Embedded Summer training

A PROJECT ON
WIRELESS SENSOR NETWORK
By Mr. Rajan Singh
M.E
TechnoCrats Engg classes
SPIT (Andheri)

AIM
AIM To design, build and test the circuit for wireless sensors
network using Embedded system programming.
OBJECTIVES
To study the Wireless Sensor Network(WSN) using some
Transmitter and Receiver module. To design (8051 series) / AVR
based circuit for WSN. To program and study the working of
microcontroller (Atmega series ) and related hardwares.

MODULES
1.RF (434 MHz, 315 MHz)
2.GSM
3.Bluetooth
4.Zigbee
5.CC2250
6.GPS

RF MODULE (434 & 315 MHZ)
The circuit of this project utilises the RF module (TX / Rx)
for making a wireless remote, which could be used to drive
an output from a distant place. RF module, as the name
suggests, uses radio frequency to send and receive signals at
same frequency and baud rate.

• GSM-Introduction
• Architecture
• Technical Specifications
• Frame Structure
• Channels
•Security
•Characteristics and features
•Applications
CONTENTS

WHAT IS GSM ?
Global system for mobile (GSM) is a second
generation cellular standard developed to cater voice
services and data delivery using digital modulation.

GSM: HISTORY
• Developed by Group Spécial Mobile (founded 1982) which was an initiative of
CEPT ( Conference of European Post and Telecommunication )
• Aim : to replace the incompatible analog system
• Presently the responsibility of GSM standardization resides with special mobile group
under ETSI ( European telecommunication Standards Institute )
• Full set of specifications phase-I became available in 1990
• Under ETSI, GSM is named as “ Global System for Mobile communication “
• Today many providers all over the world use GSM (more than 135 countries in Asia,
Africa, Europe, Australia, America)
• More than 1300 million subscribers in world and 45 million subscriber in India.

GSM IN WORLD
Figures: March, 2005
37%
1%
4%43%
4%
3%
3%
3% (INDIA)
3%
Arab World
Asia Pacific
Africa
East Central Asia
Europe
Russia
India
North America
South America

GSM IN INDIA
Figures: March 2005
Bharti
27%
BSNL
22%
Spice
4%
IDEA
13%
Hutch
19%
BPL
6%
Aircel
4%
Reliance
3%
MTNL
2%
Bharti
BSNL
Hutch
IDEA
BPL
Aircel
Spice
Reliance
MTNL

GSM SERVICES
• Tele-services
• Bearer or Data services
• Supplementary services

TELE SERVICES
• Telecommunication services that enable voice
communication via mobile phones
• Offered services
- Mobile telephony
- Emergency calling

BEARER SERVICES
• Include various data services for information transfer
between GSM and other networks like PSTN, ISDN etc
at rates from 300 to 9600 bps
• Short Message Service (SMS)
•up to 160 character alphanumeric data transmission
to/from the mobile terminal
• Unified Messaging Services(UMS)
• Voice mailbox
• Electronic mail

SUPPLEMENTARY SERVICES
Call related services :
• Call Waiting- Notification of an incoming call while on the handset
• Call Hold- Put a caller on hold to take another call
• Call Barring- All calls, outgoing calls, or incoming calls
• Call Forwarding- Calls can be sent to various numbers defined by the
user
• Multi Party Call Conferencing - Link multiple calls together
• CLIP – Caller line identification presentation

ACCESS MECHANISM
FDMA, TDMA, CDMA

FREQUENCY MULTIPLEX
• Separation of the whole spectrum into smaller frequency bands
• A channel gets a certain band of the spectrum for the whole time
•Advantages:
• no dynamic coordination necessary c
• works also for analog signals
•Disadvantages:
• waste of bandwidth if the traffic is
distributed unevenly
• Inflexible t
t
k2 k3 k4 k5k1 k6
f

•A channel gets the whole spectrum for a certain amount of time
•Advantages:
• only one carrier in the medium at any time
• throughput high even for many users
•Disadvantages:
• precise synchronization necessary
f
t
c
k2 k3 k4 k5 k6k1
TIME MULTIPLEX

