About DL Decode Info (NB-IoT)

DL Decode Info contains the decoded information from NPBCH and NPDSCH.

The upper section shows the status of each decoder.

The lower part of the table shows the decoded information for each physical channel.

The data is color coded to match the color of the corresponding channel in the Frame Summary trace. For example, text that is colored green in the screen capture below represents information about NPBCH. Text that is colored red represents information about NPDSCH.

NPBCH information

NPBCH decoded information is required for subframe 0 of every frame.

A "CRC Cyclic Redundancy Check Invalid" message is shown when NPBCH CRC fails. Otherwise the decoded NPBCH contents are shown.

The following is a list of all the information contained in the NPBCH section of the DL Decode Info trace. NPBCH contains the higher layer BCH Broadcast Channel (broadcast channel) message MasterInformationBlock-NB as specified in the 3GPP 36.331 standards document.

FrameNum - system frame number for each frame in the Measurement Interval.
NumTxAnt - number of NRS antenna ports.
HyperSFN-LSB - indicates the 2 least significant bits of hyper SFN System Frame Number.
ab-Enabled - displays whether access barring is enabled.
SchedulingInfoSIB1 - contains an index to Table 16.4.1.3-3 of TS Technical Specification 36.213 defining SystemInformationBlockType1-NB scheduling information.
NPDSCH-NumReps - number of slots allocated to NPDSCH in the frame. NPDSCH-NumReps is computed from schedulingInfoSIB1 as specified in the standard.
OpMode - indicates the current Operation Mode.
EutraNumCrsPorts - number of C-RS ports.
ChannelRasterOffset - NB-IoT offset from the LTE channel raster.

NPDSCH information

The NBIoT demodulator currently supports decoding a single NPDSCH transport block. The allocated slots must fit within the first two frames, and RB Auto Detect must be enabled.

The information from the decoded transport block is shown below the decoder on/off information.

A "CRC Invalid" message is shown when NPDSCH CRC fails. Otherwise the decoded NPDSCH contents are shown.

The following is a list of all the information contained in the NPDSCH section of the DL Decode Info trace.

TBS - Transport Block Size. TBS is expressed in decimal format.
CRC - Cyclic Redundancy Check Pass/Fail for the NPDSCH