WCDMA 06 03 01 - Stanford Universitywsl.stanford.edu/~ee392m/lectures/ee392m_0306.pdf · CDMA Era T. Ojanpera and R. Prasad, Wideband CDMA for Third Generation Mobile Communications,

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UMTS Evolution

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Bit Rate / Coverage / Mobility

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CDMA Era

T. Ojanpera and R. Prasad, Wideband CDMA for Third Generation Mobile Communications, Artech House

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WCDMA & Standard Bodies

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Why Spread Spectrum?

• Multiple access capability– CDMA

• Interference suppression– Jammer can be reduced on all/few signal coordinates

• Energy density reduction– Low probability of intercept (LPI)– Low probability of detection (LPD), LPPF, LPSE

• Finite time resolution– High resolution ranging– Accurate universal timing– Multipath resolution

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Principle of Spread Spectrum

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Spread Spectrum Types

• Signal dimensionality ⇒

D↑ ⇒ W ↑ or T ↑

• Direct sequence (DS) ⇒ W ↑• Frequency hopping (FH) ⇒ W ↑• Time hopping (TH) T ↑• Hybrids

WTD 2≈

∫

≠=

=T

kj kjkj

dttt0

*

,0,1

)()( ϕϕ TWk 2,,2,1 K=

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IMT-2000 / UMTS

( )[ ]∑ −= +

nh

tfj nTtpetC nn )()( 2 φπ

∑ −=n

hn nTtpctC )()(

∑

+−=

ns

t

n TMa

ntptC )()(

∏=i

i tctC )()( )(

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Principle of DS-CDMA

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CDMA Classifications

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CDMA Classifications

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Rake Receiver

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Carrier Spacing

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(W)CDMAParameters

IS-95

WCDMA

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