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IMPLEMENTATION OF 4G

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IMPLEMENTATION OF 4G

• OFDM• UWB• Millimeter wave technology• Scheduling • Long term prediction• Smart antennas• Adaptive modulation

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OFDM

• Multi carrier modulation• Closely spaced orthogonal sub-carriers• Slow & low bandwidth modulator

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OFDM

• Sinc shaped pulse

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OFDM

Non-overlapping sub-carriers:• Allowed channel bandwidth=2/Rs• BW α 1/Rs

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OFDM

• Overlapping sub-carriers:• Allowed channel bandwidth=1/Rs

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ADVANTAGES OF OFDM

• High spectral efficiency • Can easily adapt to severe channel conditions without complex

time-domain equalization• Robust against narrow-band co-channel interference• Efficient implementation using Fast Fourier Transform(FFT)• Tuned sub-channel receiver filters are not required• Facilitates single frequency networks(SFNs)• SNR improves

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DISADVANTAGES OF OFDM

• Sensitive to Doppler shift• Sensitive to frequency synchronization problems• High peak-to-average power ratio (PAPR)

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APPLICATIONS OF OFDM

• Digital TV• Audio broadcasting• Wireless networks• Wimax technologies

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UWB

• FCC defines UWB as a radio transmission with a spectrum that occupies more than 20% of the centre frequency or a minimum of 500MHz while adhering certain output power limits

• Base band modulation• Large bandwidth, typically 3.1 to10.6GHz• Shorter range of about 10 meters• It offers flexibility, robustness, good ranging capabilities• Operates below noise level

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PRINCIPLES OF UWB

Time domain:

• Extremely short pulses• Very low duty cycles

Frequency domain:• Ultra wide spectrum• Low spectral power density

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UWB

Two classes:• Multiband UWB• Impulse radio

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ADVANTAGES OF UWB

• Spectrum reuse• Large channel capacity• Ability to work with low signal-to-noise ratio• Hartley-Shannon’s capacity equation:

C=B*log(1+S/N)

Where C is channel capacity

B is signal bandwidth

S is signal power

N is noise power

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ADVANTAGES OF UWB

• High data rate in short distance—500Mbps at 10 meters• Low power consumption• Low cost• SNR improves

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APPLICATIONS OF UWB

• Radar sensing• Military communications• target sensors data collection• Precision locating & tracking applications• ITS(Intelligent Transport Systems)

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MILLIMETER WAVE TECHNOLOGY• Need• High standard• Applications like campus & facility enterprise network,

connection redundancy and failure recovery

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SCHEDULING

• Among sectors• Among users

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LONG TERM PREDICTION

• Distribution

• Channel properties

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SMART ANTENNAS

• Smart antennas are antenna arrays with smart signal processing algorithms

• High Efficiency • Frequency range from

450MHz to 6GHz• Wide bandwidth• Very Low Cost• One antenna replaces all others• Can reduce costs by 100x• Flexible implementation in foil

or copper

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• The antenna arrays have input or output as RF signals in the analog domain

• The baseband signals received from each antenna is then combined using the smart algorithms in a digital processing section

• One smart‐antenna variation in particular, MIMO, shows promise in 4G systems

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MIMO•  Multiple Input Multiple

Output (MIMO) requires array processing at the transmitter and receiver

• There are two different types of MIMO schemes:

•  Spatial Multiplexing • Space Division Multiplexing• Multiple antennas at both the

transmitter and the receiver• It provides essentially

multiple parallel channels that operate simultaneously

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ADAPTIVE MODULATION• Adaptive Modulation is not Fixed Modulation• Idea of Adaptive Modulation• Types of Adaptive Modulation• AMQAM-Non blocking• AMQAM-Blocking• AMPSK-Non blocking• AMPSK-Blocking

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THANK YOU