Wireless sensor network report

Wireless Sensor Network 2014

COMPUTER ENGINEERING, GPP.

Chapter 1

Introduction

A wireless sensor network (WSN) is a wireless network consisting of spatially

dispersed and dedicated autonomous devices that use sensors to monitor

physical or environmental conditions. A usual WSN system is formed by

combining these autonomous devices, or nodes with routers and a gateway.

The dispersed measurement nodes communicate wirelessly to a central

gateway, which provides a connection to the wired world where you can collect,

process, analyse, and present your measurement data. You can use routers to

gain an additional communication link between end nodes and the gateway for

extend distance and reliability in a wireless sensor network.

The wireless sensor is networked and scalable, require very little power. It is

also smart and software programmable, and also capable of fast data

acquisition, reliable and accurate over the long term, but costs little to purchase

and install, and requires nearly zero maintenance.

Wireless Sensor Network



A Wireless Sensor Network (WSN) is a wireless network consisting of spatially

distributed autonomous devices using sensors to cooperatively monitor physical

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

motion or pollutants, at different locations. The development of wireless sensor

networks was originally motivated by military applications such as battlefield

surveillance. However, wireless sensor networks are now used in many civilian

application areas, including environment and habitat monitoring, healthcare

applications, home automation, and traffic control.

In addition to one or more sensors, each node in a sensor network is typically

equipped with a radio transceiver or other wireless communications device, a

small microcontroller, and an energy source, usually a battery. The size of a

single sensor node can vary from shoebox-sized nodes down to devices the size

of grain of dust. The cost of sensor nodes is similarly variable, ranging from

hundreds of dollars to a few cents, depending on the size of the sensor network

and the complexity required of individual sensor nodes. Size and cost constraints

on sensor nodes result in corresponding constraints on resources such as

energy, memory, computational speed and bandwidth.

In computer science and telecommunications, wireless sensor networks are

an active research area with numerous workshops and conferences arranged

each year.

WSN are used to collect data from the environment. They consists of large number of sensor nodes and one or more Base Stations.

The nodes in the network are connected via Wireless communication channels.

Each node has capability to sense data, process the data and send it to rest of the nodes or to Base Station.

These networks are limited by the node battery lifetime.

http://en.wikipedia.org/wiki/Computer_science

http://en.wikipedia.org/wiki/Telecommunications



Block Diagram of Wireless Sensor Networks

Wireless Sensor Network is different from traditional network.

• Wireless Sensor Network is a Single-purpose design means serving one

specific application where as traditional network general-purpose design means

serving many applications.

• Energy is the main constraint in the design of all node and network

components in wireless sensor network where as in traditional network typical

primary design concerns are network performance and latencies, energy is not

a primary concern.

• Sensor networks often operate in environments with harsh conditions where

as in traditional network devices and networks operate in controlled and mild

environments.



1.1 HOW WIRELESS SENSOR NETWORKS WORK??

Wireless Sensor Network mechanism is quite simple and applicable

to a variety of fields. It is based on smaller nodes, controller, radio

transceiver, and battery. The key to stimulate the sensor networking is

the algorithm sponsor multi-router phenomenon. The system is totally

dependent on the nodes and the harmony established between them

through proper frequency. These nodes are of different sizes according

to the function they perform.

To activate the monitoring / tracking function of these nodes a radio

transmitter is attached to forward the information in the form of waves.

They are controlled by the microcontroller according to the function

and device in which they are used. All the system remains in working

condition with the help of energy supply which is in the form of

battery. The Wireless Sensor Networks perform function concurrently

where nodes are autonomous bodies incorporated in the field spatially

for the accurate results. The information transmits through proper

channel taking the information collecting it in the form of data and send

to the base.

http://www.freewimaxinfo.com/wireless-sensor-networks.html

http://www.freewimaxinfo.com/wireless-sensor-networks.html



Chapter 2

History

In the year of 1978, the Defence Advanced Research Projects Agency (DARPA) organized the Distributed Sensor Nets Workshop (DAR 1978), focusing on sensor network research challenges such as networking technologies, signal processing techniques, and distributed algorithms. That is the reason that the military has been a driving force behind the development of wireless sensor networks.

In the early 1980’s DARPA also operated the Distributed Sensor Networks (DSN) program which was then followed by the Sensor Information Technology (SensIT) program, which provided the present sensor networks with new capabilities such as ad hoc networking, dynamic querying and tasking, reprogramming and multitasking.

