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CHAPTER 1
INTRODUCTION
In this age of computers and fast communication, everyone looks beyond the imagination
of what technology can offer. In this era of science and technology nothing seems to be
impossible what was thought to be a dream or fascination some years ago. Imagination is such
a powerful key and creativity is its answer, with these and a lot many of small experiences have
bought science and technology to its forefront in this fast paced generation. At that moment
when everything was thought to be perfect and nothing should be changed, in a lonely corner a
group of researchers in the northern most part of Europe started to dream about a small chip
which low in cost, consumes less power and easy to install. With the help of company Ericsson
in 1994 they started to built a chip that was thought to change the face of wireless
communications forever. In 1998 that dream came true and the first Bluetooth chip was ready
to face the market and in 2000 Ericsson shipped its first consumer Bluetooth product- a
Bluetooth headset based on Ericsson solution.A typical Bluetooth device enables a user to
communicate with a wireless headset connected wirelessly with a mobile phone, a laptop with a
printer a wireless keyboard and mouse which wirelessly communicate with the CPU, this and
many more, Our motivation behind this technology is “what makes it so simple” and its vast
reach of applications coming to the wireless communication between devices which transmit
sensitive data then comes the security which got our eye and starting to explore what really
does a typical Bluetooth device offers in terms of data security and integrity, this formed a base
and a group of like minded persons joined to explore in to this region.
1.1Bluetooth
Bluetooth, is a radio-frequency standard. This is the kind of technology, which was developed,
by number of vendors in close cooperation with each other. Conceived initially by Ericsson,
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before being adopted by a myriad of other companies, Bluetooth is a standard for a small,
cheap radio chip to be plugged into computers, printers, mobile phones, etc. We can call it
cable replacement technology for all kind of lengthy wires around you. Actually it was thought
of for just putting the wire data on radio frequency but than soon was realised of the more
opportunities it can bring in.One might have given thought why is this technology developed
when IrDA (infrared Data Association) that is mostly used in television remotes can also be
used for this purpose. The problems, which take away this idea, are the line of sight, 1-meter
distance from the device to be controlled, one-way communication etc.Bluetooth is intended to
come around with the different weaknesses of the Infrared and other competing technologies.
Bluetooth was realised for more general use and wider area of technologies to be grouped
together. Taking this motto a lot of new aspects where Bluetooth could have been used or is
used are :-
1. Global usage.
2. Voice and data handling.
3. The ability to establish ad-hoc connections.
4. The ability to withstand interference from other sources in open band.
5. Very small size, in order to accommodate integration into variety of devices.
6. Negligible power consumption in comparison to other devices for similar use.
7. An open interface standard competitively low cost of all units, as compared to their non-
Bluetooth correspondents.
1.2 Bluetooth Technology
Bluetooth uses a frequency of 2.4 GHz, which has been set for industrial and scientific and m-
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edical devices (ISM). A lot of different small devices use this band i.e. baby monitors, door
openers etc. Making sure that Bluetooth and these other devices don't interfere with one
another has been a crucial part of the design process. The interference is avoided by using a
very weak signal to the receiver of about 1 milliwatt. The range of the Bluetooth is just 10
meters approximately (maximum of 100 meters), but still it can pass through the walls of the
house. Another technology, which it uses to avoid interference, is the Spread-spectrum
frequency hoping .i.e. which means the change of transmitter’s frequency at 1600 times every
second which makes available the spectrum for other devices and merely remove the problem
of interference.The protocol stacks of the Bluetooth, which includes radio, Baseband, L2CAP,
and LMP etc is explained here. These protocols used for the communication between different
Bluetooth devices. A number of devices that you may already use take advantage of this same
radio-frequency band. Making sure that Bluetooth and these other devices don't interfere with
one another has been a crucial part of the design process.
Figure 1.1: Describing the Bluetooth Networking
Looking upon at the network architecture of Bluetooth devices connecting to each other and
form a group of devices called Piconet, and when two or more piconets communicate with each
other they are called scatternets which can accommodate up till 8 devices. In this piconet there
is one master and the others are all slaves. When the two Bluetooth devices come in range of
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each other they communicate automatically and the conversation is done. When a piconet is
established the devices hop between the frequencies frequently.
Acesss Code(72 Bits) Packet Header(54 Bits) Payload(0-2745 Bits)
Figure 1.2: Bluetooth Packet
The packet through which data is transferred has a fixed format. It starts with a 72 bits access
code, which is evaluated by the master and is unique. The access code is very robust and
resistant to interference. Then come the packet header 54 bits and 0-2745 payloads, which
include all the required information to be transferred.
Fixed packet format
The link Manager is responsible for the following
1. Sending and receiving data
2. Connection set-up
3. Authentication
The protocol used for this purpose is called LMP (Link Manager Protocol)
1.3 Bluetooth Technical Details
The technology can be divided into two specifications: the core and the profile specifications.
The core specification introduces how the technology works, while the profile specification
concentrates on how to build interoperating devices using the core technologies. Bluetooth air
interface is based on a nominal antenna power of 0 dBm (1 mW) with extensions for operating
at up to 20 dBm (100 mW) . This interface Complies with ISM band rules up to 20 dBm in
America, Japan, and most European Countries. The Bluetooth radio uses frequency hopping
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method to spread the energy across the ISM spectrum in 79 hops displaced by 1 MHz, starting
from 2.402 GHz and stopping at 2.480 GHz.
When Bluetooth-capable devices come within range of one another, an electronic conversation
determines whether they have data to share or whether one needs to control the other. The
electronic conversation occurs automatically and there is no need for the users to press a button
or give a command. Once the conversation has initiated, the devices, whether part of a
computer system or a stereo, form a network. The frame consisting of a transmit packet
followed by a receive packet in Figure 1.2 is the basic communication unit. Each packet is
composed of multiple slots (1, 3, or 5) of 625 . A typical single-slot frame hops at 1600 hops/s.
Multislot frames will allow higher data rates because of the elimination of the turnaround time
between packets and the reduction in header overhead. For example, single-slot packets can
have a maximum data rate of 172 kbps, while a five-slot, one-multislot frame will support a
721-kbps rate in the five-slot direction with a 57.6-kbps rate back channel in the one-slot
direction.
1.3.1 Network Architecture
Piconet is a basic unit of Bluetooth system; it consists of a master and up to seven active slave
nodes within a distance of about 10 meters. Multiple piconets in a large room can also exist and
they are called scaternets and they can be connected with a bridge.
Figure 1.3: Scatternets of 2 and 3 piconets
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A piconet is a centralized TDM (Time Division Multiplexing) with the master controlling the
clock and determining which device gets to communicate in which time slot. The slaves can
only communicate with the master there is no possibility of slave-slave communication.The
figure 1.3 demonstrates scatternets.Piconets start with two connected devices such as portable
computer or a cellular phone, the devices are automatically configured and establish a
connection when they fall in a range of another Bluetooth device, it also permits automatic data
synchronisation. The devices are symmetric.This means that any Bluetooth radio can become a
master or slave radio, a ‘master/slave swap’ function enables to reverse the order of
master/slave configuration in a piconet. Bluetooth supports both point-point (piconet) and
point-multipoint connections (scatternet).
1.4 BLUETOOTH PROTOCOLS
The main aim of the Bluetooth specification is to guarantee the interoperability between
different applications by supporting any kind of services and providing the means to implement
Figure1.4 Bluetooth Protocol stack
them (service discovery, connection oriented, connectionless links). Figure 1.4 which shows
the complete Bluetooth core specific as well as adopted protocols, there are mainly five core
Bluetooth specific protocols which are important for communication between any two devices
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are Radio, Baseband, Link manager protocol (LMP), Logical link control and adaptation
(L2CAP), Service discovery protocol (SDP), Radio frequency communication (RFCOMM).
1.4.1 Radio
A Bluetooth unit consists of a radio unit operating at 2.4 GHz band. This band has 79 different
Radio Frequency (RF) channels that are spaced at 1MHz. It uses a technique of transmission a
frequency hopping spread spectrum (FHSS) where the hopping sequence is a pseudo-random
sequence of 79-hop length, and it is unique for each ad hoc network.The establishment of a
physical channel is associated to the definition of a channel frequency hopping sequence which
has a very long period length and which does not show repetitive patterns over short time
interval. The FHSS system has been chosen to reduce the interference of nearby system
operating in the same range of frequency (for example, IEEE 802.11 WLANs) and make the
link robust. The nominal rate of hopping between to consecutive RF is 1600 hop/s. A Time
Division Duplex (TDD) scheme of transmission is adopted. The channel is divided into time
slots, each 625 µs in length, and each slot corresponds to a different RF hop frequency. The
time slots are numbered according to the Bluetooth clock of the master. The master can
transmit in even numbered time slots. Odd numbered time slots are reserved for slaves’
transmissions. The changing of RF used after transmitting or receiving a packet reduces the
interference from signals coming from other radio modules. The Bluetooth antenna has a
nominal power that permit a range for radio link from 10 cm to 10 m. This range can be
extended up to 100 m increasing the transmit power [12].
