NPDSCH Bits (NB-IoT)

Default: Mapped

Range: Mapped, Descrambled, DeRateMatched, Decoded CB, Decoded TB

NPDSCH Bits determines the level of decoding for NPDSCH bits shown in the Decoded Symbol Table.

Mapped - no decoding is performed on NPDSCH bits. Mapped bits are shown in the Symbol Table.
Descrambled - descrambled (rate-matched) bits for each subframe are shown in the Decoded Symbol Table.
DeRateMatched - S (16 + LEN_i) bits per subframe.

Each set of bits for an NPDSCH transmission consists of a 16-bit length field (LEN_i) followed by the deratematched (channel coded) bits for each codeblock.

LEN_i indicates the number of deratematched bits for the i^th codeblock in a subframe and can be used to determine where one set of deratematched codeblock bits ends and the next set begins in the Decoded Symbol Table.

LEN = 3 * (Codeblock Length + CRC Cyclic Redundancy Check Length) because NPDCH use tail biting convolutional coding.
Decoded CB - S (16 + LEN_i) bits per subframe.

Each set of bits for a NPDSCH codeblock consists of a 16-bit length field (LEN_i), the decoded codeblock bits, and a 24-bit CRC. When codeblock segmentation is not performed (Transport Block Size is less than 6144), the codeblock + CRC bits shown are the same as the transport block + CRC bits .

LEN_i indicates the number of decoded bits (including CRC) for the i^th codeblock in a subframe and can be used to determine where a set of codeblock bits ends and the next set begins in the Decoded Symbol Table.

LEN_i = Codeblock Length + CRC Length.
Decoded TB - (Transport Block Size + 24) decoded transport block bits (including CRCs) per subframe.

Each set of bits consists of the decoded transport block bits followed by a 24-bit CRC.

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.