1. EDGE Test and Measurements

2. Agenda EDGE Measurements VSA to test EDGE
EDGE maintains the modulation scheme used in GSM (GMSK) and IS-136 (/4-DQPSK) for low data rates and for backward compatibility. For higher data rates, the 8-PSK modulation scheme is used. However, the same TS format is used with the symbols per TS. For 8-PSK, this translates into three times the bit rate for GSM.

3. Agenda EDGE Measurements VSA to test EDGE
EDGE maintains the modulation scheme used in GSM (GMSK) and IS-136 (/4-DQPSK) for low data rates and for backward compatibility. For higher data rates, the 8-PSK modulation scheme is used. However, the same TS format is used with the symbols per TS. For 8-PSK, this translates into three times the bit rate for GSM.

4. GSM/EDGE TX Measurements
Power
Mean Transmit Power
Power vs. Time
Modulation Quality
Phase Frequency error (GSM)
EVM (EDGE)
Spectral Emissions
Output RF Spectrum (ORFS)
Modulation spectrum
Switching (transient) spectrum
TX/RX Band Spurious
Cross-Band Spurious

5. Key Measurements of TX

6. GSM/EDGE RX Measurements
Sensitivity
Frame erasure rate (FER)
Residual bit error rate (RBER) Class Ib
RBER Class II
Sensitivity search Sensitivity
Selectivity
Co-channel rejection
Adjacent channel selectivity
Alternate channel selectivity

7. GSM vs. EDGE

8. GSM Modulation - 0.3 GMSK (gaussian filtered minimum shift keying)
“1” = kHz
Data
“0” = kHz
Symbol rate = Bit rate = kB/s
Phase
+90 deg
-90 deg Q I

9. Standard 8 PSK Constellation
EDGE Modulation
8 PSK constellation rotates 3/8 radians (67.5 deg) per symbol period
Rotation prevents zero crossings, reducing peak-to-average power
(1,1,1) t = 0 (symbols)
(1,1,1) t = 1
(1,1,1) t = 2
(1,1,1) t = 3
3π/8 radians
...
Standard 8 PSK Constellation

10. EDGE vs. GSM Vector (Constellation) Diagrams

11. Effect of Poor Modulation Quality
Received I Q
Transmitted
Interference I Q

12. EDGE Error-Vector Magnitude

13. { Error Vector Magnitude Q I Magnitude Error (IQ error mag)H
Error Vector Magnitude { I Q
Magnitude Error (IQ error mag)
Error Vector
Reference Signal
Phase Error (IQ error phase)
Measured
Signal 

14. The EVM Measurement Process
001110
Modulator
Demodulator
Reference Waveform
Input signal
Measured Waveform

15. Error Vector Magnitude (time domain)H
Error Vector Magnitude (time domain)
This display shows the error
vector magnitude at each
point in time.
The red lines show the
symbol times.
Errors can
be seen at the symbol
points in and between.

16. EVM Requirements for EDGE
EVMRMS
EVMpeak
EVM-95th-percentile

17. EVM Requirements in EDGE Specs

18. We found in the GSM 11.10

19. Reasons for Bad EVM Example Modulation Errors Q Q I I Gain ImbalanceH
Reasons for Bad EVM
Example Modulation Errors Q Q I I
Gain Imbalance
Phase Imbalance Q I
Origin Offset

20. Frequency-Time Power Distribution1 2 3 4 5 6 7
Amplitude
Timeslot
Frequency 1 2 3 4 5 6
ARFCN (Channel Frequency)

21. Interference - Power Measurements
Power versus Time
Timeslot
Output RF Spectrum
ARFCN

22. EDGE Power Vs Time

23. Power vs. Time
Time
Amplitude
Frequency
ABC

24. EDGE Power Vs. Time

25. Power vs. Time Masks for GSM

26. Power vs. Time Masks for EDGE
The amplitude modulation in EDGE requires that a different power versus time mask be used.

27. EDGE ORFS

28. Adjacent Channel Power (ACP)
Output RF Spectrum (ORFS)
Adjacent Channel Power (ACP)
Due to Modulation
Due to Switching

29. ORFS Specification (dBc) Tuned Average Power
Across Useful Part of Burst
Offset kHz
Power
Channel Center
Time
Frequency

30. Interference Problems from ACP (ORFS)
ARFCN 1
39 dBm
43 dBm
39 dBm
200kHz offset) B
ARFCN 4
39 dBm C
ARFCN 2 A
ARFCN 1 D
ARFCN 3

31. Agenda EDGE Measurements VSA to test EDGE
EDGE maintains the modulation scheme used in GSM (GMSK) and IS-136 (/4-DQPSK) for low data rates and for backward compatibility. For higher data rates, the 8-PSK modulation scheme is used. However, the same TS format is used with the symbols per TS. For 8-PSK, this translates into three times the bit rate for GSM.

32. VSA – EDGE Modulation Analysis
EDGE maintains the modulation scheme used in GSM (GMSK) and IS-136 (/4-DQPSK) for low data rates and for backward compatibility. For higher data rates, the 8-PSK modulation scheme is used. However, the same TS format is used with the symbols per TS. For 8-PSK, this translates into three times the bit rate for GSM.

33. VSA – EDGE EVM
EDGE maintains the modulation scheme used in GSM (GMSK) and IS-136 (/4-DQPSK) for low data rates and for backward compatibility. For higher data rates, the 8-PSK modulation scheme is used. However, the same TS format is used with the symbols per TS. For 8-PSK, this translates into three times the bit rate for GSM.

34. VSA – EDGE PvT
EDGE maintains the modulation scheme used in GSM (GMSK) and IS-136 (/4-DQPSK) for low data rates and for backward compatibility. For higher data rates, the 8-PSK modulation scheme is used. However, the same TS format is used with the symbols per TS. For 8-PSK, this translates into three times the bit rate for GSM.

35. VSA – EDGE ORFS
EDGE maintains the modulation scheme used in GSM (GMSK) and IS-136 (/4-DQPSK) for low data rates and for backward compatibility. For higher data rates, the 8-PSK modulation scheme is used. However, the same TS format is used with the symbols per TS. For 8-PSK, this translates into three times the bit rate for GSM.

36. Summary EDGE an enhancement to GSM
provides higher data rates in the same spectrum by using a higher density modulation.
most of the GSM measurements apply to the EDGE waveform
for modulation quality EVM is used for the 8-PSK signal, instead of phase error

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