Ubiso - IP: DVBS2 - Decoder |

## DVB-S2 - DecoderThe UBISO Dual DVB-S2 FEC IP is a low-cost, highly optimized dual DVB-S2 IP targeted for best performance at the smallest area. The preprocessing blocks (mapping I/Q values to LLR values, deinterleaver) and the postprocessing blocks (BCH decoder, BBHEADER extraction,..) are customized to the LDPC decoder architecture. This allows the data to get in and out to the LDPC decoder as quickly as possible, thus exploiting the full capacity of our high performance LDPC decoder. The enhanced LDPC Decoder uses a modified Gauss-Seidel-Aglrotihm resulting in a very low gate count and optimal frequency and therefore making the IP extremely competitive. We published our DVB-S/S2 IP in the international technical conference ## Block Diagram## Functionality- Receiving I and Q values of two independent channels
- Mapping I and Q values to
**L**og-**L**ikelihood-**R**atio (LLR) values (demodulate) - Deinterleaving
- Decoding each LDPC codeword using iterative soft decision decoding
(Turbo Decoding Message Passing Algorithm) - Decoding each BCH codeword
- Descrambling frame (BB scrambling)
- Capturing BB Header and depacketizing
- Computing the CRC check
## Features- Architecture reworked in order to reduce layout effort
- New architecture (lower complexity, lower power):
- Applying Gauss-Seidel (Turbo-Decoding, Layered) principle on all possible parity check nodes.
(Calculating double permutations without any latency) - Computing 90 check nodes in parallel, instead of 360 (reduced hardware)
- Applying Gauss-Seidel (Turbo-Decoding, Layered) principle on all possible parity check nodes.
**L**og-**L**ikelihood-**R**atio (LLR) compression algorithm reduces edge memory requirements- Decoding of optional code rates
- Power saving via different dynamic decoding stop criteria
- if decoding is completed (xH=0)
- if codeword is undecodable (examining the SNR via calculating the variable node reliability)
- BCH decoder reworked in order to match new LDPC decoder architecture
## LDPC improvements## ...in throughput and convergenceThe Ubiso LDPC Decoder uses a modified Gauss-Seidel Algorithm, capable of calculating any permutations in one clock cycle, even submatrices containing two or more permutations. This increases the throughput and convergence by factor two compared to conventional decoding algorithms. These facts allows us to split the size of the submatrizes from 360 to any required factor. Hence reducing gate count and relaxing the routing congestions.
=> reduced level of parallelism from 360 to 90 ## ...in memory requirementsUbisos |