• Combination of both methods (FDM +TDM)
• A channel gets a certain frequency band
for a certain amount of time.
f
TIME AND FREQUENCY MULTIPLEX
t
c
k2 k3 k4 k5 k6k1

f
•Example: GSM
•Advantages:
• Better protection against
tapping
• Protection against frequency
selective interference
• Higher data rates compared to
code multiplex
But: precise coordination required
t
c
k2 k3 k4 k5 k6k1
TIME AND FREQUENCY MULTIPLEX

GSM USES PAIRED RADIO CHANNELS
0 124 0 124
890MHz 915MHz 935MHz 960MHz
GSM combines FDM and TDM:
Bandwidth is subdivided into channels of 200khz, shared by up to eight
stations, assigning slots for transmission on demand.

CODE MULTIPLEX
• Each channel has a unique code
• All channels use the same spectrum at the same time
• Advantages:
• Bandwidth efficient
• No coordination and synchronization necessary
• Good protection against interference and tapping
• Disadvantages:
• Lower user data rates
• More complex signal regeneration
• Implemented using spread spectrum technology
k2 k3 k4 k5 k6k1
f
t
c

GSM SYSTEM ARCHITECTURE
BSC
BSC
MSC
MS
MS
MS BTS
BTS
BTS
GMSC
PSTN
ISDN
PDN
EIR
AUC
HLR
VLR

GSM NETWORK OVERVIEW
ME
SIM
BTS
BTS
BSC
BSC
MSC
HLR
EIR
VLR
AuC
Mobile
Station Base Station Subsystem Network Subsystem
PSTN
ISDN
PSPDN
CSPDN
Um Abis
A
GM
SC

GSM SYSTEM ARCHITECTURE-I
• Mobile Station (MS)
Mobile Equipment (ME)
Subscriber Identity Module (SIM)
• Base Station Subsystem (BSS)
Base Transceiver Station (BTS)
Base Station Controller (BSC)
• Network Switching Subsystem(NSS)
Mobile Switching Center (MSC)
Home Location Register (HLR)
Visitor Location Register (VLR)
Authentication Center (AUC)
Equipment Identity Register (EIR)

MOBILE STATION (MS)
The Mobile Station is made up of two entities:
1. Mobile Equipment (ME)
2. Subscriber Identity Module (SIM)

MOBILE STATION (MS) CONTD.
Subscriber Identity Module (SIM)
• Smart card contains the International Mobile Subscriber
Identity (IMSI)
• Allows user to send and receive calls and receive other
subscribed services
• Encoded network identification details
- Key Ki,Kc and A3,A5 and A8 algorithms
• Protected by a password or PIN
• Can be moved from phone to phone – contains key information
to activate the phone

BASE STATION SUBSYSTEM (BSS)
Base Station Subsystem is composed of two parts that communicate
across the standardized Abis interface allowing operation between
components made by different suppliers
1. Base Transceiver Station (BTS)
2. Base Station Controller (BSC)

Base Transceiver Station (BTS):
• Encodes, encrypts, multiplexes, modulates and feeds the RF signals
to the antenna.
• Frequency hopping
• Communicates with Mobile station and BSC
• Consists of Transceivers (TRX) units

Base Station Controller (BSC)
• Manages Radio resources for BTS
• Assigns Frequency and time slots for all MS’s in its area
• Handles call set up
• Transcoding and rate adaptation functionality
• Handover for each MS
• Radio Power control
• It communicates with MSC and BTS

NETWORK SWITCHING SUBSYSTEM(NSS)
Mobile Switching Center (MSC)
• Heart of the network
• Manages communication between GSM and other networks
• Call setup function and basic switching
• Call routing
• Billing information and collection
• Mobility management
- Registration
- Location Updating
- Inter BSS and inter MSC call handoff
• MSC does gateway function while its customer roams to other network by using
HLR/VLR.