The University of California at Los Angeles along with the Rockwell Science Centre proposed the concept of Wireless Integrated Network Sensors or WINS. One outcome of the WINS project was the Low Power Wireless Integrated Micro sensor (LWIM), produced in 1996 (Bultetal. 1996). This smart sensing system was based on a CMOS chip, integrating multiple sensors, interface circuits, digital signal processing circuits, wireless radio, and microcontroller onto a single chip.

In the year 1999 the University of California at Berkeley focused on the design of extremely small sensor nodes called motes in the Smart Dust Project (Khanetal. 1999).The main aim of this project was to demonstrate that a complete sensor system can be integrated into tiny devices, possibly the size of a grain of sand or even a dust particle.

In the year 2000 the Berkeley Wireless Research Centre (BWRC) focuses on the development of low-power sensor devices in the PicoRadio project (Rabaeyetal. 2000), whose power consumption is so small that they can power themselves from energy sources of the operating environment, such as solar or vibrational energy.

The MIT μAMPS (micro-Adaptive Multi-domain Power-aware Sensors) project focuses on low power hardware and software components for sensor nodes, which includes the use of microcontrollers capable of dynamic voltage scaling and techniques to restructure data processing algorithms to reduce power requirements at the software level (Calhounetal, 2005).



Chapter 3

Characteristics of WSN

The general structure of Wireless sensor network consists of a base station

or “gateway” which can communicate with a number of wireless sensors via a

radio link. Data is captured at the wireless sensor node, then compressed, and

transmitted to the gateway directly or, if required, uses other wireless sensor

nodes to forward data to the gateway.

The transmitted data is then passed to the system through the gateway

connection. Sensor nodes are likely as small computers, extremely basic in terms

of their interfaces and their components. They usually consist of a processing

unit with limited computational power and limited memory, sensors, a

communication device, and a power source usually in the form of a battery.

The base stations act as a gateway between sensor nodes and the end user

and they normally forward data from the WSN on to a server. Other special

components are routers, designed to compute, calculate and distribute the

routing tables.

On the basis of functionality of sensor nodes and other element, the major

characteristics of WSN are as following:-

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.



Chapter 4

Hardware Components

A Wireless Sensor Network (WSN) consists of spatially distributed sensor

nodes and each sensor node can perform some processing and sensing tasks

independently. In addition, sensor nodes communicate with each other in order

to forward their sensed information to a central processing unit or conduct

some local coordination such as data fusion. The sensor node consists of several

hardware components that include an embedded processor, a radio transceiver,

internal and external memories, and one or more sensors, a Geo-Positioning

system, a power source.

Architecture of Sensor Node



Hardware Components of WSN:-

4.1 Embedded Processor The functionality of an embedded processor in a sensor node is to schedule tasks, process data and control the functionality of other hardware components. There are several types of embedded processors available that can be used in a sensor node include Microcontroller, Digital Signal Processor (DSP), Field Programmable Gate Array (FPGA) and Application Specific Integrated Circuit (ASIC) been the most used embedded processor for sensor nodes is the Microcontroller because of its flexibility to connect to other devices and its cheap price[2]. For example, the most recent CC2531 development board provided by Chipcon (acquired by Texas Instruments) uses 8051 microcontroller, and the Mica2 Mote platform provided by Crossbow uses ATMega128L microcontroller.

4.2 Transceiver The responsibility of a transceiver is for the wireless communication of a sensor node. There are different types of wireless transmission media, which includes Radio Frequency (RF), Laser and Infrared. The most used transmission media to fits to most of WSN applications is the RF based communication. The different operational states of a transceiver are Transmit, Receive, Idle and Sleep. Mica2 Mote uses two kinds of RF radios one is RFM TR1000 and other one is Chipcon CC1000. The Mica2 Mote’s outdoor transmission range of is about 150 meters.

4.3 Memory Memories in the sensor nodes includes both program memory (from which instructions are executed by the processor), and data memory (for storing raw and processed sensor measurements and other local information). The quantities of memory and storage on board a WSN device are often limited. It include in-chip flash memory and RAM of a microcontroller and external flash memory. For example, the ATMega128L microcontroller running on Mica2 Mote has 128-Kbyte flash program memory and 4-Kbyte static RAM. Further, a 4 Mbit Atemel AT45DB041B serial flash chip can provide external memories for Mica and Mica2Motes (Hill 2003).