1.4.2 Baseband
Bluetooth baseband is responsible for (i) setting up physical connections between master and
slave (ii) sending and receiving different packets on physical channel. (iii) Synchronisation of
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devices belonging to a piconet on a master clock. (iv) Managing of different power saving
states, which devices can stay in [12].
There are two types of connection:
1) SCO: Synchronous Connection Oriente (enables point-point connection oriented
communication between master and a specific slave)
2) ACL: asynchronous connectionless communication between a master and all slaves in a
piconet. It uses ARQ (Automatic repeat request for fast and reliable communication between
the devices)
1.4.3 LMP
It is responsible for link setup between Bluetooth devices and ongoing link management, link
configuration and authentication. It discovers other LM’s and communicates with them using
the link manager protocol to perform it functions it seeks the help of underlying link controller
(LC) in the baseband
1.4.4 L2CAP
The Logical Link Control and Adaptation Protocol (L2CAP) layer interfaces to the link
controller and allows multiple channels to share a single Bluetooth link. In this manner,
multiple different high-level protocols like TCP/IP and OBEX file transfer are used
simultaneously. It provides group management, including the handling of point-to-multipoint
connections and the negotiation of quality of service (QOS) between devices.
1.4.5 Service Discovery Protocol
The Service Discovery Protocol (SDP) provides a way to discover available Bluetooth services.
A Bluetooth device can act as an SDP client looking for services, or as SDP server providing a
service or services, or it can have both functions.
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1.4.6 RFCOMM
The RFCOMM layer provides a mechanism for transmitting and receiving characters over a
Bluetooth link as if the application was talking to a serial port. Because of its simplicity and
familiarity, RFCOMM is used in many applications for serial data transfers.
1.5 Others
TCS
The Telephony Control Protocol Specification (TCS) layer controls voice and data calls,
provides group management, and handles signaling. The actual voice and data is transmitted
and received directly to and from the baseband via the HCI without going through the L2CAP
layer.
OBEX
The Object Exchange Protocol (OBEX) layer provides a simple mechanism for moving objects
like files, electronic business cards, and messages.
IrMC
The IrMC layer enables synchronization capabilities for devices like cell phones or PDAs
1.6 Bluetooth Profiles
A profile can be described as a vertical slice through the protocol stack. It defines options in
each protocol that are mandatory for the profile. It also defines parameter ranges for each
protocol. The profile concept is used to decrease the risk of interoperability problems between
different manufacturers' products.
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There are namely 13 profiles when Bluetooth first appeared in to market there is constant
updations going on and at this point of time there are many additional profiles have been added.
13 profiles are described as below :
1. GAP: Generic access profile
2. SDAP: Service discover applikation profile
3. CTP: Cordless telephony profile
4. IP: Intercom profile
5. SPP: Serial port profile
6. HS: Headset profile
7. DNP: Dial up networking profile
8. FP: Fax profile
9. LAP : LAN (local area network ) access profile
10.GOEP: Generic object Exchange profile
11.OPP: Object push profile
12. FTP: File transfer profile
13. SP: Synchronisation profile
1) GAP:
This profile defines the generic procedures related to discovery of Bluetooth devices (idle
mode procedures) and link management aspects of connecting to Bluetooth devices (connecting
mode procedures). It also defines procedures related to use of different security levels
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essentially this profile describes how the lower layers (LMP and Baseband) are used, along
with some higher layers.
2) SDP :
This profile defines the features and procedures for an application in a Bluetooth device to
discover services registered in other Bluetooth devices and retrieve any desired available
information pertinent to these services. Essentially, the service discovery profile defines the
protocols and procedures that shall be used by a service discovery application on a device to
locate services in other Bluetooth-enabled devices using the Bluetooth Service Discovery
Protocol (SDP).
3) CTP:
This profile defines the features and procedures that are required for interoperability between
different units active in the ‘3-in-1 phone’ use case. The ‘3-in-1 phone’ is a solution for
providing an extra mode of operation to cellular phones, using Bluetooth as a short-range
bearer for accessing fixed network telephony services via a base station. However, the 3-in-1
phone use case can also be applied generally for wireless telephony in a residential or small
office environment, for example for cordless-only telephony or cordless telephony services in a
PC – hence the profile name ‘Cordless Telephony’.
4) IP:
This profile defines the requirements for Bluetooth devices necessary for the support of the
intercom functionality within the 3-in-1 phone use case. The requirements are expressed in
terms of end-user services, and by defining the features and procedures that are required for
interoperability between Bluetooth devices in the 3-in-1 phone use case. More popularly, this
is often referred to as the ‘walkie-talkie’ usage of Bluetooth.
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5) SPP:
The Serial Port Profile defines the requirements for Bluetooth devices necessary for setting up
emulated serial cable connections using RFCOMM between two peer devices. The
requirements are expressed in terms of services provided to applications, and by defining the
features and procedures that are required for interoperability between Bluetooth devices.
Essentially, the Serial Port Profile defines the protocols and procedures that shall be used by
devices using Bluetooth for RS232 (or similar) serial cable emulation. The scenario covered by
this profile deals with legacy applications using Bluetooth as a cable replacement, through a
virtual serial port abstraction (which in itself is operating system-dependent).
6) HS:
The Headset profile defines the requirements for Bluetooth devices necessary to support the
Headset use case. Essentially the Headset profile defines the protocols and procedures that shall
be used by devices implementing the usage model called ‘Ultimate Headset’. The most
common examples of such devices are headsets, personal computers, and cellular phones.
7) DNP:
The Dial-up Networking profile defines the requirements for Bluetooth devices necessary to
support the Dial-up networking use case. Essentially the Headset profile defines the protocols
and procedures that shall be used by devices implementing the usage model called ‘Internet
Bridge'. The most common examples of such devices are modems and cellular phones. Two
main scenarios are implemented: the Usage of a cellular phone or modem by a computer as a
wireless modem for connecting to a dial-up internet access server, or using other dial-up
services, and Usage of a cellular phone or modem by a computer to receive data calls.
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8) FP:
The Fax profile defines the requirements for Bluetooth devices necessary to support the
Fax use case. Essentially the Fax profile defines the protocols and procedures that shall be used
by devices implementing the fax part of the usage model called ‘Data Access Points, Wide
Area Networks’. A Bluetooth cellular phone or modem may be used by a computer as a
wireless fax modem to send or receive a fax message.
9) LAP:
The LAN Access Profile for Bluetooth devices consists of 2 parts. Firstly, this profile defines
how Bluetooth-enabled devices can access the services of a LAN using PPP. Secondly, this
profile shows how the same PPP mechanisms are used to form a network consisting of two
Bluetooth-enabled devices. Basically this profile defines LAN Access using PPP over
RFCOMM. (There may be other means of LAN Access in the future).
10) GOEP:
The usage model can be, for example, Synchronization, File Transfer, or Object Push model.
Essentially, the purpose of this document is to work as a generic profile document for all
application profiles using the OBEX protocol.
11) OPP:
The object push usage model makes use of the underlying Generic Object Exchange
profile (GOEP) to define the interoperability requirements for the protocols needed by
applications. Typical scenarios covered by this profile are: Object Push, Business Card Pull &
Business Card Exchange, all of which involve the pushing/pulling of data objects between
Bluetooth devices.
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12) FTP:
The file transfer usage model makes use of the underlying Generic Object Exchange Profile
(GOEP) to define the interoperability requirements for the protocols needed by applications.
Typical scenarios covered by this profile involving a Bluetooth device browsing , transferring
and manipulating objects on/with another Bluetooth device.
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CHAPTER 2
REVIEW OF LITRATURE
Perkins C(1994) lays emphasis on adhoc network which according to him differ significantly
from existing networks. First of all the topology of interconnections may be quite dynamic.
Secondly most users will not wish to perform any administrative actions to set up such
anetwork. In order to provide service we do not assume that every computer is within comm-
unication range of every other computer. This lack of complete connectivitywould certainly be
a reasonable characteristic. Currently there is no method available which enables mobile
computers to freely roam about while still maintaining connections with each other.Thus as
regards as Routing protocols for existing networks have not been designed specically to
provide the kind of dynamic self starting behavior needed for adhoc networks Most protocols
exhibit their least desirable behaviour when presented with a highly dynamic inter-connection
topology. Moreover the convergence characteristics of existing routing protocols did not seem
good enough to fit the needs of adhoc networks. Lastly the wireless medium differs in
important ways from wired media, which would require modifications to whichever routing
protocol chosen to experiment with. DSDV is the routing method or protocol which may not be
close to any base station and can exchange data along changing and arbitary paths of
interconnection to afford computers along their number a path along which data can be
exchanged. In addition solution must remain compatible in cases where base station is
available.DSDV uses distance vector technique in which Distance Vector every node maintains
for each destination is a set of ranges over the neighbour . Node treats neighbour k as a next
hop for the paked destined x for and so on.
