Occupied Bandwidth (OBW) Measurement Description

Occupied Bandwidth (OBW) Measurement Description

Last updated: January 16, 2009

How is the occupied bandwidth measurement made?

As defined by 3GPP TS 34.121 section 5.8 Occupied Bandwidth (OBW) is the bandwidth containing 99% of the total integrated power of the transmitted spectrum, centered on the assigned channel frequency. The test set allows the percentage of total integrated power to be adjusted from 70.0 to 99.0%.

During this measurement, a Gaussian filter with a bandwidth greater than 10MHz and a resolution bandwidth (RBW) of 30 kHz or less is used to measure the distribution of the power spectrum.

First, the total power found in the measured frequency range is calculated. Then, starting at the lowest frequency in the range and moving upward, the power distributed in each frequency is summed until this sum is 0.5% of the total power. This gives the lower frequency value. Next, starting at the highest frequency in the range and moving downward, the power distributed in each frequency is summed until 0.5% of the total power is reached. This gives the upper frequency value. The bandwidth between the 0.5% power frequency points is the occupied bandwidth.

Input Signal Requirements

Trigger Source

The trigger source defaults to Auto and tries to use protocol triggering if the UE is synchronized to the test set. Immediate triggering is used if the UE is not synchronized.

If you want to measure the occupied bandwidth for a specific timeslot, use the trigger delay parameter.

Measurement Calibration

This measurement should be calibrated using the Calibrate Measurements function (see CALibration:MEASurements? ) when the temperature has changed by ± 10° C or more since the last calibration. If this situation exists, the integrity indicator value is changed to 19 and a message is displayed indicating "Uncalibrated Due to Temperature".

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