GPRS/EGPRS Mobile Measurements Tutorial

This tutorial will cover GPRS mobile measurements ideal for conformance testing of GPRS/EGPRS mobile subscribers as per 3GPP standards.

The measurements mentioned can be carried out for all the frequency bands supported, which include 850 MHz, 900 MHz, 1800 MHz, and 1900 MHz. The figure below describes the generic test setup used for GSM and GPRS compliant mobile phone testing.

As shown in the figure, the mobile phone is connected with a system simulator, which can be either R&S CMU200 or Agilent 8960.

TRANSMITTER MEASUREMENTS

Here, TEST MODE A is used for the transmit part of measurements. It includes the following measurements:

1. MS transmit power is set as ordered by the base station as a PCL value.
2. Multi-slot power measurement: The mobile should use the same output power on all the bursts in a radio block.
3. Transmit Power Mask Measurements include the following tests:
   • Power versus time Single slot
   • Power versus time of multiple bursts configuration carried in multi-slots
   • Power versus slots
4. Modulation related measurements viz. Frequency error, phase error, timing advance error, origin offset, IQ imbalance measurement, and spectrum measurement.

RECEIVER MEASUREMENTS

Here, TEST MODE B is used for the transmit part of measurements. In this mode, loopback happens after the channel decoder to the channel encoder.

It includes the following measurements:

• BER: It compares RLC data received after loopback at the Mobile with the transmitted data bits. It is the ratio of bits in error to the total bits transmitted.
• BLER: It is the block error rate. It is determined by not comparing bit by bit but the entire block of 4 bursts. BLER is based on signaling messages (ACK/NACK) in acknowledged mode of data transfer.
• DBLER: It is the ratio of received data blocks in error to the total number of transmitted blocks.
• USF BLER: (Uplink State Flag Block Error Rate) It counts the percentage rate of not received uplink radio blocks
• CRC Errors: It indicates errors in uplink data using a CRC check or Block Check Sequence (BCS) check.
• Loop back A, B, C, D, E, F and I modes

EGPRS Testmode B (ack)

In this mode, the System simulator (Example R&S CMU200) generates downlink PDCH data, and the mobile loops back downlink data on the uplink slots (one or more). BER and BLER measurements can be performed. The test is defined in 3GPP 44.014.

EGPRS SRB loopback

In this mode, Layer-1 loopback mode BER testing can be done.

OTHER MEASUREMENTS

1. Multi-slot capabilities as per different classes supported by the GPRS/EPGRS modulation and coding schemes. CS4 and MCS9 - 1R2T, 1R4T, 2R2T with and without RLC/MAC acknowledgement. Measurements should be done for multislot classes 1 to 12 and from 30 to 45.
2. BER-BLER with the above multislot configurations.

Loopback Tests

• Single Slot TCH loops (A/B/C/D/E/F/I)
• Multi-slot TCH loops (G/H)
• GPRS/EGPRS Test Modes (Test mode A, ack/unack B), as explained above.
• EGPRS Switched Radio Loopback

Above figure mentions various points from where loopback is performed in the system.

REFERENCE

• 3GPP,TS51.010-1, version 10.2.0,Release-10, MS conformance test document.
• 3GPP 44.014