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niWLANG_SetOFDMPacketExtensionThresholds

NI WLAN Generation Toolkit 17.0 Help

Edition Date: May 2017

Part Number: 373725G-01

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int32 __stdcall niWLANG_SetOFDMPacketExtensionThresholds (niWLANGenerationSession session, char channelString[], int32 PPET16[], int32 PPET8[], int32 numberOfSpatialStreams[], int32 RUSize[], int32 PPET16ArraySize, int32 PPET8ArraySize, int32 numberOfSpatialStreamsArraySize, int32 RUArraySize);

Purpose

Configures the packet extension (PE) thresholds that determine the maximum PE duration of the 802.11ax signal. This function configures the thresholds for each resource unit (RU) size and each spatial stream of the 802.11ax DUT. You must configure this table based on the packet extension requirements of the DUT.

The PE field of in 802.11ax signal provides additional processing time to the receiver to decode the last symbol. The possible durations of the PE field are 0 microseconds, 4 microseconds, 8 microseconds, 12 microseconds, or 16 microseconds. The PE duration is determined by both the pre-FEC padding factor of the Data field, and the maximum PE duration requested by the recipient, and the modulation scheme of the current PPDU. The maximum PE durations as defined by the HE Capabilities element are 0 microseconds, 8 microseconds and 16 microseconds, which can be specified using this function.

The maximum PE duration is computed by comparing the constellation index and the threshold values. Packet extension device capability threshold values are defined for all RU sizes greater than or equal to 242 tones. No thresholds are defined for an RU size less than 242 tones. The supported constellations are assigned with a unique index value as shown in following table.

Modulation Scheme Constellation Index Value
BPSK 0
QPSK 1
16-QAM 2
64-QAM 3
256-QAM 4
1024-QAM 5
Reserved 6
None 7

The PE can be defined in two modes.
  1. Max PE mode 8 microseconds: PE duration is 0, 0, 4 and 8 microseconds for pre-FEC padding factor of 1, 2, 3 and 4 respectively
  2. PE mode 16 microseconds: PE duration is 4, 8, 12 and 16 microseconds for pre-FEC padding factor of 1, 2, 3 and 4 respectively

The maximum PE is calculated from the threshold values and the constellation index for the specified MCS index as following.

  • If the constellation is greater than or equal to PPET16, you must apply the value of the maximum PPET16 parameter, or if the constellation is greater than or equal to PPET8, you must apply the value of the maximum PPET8 parameter; otherwise, there is no packet extension.
  • If no PE is required for all constellations, set PPET8 and PPET16 to "" (empty array).
  • If only the max PE 8 microseconds mode is required, set PPET16 to be "" (empty array), and PPET8 to be the constellation at which max PE 8 microseconds mode starts.
  • If only the max PE 16 microseconds mode is required, set PPET16 to be the constellation at which max PE 16 microseconds mode starts, and PPET8 to be "" (empty array).

Parameters

Input
Name Type Description
session niWLANGenerationSession Specifies the niWLAN generation session.
channelString char[] Set this parameter to "" (empty string) or NULL.
PPET16 int32[] Specifies the 16 microsecond mode PE threshold values. The default value is "" (empty array).
PPET8 int32[] Specifies the 8 microsecond mode PE threshold values. The default value is "" (empty array).
numberOfSpatialStreams int32[] Specifies the number of spatial streams for the corresponding RU size. The default value is "" (empty array).
RUSize int32[] Specifies the size of the RU in terms of the number of subcarriers. The default value is "" (empty array).
PPET16ArraySize int32 Specifies the size of PPET16 array.
PPET8ArraySize int32 Specifies the size of PPET8 array.
numberOfSpatialStreamsArraySize int32 Specifies the size of numberOfSpatialStreams array.
RUArraySize int32 Specifies the size of RU size array.

Return Value

Name Type Description
status int32 Returns the status code of this operation. The status code either indicates success or describes an error or warning condition. Examine the status code from each call to the function to determine if an error occurred.

To obtain a text description of the status code, call the niWLANG_GetErrorString function.

The general meaning of the status code is as follows:

Value Meaning
0 Success
Positive Values Warnings
Negative Values Errors

 

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