WCDMA Fundamentals
18
WCDMA RAN Fundamental
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Transcript of WCDMA Fundamentals
WCDMA RAN
Fundamental
Objectives• Upon completion of this course, you will be able to:– Describe feature of wireless propagation
– Outline the advantage of CDMA principle
– Characterize code sequence– Outline the fundamentals of RAN
Contents1.CDMA Principle2.WCDMA Fundamental
Contents1.CDMA Principle2.WCDMA Fundamental
Wireless Propagation
ReceivedSignal
TransmittedSignal
Transmission Loss:Path Loss + Multi-path Fading
Time
Amplitude
Propagation of Radio SignalSignal at Transmitter
Signal at Receiver
-40-35-30-25-20-15-10-5
dB
0
0
dBm
-20-15-10-5
5101520
Fading
Fading Categories• Fading Categories
– Slow Fading– Fast Fading
Multiple Access and Duplex Technology
• Multiple Access Technology– Frequency division multiple access (FDMA)– Time division multiple access (TDMA)– Code division multiple access (CDMA)
• Duplex Technology– Time division duplex (TDD)– Frequency division duplex (FDD)
Multiple Access Technology
freque
ncytime
power
FDMA
freque
ncytime
power
TDMA
power
time
CDMA
frequency
Duplex Technology
Time
Frequency
Power
TDDUSER 2
USER 1
DLUL
DLDL
UL
FDD
Time
Frequency
Power
UL DL
USER 2
USER 1
Contents1.CDMA Principle2.WCDMA Fundamental
Correlation (1)• Correlation measures similarity between any two arbitrary signals.
• Identical and Orthogonal signals:
Correlation = 0Orthogonal signals
-1 1 -1 1
-1 1 -1 1
1 1 1 1
+1
-1+1
-1
+1
-1
+1
-1
Correlation = 1
Identical signals
-1 1 -1 1
1 1 1 1
-1 1 -1 1
C1
C2+1
+1
C1
C2
WCDMA Channelization Code
• OVSF Code (Orthogonal Variable Spreading Factor)• SF = chip rate / symbol rate
– High data rates → low SF code– Low data rates → high SF code
SF = 8
SF = 1 SF = 2 SF = 4
Cch,1,0 = (1)
Cch,2,0 = (1,1)
Cch,2,1 = (1, -1)
Cch,4,0 = (1,1,1,1)
Cch,4,1 = (1,1,-1,-1)
Cch,4,2 = (1,-1,1,-1)
Cch,4,3 = (1,-1,-1,1)
Cch,8,0 = (1,1,1,1,1,1,1,1)
Cch,8,1 = (1,1,1,1,-1,-1,-1,-1)Cch,8,2 = (1,1,-1,-1,1,1,-1,-1)
Cch,8,3 = (1,1,-1,-1,-1,-1,1,1)Cch,8,4 = (1,-1,1,-1,1,-1,1,-1)
Cch,8,5 = (1,-1,1,-1,-1,1,-1,1)Cch,8,6 = (1,-1,-1,1,1,-1,-1,1)
Cch,8,7 = (1,-1,-1,1,-1,1,1,-1)
……
Purpose of Channelization Code• For uplink, Channelization code ( OVSF code ) is used to
separate different physical channels of one connection • For downlink, Channelization code ( OVSF code ) is used
to separate different connections in a cell
Radio bearer** SF Radio bearer** SFSpeech 4.75 UL 12
8Speech 4.75 DL 256
Speech 12.2 UL 64 Speech 12.2 DL 128Data 64 kbps UL 16 Data 64 kbps DL 32Data 128 kbps UL 8 Data 128 kbps DL 16Data 144 kbps UL 8 Data 144 kbps DL 16Data 384 kbps UL 4 Data 384 kbps DL 8Data 2048 kbps UL 4 Data 2048 kbps DL 8Speech 12.2 + Data 64 kbps UL
16 Speech 12.2 + Data 64 kbps DL
32
Correlation (2)• Cross Correlation: related to the multi-user interference characteristic
• Auto Correlation: related to the multi-path interference characteristicTime Delay
S1(t)
S1(t+t)
S1(t)
S2(t)
Code Multiplexing• Downlink Transmission on a Cell LevelScrambling code
Channelization code 1
Channelization code 2
Channelization code 3
User 1 signal
User 2 signal
User 3 signal
NodeB
Code Multiplexing• Uplink Transmission on a Cell Level
NodeB
Scrambling code 3
User 3 signalChannelization
code
Scrambling code 2
User 2 signalChannelization
code
Scrambling code 1
User 1 signalChannelization
code
End
I am The Man Himself
