The LDPC Decoder core provides designers an LDPC Decoder block used in GMR (GEO-Mobile Radio) systems, which is an ETSI standard for satellite phones.
LDPC codes are the codes that offer error detection and correction capabilities close to maximum theoretical limits. LDPC codes were discovered by Gallager in 1962. But they were not given much attention for decades as the technology was not matured enough for its efficient implementation. With the success of iterative 'turbo codes' MacKay and Neal reintroduced LDPC codes in 1995. LDPC decoder forms a Forward Error Correction (FEC) block, which is used in GMR. During encoding, the information data is added with redundant data called parity data. This parity data is useful in detecting the errors that are introduced during the transmission of information data through channel.
GMR stands for GEO (Geostationary Earth Orbit) Mobile Radio interface, which is used for mobile satellite services utilizing geostationary satellite(s).
GMR is derived from the terrestrial digital cellular standard GSM and supports access to GSM core networks. This is a standard that uses LDPC mechanism for error detection and correction.
For GMR three releases exist. Release-2 and Release-3 of GMR adopted LDPC codes in 2008 and 2009, respectively. This IP core supports the Packet Normal Bursts (PNB2) that were added in GMR Release-2 and use LDPC codes for the first time. The same burst modes and LDPC codes are also in GMR Release-3(GMR-3G).
- High speed GMR LDPC decoder
- Supports both Packet Normal Burst PNB2(5,12) and PNB2(5,3)
- Supports all code rates for PNB2(5,12) and PNB2(5,3)(2/3 C1, 2/3 C2, 3/4, 4/5 C1, 4/5 C2, 4/5 C3, 9/10 C1, 9/10 C2, 1/2)
- Programmable decoding iteration length
- Easy to integrate with other modules.
- Fully synchronous design with single clock.
- Available for both FPGA and ASIC versions.
Block Diagram of the LDPC Decoder for GEO-Mobile Radio (Release-2)