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Page 1: 4g – evolution and

Presented by : SAYAN DASETC 3rd year BESU

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NetworkGeneratio

n

Name Access technology

Speed(max in kbps)

1G AMPS/TACS TDMA 5.6

2G GSM FDMA +TDMA

9.6

2.5G GPRS FDMA +TDMA

170(theo)115(prac)

2.75G EDGE FDMA +TDMA

473(theo)384.6(prac)

3G UMTS WCDMA 2000

4G HSPA, LTE-A

OFDMA 1Gbps

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Steady growth of technology

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Complicated circuitry in mobiles (WCDMA+FDMA+TDMA)

Less coverage area (1km – off-peak hrs, 500 m-peak hrs) .... Worse than 2G

Separate 3G base stations are requaired

2.5Ghz Band spectrum is very costly

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OFDMA = Orthogonal Frequency Division Multiplexing Access Technology

UWB=Ultra Wide Band [500MHz – 3GHz]

Smart Antenna using MIMO technology

Supports IPv6

SDR= Software Radio System

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OFDMA = OFDM (d/l) + SCFDM(u/l)

large number of closely spaced orthogonal sub-carrier signals are used to carry data on several parallel data streams or channels

Since 2G or 3G spectrum can be utilised , there is no immediate need of buying separate 4G spectrum

Uses IFFT during transmission and FFT

during receiving

Cyclic prefixes removes interchannel and co-channel interference

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BLOCK DIAGRAM OF OFDMA

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OFDM can combat multipath interference with more robustness and less complexity.

OFDMA can achieve a higher MIMO spectral efficiency due to providing flatter frequency channels than a CDMA rake receiver can.

No cell size breathing as more users connect. Allows simultaneous low-data-rate transmission from

several users. Pulsed carrier can be avoided. Lower maximum transmission power for low data rate

users. Shorter delay, and constant delay. Contention-based multiple access (collision avoidance) is

simplified. Further improves OFDM robustness to fading and

interference.

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Delay Spread

Rayleigh Fading

Path Loss

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

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

Reflected signalsarrive spread outover 5 to 20microsecond

Fading problems

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Subscriber

Base Station

Paths

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Dynamic Packet Assignment~ 50 % improvement in performance

1. Mobile locks to the STRONGESTbase

2. Mobile sends measurements of path losses for nearby bases to serving base

3. Serving base forwards measurementsto nearby bases

4. Bases assign channels to all packets/mobiles

5. Bases forward channel assignment info to nearby bases

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IPv4 IPv6Address

Size32 bit number 128bit number

AddressFormat

Dotted DecimalNotation

192.168.1.1

Hexadecimal Notation3FFE:F200:0234:AB00:0123:4567:8901:ABCD

Number of Addresses

2^32 2^128

Remarks Address Exhaustion

Larger address space, Multicasting, Better

Mobility…

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IF band pass filtering equivalent, demodulation, amplification, detectors, noise reduction, noise blanking, etc. are all done in software

The phone would be automatically switch from operating on a CDMA frequency to a TDMA frequency whenever it is requaired through the use of soft ware….

Hence hardware complications , use of complex circuitry is removed..

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