Logical Link Control (LLC) Layer Configurable Parameters

BLER Frame Check Sequence

The BLER Frame Check Sequence parameter allows you to force the Logical Link Control (LLC) Frame Check Sequence (FCS) to be corrupted when establishing a BLER mode data connection. When the parameter is set to CORRupt, the test set transmits an invalid FCS to the mobile station. This setting may enable some mobiles to establish a BLER mode data connection which would not otherwise be possible with a valid FCS.

Setting this parameter to VALid ensures that the cyclic redundancy check code within the FCS is valid.

This parameter is only applicable when the data connection type is set to BLER using CALL:FUNCtion:CONNection:TYPE BLER.

If you change this parameter while the data connection type is any type other than BLER, the setting has no effect until a new BLER mode data connection is established.

This command along with CALL:FUNCtion:DATA:BLER:POLLing:INTerval and CALL:FUNCtion:DATA:FRAMe:STARt provide you with additional control over BLER data connection type settings. This may enable the test set to establish a BLER mode data connection with mobile stations which cannot connect under normal conditions.

Payload Patterns

There are two parameters that allow you to specify the type of downlink payload pattern to be sent to the mobile station.

• Payload Pattern (BLER)

  The Payload Pattern (BLER) setting allows you to specify the type of downlink payload pattern to be sent to the mobile station when the connection type is set to BLER (see CALL:FUNCtion:CONNection:TYPE ), the operating mode is set to Active Cell, with the Serving Cell set to GPRS or EGPRS, and the Logical Link Control (LLC) Frame Check Sequence (FCS) parameter is set to CORRupt (see CALL:FUNCtion:DATA:BLER:LLC:FCSequence ). See Payload Pattern Data Options for a list of your choices for Payload Pattern data.

     

  NOTE

  If the Payload Pattern (BLER) is set to any value other than GMMinfo , and you want to change the setting of the LLC Frame Check Sequence parameter from CORRupt to VALid, it is strongly recommended that you end the data connection before making this change. After the LLC Frame Check Sequence parameter has been set to VALid, the data connection can be restarted using CALL:FUNCtion:DATA:START .

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• Payload Pattern (OTHER)

  The Payload Pattern (OTHER) setting allows you to specify the type of downlink payload pattern to be sent to the mobile station when the operating mode is set to GPRS BCH+PDTCH of EGPRS BCH+PDTCH, or when the operating mode is set to Active Cell (Serving Cell GPRS or EGPRS) and the connection type is ETSI Type B or SRB loopback. See Payload Pattern Data Options for a list of your choices for Payload Pattern data.

• Multi Source Payload Pattern (OTHER)

  Multi Source Payload Pattern (OTHER) setting allows you to specify the type of each of downlink burst payload pattern to be sent to the mobile station when the operating mode is set to EGPRS BCH+PDTCH and the EGPRS Test Mode Payload Mapping is set to Multi Source, ClearCoded.See Payload Pattern Data Options for a list of your choices for Payload Pattern data.

Payload Pattern Data Options

• GMMinfo

  This option is only applicable to Payload Pattern (BLER) . The payload pattern is set to send GMM Information messages. When using Payload Pattern (BLER) , if the BLER FCS ( CALL:FUNCtion:DATA:BLER:LLC:FCSequence ) is set to VALid, this type of payload pattern is always sent regardless of the setting of this command.

• ZEROs

  The payload pattern is set to all zeros.

• ONES

  The payload pattern is set to all ones.

• ABIT

  The payload pattern is set to alternate bits.

• APAIRs

  The payload pattern is set to Alternate Pairs.

• AQUads

  The payload pattern is set to Alternate Quads.

• PRBS15

  The payload pattern is set to pseudo-random binary sequence 15 data.

• PRBS9

  The payload pattern is set to pseudo-random binary sequence 9 data.

• FIXED2B

  The payload pattern is set to Fixed 2B Hexadecimal data.

• CUSTOM

  You may set the values for the custom payload pattern that is repeated in each Radio Link Control (RLC) data block or use the default pseudo random bit sequence (PRBS) custom data pattern. The size of the custom payload pattern can be 1 to 174 octets, since the maximum size of the RLC data block that is transmitted using 8PSK clearcoded (no coding scheme is used in transmission) is 174 octets. The custom payload pattern is applied across the GSM, GPRS, and EGPRS formats. That is, the same custom payload pattern is used for the custom GSM downlink Speech , Payload Pattern (BLER) , Payload Pattern (OTHER) and GPRS/EGPRS downlink Multi Source Payload Pattern (OTHER) .

  If you specify a custom payload pattern that is longer than the length of the RLC data block, the portion of custom payload pattern is truncated to the length of the RLC data block and the end data is disregarded. If the custom payload pattern is shorter than the length of the RLC data block, the custom payload pattern is repeated as many times as necessary to fill the RLC data block.

  There is no access through the front panel to configure the custom payload pattern. The GPIB command to configure the Custom pattern is CALL:(PDTCH|PDTChannel):CUSTom:DATA .

  The query for this commands returns only the defined custom payload pattern rather than the repeated or truncated pattern used to fit to the size of the data frame.

  PRBS9 is available when the operating mode is set to any operating mode except for GSM BCH, GPRS BCH, EGPRS BCH, Cell Off and CW.

Related Topics

Protocol Control

CALL:(PDTCH|PDTChannel):CUSTom:DATA