GPRS/EGPRS Mobile Measurements
In this tutorial we 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.
Figure below describes the generic test set up used for GSM and GPRS compliant mobile phone testing. As shown in the figure, mobile phone is connected with system simulator which can be either R&S CMU200 or Agilent 8960.
Here TEST MODE A is used for transmit part of measurements. It include following measurements.
1. MS transmit power is set as ordered by base station as PCL value.
2. Multi slot power measurement:
Mobile should use same output power on all the bursts in a radio block.
3. Transmit Power Mask Measurements include 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.
Here TEST MODE B is used for transmit part of measurements. In this mode Loopback happens after channel decoder to channel encoder.
It include following measurements.
BER: It compares RLC data received after loopback at Mobile with the transmitted data bits. It is ratio of bits in error to the total bits transmitted.
BLER: It is block error rate. It is determined by not comparing bit by bit but entire block of 4 bursts. BLER is based on signalling messages(ACK/NACK) in acknowledged mode of data transfer.
DBLER: It is the ratio of received data blocks in error to total number of transmitted blocks.
USF BLER:(Uplink State Flag Block Error Rate) It counts percentage rate of not received uplink radio blocks
CRC Errors: It indicates errors in uplink data using 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 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.
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.
• 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. To Know MORE, VISIT LOOPBACK TESTS Page.
3GPP,TS51.010-1, version 10.2.0,Release-10, MS conformance test document.