This episode explores a 2017 EPFL paper on turning a soft-input soft-output decoder kernel into a reusable RFNoC FPGA block using Vivado HLS, with a focus on software-defined radio and forward error correction. It explains why SISO processing sits at the core of turbo decoding, walking through the BCJR/MAP decoding logic, trellis-based forward and backward recursions, and the hardware challenges created by state metrics, memory traffic, and iterative probabilistic updates. The discussion argues that the paper is more convincing as a case study in HLS-based FPGA block construction and RFNoC integration than as proof of a complete, production-ready decoder system. Listeners would find it interesting for its clear look at the tradeoff between modular FPGA design convenience and the stubborn algorithmic complexity that still demands careful hardware thinking.
Sources:
1. RFNoC SISO Processor via High-Level Synthesis
https://www.epfl.ch/labs/lap/wp-content/uploads/2018/11/GuerrieriSep17_DesigningAnRfnocBlockImplementingASisoProcessorUsingHighLevelSynthesis_GNURC17.pdf2. RFNoC: RF Network-on-Chip — Martin Braun, Jonathan Pendlum, Matt Ettus, 2016
https://scholar.google.com/scholar?q=RFNoC%3A+RF+Network-on-Chip3. Designing a RFNoC Block implementing a SISO Processor using High-Level Synthesis — Andrea Guerrieri, 2017
https://scholar.google.com/scholar?q=Designing+a+RFNoC+Block+implementing+a+SISO+Processor+using+High-Level+Synthesis4. Measured Latency Introduced by RF Network-on-Chip (RFNoC) Architecture — Joshua Sunderlin, 2017
https://scholar.google.com/scholar?q=Measured+Latency+Introduced+by+RF+Network-on-Chip+%28RFNoC%29+Architecture5. Adventures in RFNoC: Lessons Learned From Developing a Real-Time Spectrum Sensing Block — Rylee G. Mattingly, Justin G. Metcalf, 2022
https://scholar.google.com/scholar?q=Adventures+in+RFNoC%3A+Lessons+Learned+From+Developing+a+Real-Time+Spectrum+Sensing+Block6. The Software Radio Architecture — Joseph Mitola III, 1995
https://scholar.google.com/scholar?q=The+Software+Radio+Architecture7. State of the art baseband DSP platforms for Software Defined Radio: A survey — Omer Anjum, Tapani Ahonen, Fabio Garzia, Jari Nurmi, Claudio Brunelli, Heikki Berg, 2011
https://scholar.google.com/scholar?q=State+of+the+art+baseband+DSP+platforms+for+Software+Defined+Radio%3A+A+survey8. Sora: High-Performance Software Radio Using General-Purpose Multi-Core Processors — Kun Tan, He Liu, Jiansong Zhang, Yongguang Zhang, Ji Fang, Geoffrey M. Voelker, 2011
https://scholar.google.com/scholar?q=Sora%3A+High-Performance+Software+Radio+Using+General-Purpose+Multi-Core+Processors9. OpenRadio: A Programmable Wireless Dataplane — Manu Bansal, Jeffrey Mehlman, Sachin Katti, Philip Levis, 2012
https://scholar.google.com/scholar?q=OpenRadio%3A+A+Programmable+Wireless+Dataplane10. A Mathematical Theory of Communication — Claude E. Shannon, 1948
https://scholar.google.com/scholar?q=A+Mathematical+Theory+of+Communication11. Low-Density Parity-Check Codes — Robert G. Gallager, 1962
https://scholar.google.com/scholar?q=Low-Density+Parity-Check+Codes12. Design of Capacity-Approaching Irregular Low-Density Parity-Check Codes — Thomas J. Richardson, M. Amin Shokrollahi, Rudiger L. Urbanke, 2001
https://scholar.google.com/scholar?q=Design+of+Capacity-Approaching+Irregular+Low-Density+Parity-Check+Codes13. Channel Coding: The Road to Channel Capacity — G. David Forney Jr., Daniel J. Costello Jr., 2007
https://scholar.google.com/scholar?q=Channel+Coding%3A+The+Road+to+Channel+Capacity14. Near Shannon Limit Error-Correcting Coding and Decoding: Turbo-Codes — Claude Berrou, Alain Glavieux, Punya Thitimajshima, 1993
https://scholar.google.com/scholar?q=Near+Shannon+Limit+Error-Correcting+Coding+and+Decoding%3A+Turbo-Codes15. A Comparison of Optimal and Sub-Optimal MAP Decoding Algorithms Operating in the Log Domain — Patrick Robertson, Emmanuelle Villebrun, Peter Hoher, 1995