NETWORK SWITCHING SUBSYSTEM
• Home Location Registers (HLR)
- permanent database about mobile subscribers in a large service
area(generally one per GSM network operator)
- database contains IMSI, MSISDN, prepaid/postpaid, roaming restrictions,
supplementary services.
• Visitor Location Registers (VLR)
- Temporary database which updates whenever new MS enters its area, by
HLR database
- Controls those mobiles roaming in its area
- Reduces number of queries to HLR
- Database contains IMSI, TMSI, MSISDN,MSRN,Location Area,
authentication key

• Authentication Center (AUC)
- Protects against intruders in air interface
- Maintains authentication keys and algorithms
and provides security triplets (
RAND,SRES,Kc)
- Generally associated with HLR
• Equipment Identity Register (EIR)
- Database that is used to track handsets using the
IMEI (International Mobile Equipment Identity)
- Made up of three sub-classes: The White List, The
Black List and the Gray List
- Only one EIR per PLMN
NETWORK SWITCHING SUBSYSTEM

GSM SPECIFICATIONS-1
• RF Spectrum
GSM 900
Mobile to BTS (uplink): 890-915 Mhz
BTS to Mobile(downlink):935-960 Mhz
Bandwidth : 2* 25 Mhz
GSM 1800
Mobile to BTS (uplink): 1710-1785 Mhz
BTS to Mobile(downlink) 1805-1880 Mhz
Bandwidth : 2* 75 Mhz

GSM SPECIFICATION-II
• Carrier Separation : 200 Khz
• Duplex Distance : 45 Mhz
• No. of RF carriers : 124
• Access Method : TDMA/FDMA
• Modulation Method : GMSK
• Modulation data rate : 270.833 Kbps

LOGICAL CHANNELS
TCH
(traffic)
CCH
(control)
BCH
CCCH
Dedicated
2.4 kbps
4.8 kbps
9.6 kbps
FCCH(Frequency correction)
SCH(Synchronization)
PCH(Paging)
RACH(Random Access)
AGCH(Access Grant)
SDCCH(Stand Alone)
SACCH(Slow-associated)
FACCH(Fast-associated)
Half rate 11.4kbps
Full rate 22.8kbps
Speech
Data

OUTGOING CALL
1. MS sends dialed number to BSS
2. BSS sends dialed number to MSC
3,4 MSC checks VLR if MS is allowed the
requested service. If so, MSC asks BSS to
allocate resources for call.
5 MSC routes the call to GMSC
6 GMSC routes the call to local exchange of
called user
7, 8,
9,10 Answer back(ring back) tone is routed
from called user to MS via
GMSC,MSC,BSS

INCOMING CALL
1. Calling a GSM subscribers
2. Forwarding call to GSMC
3. Signal Setup to HLR
4. 5. Request MSRN( MS roaming no)
from VLR
6. Forward responsible MSC to GMSC
7. Forward Call to current MSC
8. 9. Get current status of MS
10.11. Paging of MS
12.13. MS answers
14.15. Security checks
16.17. Set up connection

HANDOVERS
• Between 1 and 2 – Inter BTS / Intra BSC
• Between 1 and 3 – Inter BSC/ Intra MSC
• Between 1 and 4 – Inter MSC

SECURITY IN GSM
•On air interface, GSM uses encryption and TMSI (Temperory MS
identity) instead of IMSI.
•SIM is provided 4-8 digit PIN to validate the ownership of SIM
•3 algorithms are specified :
- A3 algorithm for authentication
- A5 algorithm for encryption
- A8 algorithm for key generation

ADVANTAGES OF GSM OVER ANALOG SYSTEM
• Capacity increases
• Reduced RF transmission power and longer battery life.
• International roaming capability.
• Better security against fraud (through terminal validation and user
authentication).
• Encryption capability for information security and privacy.
• Compatibility with ISDN,leading to wider range of services