In order to keep the distance estimates upto date each node monitors the cost of its outgoing
links and periodically broadcasts to each one its neighbors its current estimate of the shortest
distance to every other node in the network.Thus DSDV models the mobile computers as
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routers which are cooperating to forward packets as needed to each other.In this approach thus
can be utilized at either the network layer layer or below the network layer but still above the
MAC layer software in layer2. The information in the routing tables is similar to what is found
in routing tables with todays distance vector algorithms but includes a sequence number as well
as settling time data useful for damping out fluctuationsin route table updates.
Corson(1996) presented a loop-free, distributed routing protocol for mobile packet radio
networks. The protocol is intended for use in networks where the rate of topological change is
not so fast as to make "flooding" the only possible routing method, but not so slow as to make
one of the existing protocols for a nearly-static topology applicable. The routing algorithm
adapts asynchronously in a distributed fashion to arbitrary changes in topology in the absence
of global topological knowledge. The protocol's uniqueness stems from its ability to maintain
source-initiated, loop-free multipath routing only to desired destinations with minimal overhead
in a randomly varying topology. The protocol's performance, measured in terms of end-to-end
packet delay and throughput, is compared with that of pure flooding and an alternative
algorithm which is well-suited to the high rate topological change environment envisioned
here. For each protocol, emphasis is placed on examining how these performance measures
vary as a function of the rate of topological changes, network topology, and message traffic
level. The results indicate thenew protocol generally outperforms the alternative protocol at all
rates of change for heavy traffic conditions, whereas the opposite is true for light traffic. Both
protocols significantly outperform flooding for all rates of change except at ultra-high rates
where all algorithms collapse. The network topology, whether dense or sparsely connected, is
not seen to be a major factor in the relative.
Johnson(1996) states that an ad hoc network is a collection of wireless mobile hosts forming a
temporary network without the aid of any established infrastructure or centralized
administration. In such an environment, it may be necessary for one mobile host to enlist the
aid of other hosts in forwarding a packet to its destination,due to the limited range of each
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mobile host’s wireless transmissions. This paper presents a protocol for routing in adhoc
networks that uses dynamic source routing. The protocol adapts quickly to routing changes
when host movement is frequent, yet requires little or no overhead during periods in which
hosts move less frequently. Based on results from a packet-level simulation of mobile hosts
operating in an ad hoc network, the protocol performs well over a variety of environmental
conditions such as host density and movement rates. For all but the highest rates of host
movement simulated, the overhead of the protocol is quite low, falling to just 1% of total data
packets transmitted for moderatemovement rates in a network of 24 mobile hosts. In all cases,
the difference in length between the routes used and the optimal route lengths is negligible, and
in most cases, route lengths are on average within a factor of 1.01 of optimal.
Murthy (1996) presented the wireless routing protocol (WRP). In WRP, routing nodes
communicate the distance and second-to-last hop for each destination. WRP reduces the
number of cases in which a temporary routing loop can occur, which accounts for its fast
convergence properties. A detailed proof of correctness is presented and its performance is
compared by simulation with the performance of the distributed Bellman-Ford algorithm
(DBF), DUAL (a loop-free distance-vector algorithm) and an ideal link-state algorithm (ILS),
which represent the state of the art of internet routing. The simulation results indicate That
WRP is themost efficient of the alternatives analysed.
Murthy S(1997) distributed algorithms for shortest-path problems are important in the context
of routing in computer communication networks. We present a protocol that maintains the
shortest-path routes in a dynamic topology, that is, in an environment where links and nodes
can fail and mover at arbitrary times. The novelty of this protocol is that it avoids the bouncing
effect and the looping problem that occur in the previous approaches of the distributed
implementation of Bellman-Ford algorithm. The bouncing effect refers to the very long
duration for convergence when failures happen or weights increase, and the nonterminating
exchanges of messages, or counting-to-infinity behavior, in disconnected components of the
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network resulting from failures. The looping problems cause data packets to circulate and, thus,
waste bandwidth.These undesirable effects are avoided without any increase in the overall
message complexity of previous approaches required in the connected part of the network The
time complexity is better than the distributed Bellman-Ford algorithm encountering failures.
The key idea in the implementation is to maintain only loop-free paths, and search for the
shortest path only from this set.
Toh (1997) presents a new, simple and bandwidth efficient distributed routing protocol for
adhoc networks. Unlike the conventional distributed routing algorithims protocol does not
attempt to consistentantly maintain routing informationin every nodes. In an adhoc mobile
network where mobile hosts are acting as routers and where routes are made incosistent by
mobile hosts movement employed a new assosiativity-based routing scheme where route is
selected based on nodes having assosiativity states that imploys periods of stability.In this
manner routes selected are likely to be long lived and hence there is no need to restart
frequently resulting in higher attainable throughput.Thus the protocol is free from loops,
deadlocks and packet duplicates and has scalable memory requirements.Simulation results
obtained reveals that shorter and better routes can be discovered during route reconstruction.
Broch J(1998) An ad hoc network is a collection of wireless mobile nodes dynamically forming
a temporary network without the use of any existing network infrastructure or centralized
administration. Due to the limited transmission range of wireless network interfaces, multiple
network "hops" may be needed for one node to exchange data with another across the network.
In recent years, a variety of new routing protocols targeted specifically at this environment have
been developed, but little performance information on each protocol and no realistic
performance comparison between them is available. This paper presents the results of a detailed
packet-level simulation comparing four multi-hop wireless ad hoc network routing protocols
that cover a range of design choices: DSDV, TORA, DSR, and AODV. Here the NS-2 network
simulator to accurately model the MAC and physical-layer behavior of the IEEE 802.11
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wireless LAN standard, including a realistic wireless transmission channel model, and present
the results of simulations of networks of 50 mobile nodes.
Traskbak(1998) give the overview of Bluetooth security and how it is designed. He also
discussed about the Bluetooth who according to him is the new technology for
wirelesscommunication.The target of the design is to connect different devices together
wirelessly in a small environment whose range at the movement is 10 meters.Bluetooth
employs several layer of data encryption and user authentication measures.It uses the
combination of Personal Identification Number (PIN) and a bluetooth adress to identify other
bluetooh devices.Also Bluetooth use a fast FHSS technique allowing only syncronised
receivers to acess the data. For security purpose these devices uses authorisation and
authenticatio to know who is the user and what are the devices and what are their rights. Also
Bluetooth employs one security level and three different security modes for prooer
scrunity.Apart from this Link Key, Encryption Key and the PIN code are the other security
measures used by the bluetooth devices.
Iwata (1999) consider a large population of mobile stations that are interconnected by a
multihop wireless network. The applications of this wireless infrastructure range from adhoc
networking (e.g., collaborative, distributed computing) to disaster recovery (e.g., fire, flood,
earthquake), law enforcement (e.g., crowd control, search-and-rescue),and military(automated
battlefield). Key characteristics of this system are the large number of users, their mobility, and
the need to operate without the support of a fixed (wired or wireless) infrastructure. The last
feature sets this system apart from existing cellular systems and in fact makes its design much
more challenging. In this environment, we investigate routing strategies that scale well to large
populations and can handle mobility. In addition,we address the need to support multimedia
communications, with low latency requirements for interactive traffic and quality-of-service
(QoS) support for real-time streams (voice/video). In the wireless routing area, several schemes
have already been proposed and implemented.(e.g., hierarchical routing, on-demandrouting,
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etc.). We introduce two new schemes—fisheye State routing (FSR) and hierarchical state
routing (HSR)—which offer some competitive advantages over the existing schemes. We
compare the performance of existing and proposed schemes via simulation.
Perkins (1999) reported that The Ad hoc On-Demand Distance Vector (AODV) routing
protocol is intended for use by mobile nodes in an ad hoc network. It offers quick adaptation to
dynamic link conditions, low processing and memory overhead, low network utilization, and
determines unicast routes to destinations within the ad hoc network. One distinguishing feature
of AODV is its use of a destination sequence number for each route entry. The destination
sequence number is created by the destination to be included along with any route information
it sends to requesting nodes. Using destination sequence numbers ensures loop freedom and is
simple to program. Given the choice between two routes to a destination, a requesting node is
required to select the one with the greatest sequence number. Route Requests (RREQs), Route
Replies (RREPs), and Route Errors (RERRs) are the message types defined by AODV. These
message types are received via UDP, and normal IP header processing. So,for instance, the
requesting node is expected to use its IP address as the Originator IP address for the messages.
For broadcast messages, the IP limited broadcast address (255.255.255.255) is used.This means
that such messages are not blindly forwarded. However,AODV operation does require certain
messages (e.g., RREQ) to be disseminated widely, perhaps throughout the ad hoc network. The
range of dissemination of such RREQs is indicated by the TTL in the IP header. Fragmentation
is typically not required. As long as the endpoints of a communication connection have valid
routes to each other, AODV does not play any role.When a route to a new destination is
needed, the node broadcasts a RREQ to find a route to the destination. A route can be
determined when the RREQ reaches either the destination itself, or an intermediate node with a
'fresh enough' route to the destination. A fresh enough' route is a valid route entry for the
destination whose associated sequence number is at least as great as that contained in the
RREQ. The route is made available by unicasting a RREP back to the origination of the
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RREQ. Each node receiving the request caches a route back to the originaton of the request,
so that the RREP can be unicast from the destination along a path to that originator, or likewise
from any intermediate node that is able to satisfy the request. Nodes monitor the link status of
next hops in active routes. When link break in an active route is detected, a RERR message is
used to notify other.nodes that the loss of that link has occurred. The RERR message indicates
those destinations (possibly subnets) which are no longer reachable by way of the broken link.
