Seminar ECE

8/13/2019 Seminar ECE

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Bluetooth Based Smart Sensor Networks

Department of ECE ,SRET Page 1

CHAPTER 1

INTRODUCTION

1.1BLUETOOTH:

The new technology named after the 10th Century Danish King Harold Bluetooth,

is a hot topic among wireless developers. Bluetooth was designed to allow low bandwidth

wireless connections to become so simple to use that they seamlessly integrate into your

daily life. A simple example of a Bluetooth application is updating the phone directory of

your mobile phone. Today, you would have to either manually enter the names and phone

numbers of all your contacts or use a cable or IR link between your phone and your PC

and start an application to synchronize the contact information. With Bluetooth, this could

all happen automatically and without any user involvement as soon as the phone comes

within range of the PC! Of course, you can easily see this expanding to include your

calendar, to do list, memos, email, etc.. This is just one of many exciting applications for

this new technology! Can you imagine walking into a store and having all the sale items

automatically available on your cell phone or PDA? It is a definite possibility with

Bluetooth.

The Bluetooth specification is an open specification that is governed by theBluetooth Special Interest Group. The Bluetooth SIG is lead by its five founding

companies and four new member companies who were added in late 1999. These nine

companies form the Promoter Group of the Bluetooth SIG.

More than 1200 additional companies are members of the Bluetooth SIG. The

magnitude of industry involvement should ensure that Bluetooth becomes a widely

adopted technology. The first Bluetooth products should begin to appear this year. The

first Bluetooth product from Ericsson is a wireless cellular phone headset to be available

in Europe in mid-2000.

Sensor nodes can be imagined as small computers, extremely basic in terms of

their interfaces and their components. They usually consist of aprocessing unitwith

limited computational power and limited memory, sensors or MEMS, a communication

device, and a power source usually in the form of a battery. Other possible inclusions


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Department of ECE ,SRET

are energy harvesting modul

devices.

The base stations ar

computational, energy and

sensor nodes and the end use

Other special components i

calculate and distribute the

outside world including mo

range Wi-Fi links etc. Many

Linux.

1.2 BLUETOOTH DIVISO

Bluetooth devices are classif

the following table.

Table:

Most portable Bluet

cost and battery life issues.

control to limit the transmitt

hungry, this will provide u

networking and other applica

1.3 DATA TRANSFER

Bluetooth communic

transceiver utilizes frequen

Bluetooth device has a range

Bluetooth Based Smart Sens

s, secondary ASICs, and possibly secondary c

e one or more components of the WSN wit

communication resources. They act as a gate

r as they typically forward data from the WSN

routing based networks are routers, designe

routing tables. Many techniques are used to c

ile phone networks, satellite phones, radio

base stations are ARM-based running a form

N BASED ON POWER:

ed according to three different power classes, a

1.2 Bluetooth division based on power

oth devices will probably be in Power Class

A Power Class 1 device requires that you ut

ed power over 0 dBm. While a little more cost

to 100m of range, which should be suffici

tions that require a greater range.

MODES:

ation occurs in the unlicensed ISM band at

y hopping to reduce interference and fadi

of about 10 meters. The communication chann

r Networks

Page 2

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much more

way between

n to a server.

to compute,

onnect to the

odems, long-

of Embedded

s shown in

1 or 2 due to

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2.4GHz. The

g. A typical

l can support


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both data and voice communications with a total bandwidth of 1 Mb/sec. The supported

channel configurations are as follows:

1.3.1 Synchronous transfer mode:

DTM is an optical networking technology standardized by the European

Telecommunications Standards Institute in 2001 with specificationETSI ES 201 803-1.

DTM is a time division multiplexing and a circuit-switching network technology that

combines switching and transport. It is designed to provide a guaranteed quality of

service (QoS) for streaming video services, but can be used for packet-based services as

well. It was marketed for professional media networks, mobile TV networks, digital

terrestrial television networks, in content delivery networks and in consumer oriented

networks, such as "triple play" networks.

In DTM, capacity is allocated to a channel by assigning a number of time slots toit. It is basically a time-division multiplexing system. What sets it apart from other TDM

systems is the capability to assign any number of time slots to a channel, and vary this

number of slots as traffic demands. The basic argument for this technique is that it

provides a guaranteed QoS for a service since resources are physically allocated to the

channel and traffic from other channels will have no impact on this channel.