https://scholar.google.com/scholar?q=A+Comparison+of+Optimal+and+Sub-Optimal+MAP+Decoding+Algorithms+Operating+in+the+Log+Domain16. Turbo Decoding as an Instance of Pearl's "Belief Propagation" Algorithm — Robert J. McEliece, David J. C. MacKay, Jung-Fu Cheng, 1998
https://scholar.google.com/scholar?q=Turbo+Decoding+as+an+Instance+of+Pearl%27s+%22Belief+Propagation%22+Algorithm17. A Survey of Three-Dimensional Turbo Codes and Recent Performance Enhancements — Dhouha Kbaier Ben Ismail, Catherine Douillard, Sylvie Kerouedan, 2013
https://scholar.google.com/scholar?q=A+Survey+of+Three-Dimensional+Turbo+Codes+and+Recent+Performance+Enhancements18. Optimal Decoding of Linear Codes for Minimizing Symbol Error Rate — Lalit R. Bahl, John Cocke, Frederick Jelinek, Josef Raviv, 1974
https://scholar.google.com/scholar?q=Optimal+Decoding+of+Linear+Codes+for+Minimizing+Symbol+Error+Rate19. From Low-Architectural Expertise up to High-Throughput Non-Binary LDPC Decoders: Optimization Guidelines Using High-Level Synthesis — Nithin George, Kimon Karras, David Novo, Vitor Silva, Paolo Ienne, Gabriel Falcao, 2015
https://scholar.google.com/scholar?q=From+Low-Architectural+Expertise+up+to+High-Throughput+Non-Binary+LDPC+Decoders%3A+Optimization+Guidelines+Using+High-Level+Synthesis20. Turbo Decoder Architecture for Beyond-4G Applications — Cheng-Chi Wong, Hsie-Chia Chang, 2014
https://scholar.google.com/scholar?q=Turbo+Decoder+Architecture+for+Beyond-4G+Applications21. A DSP Shared Is a DSP Earned: HLS Task-Level Multi-Pumping for High-Performance Low-Resource Designs — approx. recent FPGA/HLS architecture authors, 2023-2026
https://scholar.google.com/scholar?q=A+DSP+Shared+Is+a+DSP+Earned%3A+HLS+Task-Level+Multi-Pumping+for+High-Performance+Low-Resource+Designs22. Making Acceleration More Amenable with Novel High-Level Synthesis Techniques for FPGAs — approx. recent FPGA/HLS systems authors, 2023-2026
https://scholar.google.com/scholar?q=Making+Acceleration+More+Amenable+with+Novel+High-Level+Synthesis+Techniques+for+FPGAs23. High-Level Synthesis for FPGAs: A Hardware Engineer's Perspective — approx. recent survey/review authors, 2023-2026
https://scholar.google.com/scholar?q=High-Level+Synthesis+for+FPGAs%3A+A+Hardware+Engineer%27s+Perspective24. Implementation of Cognitive Radio Based on SDR and FPGA: Methods, Architectures and Practical Applicability — approx. SDR/FPGA survey authors, recent
https://scholar.google.com/scholar?q=Implementation+of+Cognitive+Radio+Based+on+SDR+and+FPGA%3A+Methods%2C+Architectures+and+Practical+Applicability25. StreamPU: A DSEL for High Throughput and Low Latency Software-Defined Radio on Multicore CPUs — approx. Cassagne and collaborators, recent
https://scholar.google.com/scholar?q=StreamPU%3A+A+DSEL+for+High+Throughput+and+Low+Latency+Software-Defined+Radio+on+Multicore+CPUs26. Run-Time Reconfigurable Systems and Algorithms for RFSoC-Based Software Defined Radio Applications — approx. recent RFSoC/SDR authors, recent
https://scholar.google.com/scholar?q=Run-Time+Reconfigurable+Systems+and+Algorithms+for+RFSoC-Based+Software+Defined+Radio+Applications27. DecodeX: Exploring and Benchmarking of LDPC Decoding Across CPU, GPU, and ASIC Platforms — approx. recent benchmarking authors, recent
https://scholar.google.com/scholar?q=DecodeX%3A+Exploring+and+Benchmarking+of+LDPC+Decoding+Across+CPU%2C+GPU%2C+and+ASIC+Platforms28. High-Throughput Software-Defined LDPC Encoder and Decoder with x86-Based Data-Level Parallelism — approx. recent communications authors, recent
https://scholar.google.com/scholar?q=High-Throughput+Software-Defined+LDPC+Encoder+and+Decoder+with+x86-Based+Data-Level+ParallelismInteractive Visualization: RFNoC SISO Processor via High-Level Synthesis