How do I test MCS Switching?

How do I test MCS Switching?

Last updated: December 2, 2008

This section is only applicable to the EGPRS lab application.

Observing MCS Switching

It is necessary for you to use the protocol logging capability of the test set to observe the MCS changes. One way to observe this is to use your mobile station as a modem and transfer a file over the air. Transferring something large allows you to more easily observe changes. See Modem Functional Test with the Data Channel or FTP Throughput Test with the Data Channel for more details. For help setting up the Wireless Protocol Advisor for protocol logging see Protocol Logging .

Setup and Activate MCS Switching

This procedure assumes that the BCH parameter for Cell Band is set up correctly for your mobile station and that the appropriate RF IN/OUT Amplitude Offsets have been set to offset loss between the mobile station and the test set. Additionally, this procedure also assumes that the WPA is running and has already established a connection with the test set.

  1. Press the CALL SETUP key.
  2. Press Operating Mode ( F1 ) and select Active Cell (EGPRS) .
  3. Select PDTCH Parameters ( F9 ) from the Call Parms menu.
  4. Select Modulation Coding Scheme ( F11 ) from the PDTCH Parms menu. The Modulation Coding Scheme popup menu appears.
  5. Highlight Downlink Modulation Coding Scheme and verify that the value is set to As Uplink .
  6. Scroll to Uplink Modulation Coding Scheme and select to change to the value you desire. For example, if you choose MCS-9 and add downlink corruption, the MCS switches to MCS-6 as retransmissions are requested.
  7. Press Close Menu ( F6 ).
  8. Press the More softkey on the left side of the front panel display to access the Control ( 2 of 3 ) menu.
  9. Select Protocol Control ( F4 ).
  10. Select RLC/MAC ( F2 ).
  11. Press the More softkey on the left side of the front panel display to access the RLC/MAC Ctrl ( 2 of 2 ) menu.
  12. Select Retransmission MCS Switching ( F1 ). The Retransmission MCS Switching popup menu appears.
  13. Select Allow MCS Switching and select On .
  14. Select Retransmissions before MCS switch and enter 2 . This forces the test set to switch the MCS when a block the mobile station requests retransmission of the same block twice.

       
    NOTE
    Another way to observe MCS Switching is corrupt some of the downlink blocks. See How to Setup Corruption of Downlink Blocks .
       

  15. If you want to enable link adaptation to MCS below MCS5, select Downlink Resegmentation from this menu and select On .
  16. Select Close Menu ( F6 ).
  17. Start protocol logging.
  18. Start transferring data.
  19. Stop protocol logging when the data transfer is complete. See Tips for analyzing protocol logs of Incremental Redundancy and Retransmission MCS Switching for help with analyzing the log.

How to Setup Corruption of Downlink Blocks

To force the mobile station to request retransmission of blocks and therefore force the test set to switch to a more robust MCS, you can set up the deliberate corruption of downlink blocks.

  1. Press the CALL SETUP key.
  2. Press the More softkey on the left side of the front panel display to access the Control ( 2 of 3 ) menu.
  3. Select Protocol Control ( F4 ).
  4. Select Layer 1 ( F1 ).
  5. Select PDTCH Downlink Corruption ( F1 ). The Downlink Corruption popup menu appears.
  6. Select Downlink Corruption and select On . Parameters for configuring the downlink corruption appear. See Downlink Corruption for more information.

How to View the Downlink Corruption Blocks in the Wireless Protocol Advisor (WPA)

This procedure assumes that the BCH parameter for Cell Band is set up correctly for your mobile station and that the appropriate RF IN/OUT Amplitude Offsets have been set to offset loss between the mobile station and the test set.

  1. Setup the Downlink Corruption parameters on the test set. See How to Setup Corruption of Downlink Blocks for more details.
  2. Configure the WPA test set filter to filter the Layer 1 Information protocol.
  3. Start the WPA. See How to use Protocol Logging for more details.
  4. Press Start Data Connection (F3).
  5. Stop the WPA. See How to use Protocol Logging for more details.
  6. View the message decode for Downlink Frame Integrity messages (for Layer 1 Protocol). The figure below is an example of a Downlink Frame Integrity message.

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Related Topics

Tips for analyzing protocol logs of Incremental Redundancy and Retransmission MCS Switching

Retransmission MCS Switching