Uplink Fast Feedback Region

In this example, you will set up an uplink signal with a fast feedback (FFB) region in a UL-PUSC zone and use the 89601A to make measurements on that uplink. This exercise continues where Uplink Ranging ended and assumes that you already have the waveform parameters and bursts set up from the Uplink Ranging exercise.

  1. In Signal Studio, click on Fast Feedback in the navigation tree and make the following changes:

    1. Fast Feedback State to on

    2. Number of Symbols at 3

    3. Symbol Offset to 6

    4. Number of Subchannels to 6

    5. Subchannel Offset to 9  

  2. Click Zone#1, PUSC, verify that the number of symbols in the zone is still 9, and change it if needed. The auto allocation may have modified this setting. See the placement of the FFB region in the zone. Note the user bursts wrap around the FFB region also.

  3. Click Fast Feedback in the navigation tree again. Click on "+” and note the different types of messages you can add.

    In the version 1.9.0.0 or earlier of N7615A/B, ACK messages were included in the fast feedback zone. Now there is a separate ACK region for those messages.

  4. Add several messages of different types, and choose slot locations so they won’t overlap. The number of subchannels required for each message and the payload values will depend on the number of bits in each message type. For example, a 4-bit fast feedback message can have payload values from 0 to 15, while a 6-bit enhanced feedback message can have a payload value from 0 to 63.

  5. Click the button on the tool bar to verify that there are no problems with the setup.  

  6. Generate and download the waveform.

  7. In the 89601A, go to MeasSetup > Demod Properties and select the Zone Definition tab. The VSA does not support or analyze FFB regions. However, you can configure a FFB region, and that will cause the user data bursts to wrap around the region correctly, enabling you to analyze user data bursts in the presence of a FFB region.

  8. Add another burst to represent the FFB region. Click the New Burst button and select Burst Type of FFB, and set up the appropriate subchannel and symbol offset and duration parameters. Note that the second user burst automatically wraps around this new burst. Click OK to finish the setup and view the measurement.