Inorder to enable this reporting mechanism, each node keeps a "precursor list", containing the
IP address for each its neighbors that are likely to use it as a next hop towards each destination.
The information in the precursor lists is most easily acquired during the processing for
generation of a RREP message, which by definition has to be sent to a node in a precursor list
If the RREP has a nonzero prefix.
Royer E(1999) states that an ad hoc mobile network is a collection of mobile nodes that are
dynamically and arbitrarily located in such a manner that the interconnections between nodes
are capable of changing on a continual basis. In order to facilitate communication within the
network, a routing protocol is used to discover routes between nodes. The primary goal of such
an ad hoc network routing protocol is correct and efficient route establishment between a pair
of nodes so that messages may be delivered in a timely manner. Route construction should be
done with a minimum of overhead and bandwidth consumption. This article examines routing
protocols for ad hoc networks and evaluates these protocols based on a given set of parameters.
The article provides an overview of eight different protocols by presenting their characteristics
and functionality, and then provides a comparison and discussion of their respective merits and
drawbacks.
Tabanne (1999) introduce here a novel routing protocol for a class of reconfigurable wireless
ad hoc networks. The main features of these ad hoc networks are increased nodes mobility, a
larger number of nodes, and a large network span. Here argued that current routing protocols
do not provide a satisfactory solution for routing in this type of environment. Here proposed a
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scheme, called the Zone RAID Routing Protocol (ZRRP), which dynamically adjusts itself to
operational conditions by sizing a single network parameter the zone radius. More specifically,
ZRRP reduces the cost of frequent updates to the constantly changing network topology by
limiting the scope of the updates to the immediate neighborhood of the change. Also
performance of the scheme, evaluating the average number of control messages required to
discover a route within the network. Furthermore, we compare the scheme's performance with
reactive flood search and RAID link-state classes of routing protocols.
Das(2000) says that Ad hoc networks are characterized by multihop wireless connectivity,
frequently changing network topology and the need for efficient dynamic routing protocols. We
compare the performance of two prominent on-demand routing protocols for mobile ad hoc
networks: Dynamic Source Routing (DSR) and Ad Hoc On-Demand Distance Vector Routing
(AODV). A detailed simulation model with MAC andphysical layer models is used to study
interlayer interactions and their performance implications. We demonstrate that even though
DSR and AODV share similar on-demand behavior, the differences in the protocol mechanics
can lead to significant performance differentials. The performance differentials are analyzed
using varying network load, mobility, and network size. Based on the observations, we make
recommendations about how the performance of either protocol can be improved.
Raju (2000) introduced WRP-Lite, which is a table-driven routing protocol that uses non-
optimal routes, and compare its performance with the performance of the dynamic source
routing (DSR) protocol, which is an on-demand routing protocol for wireless ad-hoc networks.
We evaluate the performance of WRP-Lite and DSR for varying degree of mobility and traffic
in a 20-node network. The performance parameters are end-to-end delay, control overhead,
percentage of packets delivered, and hop distribution. We show that WRP-Lite has much better
delay and hop performance while having comparable overhead to DSR.
Hong (2002) The growing interest in Mobile Ad Hoc Network techniques has resulted in many
routing protocol proposals. Scalability issues in adhoc networks are attracting more attention
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these days. In this paper, we will survey the routing protocols that address scalability. The
routing protocols we intend to include in the survey fall into three categories: (1) flat routing
protocols, (2) hierarchical routing approaches, and (3) GPS augmented geographical routing
schemes. The paper will compare the scalability properties and operational features of the
protocols and will discuss challenges in future routing protocol designs.
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CHAPTER 3
PRESENT WORK
3.1 INTRODUCTION
With the growing popularity and falling prices of the mobile hand-held computing and
information exchange devices, the need and capability of these devices are also growing.
These growth and need are creating its own set of new problems and challenges. Some
examples of recent and not so recent wireless devices are cellular phones, personal digital
assistants, tablet PCs, and lap-top PCs. All of these have the capability and need to transfer
information over wireless medium to each other in a network. Currently, the wireless networks
that allow communication between mobile devices can be classified into the following two
categories:
(i) Networks having a fixed infrastructure: an example of such a network is a cellular phone
network. A mobile cellular phone depends on a fixed infrastructure of base stations that cover
fixed areas. A mobile phone communicates with the nearest base station and the base station in
turn transmits the information to another base station, wired network, or to another mobile
phone. When a mobile phone is at an intersection of the coverage areas of two base stations, it
is switched to the base station with the stronger signal without any break in the communication
and without the user becoming aware of it.
(ii) Networks that do not have a fixed infrastructure: this is an emerging but highly useful and
promising type of network communication method. There are several situations where such a
network would be indispensable; mostly, in unplanned events like natural disasters and wars,
but also in a planned event. For example, a meeting of businessmen scattered over a large
place having no fixed infrastructure will be best supported by this kind of networks. This type
of networks can be described as a network of mobile devices that is created or destroyed as
needed and hence it is named Mobile Ad-hoc Network or Bluetooth.The most distinguishing
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aspect of Bluetooth is the lack of any fixed infrastructure and any central controlling authority.
When there is no central controlling authority, the devices comprising a network are all equal
and in such a situation, any decision needed to maintain a network becomes distributed. This
creates the need for distributed routing algorithms, resource allocation schemes, network entry
and exit rules, and network security. Moreover, as it is quite possible that a majority of the
mobile devices in such a network will be hand-held devices, the need to conserve battery power
will drive down the transmission power of the individual devices. Consequently,
communication between two devices would often require relay by intermediate devices, which
introduces the problem of multi-hop routing.
In wireless networks, physical links do not exist and a single transmission of a packet will
transfer a packet to multiple nodes within the communication range of a transmitting node at
the same time. We call this inherent broadcast of Bluetooths "local broadcast" to distinguish it
from global broadcast. It is guaranteed that at least a copy of a packet will reach a destination
node if every intermediate node, except the destination, repeats local broadcast without any
explicit routing, as long as such a path exists. However, routing is still needed for Bluetooths
because of the following reasons. If packets are transmitted by global broadcasts, excess copies
of each packet will be transmitted in the network and to the destination. Thus, global
broadcasts will entail unnecessary transmissions of packets, which waste battery power of
intermediate nodes for transmitting duplicated copies of packets at the same time that wastes
transmission bandwidth.Several routing protocols have been proposed for the mobile ad hoc
networks [1, 2, 3, 4]. These can be categorized as the proactive (also known as the table
driven) protocols, the reactive (known as source initiated or demand driven) protocols or the
hybrid of the reactive and proactive protocols. A categorization of the prominent ad hoc
routing protocols is shown in figure 3.1.
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FIG 3.1 Categorisation Of Adhoc Routing Protocols.
a) Proactive protocols: In proactive routing protocols, routing information to reach all the
other nodes in a network is always maintained in the format of the routing table at every node.
When the network topology changes (i.e., existing nodes have moved, some new links have
been created or existing ones are dropped), such changes in link states are announced to all the
nodes in a network. Thus, routes to all possible destinations are discovered in advance of
packet transmissions.
If a proactive protocol is used for BLUETOOTHs, an immediate problem is that rapid changes
in network topology might overwhelm the network with control messages (messages for
updating the routing table at every node) and the excess messaging overhead will compromise
the throughput of actual data transmissions. Examples of proactive protocols are TORa(5),
DSDV (Destination Sequenced Distance Vector) protocol [6], WRP (Wireless Routing
Protocol) [7], and FSR (Fisheye State Routing) protocol [8]. The four protocols are also called
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DSDV FSR ZRP
AODV DSR ABR WRP
Ad-hoc Routing
Protocols
Proactive
Protocols
Hybrid
Protocol
Reactive
Protocols
AODV: Ad hoc On Demand Distance VectorDSR: Dynamic Source Routing
ABR: Associativity Based Routing
DSDV: Destination Sequenced Distance VectorWRP: Wireless Routing Protocol
FSR: Fisheye State Routing
ZRP: Zone Routing Protocol
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table-driven protocols since the routing table will be updated for each change in link states in a
network and routes are discovered using information stored in routing tables.
b) Reactive protocols: As its name suggests, this type of protocols discovers a route only
when actual data transmission takes place. When a node wants to send information to another
node in a network, a source node initiates a route-discovery process. Once a route is
discovered, it is maintained in the temporary cache at a source node unless it is expired or
unless some event happens (e.g., a link failure) that requires another route discovery to start
over again. Reactive protocols require less amount of routing information at each node,
compared to proactive protocols, as there is no need to obtain and maintain the routing
information for all the nodes in a network. Another advantage in reactive protocols is that
intermediate nodes do not have to make routing decisions.
