TDSO Frame Error Rate Measurement Description

Last updated: October 28, 2004

What is a TDSO (Test Data Service Option) FER (Frame Error Rate) measurement?

TDSO FER measurements are used to test the performance of a mobile station receiver while a supplemental (high speed data) channel is connected and TDSO (Service Option 32) is selected ( Service Option ).

This measurement provides a report from the mobile station indicating the status of traffic frames received during high speed data transfer on the F-SCH (forward supplemental channel). There are two choices available for TDSO FER testing:

SO 32 (+ F-SCH)
When this service option is selected, the supplemental channel is transmitted in the forward direction only.
SO 32 (+ SCH)
When this service option is selected, the supplemental channel is transmitted in both the forward and reverse channels.

Since the measurement values displayed are obtained from the mobile station, there are no multi-measurement results available, such as measurement averaging.

How is a TDSO FER Measurement Made?

The test set automatically attempts a TDSO FER measurement when the measurement is selected and a call is connected using Service Options SO32 (+F-SCH) or SO32 (+ SCH). See CALL:SOPTion .

See CALL:SOPTion . To establish a call with Service Option 32 you must select Radio Config (Fwd3, Rvs3) or Radio Config (Fwd4, Rvs3). A mobile station originated call can be made or you can press the Originate Call (F3) key. A TDSO FER display is shown below in TDSO FER Display with 512 frames selected.

TDSO FER Display

The time period required for TDSO FER measurements depends on the timing of the call connection.

All traffic channels and the F-SCH are subdivided into segments of 10.24 seconds each. TDSO FER testing begins when the first frame (called a sync frame) in the first full segment is received by the mobile station. For example, TDSO FER With Frame Count Set to 512 Frames shows two full F-SCH segments. In this example, the SO 32 call is connected half way through the first segment. Approximately 5.12 s later the mobile station receives the first sync frame from the test set and is able to compute the PRBS data pattern the test set is about to send.

The time period between the successful negotiation of an SO32 connection and the start of the FER Count Period is based on the current long code state, and will range from 0 seconds to 10.24 seconds.

The mobile station also resets its frame counters upon receiving the first sync frame.

TDSO FER With Frame Count Set to 512 Frames

During the second sync frame interval, the mobile station keeps a running count of:

Good Frames Received
Bad Frames Received
Blank Frames Received
Bad Frames Instead of Blank Frames Received
Total Bad Frames Received

Also during the second frame interval, the test set keeps a running count of:

Good Frames Transmitted
Blank Frames Transmitted

At the end of the second frame interval, the test set retrieves frame count data from the mobile station and calculates percent FER based on the following formula:

Operating Considerations

A call must be setup using SO32 (+F-SCH) or SO32 (+ SCH) and that call must be currently connected to make TDSO FER measurements.

The measurement setup menu allows for specifying the FER confidence requirement. The FER confidence requirement establishes a target FER rate. To meet standard minimum specifications, a specified FER percentage must be attained with a confidence level of 95%. The TDSO FER measurement returns the confidence level based on the actual average FER result obtained over the fixed frame count length. If the confidence level is less than 95% for the specified FER confidence requirement, the test has not passed minimum standards.

The supplemental channel information menu provides channel setup parameters including the supplemental channel data rate, encoder type, and power level. Standards specify data rates and Eb/Nt. Eb/Nt can be set by adjusting F-SCH and AWGN level.

If trigger arm is set to Single, the first TDSO FER measurement will be displayed and then the test set will wait until it is triggered by a GPIB command or the START SINGLE key before the next sync frame is staged.

If "No F-SCH" is displayed in the bottom right portion of the display, the supplemental channel is not connected. If "No Sync" is displayed, the sync channel has not been sent to the mobile station yet.

Interim results are displayed when the frame count is greater than 512 and the test set is able to retrieve mobile station counter values after intermediate sync frames.

Integrity indicators (see Integrity Indicator ) do not apply to this measurement.

Key TIA/EIA-98-E Tests Using TDSO FER

Testing 3.4.1 Demodulation of Forward Traffic Channel in AWGN