An UEP scheme for optimal rate allocation of CCSDS LDPC codes

In this paper, it is proposed an UEP scheme for remote sensing progressive image transmission using space standards recommendations for source coding and channel coding defined by the Consultative Committee for Space Data Systems (CCSDS). Such transmission scheme take into account the different error sensitivities of the source bitstream to establish an optimized rate allocation of LDPC codes available in that standard considering high protection to the most important parts of the compressed bitstream. An analytical model was developed over BSC to compute the expected PSNR given a maximum acceptable distortion as a criterion to organize the channel coding rates according to critical parts of the compressed bitstream. Therefore, the rate allocation was defined to establish a high code rate (less redundancy) and high expected PSNR, desirable for near space applications. Computational results were based in a comparison between the UEP proposed scheme and the EEP strategy which showed a high gain of PSNR (about 30 dB) at low SNR in UEP scheme over an EEP equivalent rate.