Time slots belong to a "DTM frame". The frame is 125 s long and contains a

number of 64-bit time slots. Thus the number of time slots per frame depends on the link

bit-rate. A number of these time slots are associated to form a channel. The simplest

channel consists of 1 time slot that is repeated each 125 s. The capacity of this one slot

channel is then 64 bits / 125 s = 512 kbit/s. A channel consisting of N time slots thus

have a capacity of N x 512 kbit/s. Thus 512 kbit/s is the "granularity" of bandwidth

allocation for a service.

DTM specfiesthat channels may be switched, which sets it apart from common

transmission techniques such as Synchronous Digital Hierarchy or Synchronous optical

networking . A DTM channel is automatically provisioned end-to-end over a general

topology network using control signalling. DTM is thus a circuit switched system. The

switches are generally time-space switches with the guaranteed QoS property, since

resources are physically allocated per channel also in the switch. This is opposed to

packet or cell based switches, in which the packets and cells are competing for resources

and as a result of this competition may have packets or cells delayed or discarded. For

packet and cell switches this shared resource allocation mechanism imposes a limit to


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how high the utilization of a network can be before the QoS get un-acceptably low. In

DTM network there is no such shared resource allocation, implying that a network

theoretically can be loaded to 100% and still have guaranteed QoS for its services. Real

utilization becomes thus more a question of adapting the network topology and link

capacities to the actual traffic matrix than to accommodating for QoS.

1.3.2 Asynchronous transfer mode:

DTM is an optical networking technology standardized by the European

Telecommunications Standards Institute (ETSI) in 2001 with specificationETSI ES 201

803-1. DTM is a time division multiplexing and a circuit-switching network technology

that combines switching and transport. It is designed to provide a guaranteed quality of

service for streaming video services, but can be used for packet-based services as well. It

was marketed for professional media networks, mobile TV networks, digital terrestrial

television networks, in content delivery networks and in consumer oriented networks,

such as "triple play" networks.

1.3.3 Data transfer mode comparision:

Configuration Max.Data rate Upstream Max. Data rate Downstream

Simultaneous voice

channel

64 kb/sec X 3 channels 64kb/sec

Symmetric data 433.9kb/sec 433.9kb/sec

Asymmetric data 723.2 Kb/sec 723.6kb/sec

1.3.3 Table: Data transfer modes

The synchronous voice channels are provided using circuit switching with a slot

reservation at fixed intervals. A synchronous link is referred to as an SCO link. The

asynchronous data channels are provided using packet switching utilizing a polling access

scheme. An asynchronous link is referred to as an ACL link. A combined data-voice

SCO packet is also defined. This can provide 64 kb/sec voice and 64 kb/sec data in each

direction.


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CHAPTER 2

BLUETOOTH TOPOLOGIES

2.1 PICONET:

Bluetooth devices can interact with one or more other Bluetooth devices in several

different ways. The simplest scheme is when only two devices are involved. This is

referred to as point-to-point. One of the devices acts as the master and the other as a

slave. This ad-hoc network is referred to as a piconet. As a matter of fact, a piconet is any

such Bluetooth network with one master and one or more slaves. A diagram of a piconet

is provided in (Figure2.1). In the case of multiple slaves, the communication topology is

referred to as point-to-multipoint. In this case, the channel is shared among all the

devices in the piconet. There can be up to seven active slaves in a piconet. Each of the

active slaves has an assigned 3-bit Active Member address . There can be additional

slaves which remain synchronized to the master, but do not have a Active Member

address. These slaves are not active and are referred to as parked. For the case of both

active and parked units, all channel access is regulated by the master. A parked device has

an 8-bit Parked Member Address, thus limiting the number of parked members to 256. A

parked device remains synchronized to the master clock and can very quickly become

active and begin communicating in the piconet.

Figure 2.1: piconet


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2.2 SCATTERNET:

You may be wondering what would happen if two piconets were within the same

coverage area. For example, you might have a piconet consisting of your cell phone and

your PC, while the person in the neighboring cubicle has a piconet consisting of a cell

phone, headset, and business card scanner. A diagram is presented in Figure 2 below.

Fig2.2:Scatternet

Because the two piconets are so close, they have overlapping coverage areas. This

scenario is provided for in the Bluetooth specification and is referred to as a scatternet. As

a matter of fact, slaves in one piconet can participate in another piconet as either a master

or slave. This is accomplished through time division multiplexing. In a scatternet, the

twopiconets are not synchronized in either time or frequency. Each of the piconets

operates in its own frequency hopping channel while any devices in multiple piconets

participate at the appropriate time via time division multiplexing. Returning to the

example, you may want to set up your neighbors business card scanner to also transmit

the information that is scanned to your PC so that you will have access to his business

contacts information. Of course, this would have to be a mutually agreed upon usage.

