LDPC IP Core User Guide

ID 683381
Date 4/04/2022
Public

4.2. LDPC IP Core Parameters

Table 12.  General Parameters
Parameter Value Description
Standard

DVB-S2

NASA GSFC-STD-9100

WiMedia 1.5

DOCSIS 3.1

WiFi 802.11n

Type of LDPC code.
LDPC module Encoder or decoder

NASA GSFC-STD-9100, WiMedia 1.5, DOCSIS 3.1, and Wifi 802.11n only.

Codeword length

Encoder DVB-S2: 16200, 64800

Decoder:

  • WiMedia 1.5: 1200, 1320
  • NASA: 8160, 8176
Number of bits per codeword.
Coding rate

DVB:S2: 1/4 1/3 2/5 1/2 3/5 2/3 3/4 4/5 5/6 8/9

DOCSIS 3.1: 75% 85% 89%

NASA GSFC-STD-9100: 7/8

WiMedia 1.5: 0.5, 0.625, 0.75, 0.8

-
Number of bits per input symbol 1 to 30 Encoder only.
Number of LLRs per input symbol 2 to 40 (NASA, DOCSIS, and WiMedia) The number of LLRs you feed in parallel to the decoder
Number of softbits per input LLR 2 to 16 Decoder only. The width of the input LLR. Assume that the number of bits per output symbol is equal the number of LLR per input symbol
Table 13.  Decoder Options
Parameter Value Description
Number of decoding iterations 1 to 100 The maximum number of decoding iterations. A decoding iteration corresponds to the decoding of all the rows of the parity-check matrix. The decoder stops decoding once it finds a valid codeword.
Parallelism 1 to 100 The number of rows processed in parallel during the decoding.
Width of the decoder variables 4 or 16 The width of the input LLR. The decoder can represent the LLR it processes by a much larger number of softbits than the input LLRs.
MSA attenuation factor 1, 0.875, 0.75, 0.625, 0.5, 0.375, 0.25 The design applies a constant attenuation factor to the output of the min-sum algorithm (MSA) processing to ease convergence. This factor is a sum of inverse of power of 2.
Full-streaming architecture No or yes With full streaming architecture, the decoder can accept data while decoding if the level of parallelization is sufficient. NASA only.
Layered decoding No or yes NASA GSFC-STD-9100 decoder only
Output parity check bits No or yes Decoder provides output parity check bits or information bits only.

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