FUTURE OF GSM
2nd Generation
 GSM -9.6 Kbps (data rate)
2.5 Generation ( Future of GSM)
HSCSD (High Speed ckt Switched data)
Data rate : 76.8 Kbps (9.6 x 8 kbps)
GPRS (General Packet Radio service)
Data rate: 14.4 - 115.2 Kbps
EDGE (Enhanced data rate for GSM
Evolution)
Data rate: 547.2 Kbps (max)
 3 Generation
WCDMA(Wide band CDMA)
Data rate : 0.348 – 2.0 Mbps
 4 Generation
 Wi Max (Ultra widwBand)
 Data rate : practically ~50 Mbps & theorically 672 Mbps
 5 Generation coming soon

BLUETOOTH
Contents:
• What is Bluetooth?
• How Bluetooth Technology works ?
• Advantages of Bluetooth Technology
• Disadvantage of Bluetooth Technology
• Future of Bluetooth Technology

1. Bluetooth technology is simple, secure and everywhere.
2. This technology enable users to automatically and easily connect
a wide range of computing and telecommunication devices.
• What is Bluetooth?

3. Bluetooth is actually a IEEE 802.15.1 standard for wireless
communications between devices within a range of 10metres.
4. This is in the globally unlicensed Industrial, Scientific and
Medical (ISM) 2.4 GHz short-range radio frequency band.
5. Bluetooth was officially introduced in 1998 and its intended
basic purpose was to be a wire replacement technology in order
to rapidly transfer voice and data.

6. Bluetooth “Special Interest Group” (SIG) is a group of
companies from the telecommunications, computing and
networking industries that promotes the development and
deployment of Bluetooth technology.
7. Bluetooth is a high-speed, low-power microwave wireless
link technology, designed to connect phones, laptops, PDAs
and other portable equipments together with little or no work
by the user.
8. Unlike infra-red, Bluetooth does not require any line-of-
sight positioning of connected devices like Infra-red.

9. Connections can be point-to-point or multipoint. The
maximum range is 10 meters but can be extended to 100 meters
by increasing the power. Bluetooth devices are protected from
radio interference by changing their frequencies arbitrarily up to
a maximum of 1600 times a second, a technique known as
frequency hopping.
10. Each Bluetooth device could be connected to 200 other
devices. It supports both point to point and point to multipoint
connections.

DISADVANTAGE
• Bluetooth has a low data rate( i.e.1 MBps) in comparison to
infra-red(i.e.4 MBps).
• Also some other technologies are available in market which
required less power consumption.(Zigbee)..

ZIGBEE
• IEEE 802.15.4 specification for low data rates technology allows for
devices to communicate with one another with very low power
consumption
• ZigBee-based products can access up to 16 different 5 MHz channels
within the 2.4 GHz band, several of which do not overlap those of
802.11 and WiFi. ZigBee has been designed to transmit slowly. It has
a data rate of 250kbps while WiFi is hitting throughput of 20Mbps or
more.
• All ZigBee networks have at least one reduced-functionality device
(RFD), the full-functional device (FFD) and a network coordinator.

• It uses 27 channels in 3 separate frequency bands
• The 902–928 MHz band serves the Americas and much of the Pacific Rim,
with 10 channels and a burst rate of 40 Kbps.
• PHY layer uses binary phase shift keying (BPSK) in the 868/915 MHz bands
and offset quadrature phase shift keying (O-QPSK) at 2.4 GHz. Both are
robust and simple forms of modulation that work well in low SNR.

(LOW-COST LOW-POWER 2.4 GHZ RF TRANSCEIVER)
•2400-2483.5 MHz ISM (Industrial, Scientific and Medical) and
SRD (Short Range Device) frequency band.
•The RF transceiver is integrated with a highly configurable
baseband modem. The modem supports various modulation formats
and has a configurable data rate up to 500 kBaud.
CC2500

DESCRIPTION
• The CC2520 is second generation ZigBee/ IEEE 802.15.4 RF
transceiver for the 2.4 GHz unlicensed ISM band.
• This chip enables industrial grade applications by offering
operation up to 125°C and low voltage operation.
• CC2520 also provides extensive hardware support for frame
handling, data buffering, burst transmissions, data encryption,
data authentication, clear channel assessment and frame timing
information. These features reduce the load on the host controller.