This brings us to the next topic, Bluetooth security.


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2.3 BLUETOOTH BASED SMART SENSOR NETWORK:

The main challenge in front of Blue tooth developers now is to prove

interoperability between different manufactures' devices and to provide numerous

interesting applications. One of such applications is wireless sensor networks. Wireless

sensor networks comprise number of small devices equipped with a sensing unit,

microprocessors, and wireless communication interface and power source.

An important feature of wireless sensor networks is collaboration of network

nodes during the task execution. As deployment of smart sensor nodes is not planned in

advance and positions of nodes in the field are not determined, it could happen that some

sensor nodes end in such positions that they either cannot perform required measurement

or the error probability is high. For that a redundant number of smart nodes is deployed in

this field. These nodes then communicate, collaborate and share data, thus ensuring better

results. Smart sensor nodes scattered in the field, collect data and send it to users via

"gateway" using multiple hop routes.

It consists of spatially distributed autonomous sensors to monitorphysical or

environmental conditions, such as temperature, sound, vibration, pressure, motion or

pollutants and to cooperatively pass their data through the network to a main location.

The more modern networks are bi-directional, also enabling control of sensor activity.

The development of wireless sensor networks was motivated by military applications

such as battlefield surveillance; today such networks are used in many industrial and

consumer applications, such as industrial process monitoring and control, machine health

monitoring, and so on.

The WSN is built of "nodes" from a few to several hundreds or even thousands,

where each node is connected to one sensors. Each such sensor network node has

typically several parts: a radio transceiver with an internal antenna or connection to an

external antenna, a microcontroller, an electronic circuit for interfacing with the sensors

and an energy source, usually a battery or an embedded form of energy harvesting.

A sensor node might vary in size from that of a shoebox down to the size of a grain of

dust, although functioning "motes" of genuine microscopic dimensions have yet to be

created. The cost of sensor nodes is similarly variable, ranging from a few to hundreds of


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dollars, depending on the complexity of the individual sensor nodes. Size and cost

constraints on sensor nodes result in corresponding constraints on resources such as

energy, memory, computational speed and communications bandwidth. The topology of

the WSNs can vary from a simple star network to an advanced multi-hop wireless mesh

network. The propagation technique between the hops of the network can be routing orflooding. In computer science and telecommunications, wireless sensor networks are an

active research area with numerous workshops and conferences arranged each year.

2.3.1Main functions of the gate way:

Communication with sensor networks.

Shortage wireless communication is used.

It controls gateway interfaces and data flow to and from sensor network.

It provides an abstraction level that describes the existing sensors and their

characteristics.

It provides functions for uniform access to sensors regardless of their type,

location or N/W topology, inject queries and tasks and collect replies.

2.3.2Characteristics of a WSN:

Power consumption constrains for nodes using batteries or energy harvesting

Ability to cope with node failures

Mobility of nodes

Dynamic network topology

Communication failures

Heterogeneity of nodes

Scalability to large scale of deployment

Ability to withstand harsh environmental conditions

Ease of use

Unattended operation

Power consumption


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2.3.3 COMMUNICATION WITH USERS:

Gateway communications with users or other sensor networks over the nternet,

WAN, Satellite or some shortage communication technology. From the user point of

view,querying and tasking are two main services provided by wireless sensor networks.

Queries are used when user requires only the current value of the observed phenomenon.

Tasking is a more complex operation and is used when a phenomenon has to be observed

over a large period of time.Both queries and tasks of time to the network by the gateway

which also collects replies and forwards them to users.


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CHAPTER 3

SENSOR NETWORK IMPLEMENTATION

3.1 PRESSUR SENSOR:

The main goal of our implementation was to build a hardware platform and

generic software solutions that can serve as the basis and a test bed for the research of

wireless sensor network protocols. Implemented sensor network consists of several smart

sensor nodes and a gateway. Each smart node can have several sensors and is equipped

with a microcontroller and a Bluetooth radio module. Gate way and smart nodes are

members of the Piconet and hence maximum seven smart nodes can exist simultaneously

in the network. For example, a pressure sensor is implemented, as Bluetooth node in a

following way. The sensor is connected to the Bluetooth node and consists of the pressure

sensing element, smart signal-conditioning circuitry including calibration and temperature

compensation, and the Transducer Electronic Data Sheet . These features are built directly

into the sensor microcontroller used for node communication control plus memory for

TEDS configuration information.