An obvious disadvantage in reactive protocols is delay due to route discovery, called route
acquisition delay. Furthermore, if routing information changes frequently, as it is the case in
BLUETOOTHs, and if route discoveries are needed for those changed routes, reactive
protocols may result in a large volume of messaging overhead, since route recoveries require
global broadcasts. Currently popular reactive protocols are DSR (Dynamic Source Routing)
protocol [3], AODV (Ad hoc On Demand Distance Vector) protocol [2], and ABR
(Associativity Based Routing) protocol [9].
c) Hybrid (combination of proactive and reactive) Protocols: Because of the
initial delay due to route discovery and high control overhead in reactive protocols, a pure
reactive protocol may not be the best solution for routing in BLUETOOTHs. On the other
hand, a pure proactive protocol used for a large network may not be feasible because of the
need to keep a large routing table at all times. A protocol that uses the best features of both
reactive and proactive protocol may be a better solution for BLUETOOTHs. An example for
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such an approach is the ZRP (Zone Routing Protocol) [10], although it is not the panacea for all
the limitations of other protocols.
Performance comparisons for ad hoc routing protocols have been reported in the recent past
[11, 12, 13, 14, 15, 16]. A comparison of DSR and AODV with some other protocols shows
that the performance of DSR is superior to AODV when node mobility is high, although DSR
has higher routing overhead as compared to AODV [11]. In a similar work by Das [12], it is
observed that, for metrics like delay and throughput that have real life application implications,
DSR performs better than AODV in conditions where the node density and/or node mobility
were low. According to Das, DSR always generated less control messages for routing than
AODV. However, Das argued that AODV resulted in less control messages than DSR under
high traffic load and high node mobility. Not awaring of any previously published work that
measures how much better WRP, DSR and AODV protocols are than a classical Distance
Vector protocol in ad-hoc networks. For example, how much better those BLUETOOTH
routing protocols will be than a classical Distance Vector protocol, in what aspects they are
better than Distance Vector protocol and in what conditions those BLUETOOTH routing
protocols will be better than Distance Vector protocol, surprisingly have not been answered. In
this thesis, effort has been made to find answers for such unanswered but significant questions
to understand the advantages of the BLUETOOTH routing protocols. In addition to these goals,
understanding the major properties in the existing BLUETOOTH routing protocols is also
discussed.
3.2. ROUTING PROTOCOL
In this section, the four existing routing protocols comparison are described in terms of their
implementation, design motivations and the major known characteristics.
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DSDV (Destination Sequenced Distance Vector): DSDV protocol is a classic routing
protocol whose refined versions are used in the current wired networks. It is a proactive
protocol and is based on the concept of distance vector: every node in a network maintains a
distance table (a one-dimensional array or a vector, called distance vector), where each entry in
a distance table contains the shortest distance and the address of the next-hop router on the
shortest path to every destination in a network.
In DSDV protocol, each node knows only the distance to its directly connected neighbors at the
beginning. The distance vector initially contains only the distance to the direct neighbors (the
distance to all other nodes is initialized to be infinity). Every node exchanges its distance vector
with all its directly connected neighbors. After a node receives a distance vector from a
neighbor node, the node updates its own distance vector to reflect the least cost path to other
nodes that are not immediate neighbors. This process repeats until there is no more update in
the distance vector at all nodes in a network. When this process is completed, each node will
have a distance vector that contains the least cost path to all the other nodes in the network.
When routing information changes at any node (for example, link failures), a node sends its
new distance vector to all of its immediate neighbors. The new distance vector will be
propagated to all the other nodes in a network using the same procedure to propagate the
distance vector.
DSDV protocol has several advantages for BLUETOOTH wireless networks. First of all, the
protocol does not require a global broadcast, which is the property most essential for a routing
protocol for large networks. Another advantage is the short route acquisition delay. Since this
protocol is proactive, routing information for every destination should be available in the
routing table at each node. The lack of need for route discovery on demand results in short
route acquisition delay. The above two advantages also imply traffic load scalability, since the
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messaging overhead of the protocol will be constant irrespective of traffic load as long as there
is no change in link states in a network.
The major known disadvantages in DSDV protocol are as follows :
1) The convergence time for propagating routing information will be long especially when the
link cost is increased Due to the long convergence time, it is possible that another change in
link states occurs while the information for the previous change in link cost has not been
completely propagated to the entire network. This could cause an erroneous routing decision,
well known as “counting-to-infinity problem”, which can result in temporary routing loops.
2) Another disadvantage in DSDV protocol is the non-availability of alternative paths. Since
the protocol uses a distributed approach, each node does not maintain the complete information
about link states in a network. Lack of complete knowledge of the link states for all links in a
network, each node is not aware of alternative paths to reach a destination. The unavailability
of the information for multiple alternative paths to reach a destination (if they exist) will make
the process of finding an alternative path during a sudden link failure a time-consuming
process, if not impossible.
3) The third problem is the large routing table. For ad-hoc networks as BLUETOOTH, the
contents of the routing tables will be short-lived. Maintaining large routing tables, while their
contents dynamically change in a short time, will result in high but unnecessary maintenance
overhead. Finally, Distance Vector protocol assumes symmetric links (e.g., costs of links are
same for the two directions on a link), which is not necessarily the case for wireless networks.
This is because each transmitting host usually uses different signal frequency in wireless
networks even when two hosts communicate with each other. Because of these problems,
DSDV protocol is seldom used in its original form.
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Wireless Routing Protocol (TORA): WRP is proposed by Murthy [7]. WRP is an extension
of distance vector protocol that eliminates possibility of routing loops. Nodes in a network
using WRP maintain a set of four tables:
a) Link Cost Table: This table contains the cost of the link to each immediate neighbor node
and information about the status of the link to each immediate neighbor.
b) Distance Table: The distance table of a node contains a list of all the possible destination
nodes and their distances beyond the immediate neighbors.
c) Routing Table: The routing table contains a list of paths to a destination via different
neighbors. If a valid path exists between a source and a destination node, its distance is
recorded in the routing table along with information about the next-hop node to reach the
destination node.
d) Message Retransmission List (MRL): The MRL of a node contains information about
acknowledgement (ACK) messages from its neighbors. If a neighbor doesn’t reply with an
ACK for a hello message within a certain time, then this information is kept in its MRL and an
update is sent only to the non-responding neighbors.
WRP works by requiring each node to send an update message periodically. This update
message could be new routing information or a simple “hello” if the routing information hasn’t
changed from the previous update. After sending an update message to its all neighbors, a node
expects to receive an ACK from all of them. If an ACK message does not come back from a
particular neighbor, the node will record the non-responding neighbor in MRL and will send
another update to the neighbor node later.
The nodes receiving the update messages look at the new information in the update message
and then update their own routing table and link cost table by finding the best path to a
destination. This best path information is then relayed to all the other nodes so that they can
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update their routing tables WRP avoids routing loops by checking the status of all the direct
links of a node with its direct neighbors, each time a node updates any of its routing
information.
Dynamic Source Routing (DSR) protocol : Dynamic Source Routing protocol, as its name
implies, is a source routing protocol: a complete sequence of intermediate nodes from a source
to a destination will be determined at a source node and all packets transmitted by a source
node to a destination follow the same path. Every packet header contains the complete
sequence of nodes to reach a destination. DSR protocol is a reactive protocol and its primary
motivations are, (1) to avoid periodic announcements of link states required in proactive
protocols, by separating route discovery from route maintenance, (2) to avoid long convergence
time of routing information and (3) to eliminate a large routing table for forwarding packets at
intermediate nodes. The routing table, in a sense that it is the data structure to always hold
routing information to reach every possible destination in a network, is not used in DSR
protocol. In DSR, routes are discovered on demand and route cache is used to hold routes that
are currently in use.DSR consists of two procedures route discovery and route maintenance.
Route Discovery: Every node in a network maintains a route cache that contains a list of hop-
by-hop routes to each destination node currently active and its expiration time (i.e., the time
after which a route is considered stale and discarded). Before a source node starts transmitting
data to a destination node, it first looks up its route cache to see if a valid route to that
destination exists. If such a route exists, then the route discovery process ends and the source
starts transmitting data using the route found in its route cache. Otherwise, a source node
broadcasts a route request packet (RRP) to find a route to reach the destination. This broadcast
is a global broadcast, which floods RRP in a network through all alternative paths to reach a
destination. While a RRP is being broadcast and propagated to the destination, a RRP adds the
address of every node it encounters to its list. If the same address appears more than once in the
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list, a RRP drops itself to avoid a routing loop. When a RRP reaches the destination node, the
destination returns the learned path extracted from the RRP to the source node. For wireless
networks that consist of asymmetric links, the destination node can send that path information
back to the source node as a global broadcast, which allows DSR to work for asymmetric links.
b)Route Maintenance: Route maintenance in DSR is a mechanism to inform network failures to
all nodes in a network. Its primary motivation is to expedite detection of network failures by
explicitly announcing them to every node in a network using global broadcasts. No matter if it
is a link or node failure, a node that is connected to the other end of a failed link is responsible
for detecting a failure in DSR. On detecting a network failure, the detecting node broadcasts an
error message, called error packet, to all the other nodes in a network to inform the failure.
