About UL Decode Info (LTE)

UL Decode Info contains the decoded information from PUCCH Physical Uplink Control Channel and PUSCH Physical Uplink Shared Channel.

The upper section shows the status of the PUCCH and PUSCH decoders (On or Off). The lower part of the table shows the decoded information for each frame.

The data is color coded to match the color of the corresponding channel in the Frame Summary trace. For example, any text that is colored yellow represents information from PUCCH.

Uplink Decoded Information

The decoded information for each frame is denoted by the text Frame Num 0xNNN where NNN is the frame number in hexadecimal format.

Common information

The following fields in the UL Decode Info table are common to both PUCCH and PUSCH.

Sfn - the value n indicates the subframe number for the decoded channel information
RNTI - Radio Network Temporary Identifier. Identifies the UE User Equipment (e.g. cell phone) transmitting in this allocation.

This parameter is specified for each uplink user using the RNTI field in the LTE Long Term Evolution Allocation editor.
Nprb - Number of physical resource blocks assigned to this allocation. This parameter is always equal to 1 for PUCCH.
Chan - uplink channel type specified as PUSCH or PUCCH (format) where format is the PUCCH format and is one of the following: 1, 1a, 1b, 2, 2a, 2b.

PUCCH information

Size metrics indicate number of most-significant bits

PUCCH decoding results shown per subframe include:

HARQ Size - HARQ Hybrid Automatic Repeat Request Ack/Nack Information Size in bits

HARQ Info - HARQ Ack/Nack Information Word value (hex representation)

Due to joint CQI Channel Quality Indicator / PMI Precoding Matrix Indicator and HARQ-ACK Acknowledgement encoding in Extended CP mode, any associated HARQ-ACK Info bits will also be marked as questionable when CQI / PMI Info Size is set to Auto. To avoid this, manually specify the CQI / PMI Info Size parameter.

When HARQ-ACK Info Size set to Auto, the LTE demodulator will decode the maximum number of HARQ-ACK bits (2 bits) since it is not possible to determine the actual number of HARQ-ACK bits. This allows the user to view all potential HARQ-ACK bits and validate them against the expected bits. Also, since the actual number of HARQ-ACK bits is unknown, a question mark (?) is appended to the HARQ Info field.

The following table shows the possible formats that PUCCH can be autodetected as when PUCCH autodetection is enabled:

Possible PUCCH Formats
HARQ-ACK Info Size	Normal CP 1) Contention period, or 2) Cyclic prefix	Extended CP
2	1b, 2b	1b, 2
1	1a, 2a	1a, 2
0	1, 2	1, 2

CQI / PMI Size - Channel Quality & Precoding Matrix Indicator Information Size in bits
CQI / PMI Info - Channel Quality & Precoding Matrix Indicator Information bits (hex representation). The CQI / PMI Info field contains space for eight 32-bit words of data for alignment purposes. The CQI / PMI bits are placed in the most-significant section of the bit field.

When CQI / PMI Info Size is set to Auto, the LTE demodulator will decode the maximum number of CQI/PMI bits (11 bits) since it is not possible to determine the actual number of CQI/PMI bits. This allows the user to view all potential CQI/PMI bits and validate them against the expected bits. Also, since the actual number of CQI/PMI bits is unknown, a question mark (?) is appended to the CQI / PMI Info field. You can manually specify the CQI / PMI Info Size parameter to validate any bits marked as questionable.

Due to joint CQI / PMI and HARQ-ACK encoding in Extended CP mode, any associated HARQ-ACK Info bits will also be marked as questionable when CQI / PMI Info Size is set to Auto. To avoid this, manually specify the CQI / PMI Info Size parameter.

When CQI / PMI Info Size is manually specified and decoding the CQI / PMI bits results in a CRC Cyclic Redundancy Check failure or detected bit errors, the VSA will append the letter F to the bits to indicate decode failure. In this case, the user should confirm the manually specified CQI / PMI Info Size matches the test signal.
SR Size - Scheduling Request Information Size in bits
- 0 = SR 1) Spread rate: also know as the chip rate and is the rate of the digital code used to spread the information. The spreading rate is typically at least 100x the information rate. or, 2) Sample Rate: rate at which samples are taken from an input signal or, 3) Scheduling Request not present
- 1 = SR present
SR Info - Scheduling Request Information Word value (hex representation)
- 0 = expected SR BPSK Binary phase shift keying - A type of phase modulation using 2 distinct carrier phases to signal ones and zeros. sym d(0) fixed encoding
- 1 = unexpected SR BPSK sym d(0) fixed encoding
nPUCCH(1) - Resource index for PUCCH formats 1/1a/1b (decimal representation)
nPUCCH(2) - Resource index for PUCCH formats 2/2a/2b (decimal representation)

Decoded PUCCH HARQ-ACK, CQI / PMI, and SR information bits are aligned in the most-significant bits within the respective Info hexadecimal value.

