Ubiso - IP: FEC - LDPC Decoder

Generic LDPC Decoder

Our LDPC Decoder is based on a message passing algorithm. In order to increase the throughput and the convergence behaviour, we use a modified Gauss-Seidel arithmetic. Our LDPC design is parameterisable, programmed via generics and can be used for modern standards, where information groups are connected to check node group via permutation matrices.

Our LDPC decoder is part of the DVB-S/S2 IP and was published on the international technical conference:  "Design, Automation and Test in Europe"(DATE) 2009, see...

Block Diagram



  • Modifed Gauss-Seidel Algorithm
  • Computing superposition of permutation of matrices without latency
  • Number of parallel processing units and clock frequency trade off are parameterisable
  • Code type and parity check matrix configuration are saved in ROM or RAM
  • Optimised memory layout using LLR compression algorithm
    • E.g. conventional DVB-S2 requires 1 700kBit, Ubiso design requires 972 kBit
  • Two robust & programmable decoding stop-criteria to save power
    • Stop, if check equation is completely fulfilled (xH=0)
    • Stop, if codeword is undecodable
      • the variable node reliability is checked during decoding


  • DVB-S2
  • DVB-T2
  • DVB-C2
  • 10 GBase – T Ethernet, IEEE 802.3ae, IEEE 802.3an, IEEE 802.3u, IEEE 802.3z, IEEE 802.3ba
  • G.hn­/G.9960 , ITI-T Standard for networking over power lines, phone lines and coaxial cable;
  • IEEE 802.11n, Wireless LAN Medium Access Control;
  • IEEE 802.15.3c, Wireless Personal Area Network (WPAN);
  • IEEE 802.16e, Air Interface for Fixed and Mobile Broadband Wireless Access System.
  • DTMB

All these codes have structure according to:



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