SHREEJEE INSTITUTE OF TECHNOLOGY AND MANAGEMENT

Wireless Communication

• Guided By:- Mr.Prakash Singh Panwar

• By:- Krishna Rathor• EC BRANCH 1ST YEAR

WHY WIRELESS COMMUNICATION?

Freedom from wires.No bunch of wires running from here and there.“Auto Magical” instantaneous communication without physical connection setup e.g.- Bluetooth, Wi-Fi.Global coverageCommunication can reach where wiring is infeasible or costly E.g.- rural areas ,buildings,battlefield,outerspace.Stay connected , flexiblity to connect multiple devices.

WHAT IS WIRELESS COMMUNICATION?

• Transmitting/receiving voice and data using electromagnetic waves in open space.

• The information from sender to receiver is carried over a well defined channel.

• Each channel has a fixed frequency bandwidth & capacity(bit rate).

• Different channels can be used to transmit information in parallel and independently.

TYPICAL FREQUENCIES• FM RADIO 88 MHZ• TV BROADCAST 200 MHZ• GSM PHONES 900 MHZ• GPS 1.2 GHZ• PCS PHONES 1.8 GHZ• BLUETOOTH 2.4 GHZ• Wi-Fi 2.4 GHZ

How communication takes place?

Transmitting SignalReceived Signal

Satellite

Transmitting Antenna

Receiving Antenna

TYPES OF WIRELESS COMMUNICATION?

RADIO TRANSMISSION:- easily generated, Omni-directional , travel long distance , easily penetrates buildings.

• PROBLEMS:- frequency dependent , relatively low bandwidth for data communication , tightly licensed by government.

MICROWAVE TRANSMISSION:- widely used for long distance communication , relatively inexpensive.

• PROBLEMS:- don’t pass through buildings , weather and frequency dependent.

TYPES CONTINUED….INFRARED AND MILIMETER WAVES:- Widely used for short range communication , unable to pass

through solid objects , used for indoor wireless LANs , not for outdoors.

LIGHT WAVE TRANSMISSION:- unguided optical signal such as laser , unidirectional , easy to install , no license required.

PROBLEMS:- unable to penetrate rain or thick fog , laser beam can be easily diverted by air.

CURRENT WIRELESS SYSTEMS

• CELLULAR SYSTEM

• WIRELESS LANs

• SATELLITE SYSTEM

• PAGING SYSTEM

• PANs(BLUETOOTH)

What is cellular system?• Definition

Wireless communication technology in which several small exchanges (called cells) equipped with low-power radio antennas (strategically located over a wide geographical area) are interconnected through a central exchange. As a receiver (cell phone) moves from one place to the next, its identity, location, and radio frequency is handed-over by one cell to another without interrupting a call.

Cont.…• Communication between the base station and mobiles

is defined by the standard common air interface (CAI)– Forward voice channel (FVC): voice transmission from

base station to mobile– Reverse voice channel (RVC): voice transmission from

mobile to base station– Forward control channels (FCC): initiating mobile call

from base station to mobile– Reverse control channel (RCC): initiating mobile call

from mobile to base station

Cellular Telephone Systems• Provide connection to the PSTN for any user location within the radio

range of the system.• Characteristic

– Large number of users– Large Geographic area– Limited frequency spectrum– Reuse of the radio frequency by the concept of “cell’’.

• Basic cellular system: mobile stations, base stations, and mobile switching center.

Cordless Telephone System• Cordless telephone systems are full duplex communication systems.• First generation cordless phone

– in-home use– communication to dedicated base unit– few tens of meters

• Second generation cordless phone– outdoor– combine with paging system– few hundred meters per station

Evolution of Mobile Radio Communications

• Major Mobile Radio Systems– 1934 - Police Radio uses conventional AM mobile communication system.– 1935 - Edwin Armstrong demonstrate FM– 1946 - First public mobile telephone service - push-to-talk– 1960 - Improved Mobile Telephone Service, IMTS - full duplex– 1960 - Bell Lab introduce the concept of Cellular mobile system– 1968 - AT&T propose the concept of Cellular mobile system to FCC.– 1976 - Bell Mobile Phone service, poor service due to call blocking– 1983 - Advanced Mobile Phone System (AMPS), FDMA, FM– 1991 - Global System for Mobile (GSM), TDMA, GMSK– 1991 - U.S. Digital Cellular (USDC) IS-54, TDMA, DQPSK– 1993 - IS-95, CDMA, QPSK, BPSK

Example of Mobile Radio Systems• Examples

– Cordless phone– Remote controller– Hand-held walkie-talkies– Pagers– Cellular telephone– Wireless LAN

• Mobile - any radio terminal that could be moves during operation• Portable - hand-held and used at walking speed • Subscriber - mobile or portable user

a• Classification of mobile radio transmission system– Simplex: communication in only one direction– Half-duplex: same radio channel for both transmission and reception (push-to-

talk)– Full-duplex: simultaneous radio transmission and reception (FDD, TDD)

• Frequency division duplexing uses two radio channel– Forward channel: base station to mobile user– Reverse channel: mobile user to base station

• Time division duplexing shares a single radio channel in time.

