Title: A Survey of Design Issues in Self Organizing Wireless Networks
Author: Yasir Drabu
Prepared for Prof. Javed I. Khan
Department of Computer Science, Kent State University
Date: November 2001
Abstract: Since the inception of communication, self-organizing
wireless networks has been an intellectual fantasy of communication researchers.
Self organizing networks are based on sophisticated protocols that allow
diverse computing devices to establish a communication system without human
intervention. This survey investigates these networks and tries to present
the various issues and challenges they pose. Further the contributions
made towards solving these problems are also outlined.
Keywords: self-organizing networks, ad hoc wireless networks,
dynamic reorganizing networks.
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Table of Contents:
are self-organizing networks?
Problems and Proposed Solutions
With miniaturization of computing elements we have seen many mobile devices
appear in the market. In the present day scenario an average user has a
multitude of devices ranging for PDAs to laptops. To make communication
between these devices as well as other users for any kind of collaboration
becomes very cumbersome and to some extend counter productive. With the
idea of simplifying the networking of diverse computing devices this survey
investigates the concept of self organizing networks. It is important to
observe that self organizing network are more than just smart wireless
cabling technologies like Bluetooth in that they are actual networks with
routing elements. They can be used as fully functional autonomous networks
(e.g. Tactical Network) or as an extension to the current infrastructure
network by extending its reach.
First we understand what self organizing networks are, then in the next
section we discuss the key issues and challenges posed in the development
of these networks.
What are self-organizing networks?
A self organizing network is an ad hoc network architecture that can be
rapidly deployed without relying on a pre-existing fixed network infrastructure
with minimal or no human administration. They are also know as zero-config
or Reconfigurable Wireless Networks (RWN) The nodes in this type of network
can join and leave the network frequently, often without any prior warning
and possibly without disruption of other nodes’ communication. The
nodes of this type of network have assumed to be highly mobile and thus
can rapidly change the node constellation and the presence of absence of
Some typical self organizing networks are:
These are just a few examples; once realized this type of extreme networking
based applications can have far reaching implications.
Collaboration in a business or educational environment, to share ideas,
plans and information among diverse electronic devices.
Military operation, to create network in hostile locations.
Sensory networks – for communication between intelligent sensors to exchange
Problems and Proposed Solutions
There are lot of technical issues involved in the creation of an ad hoc
network and then making it self organizing. Configuration, discovery, routing,
MAC layer adaptation, security are some of the key issues. Further
power and processing capabilities are scarce resources in mobile device,
thus making protocols design even more complex.
In this section we discuss these unique challenges associated with a
self organizing network.
Most of today’s networks are relatively static. They involve a large management
cost to be setup and maintained. Today to setup connection to the Internet
we need to have an IP address assigned by a network administrator and some
manual entries in the DNS server. Further if the node moves to a new location
this configuration has to be changes. This technique though workable, is
highly inefficient for a frequently changing network. Further the problem
is complicated by a multitude of devices and diverse platforms. Here the
key paradigm shift with respect to self organizing networks is that these
networks do not need any human intervention to lay down the address plan.
The best automatic configuration that can simplify some of the above
issues is the use of Dynamic Host Configuration Protocol (DHCP), which
assigns IP addresses to hosts dynamically from a pool of addresses. This
technique though becomes ineffective when it come to self organizing networks
as each node is not expected to have access to a central DHCP server. Thus
a technique to configure the network has to be developed that can be effective
and efficient in this scenario.
One way to configure the nodes to give each node an international name
using the International Naming Scheme as suggested in . In this scheme
the name of the network element describes its attributes like location
(which is hierarchal), services it provides, and owner of the node, a unique
id, and access privileges. Thus just by acquiring the name of a networking
element, all this information becomes available. This has the dual advantage
of providing service discovery, but at that same time can be too much data
overhead for just knowing the name of a computing device.
Another method suggested by  is to have a permanent End-System Unique
Identifier (EUI) and then have a Location Dependent Address (LDA). The
LDA is a triplet formed by giving the node its latitude, longitude and
altitude. How these parameters are obtained is discussed in the next section.
Discovery is a very important aspect of making an ad hoc network self organizing.
Discovery deals with two issues –
The simplest way a node can discover itself is by using a Global Positioning
System (GPS). The GPS can provide the node with its location and then it
can start looking for nodes in its “zone”. If the GPS service is not available
for reasons like weak signal, signal jamming, etc, then we can use a Self
Positioning Algorithms (SPA) . This technique uses the distance between
nodes to form a Network Coordinate System, which is used to define the
location of the node.
The discovery of the node itself within the network.
The discovery of the services available to the node once it has placed
itself in the network.
Once a node has discovered the network, the next natural aspect is for
it to look for services provided to it by the network it is connected to.
