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.

OBJECTIVESTo 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.

PIN DIAGRAM

ENCODER AND DECODER CIRCUIT

AMPLITUDE SHIFT KEYING (ASK)

GSM GSM (900)GSM (1800)

• 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

Bharti27%

BSNL22%

Spice 4%

IDEA13%

Hutch19%

BPL6%

Aircel4%

Reliance3%

MTNL2%

BhartiBSNLHutchIDEABPLAircelSpice RelianceMTNL

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 SERVICESCall 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 tocode 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

UPLINK

DOWNLINK

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

VARIOUS ACCESS METHOD

GSM SYSTEM ARCHITECTURE

BSC

BSC

MSC

MS

MS

MS BTS

BTS

BTS

GMSC

PSTNISDNPDN

EIRAUC

HLR

VLR

GSM NETWORK OVERVIEW

ME

SIM

BTS

BTS

BSC

BSC

MSC

HLR

EIR

VLR

AuC

Mobile Station

Base Station Subsystem

Network Subsystem

PSTN ISDNPSPDN CSPDN

Um Abis

A

GMSC

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 STATION SUBSYSTEM (BSS)

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 SUBSYSTEM (BSS)

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

GSM-FRAME STRUCTURE

LOGICAL CHANNELS

TCH (traffic)

CCH(control)

BCH

CCCH

Dedicated

2.4 kbps4.8 kbps9.6 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 CALL1. MS sends dialed number to BSS 2. BSS sends dialed number to MSC3,4 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 GMSC6 GMSC routes the call to local exchange of

called user7, 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 subscribers2. Forwarding call to GSMC3. Signal Setup to HLR4. 5. Request MSRN( MS roaming no)

from VLR6. Forward responsible MSC to GMSC7. Forward Call to current MSC8. 9. Get current status of MS10.11. Paging of MS12.13. MS answers14.15. Security checks16.17. 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

AUTHENTICATION IN GSM

KEY GENERATION AND ENCRYPTION

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 GenerationWCDMA(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.

WIRELESS SPACE

• 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

BLOCK DIAGRAM

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

HOW DOES GPS WORK?

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 + 3Distance 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

• Most GPS receivers understand the most popular NMEA format NMEA 0183

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 positionRecord at least one of the 3 sentences: $GPGGA, $GPGLL,

$GPRMC

GG A S EN TEN CE FO RM AT

$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.sssLatitude 4250.5589 ddmm.mmmmN/S Indicator S N = North, S = SouthLongitude 14718.5084 dddmm.mmmmE/W Indicator E E = East, W = WestPosition Fix 1 0 = Invalid, 1 = Valid SPS, 2 = Valid DGPS, 3 = Valid PPSSatellites Used 04 Satellites being used (0-12)HDOP 24.4 Horizontal dilution of precisionAltitude 19.7 Altitude (WGS-84 ellipsoid)Altitude Units M M= MetersGeoid Separation  Geoid separation (WGS-84 ellipsoid)Seperation Units  M= MetersTime since DGPS   in secondsDGPS 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

THANK YOU