PUSCH information

Size metrics indicate number of most-significant bits

This trace shows the following PUSCH channel decoded message content for each subframe:

HARQ-ACK Size - HARQ Ack/Nack Information Size in bits
HARQ-ACK Info - HARQ Ack/Nack Information Word value (hex representation)
CQI / PMI Size - Channel Quality & Precoding Matrix Indicator Information Size in bits. The CQI / PMI Info field contains space for eight 32-bit words of data for alignment purposes. The CQI / PMI bits are placed in the most-significant section of the bit field.
CQI / PMI Info - Channel Quality & Precoding Matrix Indicator Information Word value (hex representation)
RI Size - Rank Indicator Information Size
RI Info - Rank Indicator Information Word value (hex representation)
Imcs(n) - Modulation and Coding for transport block n

For UL Up Link (reverse link: from cell phone to base station) PUSCH 16QAM transmissions, which are encoded with I_{MCS modulation and coding scheme} = 20, the VSA reports I_MCS = 21 as the value resulting in a successful PUSCH decode (CRC Pass). This is because TS Technical Specification 36.213, Section 8.6.1, Table 8.6.1-1 defines the same transport block size (I_TBS = 19) for both I_MCS = 20 and 21 for 16QAM PUSCH transmissions and the VSA has been configured to show the highest possible I_MCS when there is ambiguity.
RV(n) - Redundancy Version for transport block n
TBS(n) - Transport Block Size for transport block n. TBS(n) is expressed in decimal format.
CRC(n) - Cyclic Redundancy Check Pass/Fail for PUSCH transport block n, where n = 1 only for 3GPP Rel 8

The CRC Pass/Fail data result is reported when PUSCH Bits is set to a value other than Mapped.

When PUSCH HARQ-ACK, RI Rank Indicator, or CQI / PMI Info Size is specified manually, if decoding results in either a CRC failure or there are detected bit errors for the corresponding information bits, the demodulator will append the letter F after the decoded bits for the appropriate Info field in UL Decode Info table, indicating decode failure. In this case, the user should confirm that the Info Size and Offset Index parameters match the expected signal content.

When the Auto checkbox is enabled for the HARQ-ACK, RI, or CQI / PMI Info Size parameters within Decode tab, the demodulator will attempt to auto detect the appropriate multiplexed control region information size as far as possible.

For certain test signal configurations there may not be an adequate number of mapped control information resource elements for reliable auto detection. In this situation, autodetected HARQ-ACK, RI, or CQI / PMI Info Size is questionable, and a question mark (?) will be appended to the bits for the corresponding Info field in the UL Decode Info table, indicating that the decoded bits are questionable.

Any bits are marked as questionable should then be validated against expected test signal content. Note that you can manually specify HARQ-ACK, RI, or CQI / PMI Info Size parameters to validate any questionable size results.

Decoded PUCCH HARQ-ACK, CQI / PMI, and RI information bits are aligned in the most-significant bits within the respective Info hexadecimal value.

Querying summary table data results programmatically

To programmatically query the Trace Summary Table data results using the Summary() and SummaryUnit() methods in the MeasurementData object.

See the How To Query Summary Table Data Results topic for more information.

Syntax: app.Display.Traces.SelectedItem.DataName = "Demod UL Decode Info1";

The indexes of the UL Decode Info data values change depending on which channels are enabled in the Profile tab of the LTE Demod Properties dialog box. Instead of using hardcoded indexes to retrieve the data values, you can use a data result name to query the data value.

Below is a table with the list of possible data result names.

UL Decode Info data results
Data Result Name	Description
PUCCH Decoder PUSCH Decoder	Decoder status for channel: On or Off
SFN System Frame Number_Fx_IE	Header for decoded information from frame x
PUSCH_Fx_SF 1) Spreading Factor, or 2) service flow: A unidirectional flow of medium access control (MAC) service data units (SDUs) on a connection that is provided a particular Quailty of Service (QoS).nIE#t	Decoded PUSCH information for frame x, subframe n, and transport block t
PUCCH_Fx_SFnIE#t	Decoded PUCCH information for frame x, subframe n, and transport block t

In the data result names above, x = 0 indicates the first frame found in the Measurement Interval.