It measures pressure, typically of gases or liquids. Pressure is an expression of the

force required to stop a fluid from expanding, and is usually stated in terms of force per

unit area. A pressure sensor usually acts as a transducer; it generates a signal as a functionof the pressure imposed. For the purposes of this article, such a signal is electrical.

Pressure sensors are used for control and monitoring in thousands of everyday

applications. Pressure sensors can also be used to indirectly measure other variables such

as fluid/gas flow, speed, water level, and altitude. Pressure sensors can alternatively be

called pressure transducers, pressure transmitters, pressure senders, pressure indicators

and piezometers, manometers, among other names.

Pressure sensors can vary drastically in technology, design, performance,

application suitability and cost. A conservative estimate would be that there may be over

50 technologies and at least 300 companies making pressure sensors worldwide.

There is also a category of pressure sensors that are designed to measure in a

dynamic mode for capturing very high speed changes in pressure. Example applications


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for this type of sensor would be in the measuring of combustion pressure in an engine

cylinder or in a gas turbine. These sensors are commonly manufactured out of

piezoelectric materials such as quartz.

Some pressure sensors, such as those found in some traffic enforcement cameras, function

in a binary (on/off) manner, i.e., when pressure is applied to a pressure sensor, the sensor

acts to complete or break an electrical circuit. These types of sensors are also known as a

pressure switch.

3.2 PRESSURE MEASUREMENTS:

Pressure sensors can be classified in terms of pressure ranges they measure,

temperature ranges of operation, and most importantly the type of pressure they measure.

In terms of pressure type, pressure sensors can be divided into five categories:

3.2.1Absolute pressure sensor:

This sensor measures the pressure relative to perfect vacuumpressure .

Atmosphericpressure, is 101.325 k at sea level with reference to vacuum.

3.2.2Gauge pressure sensor:

This sensor is used in different applications because it can be calibrated to measure

the pressure relative to a given atmospheric pressure at a given location. A tire pressure

gauge is an example of gauge pressure indication. When the tire pressure gauge reads 0

PSI, there is really 14.7 PSI in the tire.

3.2.3Vacuum pressure sensor:

This sensor is used to measure pressure less than the atmospheric pressure at a

given location. This has the potential to cause some confusion as industry may refer to a

vacuum sensor as one which is referenced to either atmospheric pressure or relative to

absolute vacuum.


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3.2.4Differential pressure sensor:

This sensor measures the difference between two or more pressures introduced as inputs

to the sensing unit, for example, measuring the pressure drop across an oil filter.

Differential pressure is also used to measure flow or level in pressurized vessels.

3.2.5Sealed pressure sensor:

This sensor is the same as the gauge pressure sensor except that it is previously

calibrated by manufacturers to measure pressure relative to sea level pressure.

3.3 PRESSURE-SENSING TECHNOLOGY:

There are two basic categories of analog pressure sensors.

3.3.1Force collector types:

These types of electronic pressure sensors generally use a force collector to

measure strain due to applied force over an area.

3.3.2Piezoresistive strain gauge:

Uses thepiezoresistive effect of bonded or formed strain gauges to detect strain

due to applied pressure. Common technology types are Silicon, Polysilicon Thin Film,

Bonded Metal Foil, Thick Film, and Sputtered Thin Film. Generally, the strain gauges are

connected to form a Wheatstone bridge circuit to maximize the output of the sensor. This

is the most commonly employed sensing technology for general purpose pressure

measurement. Generally, these technologies are suited to measure absolute, gauge,

vacuum, and differential pressures.

3.3.3Capacitive:

Uses a diaphragm and pressure cavity to create a variable capacitor to detect strain

due to applied pressure. Common technologies use metal, ceramic, and silicon

diaphragms. Generally, these technologies are most applied to low pressures.


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3.3.4Electromagnetic:

Measures the displacement of a diaphragm by means of changes in

inductanceLVDT, Hall Effect, or by eddy current principle.

3.3.5Piezoelectric:

Uses the piezoelectric effect in certain materials such as quartz to measure the

strain upon the sensing mechanism due to pressure. This technology is commonly

employed for the measurement of highly dynamic pressures.