• CC2500 is configured via a simple 4-wire SPI compatible interface
(SI, SO, SCLK and CSn) where CC2500 is the slave. This interface
is also used to read and write buffered data. All transfers on the SPI
interface are done most significant bit first.
•Low Power
• RX (receiving frame, –50 dBm) 18.5 mA
• TX 33.6 mA @ +5 dBm
• TX 25.8 mA @ 0 dBm
• <1µA in power down
• High sensitivity.
• Operation voltage: 1.8~3.6 Volts.

FEATURES
• Adjacent channel rejection:49 dB
Alternate channel rejection: 54 dB
• Modulation techniques: DSSS
• 400 m Line-of-sight range
• Extended temp range (–40 to +125°C)
• Wide supply range: 1.8 V – 3.8 V
• Extensive IEEE 802.15.4 MAC hardware support to
offload the microcontroller
• AES-128 security module

• Automatic clear channel assessment for CSMA/CA
• Automatic CRC
• 768 bytes RAM for flexible buffering and security
processing
• Fully supported MAC 128 bits security
• 4 wire SPI
• 6 configurable IO pins
• Interrupt generator
• Random number generator
Microcontroller Support

GLOBAL POSITIONING SYSTEM (GPS)
• GPS is a revolutionary navigation system
• 24 satellites orbiting the earth
• Provide location within meters or less anywhere on the globe.
• Now available in many cars as an option
• Created and operated by the US Department of Defense

MORE ABOUT GPS SATELLITES
• Constellation of 27 satellites
• (24 active + 3 spare)
• Orbit 12,600 miles above earth
• (10,900 nautical miles)
• Satellites in 12 hour orbit
• First satellite launched in 1978, 24th became operational in 1994
• Selective availability was removed in May, 2000
• Handheld receivers are now much more accurate

DISTANCE CALCULATION
• Measuring distance by measuring time
• Satellites send coded signals indicating their position in space and the
exact time the signals are being sent
• Receivers use the time it takes signal to travel from satellite to receiver
to determine distance from satellite to receiver
• Information from multiple satellites is used to determine position
through ‘triangulation’.

POSITION IS BASED ON TIME
T + 3
Distance between satellite and
receiver = “3 times the speed of
light”
T
Signal leaves satellite at
time “T”
Signal is picked up by the
receiver at time “T + 3”

THREE SATELLITES (2D POSITIONING)

SOURCES OF GPS ERROR
• Standard Positioning Service (SPS ): Civilian Users
• Source Amount of Error
 Satellite clocks: 1.5 to 3.6 meters
 Orbital errors: < 1 meter
 Ionosphere: 5.0 to 7.0 meters
 Troposphere: 0.5 to 0.7 meters
 Receiver noise: 0.3 to 1.5 meters
 Multipath: 0.6 to 1.2 meters
 Selective Availability (see notes)
 User error: Up to a kilometer or more

COMMON GPS DATA FORMAT
•NMEA (National Marine Electronics Association)
• Transmission of data between GPS receiver and other devices (e.g. GPS
antenna PDA with ArcPad software)
• For real time positioning
•RTCM (Radio Technical Commission for Maritime Services)
• Transmission of data between GPS receivers (e.g Base  Rover)
• Binary file (more compact but difficult to understand)
• For real time DGPS/RTK corrections
•RINEX
• Combine data from different manufacturer’s GPS receivers
• For static data processing and archive

FLOW OF NMEA DATA BETWEEN DEVICES
NMEA data transfer from GPS
antenna to PDA with ArcPAD
software
Real-time positioning
using the NMEA data

WHAT IS NMEA DATA?
• Developed by National Marine Electronics Association
• Standard for interfacing marine electronic devices (GPS, , Compass, Echo
-sounder)
• Standard specifies the electrical signal requirements, data transmission
protocol (i.e. agreed format for transmitting data between two devices),
message formats

