13.17.1a Frequency error and Modulation accuracy in EGPRS2A Configuration

3GPP51.010-1Mobile Station (MS) conformance specificationPart 1: Conformance specificationTS

13.17.1a.1 Definition

The frequency error is the difference in frequency, after adjustment for the effect of the modulation accuracy between the RF transmission from the MS and either:

– the RF transmission from the BS; or

– the nominal frequency for the ARFCN used.

Modulation Accuracy.

For GMSK, the modulation accuracy of the transmitted signal is described as the phase accuracy (phase error) of the GMSK modulated signal. The phase error for GSMK modulation is the difference in phase, after adjustment for the effect of the frequency error, between the RF transmission from the MS and the theoretical transmission according to the intended modulation.

Since the conformance requirement, test procedure and test requirement for GMSK modulation accuracy (RMS Phase error and maximum peak deviation) are defined in subclause 13.16.1 for GPRS MS, being thereby defined also for all EGPRS MS in that section and 8PSK modulation accuracy conformance requirement, test procedure and test requirement are defined in subclause 13.17.1, only 16QAM modulation accuracy conformance requirement, test procedure and test requirement are defined in this subclause.

For 16QAM, the error vector between the vector representing the transmitted signal and the vector representing the error-free modulated signal defines modulation accuracy. The magnitude of the error vector is called Error Vector Magnitude (EVM). Origin suppression is defined to be the ratio of the carrier leakage to the modulated signal.

13.17.1a.2 Conformance requirement

1. The carrier frequency under 16QAM modulation shall be accurate to within 0,2 ppm for GSM 400 and 0,1 ppm for all other bands compared to signals received from the SS.

1.1 Under normal conditions; 3GPP TS 45.010, subclause 6.1.

1.2 Under extreme conditions; 3GPP TS 45.010, subclause 6.1; 3GPP TS 45.005, subclause 4.4; 3GPP TS 45.005, annex D subclauses D.2.1 and D.2.2.

2. The RMS EVM over the useful part of any burst of the 16QAM modulated signal shall not exceed.

2.1 7,0% Under normal conditions; 3GPP TS 45.005, subclause 4.6.2.1

2.2 8,0% Under extreme conditions; 3GPP TS 45.005, subclause 4.6; 3GPP TS 45.005, annex D subclauses D.2.1 and D.2.2.

3. The peak EVM values averaged over at least 200 bursts of the 16QAM modulated signal shall be  30 %.

3.1 Under normal conditions; 3GPP TS 45.005, subclause 4.6.2.3.

3.2 Under extreme conditions; 3GPP TS 45.005, subclause 4.6.2.3; 3GPP TS 45.005, annex D subclauses D.2.1 and D.2.2.

4. The 95:th-percentile value of any burst of the 16QAM modulated signal shall be  15 %.

4.1 Under normal conditions; 3GPP TS 45.005, subclause 4.6.2.4.

4.2 Under extreme conditions; 3GPP TS 45.005, subclause 4.6.2.4; 3GPP TS 45.005, annex D subclauses D.2.1 and D.2.2.

5. The Origin Offset Suppression for any 16QAM modulated signal shall exceed 30 dB.

5.1 Under normal conditions; 3GPP TS 45.005, subclause 4.6.2.2.

5.2 Under extreme conditions; 3GPP TS 45.005, subclause 4.6.2.2; 3GPP TS 45.005, annex D subclauses D.2.1 and D.2.2.

13.17.1a.3 Test purpose

To verify that the carrier frequency error does not exceed conformance requirement 1:

1.1 Under normal conditions.

1.2 Under extreme conditions.

To verify that the RMS EVM over the useful part of the burst, excluding tail bits, transmitted by the MS does not exceed conformance requirement 2:

2.1 Under normal conditions.

2.2 Under extreme conditions.

To verify that the peak EVM values over the useful part of the burst, excluding tail bits, transmitted by the MS does not exceed conformance requirement 3:

3.1 Under normal conditions.

3.2 Under extreme conditions.

To verify that the 95:th percentile EVM over the useful part of any burst, excluding tail bits, does not exceed conformance requirement 4:

4.1 Under normal conditions.

4.2 Under extreme conditions.

To verify that the origin offset suppression does exceed conformance requirement 5:

5.1 Under normal conditions.

5.2 Under extreme conditions.

13.17.1a.4 Method of the test

Initial conditions

The test shall be run under the default EGPRS conditions defined in clause 50, with power control parameter ALPHA (α) set to 0.

The SS shall command the MS to hopping mode (for the choice of frequencies in the frequency hopping mode, see subclause 6.2 and tables 6-1 and 6-2).