Forward Channel

Reverse Channel

Wireless local area network(WLAN)

• WLAN connect local computers• Range (100 m) confined region• Break data into packets• Channel access is shared• Backbone internet provides best service• Poor performance in some application like

videos• Low mobility

Satellite system ?• Global coverage• Optimized for good transmission• Expensive base stations.• Voice and data transmission• Telecommunication application• GPS , global telephone connection• TV broadcasting , military , weather

broadcasting

Paging system ?• Broad coverage for short messages• Message broadcast from all base stations• Simple terminals• Optimized for one way transmission• Answer back hard• Overtaken by cellular

Paging Systems• Conventional paging system send brief

messages to a subscriber• Modern paging system: news headline, stock

quotations, faxes, etc.• Simultaneously broadcast paging message

from each base station.• Large transmission power to cover wide area.

Modes of wireless communication!

• Bluetooth

• NFC (Near Field Communication)

• Wi-Fi

• Lifi

What is Bluetooth?

• Bluetooth is a method for data communication that used short range radio links to replace cables between computers and their connected units.

• Named on – Danish king harald Bluetooth• Developed in Scandinavia.

How does Bluetooth works?

• Bluetooth networking transmits data via low-power radio waves. It communicates on a frequency of 2.45 gigahertz.

• Bluetooth doesn't require line of sight between communicating devices.

• Bluetooth can connect up to eight devices simultaneously.

• Bluetooth uses a technique called spread-spectrum frequency hopping

Bluetooth is essentially a networking standard that works at two levels:

• It provides agreement at the physical level -- Bluetooth is a radio-frequency standard.

• It provides agreement at the protocol level, where products have to agree on when bits are sent, how many will be sent at a time, and how the parties in a conversation can be sure that the message received is the same as the message sent.

Applications of Bluetooth!

• Bluetooth speakers• Bluetooth headphones• Cable less connections to the printers• Bluetooth keyboard

What is NFC?

• NFC is a short-range high frequency wireless communication technology that enables the exchange of data between devices over about a 10 cm distance.

• It allows devices to establish peer-to-peer radio communications, passing data from one device to another by touching them or putting them very close together.

How NFC works?

• NFC came out of RFID. RFID, or radio-frequency identification, is the technology used by superstores to keep track of goods, it uses electromagnetic induction in order to transmit information. NFC is similar technology, but standardized for consumer smartphones.

• NFC is a means of sending data over radio waves. In that sense it is similar to Wi-Fi or Bluetooth, but unlike those protocols (and like RFID) NFC can be used to induce electric currents within passive components as well as just send data. And it is faster than Bluetooth.

Benefits over Bluetooth..

• The significant advantage of NFC over Bluetooth is the shorter set-up time.

• Due to its shorter range, NFC provides a higher degree of security than Bluetooth and makes NFC suitable for crowded areas.

• NFC can also work when one of the devices is not powered by a battery.

• Unlike Bluetooth, no pairing code is needed.

Applications…

• NFC chips or tags are very small in size, it can be embedded in the movie posters, real estate agent posters etc.

• Health care department.• NFC will replace car keys, ID badges and

credit/debit cards.• Implementation in food packaging, flyers and

merchandisers as well.

What is Wi-Fi? Wi-Fi or wireless fidelity, allows you to access the internet while

on the move; you can remain online while moving from one area to another in a wireless mode.

Wi-Fi enabled computers send and receive data indoors and out ;anywhere within the range of a base station.

Its just as fast as cable modem connection.

Wi-Fi is a generic term that refers to the IEEE 80211 communications standard for wireless local area networks(WLANs)

Lifi? (light fidelity)

lifi is transmission of data through illumination by taking the fiber out of fiber optics by sending data through LED light bulb. This varies in intensity faster than human eye can follow.It is the fast and cheap wireless communication system which is optical version of Wi-Fi.

Applications

• In vehicles and traffic lights.• In aircrafts and underwater.• Hospitals• Street lamps• Petroleum and Chemical industries

Advantages of wireless communication

• Wireless• Speed• Cost• Durability• Flexibility• Place of device

Disadvantages of wireless communication

• Power consumption

• Security issues

• Compatibility issues