4.4 Sensors

Due to limited bandwidth and power, Wireless Sensor Network devices

primarily support only low-data-rate sensing. There are various applications call

for multi-modal sensing, as a result each device may have several sensors on

board. The specific sensors are used according to the requirement of the

application. For example, they may include temperature sensors, light sensors,

humidity sensors, pressure sensors, accelerometers, magnetometers, chemical

sensors, acoustic sensors, or even low-resolution imagers.

4.5 Geo-Positioning System(GPS)

It is important for all sensor measurements to be location stamped in

numerous WSN applications. To obtain positioning you need to pre-configure

sensor locations at deployment, but this may only be possible in limited

deployments. Mainly for outdoor operations, when the network is deployed in

an ad hoc manner, such information is most easily obtained via satellite based

GPS. The Global Positioning System (GPS) is a space-based Global Navigation

Satellite System (GNSS) which provides location and time information in all

weather, anywhere on or near the Earth, where there is a clear line of sight to

four or more GPS satellites.

4.6 Power Source

In deployment of the WSN device is likely to be battery powered. Power is

consumed by sensing, communication and data processing by a sensor node. .

Batteries are the main source of power supply for sensor nodes. For example,

Mica2 Mote runs on 2 AA batteries. While some of the nodes may be wired to a

continuous power source in some applications, and energy harvesting

techniques may provide a degree of energy renewal in some cases, the finite

battery energy is probable to be the most critical resource bottleneck in most

applications.



Chapter 5

Software Components The software component plays major role in the development of wireless sensor network. The development of wireless sensor network composed of three custom software components, such as:- The Web program WiseDB Tiny OS

5.1 The Web Program Web program was written in PHP and make use of the Chart-Director charting software. The web application queried MySQL database for the data, then we use a Chart-Director to generate a graph of that data. 5.2 WiseDB WiseDB is the custom software component that interfaced with the gateway via a serial link to and with the SQL database via a TCP/IP link. WiseDB was written in C++ and utilized two open-source API’s (application programming interface). WiseDB collects the data captured by sensor nodes of sensor mots network and passed through gateway and accessed by using SQL server applications. This is the way that, the WiseDB interacted with the rest of the system in the wireless sensor network. 5.3 TinyOS The one of the most important custom software component is the TinyOS. It is an operating system specifically designed to address the needs of wireless sensor networks. It is based on an event driven execution engine that simultaneously provides efficiency and fine-grained concurrency. As you know, TinyOS is a real-time operating system designed for use in sensor network applications where low-power, limited resources and hard real-time constraints are critical parameters.



Chapter 6

Architecture of WSN The entire system can be described as consist as two subsystems depending upon the operation performed by the entire system, such as:- Data Analysis Data Acquisition

Data Analysis subsystem is software-only. It relied on existing Internet and web (HTTP) infrastructure to ensure communications between the Client and Server components. The main use of this subsystem was to selectively present the gathered environmental data to the end user in a graphical manner. Data Acquisition subsystem is used to collect and store environmental data for later processing by the Data Analysis subsystem. This subsystem is consists of PC, embedded system software and also embedded system hardware. In the other word you can say, it is composed of both the Server and Sensor Mote Network components.

Wireless Sensor Network Architecture

Client



The Client component is external to the development of wireless sensor network. That means, any computer with a web browser and Internet access could be a Client. It served only as a user interface to the Data Analysis subsystem.

Server The Server plays a significant role between the Data Acquisition and Data Analysis subsystems. In case of Data Analysis, in this side, a web (HTTP) server hosting a web application. When a page request came in, the web server executes the web application, which retrieved data from the database, processes it, and returns a web page that is transmitted to the Client through the web server. In case of Data Acquisition system, there is a daemon (WiseDB) running to provide the facility to establish the communication with the Sensor Mote Network.

This daemon collects raw data packets from the Sensor Mote Network. Then these packets are then processed and then convert the raw data into meaningful environmental data. Then this processed data is then inserted into the database. Thus the database is the link between the Data Analysis and Data Acquisition subsystems.