3.3.6Optical:

Techniques include the use of the physical change of an optical fiber to detect

strain due to applied pressure. A common example of this type utilizes Fiber Bragg

Gratings. This technology is employed in challenging applications where the

measurement may be highly remote, under high temperature, or may benefit from

technologies inherently immune to electromagnetic interference. Another analogous

technique utilizes an elastic film constructed in layers that can change reflected

wavelengths according to the applied pressure.

3.3.7Potentiometric:

Uses the motion of a wiper along a resistive mechanism to detect the strain caused

by applied pressure

3.3.8Resonant:

Uses the changes in resonant frequency in a sensing mechanism to measure stress,

or changes in gas density, caused by applied pressure. This technology may be used in

conjunction with a force collector, such as those in the category above. Alternatively,

resonant technology may be employed by expose the resonating element itself to the

media, whereby the resonant frequency is dependent upon the density of the media.

Sensors have been made out of vibrating wire, vibrating cylinders, quartz, and silicon


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MEMS. Generally, this technology is considered to provide very stable readings over

time.

3.3.9Thermal:

Uses the changes in thermal conductivity of a gas due to density changes to

measure pressure. A common example of this type is the Pirani gauge.

3.3.10Ionization:

Measures the flow of charged gas particles which varies due to density changes to

measure pressure. Common examples are the Hot and Cold Cathode gages.

3.4TESTING:

3.4.1Leak testing:

A pressure sensor may be used to sense the decay of pressure due to a system

leak. This is commonly done by either comparison to a known leak using differential

pressure, or by means of utilizing the pressure sensor to measure pressure change over

time.

3.4.2Ratiometric Correction of Transducer Output:

Piezoresistive transducers configured as Wheatstone bridges often exhibit

ratiometric behavior with respect not only to the measured pressure, but also the

transducer supply voltage.

=

3.4.2.1

where:

Vout is the output voltage of the transducer.

P is the actual measured pressure.

Kis the nominal transducer scale factor (given an ideal transducer supply voltage) in units

of voltage per pressure.


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Vsactual is the actual transducer supply voltage.

Vsideal is the ideal transducer supply voltage.

Correcting measurements from transducers exhibiting this behavior requires measuring

the actual transducer supply voltage as well as the output voltage and applying the inverse

transform of this behavior to the output signal:

=

3.4.2.2

NOTE: Common mode signals often present in transducers configured as Wheatstone

bridges are not considered in this analysis.

3.5 APPLICATIONS:

There are many applications for pressure sensors:

3.5.1 Pressure sensing:

This is where the measurement of interest is pressure, expressed as a force per unit

area . This is useful in weather instrumentation, aircraft, automobiles, and any other

machinery that has pressure functionality implemented.

3.5.2 Altitude sensing:

This is useful in aircraft, rockets, satellites, weather balloons, and many other

applications. All these applications make use of the relationship between changes in

pressure relative to the altitude. This relationship is governed by the following equation:

= (1 ( )10.908 )*145366.45 ft---------------------3.5.2.1

This equation is calibrated for an altimeter, up to 36,090 feet (11,000 m). Outside that

range, an error will be introduced which can be calculated differently for each different

pressure sensor. These error calculations will factor in the error introduced by the change

in temperature as we go up.


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Department of ECE ,SRET

Barometric pressure sensors

significantly better than GPS

applications altimeters are

navigation and floor levels i

3.5.3 Flow sensing:

This is the use of

measure flow. Differential p

that have a different apert

directly proportional to the

almost always required as th

3.5.4 Level / depth sensin

A pressure sensor ma

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Page 16

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CHAPTER 4

HARDWARE ARCHITECTURE

4.1 HARDWARE REQUIREMENTS:

Now that you have a basic understanding of what the Bluetooth specification is

and how Bluetooth devices can interact with each other, you are probably beginning to

wonder what makes all this work in terms of real hardware and software. The remainder

of this article will focus on Bluetooth hardware. We will leave a detailed software

discussion for a future article.

Bluetooth hardware can be divided into two primary functions, the Radio Module

and the Link Module. At this time, a complete Bluetooth hardware module including both

Radio and Link subsystems costs between $25-30 in additional parts. However, within the

next couple of years this is expected, by most in the industry, to approach.

4.1.1Radio Module:

As mentioned above, Bluetooth devices operate in the 2.4GHz Industrial

Scientific Medicine band. This is an unlicensed band and, in most countries, includes the

frequency range from 2400 to 2483.5 MHz. Of course, as always when dealing withinternational standards, there are a few exceptions. The primary geographies with

exceptions are France (2446.5 to 2483.5 MHz) and Spain (2445 to 2475 MHz). At this

time, Bluetooth products for these two markets are local versions that are not

interoperable with the international versions which implement the full range. These

localized versions have a reduced frequency band and a different hopping algorithm.

