4G Technology by harsha

7/28/2019 4G Technology by harsha

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0G (Zero Generation Mobile System)

At the end of the 1940s, the first radio telephoneservice was introduced, and was designed tousers in cars to the public land-line basedtelephone network.

In the 1960s, a system launched by Bell Systems,called, Improved Mobile Telephone Service(IMTS), brought quite a few improvements such asdirect dialing and more bandwidth. The very firstanalog systems were based upon IMTS and werecreated in the late 60s and early 70s.


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1G Technology

1G refers to the first-generation of wireless telephonetechnology was developed in 1970s.

1G had two major improvements: the invention of the microprocessor

the digital transform of the control link between thephone and the cell site.

Analog signal


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2G Technology

Used from 1980s

Better quality & capacity - More people could use

there phones at the same time

Digital Signals consist of 0s & 1s


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Previous Technology - 2G


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Advantages in Previous Technology - 2G

The digital voice encoding allows digital errorchecking

increase sound quality lowers the noise level

Going all-digital allowed for the introduction ofdigital data transfer

SMS short message service E-mail


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Disadvantages in Previous Technology - 2G

Cell towers had a limited coverage area

Jagged Decay curve

Abrupt dropped calls

Analog gradual sound reduction

Spotty coverage


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Spontaneous self organizationof networks of devices

Not necessarily connected to

internet

4G will create hybrid wirelessnetworks using Ad Hocnetworks

Form of mesh networkingVery reliable


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OFDM for 4G Wireless

~ 6 kHz

~ 800tones

~ 5 MHz

OFDM is being increasingly usedin high -speed informationtransmission systems:

- European HDTV- Digital Audio Broadcast (DAB)

- Digital Subscriber Loop (DSL)- IEEE 802.11 Wireless LAN

5 MHz channels

~ 6 KHz tones~ 13/26 MHz sample rate2048 FFT size (160 usec OFDM blocks)256/512 sample OFDM block guard timeQPSK & 16-QAM modulation adaptive modulation/coding1 to 2 msec time-slots in 20 to 40 msec frames

Mobile OFDM parameters: ex.


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GPRS Networks

consists of packet wireless access network and IP-basedbackbone

shares mobility databases with circuit voice services and addsnew packet switching nodes (SGSN & GGSN)

will support GPRS, EDGE & WCDMA airlinks

provides an access to packet data networkso Interneto X.25

provides services to different mobile classes ranging from 1-slotto 8-slot capable

radio resources shared dynamically between speech and dataservices


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IPv4 vs. IPv6

IPv4 IPv6

Structure 32 bits 128 bitsSecurity Poor security Enhance security

Function Addressing1. Multi-fun. and mobile fun. are built-in

2. Plug & Play (Auto-Configuration)


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The 3G

Large CoverageOutdoor - High MobilityUp to 14Mbps


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The 4G

What we needo Adaptive high performance transmission systemo Great candidate for SDR

Large Coverage 100Mbps CoverageOutdoor - High Mobility

Macro Cells Pico Cells

Isolated HotSpots 1Gbps CoverageIndoor Very Low Mobility


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4G WOFDM high speed downlink awireless cable modem

Complement to EDGE/UMTS

High peak data rates (up to 10 Mb/s) ina 5 MHz channel

spectrum - 500 MHz to 3 GHz 3G EDGE/WCDMA network for uplink,

downlink,control and signalling

4G Wireless: One View


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One of the most challenging problemsfacing deployment of 4G technology is

how to access several and different mobileand wireless networks

There are two possible architectures Multimode Devices

Overlay Network

4G Wireless Networks Challenges

First Challenge: Accessing Different Networks


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4G Wireless Networks Challenges

Second Challenge: Terminal Mobility In order to provide wireless services at

any time and anywhere, terminal mobilityis a must in 4G infrastructure

Terminal mobility allows mobile clients toroam across geographical boundaries ofthe wireless networks

There are two main issues in terminal

mobility: location management handoff management


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DelaySpread

RayleighFading

Path

Loss

rapid fading of 20 to 30 dB(power varies by 100 to 1000 timesin level at rates of about 100 times persecond)

path loss up to~ 150 dB(that is a 1followedby 15 zeroes)

Reflectedsignalsarrive spreadoutover 5 to 20microsecond

Path Loss and Fading Challenge


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