Architectures GSMUMTS

1
Part 2 Frequency Manipulation
2
Summary

• Introduction
• QPSK Modulation
• QPSK Demodulation
• Modulation QAM
• Up-down conversion
• Conclusion

3
1. Introduction
GSM modulation
BS Base Station
MS Mobile Station
GMSK
Downlink (Rx)
Uplink (Tx)
GMSK
GSM Gaussian-Modulated-Shift-Keying
4
1. Introduction
UMTS modulation
NodeB
UE
Downlink (Rx)
Uplink (Tx)
5
2. QPSK Modulation
Quadrature Phase Shift Keying
Two sinusoidal waves at same frequency, but
different phases
sq
Data
si
0
0
0
1
1
0
1
1
-1
00
-1
-1
1
01
time
S(t) I(t)Q(t)
1
-1
10
I(t) sicos(?t) Q(t) sqsin(? t)
11
1
1
6
2. QPSK Modulation
Quadrature Phase Shift Keying (QPSK) 
Amplitude
time
Frequency
time
7
2. QPSK Modulation
Quadrature Phase Shift Keying (QPSK) 
Digital signal processor
Serial data
sinus
I
QPSK
QPSK codeur
Addition
cosinus
00 01 10 11
Q
?
90
Clock
8
2. QPSK Modulation
GSM Gaussian Modulated Shift Keying (GMSK) 
Soft phase transitions required to limit the
spread in frequency
GSMK
QPSK
9
3. QPSK Demodulation
Gives its secret by multiplying by SIN and COS 
19xx MHz
I
Antenna
cos
Q
LNA
sin
LNAlow noise amplifier VCOVoltage contr.
oscillator
VCO 19xx MHz
Select channel
10
3. QPSK Demodulation
Ideal case
Multiplication by sin (wt)
Multiplication by cos (wt)
11
3. QPSK Demodulation
Little mismatch between emitter and receiver
Multiplication by sin (wt)
Multiplication by cos (wt)
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3. QPSK Demodulation
Antenna
100KHz
I
A/D 8bits
20xx MHz
LPF
DSP
cos
Q
A/D 8bits
LPF
sin
LNA
VCO 19xx MHz
The DSP is in charge of reconstruction the
original digital information
13
4. QAM Modulation

• Quadrature Amplitude Modulation (QAM) both phase
  and amplitude
• QAMn 2n phase,amplitude solutions
• Can code n bits

16-QAM (24 -gt 4-bit) Used for HSDPA downlink
14
4. QAM Modulation

• Hello in QAM16

H0x48
e0x65
15
4. QAM modulation

• Hello in QAM64 Used for HSPA (or HSPA
  enhanced)

Si
Sq
16
5. Up-down conversion
Up/Down Frequency converter
Authorized band for Tx
Amplitude
Desired band for Rx
Up-converter
UMTS
Frequency
f0
Base-band
Down-converter
17
5. Up-down conversion
Frequency Multiplication
S(t) cos(?m t).cos(?p t)
Modulation ?m
time
time
time
Frequency
Carrier ?p
18
5. Up-down conversion

• How do we multiply signals?

19
5. Up-down conversion
Down-converter in practice
Filter 100 MHz
Low noise amplifier
modulation
Local oscillator f0
f(MHz)
Rx
Rx
Rx
2010
2025
2110
2170
2200
20
5. Up-down conversion
UMTS
19__, 19__ MHz
15.36 MHz
240 kHz
1/__
Quartz
Phase lock loop
Power amplifier
N from ___ to ____
935, 960 MHz
GSM
13 MHz
200 kHz
1/65
Quartz
Phase lock loop
Power amplifier
N from ___ to ____
21
Conclusion
Conclusion

• Basis of QPSK modulation described
• QPSK demodulation uses high precision sin/cos
  multiplication
• Frequency multiplication is the base for up/down
  conversion
• Phase/amplitude combination enhances bit rate
• 16QAM and 64QAM illustrated
• Bases for GSM and UMTS telecommunication systems