Sensor Motes The main focus of wireless sensor network is the development of the Sensor Mote Network component. Wireless Sensor Networks are collections of motes. Motes are the individual computers that work together to form networks. It is the component responsible for collecting and transmitting raw environmental data to the Server. The requirements for motes are extensive. They must be small, energy efficient, multifunctional, and wireless. The component consists of two parts. Such as:- The sensor mote The gateway mote

The sensor mote is developed to collect and transmit raw environmental data. When not doing this, it went into a low-power idle mode to conserve energy. It also have some other feature involved ad-hoc networking and may be for multi-hop routing; The second part of the Sensor Mote Network is the gateway mote .The gateway mote is responsible for serving as the liaison between the Server and the Sensor Mote Network and transport all the data packets to WiseDB. It is possible to implement both sensor and gateway motes on the same hardware PCB and with the same software.



Block Diagram of WSN Architecture



Chapter 7

Networking Topologies of WSN

You need to coordinate the WSN gateway, end nodes, and router nodes. For which you can use several network topologies. You can use Router nodes in two different ways, one way Router nodes are similar to end nodes as they can acquire measurement data, in other way you also can use them to pass along measurement data from other nodes.

Star Topology Cluster or Tree Topology Mesh Topology Ring Topology, etc.

Star Topology:

The most basic topology is the star topology, in which each node is directly connected with

the gateway. This topology is simple but restricts the overall distance that your network can achieve.

Cluster or Tree Topology:

You can implement a cluster, or tree, topology to increase the distance a network can

cover. This is a more complex structure and in this each node still maintains a single communication path to the gateway but can use other nodes to route its data along that path.

This topology suffers from a problem that if a router node goes down, all the nodes that depend on that router node also lose their communication paths to the gateway.

Mesh Network Topology: The mesh network topology eliminates the issue evolved during the Cluster / Tree Topology by using redundant communication paths to increase system reliability. In a mesh network,

nodes maintain multiple communication paths back to the gateway, hence if one router node goes down, the network automatically reroutes the data through a different path. The mesh

topology is very reliable but from an increase in network latency as data must make multiple hops before arriving at the gateway.

Ring Topology:

In a ring topology, each device has a dedicated point-to-point connection with only the two

devices on either side of it. A signal is passed along the ring in one direction, from device to device, until it reaches its destination. Each device in the ring incorporates a repeater. When

a device receives a signal intended for another device, its repeater regenerates the bits and

passes them along.



Star Topology Cluster / Tree Topology

Fully Connected Mesh Topology

Ring Topology



Chapter 8

Applications of WSN

The applications for WSNs are many and varied. They are used in commercial

and industrial applications to monitor data that would be difficult or expensive

to monitor using wired sensors. They could be deployed in wilderness areas,

where they would remain for many years (monitoring some environmental

variable) without the need to recharge/replace their power supplies. They could

form a perimeter about a property and monitor the progression of intruders

(passing information from one node to the next). There are a many uses for

WSNs.

Typical applications of WSNs include monitoring, tracking, and controlling. Some

of the specific applications are habitat monitoring, object tracking, nuclear

reactor controlling, fire detection, traffic monitoring, etc. In a typical application,

a WSN is scattered in a region where it is meant to collect data through its sensor

nodes.

Wireless Sensor Networks are applied for:-

Environmental monitoring Habitat monitoring Acoustic detection Seismic Detection Military surveillance Inventory tracking Medical monitoring Smart spaces Process Monitoring, etc.



Military application was the original motivation behind the research into WSNs

.At the later period of time costs for sensor nodes and communication networks

have been reduced and thus the application area has also increased.

Military surveillance and target tracking:

Wireless sensor networks originated mainly in military-related research in the

year 1978.

Unattended sensor networks can be rapidly deployed for surveillance and used

to provide battlefield intelligence regarding the location, numbers, movement,

and identity of troops and vehicles, and for detection of chemical, biological, and

nuclear weapons. Faster development of wireless sensor networks has been

provided though several programs funded by the US Defence Advanced

Research Projects Agency (DARPA), through a program known as Sensor

Information Technology (SensIT) which provides the present sensor networks

with new capabilities such as ad hoc networking, dynamic querying and tasking,

reprogramming and multitasking.

Environmental Monitoring:

Environmental monitoring can be used for animal tracking, forest surveillance,

flood detection, and weather forecasting. It is a natural candidate for applying

WSNs because the variables that is considered to be temperature, are usually

distributed over a large region.