NOTE: It is not necessary to test in hopping mode but is done here as a simple means of making the MS change channel, it would be sufficient to test in non hopping mode and to make sure bursts are taken from a few different channels.

The MS shall be operated with its highest number of uplink slots.

The Test Mode defined in 3GPP TS 44.014 subclause 5.4 shall be utilised.

If the MS is capable of both:

Mode (a) transmitting pseudo-random data sequence in RLC data blocks;

Mode (b) transmitting looped-back RLC data blocks;

then Mode (a) will be used.

For the 16QAM procedure described below, the initial power value of each active timeslot shall be set to a mid-range power value.

13.17.1a.4.2 Test procedure

Procedure for 16QAM Frequency error and modulation accuracy measurements

a) For one transmitted burst on the last slot of the multislot configuration, the SS captures the transmitted signal by taking at least four samples per symbol. The transmitted signal is modelled by:

Y(t) = C1{R(t) + D(t) + C0}Wt

R(t) is defined to be an ideal transmitter signal.

D(t) is the residual complex error on signal R(t).

C0 is a constant origin offset representing carrier feed through.

C1 is a complex constant representing the arbitrary phase and output power of the transmitter.

W = e   + j 2f accounts for both a frequency offset of "2f" radians per second phase rotation and an amplitude change of "" nepers per second.

The symbol timing phase of Y(t) is aligned with R(t).

b) The SS shall generate the ideal transmitter signal as a reference. The ideal transmitter signal can be constructed from a priori knowledge of the transmitted symbols or from the demodulated symbols of the transmitted burst. In the latter case, unknown symbols shall be detected with an error rate sufficiently small to ensure the accuracy of the measurement equipment (see annex 5).

c)

c.1) The transmitted signal Y(t) is compensated in amplitude, frequency and phase by multiplying with the factor:

W-t/C1

The values for W and C1 are determined using an iterative procedure. W(,f), C1 and C0 are chosen to minimise the RMS value of EVM on a burst-by-burst basis.

c.2) After compensation, Y(t) is passed through the specified measurement filter (3GPP TS 45.005, subclause 4.6.2) to produce the signal:

Z(k) = S(k) + E(k) + C0

where:

S(k) is the ideal transmitter signal observed through the measurement filter;

k = floor(t/Ts), where Ts =1/270.833 kHz corresponding to the symbol times.

c.3) The error vector is defined to be:

E(k) = Z(k) – C0 –S(k)

It is measured and calculated for each instant k over the useful part of the burst excluding tail bits. The RMS vector error is defined as:

c.4) Steps c.1) to c.3) are repeated with successive approximations of W(,f), C1 and C0 until the minimum value of RMS EVM is found. The minimised value of RMS EVM and the final values for C1, C0 and f are noted. (f represents the frequency error of the burst).

d) For each symbol in the useful part of the burst excluding tail bits, the SS shall calculate the error vector magnitude as:

The peak value of symbol EVM in the useful part of the burst, excluding tail bits, is noted.

e) The SS shall calculate the value for Origin Offset Suppression for the burst as:

f) Steps a) to e) are repeated for a total of 200 bursts.

g) The peak values of symbol EVM noted in step d) are averaged for the 200 measured bursts.

h) The origin offset suppression values derived in step e) are averaged for the 200 measured bursts. The resulting average is converted to log format.

i) From the distribution of symbol EVM values calculated in step d) for the 200 measured bursts, the SS shall determine the 95: the percentile value.

j) The SS instructs the MS to its maximum power control level by setting the power control parameter ALPHA () to 0 and GAMMA_TN (CH) for each timeslot to the desired power level in the Packet Uplink Assignment or Packet Timeslot Reconfigure message (Closed Loop Control, see 3GPP TS 45.008, clause B.2), all other conditions remaining constant. Steps a) to i) are repeated.

k) The SS instructs the MS to the minimum power control level, all other conditions remaining constant. Steps a) to i) are repeated.

l) Steps a) to i) are repeated under extreme test conditions (see annex 1, TC2.2).

13.17.1.5 Test Requirements

1. For all measured bursts, the frequency error, derived in step c.4), shall be less than 0,2ppm for GSM400 and 0,1ppm for all other bands compared to the signal received from the SS.

2. For all measured bursts, the RMS EVM, derived in step c.3) shall not exceed 7,0 % under normal conditions and 8,0% under extreme conditions.

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

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

5. The origin offset suppression derived in subclause 13.17.1a.4.2 step h) shall exceed 30 dB for MS.