However, the Bluetooth SIG is working with authorities in both countries to open the full

range. For the sake of simplicity, this article will only deal with the international

frequency range implementation.

The RF channels used are from 2402 to 2480 MHz with a channel spacing of 1

MHz. Frequency hopping has been implemented to reduce interference and fading. This

means that every 625 sec the channel will hop to another frequency within the 2402 to

2480 MHz range. This translates to 1600 hops every second. Each piconet has a unique

hopping sequence which is determined using an algorithm the uses the Bluetooth device


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address of the master device. All Bluetooth units in the piconet are then synchronized to

this hopping sequence.

All packet transmissions are started at the beginning of one of the 625 sec time

slots. A packet may last up to 5 time slots. A time division duplex scheme is used to

facilitate full duplex transmission. During even numbered slots, the master may begin a

transmission. During odd numbered slots, a slave may begin a transmission. In addition,

these time slots can be reserved for synchronous applications such as voice data.

Bluetooth radio modules use Gaussian Frequency Shift Keying (GFSK) for

modulation. A binary system is used where a one is signified by a positive frequency

deviation and a zero is signified by a negative frequency deviation. The data is

transmitted at a symbol rate of 1 Ms/sec. The radio module is covered in detail in Part A

of the Specification of the Bluetooth System published by the Bluetooth SIG.

4.1.2Link Module:

The Link Module and the closely associated Link Manager software is responsible

for the baseband protocols and some other low level link functions. This includes

sending/receiving data, setting up connections, error detection and correction, data

whitening, power management, and authentication.The link module is responsible for

deriving the hop sequence. This is accomplished using the Bluetooth Device Address(BD_ADDR) of the master device. All Bluetooth devices are assigned a 48-bit IEEE 802

address. This 48-bit master device address is used by each of the devices in the piconet to

derive the hop sequence.The Link Module is also responsible for performing the three

error correction schemes that are defined for Bluetooth:

1/3 rate FEC

2/3 rate FEC

ARQ scheme for the data

The purpose of the two FEC (forward error correction) schemes is to reduce the

number of retransmissions. The ARQ scheme (automatic retransmission request) will

cause the data to be retransmitted until an acknowledgement is received indicating a

successful transmission (or until a pre-defined time-out occurs). A CRC (cyclic

redundancy check) code is added to each packet and used by the receiver to decide


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whether or not the packet has arrived error free. Note that the ARQ scheme is only used

for data packets, not synchronous payloads such as voice.

In order to reduce highly redundant data and minimize DC bias, a data whitening

scheme is used to randomize the data. The data is scrambled by a data whitening word

and then unscrambled using the same word at the receiver. This descrambling is done

after the error detection/correction process.

Bluetooth provides provisions for three low power modes to conserve battery life.

These states, in decreasing order of power requirements are Sniff Mode, Hold Mode, and

Park Mode. While in the Sniff mode, a device listens to the piconet at a reduced rate. The

Sniff interval is programmable, providing flexibility for different applications. The Hold

mode is similar to the Park mode, except that the Active Member address (AM_ADDR)

is retained. In the Park mode, the devices clock continues to run and remains

synchronized to the master, but the device does not participate at all in the piconet.

4.2 SMART SENSOR NODE ARCHITECTURE:

The architecture shown in figure can easily be developed for specific sensor

configurations such as thermocouples, strain gauges, and other sensor technologies and

can include sensor signal conditioning as well as communications functions. Conditioned

along sensor signal is digitized and digital data is then processed using stored TEDs data.The pressure sensor node collects data from multiple sensors and transmits the data via

Bluetooth wireless communications in the 2.4 GHZ base band to a network hub or other

internet appliance such as a computer. The node can supply excitation to each sensor, or

external sensor power can be supplied. Up to eight channels are available on each node

for analog inputs as well as digital output. The sensor signal is digitized with 16-bit A/D

resolution for transmission along with the TEDS for each sensor. This allows each

channel to identify itself to the host system. The node can operate from either an external

power supply or an attached battery. The maximum transmission distance is 10 meters

with an optional capability to 100 meters.The IEEE 1451 family of standards are used for

definition of functional boundaries and interfaces that are necessary to enable smart

transducer to be easily connected to a variety of networks. The standards define the

protocol and functions that give the transducer interchangeability in networked system,

with this information a host microcomputer recognized a pressure sensor, a temperature