Health Monitoring:

Wireless sensor network is a major application in health sector. WSNs can be

embedded into a hospital building to track and monitor patients and all medical

resources. There are various kinds of sensors which can measure blood pressure,

body temperature and electrocardiograph

(ECG). A special kind of sensor network called a body sensor network (BSN)

formed When the sensors are worn or implanted for healthcare purposes. BSN

is a rich interdisciplinary area which reforms the healthcare system by allowing

inexpensive, continuous and ambulatory health monitoring with real-time

updates of medical records via the Internet. Now a days a specialized BSN sensor

node and BSN Development Kit are available for use in health monitoring

system.



Traffic Control:

Traffic control is another area where wireless sensor network plays a major role.

Wireless sensor networks have been used for vehicle traffic monitoring and

control for some time. There are either overhead or buried sensors used to

detect vehicles and to control the traffic lights. WSNs will completely change the

landscape of traffic monitoring and control by installing cheap sensor nodes in

the car, at the parking lots, along the roadside. Streetline, Inc. is a company

which uses sensor network technology to help drivers find unoccupied parking

places and avoid traffic jams.

Industrial Sensing:

Sensor nodes can be deeply embedded into machines and there is no

infrastructure, WSNs make it economically feasible to monitor the “health” of

machines and to ensure safe operation. Aging pipelines and tanks have become

a major problem in the oil and gas industry. Monitoring corrosion using manual

processes is extremely costly, time consuming, and unreliable. A network of

wireless corrosion sensors can be economically deployed to reliably identify

issues before they become catastrophic failures.

Infrastructure Security:

WSNs can be used for infrastructure security and counterterrorism applications.

Security is the major aspect of wireless sensor network. Critical buildings and

facilities such as power plants, airports, and military bases have to be protected

from attacks. Networks of video, acoustic, and other sensors can be deployed

around these facilities.



Chapter 9

Pros and Cons of WSN’s

There are several advantages of wireless sensor networking as they can store

a limited source of energy, they have no hassle of cables and have mobility. The

major advantage is that it can work efficiently under the harsh conditions, and

it has deployment up to large scale etc. Same time it also has some

disadvantages which really take the moral of this technology down as they have

very insufficient speed of communication, it is to disturb the propagation of

waves and hack your networking and the major disadvantage of wireless sensor

networking is it is too costly to use.

Advantages:

• It avoid lot of wiring.

• It can accommodate new devices at any time.

• It’s flexible to go through physical partitions.

• It can be accessed through a centralized monitor.

• WSN’s can be applied on large scale and in various fields.

Disadvantages:

• It is very easy for hackers to hack it as we can’t control

propagation of waves.

• Comparatively low speed of communications.

• Gets distracted by various elements like Blue-tooth.

• Still costly at large.



Chapter 10

Future Work

As the wireless sensor network is under research, there are a number of

improvements we can think of.

We can think of expanding the sensor mote network by adding

more motes. This would allow the development and testing of

advanced network-layer functions, such as multi-hop routing.

We can think of alternative energy sources to extend mote

battery life. Which may include solar cells and rechargeable

batteries, these systems could provide a long term, maintenance

free, wireless monitoring solution.

Wireless sensor network has the potential to trigger the next

revolution in computing. While its applications and potential

benefits can spread far and beyond, and could finally break the

barrier between physical and digital worlds to allow

disappearance of computation.



Chapter 11

Conclusion

Wireless sensor networks must be designed to meet a number of

challenging requirements including extended lifetime in the face of

energy constraints, robustness, scalability, and autonomous operation.

Wireless sensor networks are getting smaller and faster, increasing their

potential applications in commercial, industrial, and residential

environments.

However, the limit of applications depends only upon the sensors

used and the interpretation of the data obtained. As the technology

improves and new low-power digital sensors become more readily

available, motes will increase functionality without increasing power

consumption and will expand the wireless sensing market.

The flexibility, fault tolerance, high sensing fidelity, low-cost and

rapid deployment characteristics of sensor networks create many new

and exciting application areas for remote sensing. In the future, this

wide range of application areas will make sensor networks an integral

part of our lives. However, realization of sensor networks needs to

satisfy the constraints introduced by factors such as fault tolerance,

scalability, cost, hardware, topology change, environment and power

consumption.

Since these constraints are highly stringent and specific for sensor

networks, new wireless ad hoc networking techniques are required.

Many researchers are currently engaged in developing the technologies

needed for different layers of the sensor networks protocol stack.

Wireless sensor network report

Engineering

Transcript of Wireless sensor network report