4g – evolution and
TRANSCRIPT
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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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