Troubleshooting Data Connection Processing

Possible Setup Issues

• It is recommended not to execute a preset/reset (full or partial) when a session is open with an AT. This is because executing a preset/reset (full or partial) will take the test set to Idle state without signaling to the AT and may cause the test set and AT in a mismatched state. In this case, some ATs can not open a new session with the test set.
• If you are trying to establish a session or connection:
  • Cell band and channel must be set to the proper values for your access terminal (see How Do I Change Call Parameters? ).
  • Verify that your AT supports protocol release A prior to changing the Protocol Rel set to release A (1xEV-DO-A) . Otherwise, negotiating a session will fail.
  • The PL Subtype 2 Access Channel MAC Subtype defaults to the Enhanced setting. Negotiating a session when the Protocol Rel set to release A (1xEV-DO-A) and the Release A Physical Layer Subtype set to Subtype 2 will fail if the AT does not support Enhanced Access Channel MAC protocol. When using an AT that does not support Enhanced Access Channel MAC Protocol, the PL Subtype 2 Access Channel MAC Subtype should be changed from Enhanced to Default.
  • Call Limit Mode must be set to off.
  • Cell Power must be set to an adequate level and AWGN Power must be set to an adequately low level to allow for successful data connection processing.
  • The input signal from the access terminal must meet the Input Signal Requirements .
  • If you are manually controlling the receiver, you must have the expected power and frequency set to the proper values (see Receiver Control ).
• Ensure that the Preferred Control Channel Cycle is set to the correct setting for your test conditions.
• Ensure that Reverse Closed Loop Power Control mode is set to the correct setting for your test conditions.
• Ensure that Test Application Protocol is set to the correct value for your test conditions.
     

  IMPORTANT

  In order for the test set to successfully decode signalling from the AT, the signal level into the test set's RF IN/OUT connector must be within 9 dB of the expected input power (see Expected Power ). When Reverse Closed Loop Power Control is set to All Up Bits or All Down Bits, the AT's power will not be within the required range, and all signalling will fail. Before attempting any signalling between the test set and AT, you must either set Reverse Closed Loop Power to Active Bits, or manually range the Receiver Power to the level that the AT is currently transmitting based on the Reverse Closed Loop Power Control setting (see Manual receiver power ).

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• lab application only :
  • If you are trying to establish a packet data connection, ensure that the Session Application Type is set to the Default Packet Application.
  • The packet data connection can not be started from the test set. Starting a data connection by sending a CALL:FUNCtion:DATA:STARt command will result in an error due to without having a PPP connection established.
  • If you are trying to end a packet data connection from the test set, use CALL:FUNCtion:DATA:DORMant command instead of the CALL:FUNCtion:DATA:STOP. This results in data connection status going to Dormant state which indicates that the physical connection (air-link) is closed but PPP connection is maintained. See Dormant State .

Other Considerations

• While on a connection, if you change a parameter that is configured during the Session Negotiate State , the connection is closed. You must re-open the connection. This behavior is specified by C.S0024.
• You can not change a parameter which is configured during the Session Negotiate State when a session is open and Call Limit Mode is set to on.
• Close Session Before Testing New AT

  When you have finished testing your AT, before disconnecting it from the test set and connecting a new AT to test, you should close the current session (see Session Closing State ). If you do not close the session before disconnecting the old AT and connecting a new AT, when the new AT sends a UATI Request message to initiate a session, the following error will be returned by the test set +271 Closing current session due to new RATI-addressed packet received , and there will be a short delay before a session is established with the new AT. The fastest way to establish a session with the new AT is to close the session with the old AT before disconnecting it from the test set.
  
  DO NOT close an session when the data connection is open by the command CALL:FUNCtion:DATA:STOP (close data connection) and then followed by CALL:SCLose (close the session). Sometimes it may cause problems. Some AT is instantly sleeping after the data connection is closed so that AT can not guarantee to listen the close session (CALL:SCLose) command. This leaves the AT and the test set in different states and can cause bad problems. It's recommended to directly send CALL:SCLose to close the session when the data connection is open. This will close the data connection and the session at one time.

• You can close the session at any time. However, most ATs will try to immediately re-establish a session. To prevent the AT from re-establishing a session, the recommended procedure is as follows:

  • Establish a data connection.
  • Set Call Limit Mode to On .
  • Execute Session Close .
  • Set Cell Power to Off . (Turning the cell power to off can prevent the AT from sending the UATIRequest message. If the AT can detect the pilot signal from the test set, it will keep sending the UATIRequest messages to try to get a response from the test set. This may result in negative consequences in most ATs.)

  To re-establish a session, the following steps should be taken:

  • Set Call Limit Mode to Off .
  • Set Cell Power to On .

• Set Pilot Drop to proper value to avoid dropped connections

  The A.01.37 Release - August 2003 and above firmware for the E1966A allow you to set the pilot drop parameter to any value between 0 and 63. The pilot drop parameter should be set to 18 (-9 dB) for most operations and test scenarios (some C.S0033 tests specify that pilot drop be set to -14 dB, such as 3.2.1 Demodulation of Forward Traffic Channel in AWGN ).
  The A.01.34 Release - July 2003 firmware for the E1966A incorrectly sends a fixed pilot drop value of 60 (-30 dB) instead of the intended 28 (-14 dB). This low pilot drop value can cause dropped connections when moving from high to low cell power levels, during a handoff, or when operating with a high level of AWGN.

• When testing an access terminal that requires setting Limited TAP to on:
  • The access terminal may not implement the parameter settings sent in the Traffic Channel Assignment message (see TAP/ETAP Data Connection Call Flow ). In this case, to change a parameter that is sent in the Traffic Channel Assignment message, you must close the connection, change the parameter, and then re-open the connection (this includes a handoff to a new band and/or channel).
• The test set defaults the Short Packet Enabled Threshold to 4096 bits. This allows for all non-canonical (short packet) formats. It is not expected to be changed unless some ATs failed to open a session with this value. The default value set in the test set is not the protocol default value (2048 bits) as defined in the C.S0024-A. This opens the possibility of session failure for some ATs that only support the protocol default value. In this case, you may need to change the Short Packet Enabled Threshold to the value supported by your AT. See Short Packet Enabled Threshold for details.

Related Topics

TAP/ETAP Data Connection Processing States Lifecycle

TAP/ETAP Data Connection Call Flow

Packet Data Connection Processing States Lifecycle ( Lab Application Only )

Packet Data Connection Call Flow ( Lab Application Only )

Fixed Settings

Troubleshooting Setting Power Levels