths The Terminode may contact its friends in order to find an

Anchored path to the destination of interest

Path maintenances Allows a Terminode to improve the acquired paths

Multipath routing Maintain several paths to a single destination

GPS and SPA

1) Global Positioning system (GPS) Nodes know their geo coordinates Route to move packet closer to end point Propagate geo info by flooding Not efficient with bad signals

2) A Self Positioning Algorithm (SPA) Using the distance between nodes to form a coordinate system

which is then used to locate and discover the node. Uses time of arrival to obtain the distance between neighbors

GRID Routing

Divide the physical into squares called grids, with increasing the size of the grid Server location: Each Node selects location servers in each of the three sibling

squares in each level Ex: Node B selects at :

• Level 0: 10, 23 and 17, Level 1: 22,33 and 60 and Level 2: 19,21 and 28Level 0

Level 1

Level 2

Level 3

7

B

1044

67

33

44 88

54

451723 22

8060

77

28

47

841

21 27

4956

50

99 34

26

19

Location Servers

Cont.

Packet Forwarding: Sender forwards packets using geographic forwarding to the least node greater than or equal to node desired destination ID.

• Ex: A sends packets to B using servers located at 26, 19 and 7

7 1044

67

33

44 88

54

451723 22

8060

77

28

47

841

21 27

4956

5099

34

32

19

B

A

26 62

90

Comparison

GRID Hierarchical routing

approach: scalable No GPS: allows position-

unaware nodes to use position-aware nodes as proxies

Simpler and less information May Fail to find a path to

destination

Terminode Hierarchical routing

approach: scalable No GPS: SPA Complex and more

information Always find a path to

destination

Conclusion

Self Organization Ad hoc Networks have some specific characteristics Small world graphs with low characteristic paths and high level of

clustering can organize a model for Self Organization Ad hoc Networks

Terminode and GRID routing can solve configuration, discovery, and routing problems faced in self configured ad hoc networks

When GPS is available, GRID routing is simpler to process. When GPS is not Available, Terminode routing is more robust

and has less probability of failure. Next step, look for solutions for cooperation and security problems

References

[1] Chlamtac I., Conti M., Liu J. J.-N.: "Mobile ad hoc networking: imperatives and challenges". Ad Hoc Networks,Elsevier, Vol. 1, Issue 1, p. 13-64 (2003).

[2] F. Dressler, "Self-Organization in Ad Hoc Networks: Overview and Classification," University of Erlangen, Dept. of Computer Science 7, Technical Report 02/06, March 2006.

[3] L. Buttyán, J.-P. Hubaux, “Nuglets: a Virtual Currency to Stimulate Cooperation in Self-Organized Mobile Ad Hoc Networks,” Technical report No. DSC/2001/001, Swiss Federal Institution of Technology, Lausanne, January 2001. http://icawww.epfl.ch/hubaux/

[4] Zhijiang Chang, G. Gaydadji ev, S. Vassiliadis, "Routing Protocols for Mobile Ad hoc Networks: Current Development and evaluation.“ Computer Engineering laboratory, EEMCS, Delft University of Technology, April 2005.

[5] J.Haas and M. R. Pearlman, "The Zone Routing Protocol (ZRP) for Ad Hoc Networks," IETF Internet Draft, June 1999

Cont.[6] Nature Publishing Grouping. “Collective dynamics of 'small-world' networks“.

From http://www.nature.com/nature/journal/v393/n6684/full/393440a0.html

[7] L. Blazevic, S. Giordano, J. Y. Le Boudec “Self organized terminode routing simulation“ Proceedings of ACM International Workshop on Modeling Analysis and Simulation of Wireless and Mobile systems (MSWiM 2001), Rome, Italy, July 2001

[8] L. Blazevic, S. Giordano, J. Y. Le Boudec "Anchored Path Discovery in Terminode Routing" The Second IFIP-TC6 Networking Conference (Networking 2002) Proceedings, Pisa, May 2002

[9] L. Blazevic, L. Buttyan, S. Capkun, S. Giordano, J. Hubaux, and J. Boudec,”Self-Organization in Mobile Ad-hoc Networks: The Approach of Terminodes,"IEEE Communication Magazine, vol. 39, no. 6, pp. 166{174, June 2001.

[10] W.-H. Liao, Y.-C. Tseng, and J.-P. Sheu, “GRID: a fully location-aware routing protocol for mobile ad hoc networks,” Telecommunication Systems, vol. 18,no. 1, pp. 37–60, Sep. 2001.

Questions