WHAT IS NMEA DATA?
• ASCII file
• Easily readable (even by people)
• Less compact than binary
• Numerous sentence types
• Not all related GPS application
• Some popular GPS-related sentences are described in this presentation

NMEA SETTINGS
• Baud rate: 4800 (4800 characters in one second )
• Data bits: 8 (Bit 7 set to 0)
• Stop bits: 1 or 2
• Parity: none
• The “send” device and “receive” device should have same setting
so as to transfer the NMEA data

STANDARD MESSAGE FORMAT
•$aaaaa, df1,df2……… [Carriage Return][Line Feed]
• Each message start with $
• Five characters after $ are address field
• Multiple data fields delimited by commas
• Check sum (optional): a 2-character field (0-9,A-F) to
increase data integrity
• (*) character placed after the last data field

SENTENCE STRUCTURE
•There are three sentence structures
• Talker: output from talker (e.g. GPS receiver) to other
devices (PAD)
• Query: means for listener (e.g. notebook) to request
specified talker sentence from talker (GPS receiver)
• Proprietary: means for manufactures to use non-
standard sentences for special purpose

TALKER SENTENCE
•Format: $ttsss, df1, df2…[CR][LF]
• tt: defines device (for gps receivers the prefix is GP)
• sss: sentence type
Example
$GPGGA,031956,2218.2035,N,11410.7595,E,1,04,3,9,005.9,M,-001.3,M,,*51
•The talker sends the GPS data in GGA sentence
format.

QUERY SENTENCE
• Format: $ttllQ, sss, [CR][LF]
Example
CCGPQ,GGA, [CR][LF]
• A computer (CC) is requesting from GPS device (GP) the GGA
sentence

PROPRIETARY SENTENCE
• Format: $PmmmA,df1,df2,….[CR][LF]
• “P” indicates it is a proprietary message
• “mmm” define as the manufacture
• The fifth character is a letter (A-Z) defines the specific message
type
Example
$PLEIS,AHT,0,1.90,0*34
• “LEI" is Leica manufacturer
• “S” for set command
The message set the antenna height at 1.9m in the configuration of
the internal sensor setting.

COMMON NMEA-0183 SENTENCE
Sentence Description
$GPGGA: Global positioning system fixed data
$GPGLL: Geographic position - latitude / longitude
$GPGSA: GNSS DOP and active satellites
$GPGSV: GNSS satellites in view
$GPRMC: Recommended minimum specific GPS data
$GPVTG: Course over ground and ground speed
To extract information related to surveyed position
Record at least one of the 3 sentences: $GPGGA, $GPGLL,
$GPRMC

GGA SENTENCE FORMAT
$GPGGA,092204.999,4250.5589,S,14718.5084,E,1,04,24.4,19.7,M,,,,0000*1F
Field Example Comments
Sentence ID $GPGGA
UTC Time 092204.999 hhmmss.sss
Latitude 4250.5589 ddmm.mmmm
N/S Indicator S N = North, S = South
Longitude 14718.5084 dddmm.mmmm
E/W Indicator E E = East, W = West
Position Fix 1 0 = Invalid, 1 = Valid SPS,
2 = Valid DGPS, 3 = Valid PPS
Satellites Used 04 Satellites being used (0-12)
HDOP 24.4 Horizontal dilution of precision
Altitude 19.7 Altitude (WGS-84 ellipsoid)
Altitude Units M M= Meters
Geoid Separation Geoid separation (WGS-84 ellipsoid)
Seperation Units M= Meters
Time since DGPS in seconds
DGPS Station ID
Checksum *1F always begin with *
http://aprs.gids.nl/nmea/

APPLICATIONS OF GPS
• In-vehicle Navigation (car, boat, airplane)
• Asset Management
• Construction
• Geologic Research & Mining
• Military Navigation and Operations
• Mapping & Surveying
• Precision Agriculture
• Public Health
• Public Safety
• Wireless Communications

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