Block Error Troubleshooting

GPRS

The error correction which is a feature of channel coding scheme CS-1 will mask low to medium block error rates if used during BLER measurements. This will result in measurement results which are not ideal. Therefore, CS-4 is the recommended coding scheme for BLER measurements. You use the command "CALL:(PDTCH|PDTChannel):CSCHeme:UPLink" on page 18 to set the channel coding scheme.

During remote operation of the block error measurement you should configure the trigger arm to single, see "SETup:BLERror:CONTinuous" on page 35.

The BLER measurement only provides results when the test set's operating mode is:

• GPRS BCH+PDTCH test mode, or
• Active Cell, and the Data Connection Type is set to ETSI Type B, ETSI Type B Acknowledged, or BLER. For details on setting the Connection Type see "CALL:FUNCtion:CONNection:TYPE" on page 31. For details on setting the cell operating mode, see "CALL:OPERating:MODE" on page 158.

Changing the test set's operating mode while a block error measurement is running causes the measurement to abort and restart.

Any change to the multislot configuration or the channel coding scheme affects the rate at which bits are tested. Increasing the number of uplink timeslots per frame enables more blocks to be tested per second, whereas decreasing the number of uplink timeslots per frame reduces the number of blocks that can be tested per second. Changing the coding scheme does not affect the rate at which blocks can be tested, but does alter the performance of the link. In order to correctly handle these changes, the BLER measurement aborts and restarts whenever a multislot configuration or channel coding scheme change occurs.

BLER measurements cannot be run concurrently with BER measurements. Starting a BLER measurement while a BER measurement is currently running, closes the BER measurement.

EGPRS

During remote operation of the block error measurement you should configure the trigger arm to single, see "SETup:BLERror:CONTinuous" on page 35.

The BLER measurement only provides results when the test set's operating mode is:

• EGPRS BCH+PDTCH test mode, or
• Active Cell, and the Data Connection Type is set to ETSI Type B (unacknowledged), ETSI Type B Acknowledged, or BLER. For details on setting the Connection Type see "CALL:FUNCtion:CONNection:TYPE" on page 31. For details on setting the cell operating mode, see "CALL:OPERating:MODE" on page 158.

Changing the test set's operating mode while a block error measurement is running causes the measurement to abort and restart.

Any change to the multislot configuration or the modulation coding scheme affects the rate at which bits are tested. Increasing the number of uplink timeslots per frame enables more blocks to be tested per second, whereas decreasing the number of uplink timeslots per frame reduces the number of blocks that can be tested per second. Changing the modulation coding scheme does not affect the rate at which blocks can be tested, but does alter the performance of the link. In order to correctly handle these changes, the BLER measurement aborts and restarts whenever a multislot configuration or channel coding scheme change occurs.

BLER measurements cannot be run concurrently with BER measurements. Starting a BLER measurement while a BER measurement is currently running, closes the BER measurement.

If you encounter problems with respect to call connections dropping when doing EGPRS BLER measurements, you may need to change the Downlink TX power levels or maximum transmit power level. See Problems with BLER Measurements in GPRS/EGPRS for detailed information.