EDGETest and Measurements

Agenda

• EDGE Measurements• VSA to test EDGE

Agenda

• EDGE Measurements• VSA to test EDGE

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

Key Measurements of TXGSM EDGE

Output Power overuseful part of burst

Not data dependent Use Random Data

Spectrum due toModulation

Yes Different Mask

Spectrum due toSwitching

Yes Same as MSK

Spurious Yes Same as MSK

Power Vs. Time Yes Different Mask

ModulationAccuracy

Phase Error: Peakand RMS

EVM: Peak, RMS,95th%Origin Offset

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

GSM vs. EDGE

GSM EDGEModulation GMSK 3PI/8 8PSK

Bits/Symbol 1 3

Data Bits per Burst 114 342

Symbol Rate 270.833k 270.833k

Filter 0.3 Gaussian Linearized Gaussian

GSM Modulation - 0.3 GMSK(gaussian filtered minimum shift keying)

Data

Symbol rate = Bit rate = 270.833 kB/s

“1” = -67.708 kHz

“0” = +67.708 kHz

Phase +90 deg -90 deg

Q

I

(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

EDGE Modulation

• 8 PSK constellation rotates 3/8 radians (67.5 deg) per symbol period

• Rotation prevents zero crossings, reducing peak-to-average power

EDGE vs. GSM Vector (Constellation) Diagrams

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QTransmitted

IQ

Interference

I

QReceived

Effect of Poor Modulation Quality

EDGE Error-Vector Magnitude

H

Error Vector Magnitude

{

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QMagnitude Error (IQ error mag)

Error Vector

Reference Signal

Phase Error (IQ error phase)

MeasuredSignal

H

The The EVMEVM Measurement Measurement ProcessProcess

Demodulator Modulator

001110

Reference Waveform

Measured Waveform

Input signal

H

Error Vector Magnitude (time domain)

This display shows the errorvector magnitude at each point in time. The red lines show thesymbol times. Errors canbe seen at the symbolpoints in and between.

EVM Requirements for EDGE

• EVMRMS

• EVMpeak

• EVM-95th-percentile

kEVMRMSEVM rms

)(max kEVMEVM peak

%9595 kEVMPpercentileth EVMEVM

EVM Requirements in EDGE Specs Test Condition Value Comments

RMS EVM For MS: undernominal conditions

9.0% Measured over at least 200 bursts

For MS: underextreme conditions

10.0% Measured over at least 200 bursts

Origin OffsetSuppression

MS >30 dB suppression

BTS >35 dB suppression

Peak EVM MS < 30% Peak EVM limit per burstaveraged over 200 bursts

BTS < 22% Peak EVM limit per burstaveraged over 200 bursts

95:th Percentile MS <15% Only 5% of symbols over 200bursts are allowed to exceed thisEVM limit

BTS <11% Only 5% of symbols over 200bursts are allowed to exceed thisEVM limit

We found in the GSM 11.10

1. For all measured bursts, the frequency error, derived in steps c.6) and l.4), shall be less than 10E-7.

2. For all measured bursts, the RMS phase error, derived in step c.8), shall not exceed 5 degrees.

3. For all measured bursts, each individual phase error, derived in step c.7), shall not exceed 20 degrees.

4. For all measured bursts, the RMS EVM, derived in step l.3) shall not exceed 9.0% under normalconditions and 10.0% under extreme conditions.

5. The (averaged) value of peak EVM derived in step p) shall not exceed 30%.

6. The 95:th percentile value derived in step q) shall not exceed 15%.

7. For all measured bursts, the origin offset suppression derived in step n) shall not exceed 30dB.

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Example Modulation ErrorsExample Modulation Errors

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Q

I

Q

Phase ImbalanceGain Imbalance

Reasons for Bad EVMReasons for Bad EVM

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Q

Origin Offset

Time

Frequency

Amplitude

ARFCN (Channel Frequency)

Timeslot

0 1 2 3 4 5 6 7

1 2 3 4 5 6

Frequency-Time Power Distribution

TimeslotPower versus Time

ARFCNOutput RF Spectrum

Interference - Power Measurements

EDGE Power Vs Time

ABC

Time

Frequency

Amplitude

Power vs. Time

EDGE Power Vs. Time

Power vs. Time Masks for GSM

Power vs. Time Masks for EDGE

• The amplitude modulation in EDGE requires that a different power versus time mask be used.

EDGE ORFS

Due to Modulation

Due to Switching

Output RF Spectrum (ORFS)Adjacent Channel Power (ACP)

Channel Center

Offset kHz

Tuned Average PowerAcross Useful Part of Burst

Frequency

Time

Power

Specification (dBc)

ORFS

ARFCN 4

ARFCN 3

43 dBm

(18dbm @ 200kHz offset)

39 dBm A

B

D

ARFCN 2

39 dBm

CARFCN 1

ARFCN 1

Interference Problems from ACP (ORFS)

39 dBm

Agenda

• EDGE Measurements• VSA to test EDGE

VSA – EDGE Modulation Analysis

VSA – EDGE EVM

VSA – EDGE PvT

VSA – EDGE ORFS

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

End of the Course...

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