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Difference between Test mode A vs test Mode B

The test mode A and test mode B as defined in ETSI 44.014 are used for testing GPRS/EGPRS compliant mobiles. Test mode A is used for transmitter measurements and test mode B is used for both transmitter and receiver measurements. Following are the measurements carried out for these modes.

Test mode A performs Tx measurements viz. power versus time, phase and frequency and spectrum including modulation/ switching. It covers multislot measurements too. Test mode B performs Rx tests viz. BER and DBLER including multislot measurements as mentioned in test mode A. The popular equipment used for these measurements is Rohde and Schwarz CMU200.


This test mode puts the mobile under test to transmission mode as per PN sequence set for example 2E9-1 PSR Bit Pattern. Following diagram depicts the same test using CMU200.


This test mode internally closes loop back in the mobile under test and the data received is transmitted back without any modifications. The tests is performed for GPRS modulation and coding schemes viz. CS1 to CS4 and EGPRS modulation and coding schemes viz. MSC1 to MCS9. The test is useful for BER, BLER and DBLER measurements. Following diagram depicts the same test performed using CMU200. In Test Mode B, CMU200 sends blocks containing PRBS data and compares them with the data transmitted back from the mobile phone which provides BER measurement.

If CMU200 finds bit errors in data field of the received current block from the mobile, It declares the block as invalid. This provides Data Block Error Rate or DBLER.


GPRS protocol stack
GPRS Modem vendors
GSM versus GPRS
What is GPRS
GPRS/EGPRS Modulation-Coding Schemes

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Useful GSM Tutorial Links

• GSM Tutorial
• GSM Frame Structure
• GSM Burst types
• GSM speech processing
• GSM Channel types-logical,physical
• GSM logical channels and mapping
• GSM Mobile network entry procedure
• GSM Mobile originated call flow

RF and Wireless Terminologies