This aspect of service discovery was realized and lot of research is going
on to develop and effective protocol. The protocols being developed are
discussed and compared in . Some of the vendors that are developing
service location protocols are:
The IETF is developing the Service Location Protocol, SLP. This protocol
is intended to be vendor independent (version 2 is currently available).
This protocol consists of three main components, the User Agent (UA) –
which looks of a service on behalf of the user, the Service Agent (SA)
– which advertises its services and the Directory agent – which collects
information from SA and provides it to the UA.
Microsoft is developing Universal Plug n Play (UPnP)
Sun Microsystems is pushing Jini which is java based
Salutation being developed by a group of companies (Fuji, Konica, IBM etc).
Bluetooth Service Discovery Protocol.
These service discovery protocols need to be modified to better suit
self organizing networks.
Routing is one of fundamental operations of a network. Thus there are a
lot of routing protocols proposed to work with ad hoc networks. Link state
and distance vector are two common approaches to solve the routing problem.
In the link state each router has a good picture of the network topology
and thus does not prove to be a good approach for self organizing networks.
Broadly speaking routing protocols are classified into two –
Proactive protocols have a low delay as the route is already known, but
they consume too much bandwidth to propagate the routing information. Reactive
protocols use bandwidth efficiently but have a high delay and thus are
not suitable for real time traffic.
Proactive: These types of protocols constantly evaluate the routes within
the network so that when a packet needs to be forwarded the route id already
known. E.g. Open Shortest Path First (OSPF), Wireless Routing Protocol
(WRP), Destination-Sequenced Distance-Vector (DSDV).
Reactive: This type of protocols determines the route on demand. E.g. Temporally-Ordered
Routing Algorithm (TORA), Ad hoc On Demand Distance Vector (AODV) and Dynamic
Source Routing (DSR).
Ideally the routing protocol for a self organizing network should be
a combination of both the scheme, like the Zone Routing Protocol. ZRP limits
the scope of the proactive procedure to the node’s local neighborhood,
but the search throughout the network, although global, is done by querying
only a subset of the network nodes. The protocol is discussed in .
Self organizing network are highly cooperative, since each node of the
network acts as an autonomous network elements and provides all the services
themselves. Since providing service to the network does not provide any
direct advantage to the users of such a node, they may just consume services
and not provide any. So mechanisms are required to encourage end-users
to let their node act as a relay, and keep their terminal turned on and
not tamper with them. Further such a mechanism should also discourage end-users
from overloading the network, in particular limit the number of long distance
This incentive can be provided by using virtual currency, called the
nuglet . This can be implented as two models models :
In each of these models the integrity and fairness of the nuglet has to
Packet Purse Model in which the payment by the sender
Packet Trade Model in which the payment by the receiver.
Mojo Nation (http://www.mojonation.net)
has implemented such a mechanism on the Internet, for peer to peer file
sharing providing an incentive for peers to remain online and share digital
Security issues like legitimacy of the users, confidentiality and integrity
of information in self organizing networks are similar to that of conventional
networks. But this type of network has more complex issues as listed below:
To secure a self organizing network, we consider the following attributes:
availability, confidentiality, integrity, authentication, and non-repudiation.
The medium used it wireless, thus it becomes easier to eavesdrop.
These networks do not have a centralized monitoring or management point.
The network configuration changes dynamically owing to the dynamic nature
of the network.
Mobile devices have a limited processing capacity and battery life, so
any kind of solution has to take these factors into account.
Mobile devices can be captured unlike fixed
To ensure that the message delivered has not been modified a technique
called diversity coding can be used. The basic idea is to transmit redundant
information through additional routes for error detection and correction
without message retransmission. Thus even if one route is compromised,
the other routes can be used to get the correct information across.
To authenticate a user  proposes a technique called threshold cryptography
which takes advantage of the link redundancy of these types of network.
It discusses the how distribution of trust can make Certification Authorities
more robust and resistant to attack.
Further since each node itself it a router or a relay, it should protect
its routing information. As we have discussed above that routing protocols
for ad hoc networks must handle outdated routing information to accommodate
the dynamically changing topology. False routing information generated
by compromised nodes could, to some extent, be considered outdated information.
As long as there are sufficiently many correct nodes, the routing protocol
should be able to find routes that go around these compromised nodes. Such
capability of the routing protocols usually relies on the inherent redundancies
in such networks. If routing protocols can discover multiple routes, nodes
can switch to an alternative route when the primary route appears to have
The design of self organizing networks as we have seen involves the resolution
of lot of complex issues. In this survey we have discuss some of these
issues ranging from configuration to security. We have also outlined some
of the possible approaches that can be adopted to resolve them. But the
potential benefits like ease of use, robustness and overall efficiency
of such networks warrant further research till they can be commercially
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1.Key words: Self configuration, dynamic configuration
2. Self organizing, dynamic reorganizing wireless/mobile
The Digital Libraries used for locating the documents where:
1.The Research Index
3.ACM Search Portal