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A switchable-rate quasi-cyclic low-density parity-check (QC-LDPC) coding scheme has been proposed for integration within the legacy and next-generation high-frequency internet protocol (HF-IP) systems. The novelty in this work is based upon using a class of switchable-rate short-block-length (<;1500 bits) QC-LDPC codes for the HF fading channel modelled by the ITU-R F.1487 for all latitudes and conditions. The QC-LDPC codes are constructed using a switchable-rate approach based on finite fields which provides the ability to switch among three rates to combat varying channel conditions using a single encoder/decoder structure. The proposed structure enables low-complexity implementation of the low-density parity-check encoder/decoder for use within the existing data link (DL) layer of the standardisation agreement (STANAG) 5066 profile. The performance of the proposed scheme has been evaluated comprehensively for all the HF channel conditions and latitudes. A comparison between the proposed and the current coding scheme in HF-IP systems (based on convolutional coding) shows an improvement in error-rate performance.
Date of Publication: March 2011