When other nodes receive an error packet, they will disable the paths that go through the failed
link in their route cache.
An obvious advantage in DSR is that source nodes are aware of existence of alternative paths,
which implies that recovery from a link failure will be easy and quick. Another advantage is
that there will not be a chance of a routing loop (or it is easy to detect and avoid one).
Furthermore, nodes do not have to maintain routing table, which is an advantage especially for
a large network where nodes continue to move.
Being a reactive protocol also means that a route is stored in the route cache only when one is
needed, which implies low maintenance overhead. Since most routes are short-lived and
network topology frequently changes in BLUETOOTHs, on-demand routing will make more
sense than proactive protocols in terms of maintenance overhead for routing information at
each node (this is because a node does not have to modify anything if a failed and/or changed
link is not a part of any active path from this node).
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The disadvantage in DSR is long route acquisition delay due to route discovery if short
transmission delay is a significant factor. Long route acquisition delay may not be acceptable in
certain situations, such as mobile communication at a battlefield. It is also quite possible that
the path between a source and a destination may not be the shortest path (this is because
resumed links will not be explicitly advertised in DSR), resulting paths with in suboptimal end-
to-end delay. Another disadvantage is that messaging overhead of the protocol will be high
during busy time, when many connections must be established in a short time since broadcast is
used in route discovery. Large packet header will also cause low payload utilization, since each
packet has to contain a list of all the intermediate routers to reach a destination.
Ad hoc On Demand Distance Vector Routing : Ad-hoc On Demand Distance Vector
(AODV) protocol is a reactive routing protocol that has a motivation of providing a good
compromise between reactive source routing protocols and proactive protocols. The trade-off
problem AODV addresses is the one between high messaging overhead due to periodic
announcements of links states in proactive protocols and the large packet header to contain the
entire route information to reach a destination in source routing protocols. Unlike pure distance
vector protocols, routes are discovered and maintained on demand in AODV. Different from
DSR, AODV uses a distributed approach, meaning that source nodes do not maintain a
complete sequence of intermediate nodes to reach a destination. Different from Distance Vector
and WRP, each path is established as a pair of two streams of pointers chained between a
source and a destination node (details of this are described in a later section), which eliminates
need of broadcasting error packets on a link failure. Similar to DSR, AODV uses the route
discovery and route reply mechanism to create and maintain a route on demand.
a) Route Discovery: When a source node wants to send information to a destination node, it
first looks up its own routing table to see if a valid route exists. If a valid route does not exist, a
source node broadcasts a route request message that contains the source address, source
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sequence number, destination address, destination sequence number, broadcast ID, and hop
count. The combination of the source address and the broadcast-ID is used to uniquely identify
each route request message while a route request message is globally broadcast. Any node that
has a valid route to the destination or the destination node is supposed to respond to route
request messages by sending a route reply message.
During a route discovery, two pointers are set up at every intermediate node between the source
and the destination nodes. The two pointers are the back pointer and the forward pointer. A
chain of the forward pointers is set up between a source and destination node while a route
request message propagates from the source node to a destination. Similarly, a chain of the
back pointers is set up while a route reply message propagates back from the destination (or
from a node that already has a valid route to the destination) to the source. As a result, all the
intermediate nodes on a route maintain a pair of the forward pointer and the back pointer for
every connection that goes through them.
Every route request contains a list of intermediate nodes that have been encountered. If the
same intermediate node appears more than once in the list, the route request message will be
dropped (the chain of forward pointers must be deleted for a route request message to be
deleted). This guarantees loop-free routing.
b) Route Maintenance: The route maintenance is performed using three different types of
messages: route-error message, “hello” message and route time-out message. The purpose of
the time-out message is obvious: if there is no activity on a route for a certain amount of time,
the route pointers at the intermediate nodes will time out and the link will be deleted at the
intermediate nodes. The periodic “hello” messages between immediate neighbors are required
to prevent the forward and backward pointers from expiration. If one of the links in a route
fails, a route-error message is generated by the node upstream (i.e., from an intermediate node
to source nodes on the link and the message is propagated to every source node in its upstream
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that uses the failed link. Thus, the error packets will not be globally broadcast in AODV. Then,
the source nodes in the upstream will initiate the route discovery process.
Primary advantages in AODV protocol are as follow. Route caches are small in AODV,
because of its on-demand routing. Routes are guaranteed to be loop-free and valid.
Convergence time is short for propagating changes in link states because link failure
information will be propagated only to the nodes that are using a failed link (i.e., no broadcast
for error packets). Information of a link failure will be propagated following the back pointers
to reach such nodes. This implies that messaging overhead to announce link failures will be less
than that of DSR, where link failure information is broadcast. As another advantage, each data
packet does not contain the complete list of all the nodes on a route in AODV, which reduces
the size of message packet. Similar to DSR, a source node is aware of multiple alternative
paths.
One of the disadvantages in AODV protocol is that nodes can not perform routing (forwarding)
packets as aggregate (at least in the latest existing implementation of AODV). This is because a
set of pointers is used to maintain a route and each "flow" requires its own pair of back and
forward pointers. For the nodes where a large number of connections exist, overhead for
maintaining pairs of two pointers will be significant and may not be traffic-load scalable.
Another disadvantage is longer route acquisition delay compared to that for proactive protocols
since route discovery still must take place on demand. Different from DSR, AODV requires
periodic “hello” messages to maintain pointers set up at every node on a path. Use of broadcast
during route discovery, which contributes to high messaging overhead, is still the major
overhead. Yet another disadvantage of this protocol is that intermediate nodes can lead to
inconsistent routes if the source sequence number is very old and the intermediate nodes have a
higher but not the latest destination sequence number, thereby having stale entries. Also
multiple RouteReply packets in response to a single RouteRequest packet can lead to heavy
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control overhead.Table 3.1 summarizes the discussions regarding the four routing protocols in
this section.
Table 3.1–
Major properties of the DSDV,TORA,DSR,AODV Protocols.
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Properties DSDV TORA DSR AODV
Type of
routing
Proactive Proactive Reactive Reactive
Distributed YES (hop-by-hop)
YES (hop-by-hop)
NO (sourcerouting)
YES (hop-by-hop)
Routing loops Possible Not Possible Not Possible Not Possible
Use of
broadcast
No No Yes Yes
Control
Overhead
Constant to thenumber of sessions
Constant to thenumber of sessions
Affected by thenumber of sessions
Affected by thenumber of sessions
Routing
entries
All destinations All destinations Destinations inuse
Destinations inuse
Alternative
paths
Not available Not available Available Available
Request
response
Short Short Long (if notcached)
Long (if notcached)
Advantage Short responsetimeLow messageOH
Short responsetime
Quick pathrecovery
Small routingtableQuick recovery
Disadvantage Routing loopsLarge routingtableLongconvergencetime
Large routingtable
Long responsetimeLarge packetheader
Long responsetimeAggregaterouting is not
possible atintermediatenodes
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CHAPTER 4
PROBLEM FORMULATION
4.1 PROBLEM STATEMENT
To compare the performance of the four routing protocols viz AODV,DSDV,DSR and TORA
described in the previous sections, simulation experiments are performed. In this section,
experiment modeling and design are described.
4.2 Methodology
To compare the four routing protocols, a parallel discrete event-driven simulator, Ns2, is used.
Observations focuses on three performance measurements to compare the four routing
protocols: mean end-to-end delay, packet delivery rate and routing overhead as measured by
the number of control packets generated for routing. The three measurements in our
experiments are defined as follows:
End-to-end Delay: The average time from the beginning of a packet transmission (including
route acquisition delay) at a source node until packet delivery to a destination.
Packet Delivery Rate(Throughput): Packet delivery rate is the ratio of the number of user
packets successfully delivered to a destination to the total number of user packets transmitted
by source nodes.
Messaging Overhead: The number of control packets generated for routing by each routing
protocol.
4.2.1 Network Simulator
Ns2 is an object oriented simulator, written in C++, with an OTcl interpreter as a frontend. Ns2
uses two languages because simulator has two different kinds of things it needs to do. On one
hand, detailed simulations of protocols require a systems programming language which can
efficiently manipulate bytes, packet headers, and implement algorithms that run over large data
sets. For these tasks run-time speed is important and turn-around time (run simulation, find
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bug, fix bug, recompile, re-run) is less important. On the other hand, a large part of network
research involves slightly varying parameters or configurations, or quickly exploring a number
of scenarios. In these cases, iteration time (change the model and re-run) is more important.
Since configuration runs once (at the beginning of the simulation), run time of this part of the
task is less important. Ns2 meets both of these needs with two languages, C++ and OTcl .C++
is fast to run but slower to change, making it suitable for detailed protocol implementation.
OTcl runs much slower but can be changed very quickly (and interactively), making it ideal for
simulation configuration. In Ns2, the frontend of the program is written in TCL(Tool
Command Language). The backend of Ns2 simulator is written in C++ and when the tcl
program is compiled, a tracefile and namfile are created which define the movement pattern of
the nodes and keeps track of the number of packets sent, number of hops between 2 nodes,
connection type etc at each instance of time. In addition to these, a scenario file defining the
destination of mobile nodes along with their speeds and a connection pattern file(CBR file)
defining the connection pattern, topology and packet type are also used to create the trace files
and nam files which are then used by the simulator to simulate the network.