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sensor, or another sensor type along with the measurement range and scaling information

based on the information contained in the TEDS data. With blue tooth technology, small

transceiver modules can be built into a wide range of products including sensor systems,

allowing fast and secure transmission of data within a given radius .A blue tooth module

consists primarily of three functional blocks - an analog 2.4 GHz., Blue tooth RFtransceiver unit, and a support unit for link management and host controller interface

functions. The host controller has a hardware digital signal processing part- the Link

Controller (LC), a CPU core, and it interfaces to the host environment. The link controller

consists of hardware and software parts that perform blue tooth based band processing,

and physical layer protocols. The link controller performs low-level digital-signal

processing to establish connections, assemble or disassemble, packets, control frequency

hopping, correct errors and encrypt data.

The CPU core allows the blue tooth module to handle inquiries and filter page

request without involving the host device. The host controller can be programmed to

answer certain page messages and authenticate remote links. The link manager(LM)

software runs on the CPU core. The LM discovers other remote LMs and communicates

with them via the linkmanager protocol (LMP) to perform its service provider role using

the services of the underlying LC. The link manager is a software function that uses the

services of the link controller to perform link setup, authentication, link configuration,

and other protocols. Depending on the implementation, the link controller and linkmanager functions may not reside in the same processor. Another function component is

of course, the antenna, which may be integrated on the PCB or come as a standalone item.

A fully implemented blue tooth module also incorporates higher-level software protocols,

which govern the functionality and interoperability with other modules. Gate way plays

the role of the Piconet's master in the sensor network. It controls establishments of the

network, gathers information about the existing smart sensor nodes and sensor attached to

them and provides access to them. Discovery Of The Smart Sensor Nodes Smart sensor

node discovery is the first procedure that is executed upon the gateway installation. Itgoals to discover all sensor nodes in the area and to build a list of sensor's characteristics

and network topology. Afterwards, it is executed periodically to facilitate addition of new

or removal of the existing sensors. The following algorithm is proposed. When the

gateway is initialized, it performs bluetooth inquiry procedure. When the blue tooth

device is discovered, the major and minor device classes are checked. These parameters


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are set by each smart node to define type of the device and type of the attached sensors.

Service class field can be used to give some additional description of offered services. if

discovered device is not smart node it is discarded. Otherwise service database of the

discovered smart node is searched for sensor services. As currently there is no specific

sensor profile, then database is searched for the serial port profile connection parameters.Once connection strings is obtained from the device.

4.3 HARDWARE IMPLEMENTATIONS:

Companies such as Cambridge Silicon Radio are working on single chip

Bluetooth solution with roadmaps towards the $5 cost target. Cambridge Silicon Radio

expects to be shipping its first silicon in volume by June of 2000. In future designs the

host controller software will be frozen and the flash memory will be integrated as mask

ROM into the silicon, further reducing the size of the design.

Fig4.3 Bluetooth hardware implementation

4.4 AUTHENTICATION AND PRIVACY:

While authentication and privacy could be handled at the software protocol layer,

it is also provided in the Bluetooth physical layer. A particular connection can be

specified to require either one-way, two-way, or no authentication. The authentication is

provided using a challenge/response system. The system supports key lengths of 40 or 64

bits. The key management is left to software layers. These security mechanisms and the

associated software allow a user to set up his or her devices to only communicate with


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each other. All Bluetooth devices implement this physical layer security in the same way.

Of course, for highly sensitive applications, it is also recommended that you utilize more

advanced algorithms in the network transport or application layer.

4.5 APPLICATIONS:4.5.1 Area monitoring:

Area monitoring is a common application of WSNs. In area monitoring, the WSN

is deployed over a region where some phenomenon is to be monitored. A military

example is the use of sensors to detect enemy intrusion; a civilian example is the geo-

fencing of gas or oil pipelines.When the sensors detect the event being monitored (heat,

pressure), the event is reported to one of the base stations, which then takes appropriate

action (e.g., send a message on the internet or to a satellite). Similarly, wireless sensor

networks can use a range of sensors to detect the presence of vehicles ranging from

motorcycles to train cars.

4.5.2 Environmental sensing:

The term Environmental Sensor Networks has evolved to cover many applications

of WSNs to earth science research. This includes sensing volcanoes, oceans, glaciers,

forests, etc. Some other major areas are listed below.

