AffiliationDepartment of Electrical Engineering and Computer Science, University of Kansas
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CitationPerrins, E. (2023). LDPC Codes for IRIG-106 Waveforms: Part I – Code Design. International Telemetering Conference Proceedings, 58.
AbstractLow density parity check (LDPC) codes allow a communications link to operate reliably at signal to noise ratios that are very close to the Shannon limit. Because of this, in the early 2000s they were studied in connection with SOQPSK-TG and were eventually adopted into the IRIG-106. The deployment for SOQPSK-TG has proved to be very successful, which has motivated interest in finding an LDPC solution for PCM/FM and ARTM CPM. Such a solution, however, has proved to be elusive for reasons that were not entirely clear in the past. In this paper, we lay out the fundamental considerations that must be made in order to design LDPC codes for a specific modulation format. In doing so, we show that SOQPSK-TG enjoys specific similarities with BPSK that allowed an “easy path” toward an LDPC solution in IRIG-106. Most importantly, we show that when the design process begins at the proper starting point, it is just as easy to design LDPC codes that are customized to a particular modulation. We then apply this straightforward design process to PCM/FM and ARTM CPM and demonstrate that the resulting LDPC codes perform around one dB from the respective channel capacities of these modulations. In our companion paper, we develop parallel decoder architectures for these schemes that can achieve high throughput. As such, these codes can be considered to fill in the options for LDPC codes that are currently absent in the IRIG-106 standard.