Packet Error Rate Measurement Troubleshooting

Possible Setup Issues

• You must establish an FTAP (for subtype 0 physical layer) or FETAP (for subtype 2 physical layer) or FMCTAP (for subtype 3 physical layer) connection to perform the Packet Error Rate (PER) measurement (see How Do I Open a Session and Test Data Connection? ).
• DRC Value Fixed Mode Attribute should be set to on and AT Directed Packets must be set to a non-zero value.
• If Limited TAP is on (while Test Application Protocol is set to FTAP), AT Directed Packets must not be greater than 50%, and RTAP Rate must be set to 9.6 kbps
• Before turning AWGN on, verify that cell power is not set to a level significantly below the AWGN level, or the connection may be dropped (see Troubleshooting Setting Power Levels ).
• Confidence level is only available when confidence state is set to on (see PER Measurement Parameters ).

Troubleshooting Techniques

• Check to see if an integrity indicator other than 0 (normal) was returned with a measurement result (see Integrity Indicator ).
• During the PER measurement, if the loopback packets are not returned to the test set, or the AT's input buffer overflows as a result of packets received from the test set, or a duplicate loopback packet is received by the test set, the PER measurement returns the Integrity Indicator "Missing Loopback Packets or AT Overflow".

Other Considerations

• The AT sends one Loop Back Packet containing a record for each FTAP/FETAP/FMCTAP Test Packet in the observation interval. If you have set Maximum Packet Count to 100 (for example), the FTAP/FETAP/FMCTAP Test Packet which relays information about packet number 100 will often contain information about packets numbered greater than 100. The test set displays the results for all of the packets reported by this final FTAP/FETAP/FMCTAP Test Packet. Thus, the Packets Tested will often exceed the Maximum Packet Count.

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• To avoid over range or under range integrity indicators, correct for system path loss (see Amplitude Offset ).
• If you are manually controlling the test set's receiver, be certain that you have entered the correct frequency and power values for your test setup (see Receiver Control ).
• PER Input Signal Requirements

Related Topics

Packet Error Rate (PER) Measurement Description