4.5.3 Air pollution monitoring:

Wireless sensor networks have been deployed in several cities to monitor the

concentration of dangerous gases for citizens. These can take advantage of the ad-hoc

wireless links rather than wired installations, which also make them more mobile for

testing readings in different areas. There are various architectures that can be used for

such applications as well as different kinds of data analysis and data mining that can be

conducted.

4.5.4 Forest fires detection:

A network of Sensor Nodes can be installed in a forest to detect when a fire hasstarted. The nodes can be equipped with sensors to measure temperature, humidity and

gases which are produced by fires in the trees or vegetation. The early detection is crucial

for a successful action of the firefighters; thanks to Wireless Sensor Networks, the fire

brigade will be able to know when a fire is started and how it is spreading.

4.5.5 Greenhouse monitoring:


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Wireless sensor networks are also used to control the temperature and humidity

levels inside commercial greenhouses. When the temperature and humidity drops below

specific levels, the greenhouse manager must be notified via e-mail or cell phone text

message, or host systems can trigger misting systems, open vents, turn on fans, or control

a wide variety of system responses.

4.5.6 Machine health monitoring:

Wireless sensor networks have been developed for machinery condition-based

maintenance (CBM)as they offer significant cost savings and enable new functionalities.

In wired systems, the installation of enough sensors is often limited by the cost of wiring.

Previously inaccessible locations, rotating machinery, hazardous or restricted areas, and

mobile assets can now be reached with wireless sensors.

4.5.7 Data Logging:

Wireless sensor networks are also used for the collection of data for monitoring of

environmental information, this can be as simple as the monitoring of the temperature in a

fridge to the level of water in overflow tanks in nuclear power plants. The statistical

information can then be used to show how system have been working.

4.5.8 Water/wastewater monitoring:

There are many opportunities for using wireless sensor networks within the

water/wastewater industries. Facilities not wired for power or data transmission can be

monitored using industrial wireless I/O devices and sensors powered using solar panels or

battery packs and also used in pollution control board.

4.5.9 Agriculture:

Using wireless sensor networks within the agricultural industry is increasingly

common; using a wireless network frees the farmer from the maintenance of wiring in a

difficult environment. Gravity feed water systems can be monitored using pressure

transmitters to monitor water tank levels, pumps can be controlled using wireless I/O

devices and water use can be measured and wirelessly transmitted back to a central

control center for billing. Irrigation automation enables more efficient water use and

reduces waste.


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4.5.10 Structural monitoring:

Wireless sensors can be used to monitor the movement within buildings and

infrastructure such as bridges, flyovers, embankments, tunnels etc... enabling Engineering

practices to monitor assets remotely without the need for costly site visits, as well as

having the advantage of daily data, whereas traditionally this data was collected weekly

or monthly, using physical site visits, involving either road or rail closure in some cases.

It is also far more accurate than any visual inspection that would be carried out.

4.5.11 On-site tracking of materials:

Since the cost of ownership of wireless sensors is lowering it will provide the

opportunity to track and trace large and expensive products, but also small and cheap

products, creating intelligent products.


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CHAPTER5

CONCLUSION

5.1 CONCLUSION:

As you can see, the Bluetooth specification is definitely real and is being widely

adopted by industry leaders. The possibilities for new applications are very exciting with

this versatile technology.

Bluetooth represents a great chance for sensor-networked architecture. This

architecture heralds wireless future for home and also for industrial implementation. With

a Bluetooth RF link, users only need to bring the devices within range, and theautomatically link up and exchange information.

Thus implementation of Bluetooth technology for sensor networks not only cuts

wiring cost but also integrates the industrial environment to smarter environment.


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5.2 REFERENCES

[1] Zaruba, G. V., Chlamtac, I. Accelerating Bluetooth inquiry for personal area

networks.

[2] Specifications of Bluetooth system version 1.2, 05 November 2003.

[3] Bluetooth 2000: To enable the star generation, Cahners In-Stat group MM00-09BW,

June 2000.

[4] S. Kreo, Bluetooth based wireless sensor network implementation issues and

solutions, 10th telecommunication forum (TELEFOR2002) NOV. 2002.

[5] Nicholas Weaver (UC Berkeley), Vern Paxson (ICSI), Stuart Staniford (Silicon

Defence), Robert Cunnigham (MIT Lincoln Laboratory). A taxonomy of computer

worms.

[6] F-Secure http://www.f-secure.com

[7] Symantec Corporation http://symantec.com

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