FIG 4.1 Simplified Users View Of NS2
[1][2] Also the network parameters can be explicitly mentioned during the creation of the
scenario and connection-pattern files using the library functions of the simulator.
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4.2.2 Simulation
Here simulation is performed using ns2 over a three node network over an area of size 500m
over 400m.The location process is as follows The initial location of nodes 0,1,2 are
respectively (5,5),(490,285),(150,240)(the z coordinatesis assumed throughout to be zero).
1) At time 10,node 0 starts moving towards point (250,250)at a speed of 3m/sec.
2) At time 15,node 1 starts moving towards point (45,285) at a speed of 5m/sec.
3) At time 110 node o starts moving towards point (480,300) at a speed of 5m/sec.
This simulation is done for all the four routing protocols to be compared and lasts for 150 sec.A
TCP connection is initiated between the node 0 and node1
4.3 SAMPLE TCL SCRIPT
# A 3-node example for ad-hoc simulation with DSDV
# Define options
set val(chan) Channel/WirelessChannel # channel type
set val(prop) Propagation/TwoRayGround # radio-propagation model
set val(netif) Phy/WirelessPhy # network interface type
set val(mac) Mac/802_11 # MAC type
set val(ifq) Queue/DropTail/PriQueue # interface queue type
set val(ll) LL ≠link layer type
set val(ant) Antenna/OmniAntenna ≠ antenna model
set val(ifqlen) 50 # max packet in ifq
set val(nn) 3 # number of mobilenodes
set val(rp) DSDV # routing protocol
set val(x) 500 # X dimension of topography
set val(y) 400 # Y dimension of topography
set val(stop) 150 # time of simulation end
set ns [new Simulator]40
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set tracefd [open simple-dsdv.tr w]
set windowVsTime2 [open win.tr w]
set namtrace [open simwrls.nam w]
$ns trace-all $tracefd
$ns use-newtrace
$ns namtrace-all-wireless $namtrace $val(x) $val(y)
# set up topography object
set topo [new Topography]
$topo load_flatgrid $val(x) $val(y)
create-god $val(nn)
# Create nn mobilenodes [$val(nn)] and attach them to the channel.
# configure the nodes
$ns node-config -adhocRouting $val(rp) \
-llType $val(ll) \
-macType $val(mac) \
-ifqType $val(ifq) \
-ifqLen $val(ifqlen) \
-antType $val(ant) \
-propType $val(prop) \
-phyType $val(netif) \
-channelType $val(chan) \
-topoInstance $topo \
-agentTrace ON \
-routerTrace ON \
-macTrace OFF \
-movementTrace ON
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for {set i 0} {$i < $val(nn) } { incr i } {
set node_($i) [$ns node]
}
# Provide initial location of mobilenodes
$node_(0) set X_ 5.0
$node_(0) set Y_ 5.0
$node_(0) set Z_ 0.0
$node_(1) set X_ 490.0
$node_(1) set Y_ 285.0
$node_(1) set Z_ 0.0
$node_(2) set X_ 150.0
$node_(2) set Y_ 240.0
$node_(2) set Z_ 0.0
# Generation of movements
$ns at 10.0 "$node_(0) setdest 250.0 250.0 3.0"
$ns at 15.0 "$node_(1) setdest 45.0 285.0 5.0"
$ns at 110.0 "$node_(0) setdest 480.0 300.0 5.0"
# Set a TCP connection between node_(0) and node_(1)
set tcp [new Agent/TCP/Newreno]
$tcp set class_ 2
set sink [new Agent/TCPSink]
$ns attach-agent $node_(0) $tcp
$ns attach-agent $node_(1) $sink
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$ns connect $tcp $sink
set ftp [new Application/FTP]
$ftp attach-agent $tcp
$ns at 10.0 "$ftp start"
# Printing the window size
proc plotWindow {tcpSource file} {
global ns
set time 0.01
set now [$ns now]
set cwnd [$tcpSource set cwnd_]
puts $file "$now $cwnd"
$ns at [expr $now+$time] "plotWindow $tcpSource $file" }
$ns at 10.1 "plotWindow $tcp $windowVsTime2"
# Define node initial position in nam
for {set i 0} {$i < $val(nn)} { incr i } {
# 30 defines the node size for nam
$ns initial_node_pos $node_($i) 30
}
# Telling nodes when the simulation ends
for {set i 0} {$i < $val(nn) } { incr i } {
$ns at $val(stop) "$node_($i) reset";
}
# ending nam and the simulation
$ns at $val(stop) "$ns nam-end-wireless $val(stop)"
$ns at $val(stop) "stop"
$ns at 150.01 "puts \"end simulation\" ; $ns halt"
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proc stop {} {
global ns tracefd namtrace
$ns flush-trace
close $tracefd
close $namtrace
}$ns run
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CHAPTER 5
SIMULATION RESULTS
5.1 RESULTS AND ANALYSIS
As described in the previous chapter to obtain the results for four routing protocols using
simulation, discrete event simulator Ns2 is used. After simulating the program using constant
bit rate and scenario files we get the output in form of two files. One is called as the network
animator file (NAM) and the other is called the trace file. These two files are created in the due
course of running the program. Basically the two files stores the same things but in different
format. NAM file stores the output in such a way that it can be used by the animator to show an
animated result, and the trace file stores the output so that it can be analyzed.
Ns2 uses the TCL script for simulating the above mentioned scenario and its results are
depicted in Network Animator(NAM) which is infact the part of Ns2.Along with this Graphical
analysis is done using the another program called Tracegraph for the trace file generated.In this
section animation and graphical analysis is done one by one.
5.1.1 Animation Analysis
After simulation as per the parameters described in previous chapter(refer section4.2.3) the
animation results are obtained uning NAM.Details of these animations for which the simulatio
scenario is is common for all thethe routing protocols is described here.
Results
As simulation is of three node adhoc network for each of the routing oprotocols,at the
beginning nodes are too far away and a connection can not be set.The first TCP signalling
packet is transmitted at 10s but the connection can not be opened.Meanwhile nodes 0 and nodes
1 starts moving towards node 2.After 6 sec(pause time) a second reattempt occurs but still the
connection can not be established the pause time value is doubled to 12 sec.At time 28s
another transmission attempts occurs.The pause time value is doubled again to 24 sec and then
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again to 48 sec.Thus only at time 100s connection has been established.The nodes 1 and 0 are
close to
each other so there is direct connection established.The nodes become further apart till the
direct link brakes.This scenario is shown in the following figures 5.1 and 5.2 which is a snap
shots of NAM at 124.15 sec.
Fig 5.1 TCP in a three node scenario for routing protocols for time 124.14 sec.
Fig 5.2 TCP in a three node scenario for routing protocols for time 58 sec.
When performing the simulation five phases of operation are observed.In the first and last
nodes are too far away and there is no connectivity.During phase 2 and 4 connection between
nodes 0 and 1 usind node 2 as a relay whereas in third phase,there is a direct path between node
0 and 1.Phase 2 at around time 40.Phase 3 starts at around 60 sec.At time 125.50 the fourth
phase starts and at time 149 sec it ends,which ends the whole connection.
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5.1.2 Graphical Analysis
In the graphical analysis trace files(.tr) generated for all the four routing protocols viz
AODV,DSDV,DSR,TORA are analyzed for the parameters Throughput,End To End Delay and
Overhead using the graphs generated and Network information. Program used here is
tracegraph.In the following section results are depicted for the above mentioned protocols one
by one.
5.1.2.1 Results for Protocols
1) AODV Protocol
a)Simulation Information
TABLE 5.1 Simulation Information Of AODV protocol.
b)Throughput
● Throughput Of Sending Packets :
Figure 5.3 shows Throughput varies slowly with time.For simulation time range of 0-25
sec.Throughput varies in the range of 0 to 3 packets.Above that i.e. for the simulation time 25-
50 secThroughput is almost 0 packets.It abruptly rises to 45 packets for the time 51 sec.At
simulation time of 60 sec throughput falls to around 38 packets.It againvaries from 38 to 42
packets for a time range of 60 to 140 sec.Throughput immediately falls to about 5 packets at the
simulation time of about 150 sec.
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Simulation Length In Seconds 139.5
Number Of Nodes 3
Number Of Sending Nodes 3
Number Of Receiving Nodes 3
Throughput 0.99
End To End Delay0.240 s
Routing Overhead 07
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Fig 5.3 Throughput Of Sending Packets for AODV
● Throughput Of Receiving Packets :
As seen in figure 5.4 Throughput for receiving packets is concerned it is almost same for 0 to
50 sec period.At 50 second interval it increases to around 85 packets at almost around 55 sec.At
simulation time 65 sec it rises to around 90 packets.It varies from 75 to 90 for the simulation
time range of 66 to 145 sec.Throughput drops to around 1 packet beyond this.
Fig 5.4 Throughput Of Receiving Packets for AODV
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c) End To End Delay :
Fig 5.5 Average End To End Delay for AODV
Figure 5.5 above average end to end delay varies in the range of 0 to 0.2 sec for a packet size
values of 0 to 50 packets. After the packet size of 60 end to end delay varies linearly with the
packet size upto the packet size of even 1000.
2)DSDV Protocol
a)Simulation Information:
TABLE 5.2 Simulation Information Of DSDV protocol
Simulation Length In Seconds 148.8
Number Of Nodes 3
Number Of Sending Nodes 3
Number Of Receiving Nodes 2
Throughput 0.993
End To End Delay 0.1184 s
Routing Overhead 29
b)Throughput
● Throughput Of Sending Packets :
From figure it is seen that throughput rise swiftly from 10 to 85 packets for the simulation time
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Fig 5.6 Throughput Of Sending Packets for DSDV
range of 100 to 103 sec.It varies in the range of 75 to maximum upto 90 packets for rest of the
simulation time values i.e.upto around 125 sec.
● Throughput Of Receiving Packets
Fig 5.7 Throughput Of Receiving Packets for DSDV
Figure 5.7 shows almost the same throughput as that of sending packets for the simulation time
range of 0 to 100 sec that is negligible.It rapidly rise to 172 packets for simulation time of
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above 100 sec.It again falls down to 140 packets for a simulation time range of 100 to 135
sec.Above 135 sec throughput again falls near to 0 packets.
c) End To End Delay :
Fig 5.8 Average End To End Delay for DSDV
Figure 5.8 demonstrates average end to end delay varies in the range of 0 to 0.2 sec for a
packet size values of 0 to 50 packets. After the packet size of 60 end to end delay varies
linearly with the packet size upto the packet size of even 1000.
3) DSR Protocol :
a)Simulation Information :
TABLE 5.3 Simulation Information Of DSR protocol
Simulation Length In Seconds 140
Number Of Nodes 3
Number Of Sending Nodes 3
Number Of Receiving Nodes 2
Throughput 0.99
End To End Delay 0.155 s
Routing Overhead 50
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b)Throughput
● Throughput Of Sending Packets :
Fig 5.9 Throughput Of Sending Packets for DSR
From the figure it is clear that throughput immidiately increases from 0 to 38 packets in around
0 to 10 sec simulation time.It varies between 30 to 40 packets for th e simulation time values of
10 to 63 sec. At above 63 sec time throughput swiftly rises to about 83 packets from where it is
rises to about 83 packets from it is varies in the range of 62 to 128 sec.After 128 seconds
throughput abruptly to thr value of about 10 packets and from here onwards it again varies from
10 to 38 packets for the simulationtime range of 129 to 140 sec and above.
● Throughput Of Receiving Packets :
Figure 5.10 below shows Throughput is negligible or close to 0 for the simulation time upto 40
sec.At 40 sec Throughput rises to the value f 150 packets and from their on it changes gradually
from 125 to 150 packets for the simulation time range of about 40 to 60 sec.At above 60 sec
time throughput again rises fastly to about 250 packets.Upto simulation time of 130 sec
throughput range varies in between 225 to 250.At above 130 sec throughput again falls to the
value of less than 50 packetsand then again gain the value of nearly 145 packets at simulation
time of around 135 sec.For the time 135 and above it again varies between 125 to150 packets.
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Fig 5.10 Throughput Of Receiving Packets for DSR
c) End To End Delay :
Fig 5.11 Average End To End Delay for DSR
Figure suggests that Average End To End delay rises from 0 to 0.15 second fastly for the
packet size of about 20. It falls down to 0 for the packet size of around 40.End To End delay
remains 0 for packet size range of 41 to 80. After that it rises linearly with packed size from 0
to 0.16 before again falling to 0 at the packet size of above 1000.Thus their is uneven rise and
fall in End To End Delay.
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3) TORA Protocol :
a)Simulation Information :
TABLE 5.4 Simulation Information Of TORA protocol
Simulation Length In Seconds 148.8
Number Of Nodes 4
Number Of Sending Nodes 4
Number Of Receiving Nodes 2
Throughput 0.992
End To End Delay 0.262s
Routing Overhead 5
b)Throughput
● Throughput Of Sending Packets :
Fig 5.12 Throughput Of Sending Packets for TORA
Figure 5.12 shows throughput is 0 for the simulaton time upto 20 sec.After that it increases to
near 30 packets very rapidly for the simulation time between 19 to 22 .For the time values of
22to 40 sec it remains near to30 packets.It rises rapidly to 44 packets at simulation time of
around 45 sec and remains almost constan with avery small change upto 60 sec.At around 61 it
falls to 0 and remains near to zero for rest of the simulation time intervals.
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● Throughput Of Receiving Packets
Fig 5.13 Throughput Of Receiving Packets for TORA
Here throughput rises from 0 to 28 packets for the time range of 10 to 22sec.It varies to a very
small values in the range of 23 to 28 packets for for the time values 23 to 37 sec.Throughput
toches the highest vlalue of aroun 45 packets at the simulation time of around 37. It varies in
the range of 32 to 45 packets for rest of the time intervals.
c) End To End Delay :
Fig 5.14 Average End To End Delay for TORA
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Average End To End delay is 0 to 0.3 for the packet size of of 10 to 30.It falls to 0 for packet
size of around 40sec.From thereon End To End delay linearly with packet size frm 100 to 1000
before again decreasing slowly to zero at packet size above 1000.
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CHAPTER 6
CONCLUSIONS AND FUTURE WORK
5.1 CONCLUSIONS
This research work evaluates the performance of four routing protocols for bluetooth (TORA, AODV
and DSR and DSDV protocol in their throughput, end-to-end delay and messaging overhead to
understand the advantages in the four protocols developed for bluetooth.Following things are
concluded.
1) Although DSR and AODV are both reactive protocols, DSR resulted in the best (i.e., the least)
messaging overhead and AODV generates higher throughput even than the two proactive protocols
(DSDV and TORA). Since the major difference between DSR and AODV for control overhead is the
lack of periodic route maintenance in DSR, the periodic “hello” messages used in AODV to maintain
routes was most probably responsible for DSR’s high control overhead.
2) Contrary to our prediction, DSDV performed much better than expected. DSDV resulted in nearly the
similar results in throughput (Figure 5.6 and 5.7) and even better in end-to-end delay, especially
compared to the two reactive protocols (AODV and DSR). The category where DSDV mostly resulted
in poor performance than the other three BLUETOOTH protocols was the messaging overhead (in the
number of control packets). DSR, against our expectation, resulted in worse performance in messaging
overhead. End-to-end delay for DSR is constantly longer than those of the three other protocols.
3) The impact of traffic load to the amount of messaging overhead for routing is observed high in
AODV.
4) Results suggest that DSR has the best scalability in messaging overhead, meaning that the number of
control packets in DSR will not increase sharply.
5) Throughput is quite high for all the four routing protocols
6) It is found that the DSR had the longest end-to-end delay and that TORA has the shortest end-to-end
delay..
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7) Results suggest that one of the advantages in using the four routing protocols designed for
BLUETOOTHs is the good scalability for node density in messaging overhead. The results show that
increase throughput is minor for the three protocols designed for BLUETOOTHs (AODV, DSR and
TORA) .when node density is increased. The largest increase in the number of control packets when
node density is increased from low to high is 124.8% for AODV, 210.7% for DSR and 139.6% for
WRP, while it is 353.6% for Distance Vector.
8) It is observed that TORA resulted in a poor packet delivery rate or throughput.
9) DSDV results in the worst scalability, DSDV results in the highest increase rate in end-to-end delay.
This inversely implies that one of the primary advantages in the three routing protocols designed for
BLUETOOTHs is the scalability for node mobility in end-to-end delay.
10) Total number of packets transfered for DSR is much larger than DSDVand AODV.
11) TORA gives nopacket transfer at all for a three node network.
6.2 FUTURE SCOPE
Future study includes measuring the actual number of bytes transmitted for control messages, which
would be useful to better differentiate the two on-demand protocols. Another future work is to perform
the experiments for various different node migration speeds and increased number of nodes. We used
the node mobility of 3m/sec and 5m/sec this time. However, these node migration speeds are just one of
the possible velocities. Keeping the migration speed lower may lessen or rule out the cases of packets
getting dropped even before routing information is updated. This may affect the simulation results and
perhaps will bring out the strengths and weaknesses of different protocols unambiguously.
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Appendix
ACO Authenticated Ciphering Offset
BD_ADDR Bluetooth Device Address
CA Certification Authority
CDC Certification Distribution Center
COF Ciphering Offset Number
FEC Forward Error Correction
FHSS Frequency Hoping Spread Spectrum
GFSK Gaussian Frequency Shift Keying
IEEE Institution of Electrical and Electronics Engineers
KDC Key Distribution Center
LFSR Linear Feedback Shift Register
LM Link Manager
LMP Link Manager Protocol
PDA Personal Digital Assistant
PIN Personal Identification Number
PKI Public Key Infrastructure
SIG Special Interest Group (as in Bluetooth SIG)
TTP Trusted Third Party
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