With the increasing complexity of space exploration requirements and the development of high-resolution payloads

satellite-ground downlink data transmission systems have been requested for transmitting increasing volumes of data. In order to meet the requirements of high throughput

low power

and high reliability for variable coding modulation (VCM) transmission systems of low Earth orbit (LEO) satellites

a new fast accumulated parallel recursive low-density parity-check (LDPC) encoding algorithm based on the second generation digital video broadcast (DVB-S2) standard was proposed

and an efficient encoder with low power was designed. The encoder was lower power consumed by simplifying the intermediate variables of parity-check bits based on the randomness of input information bits and the characteristic of binary operation. By analyzing the similarities between different LDPC codes and reusing the computation units and memories

the utilization of hardware resources was improved. Benefitting from the dynamic encoder structure

the encoder was compatible with three VCM modes

and the correctness was guaranteed when VCM modes changed

which increased the flexibility of the encoder. Furthermore

the new parity-check bits storage schemes that match with the modulation mode could output M parallel bits in sequence and increase the encoder throughput with high efficiency. The proposed encoder design was implemented on the Xilinx XC7K325t-3fbg900 FPGA

and experimental results showed that the maximum encoding throughput was up to 1.104 Gb/s when operating at a system clock of 347.5 MHz

the total throughput was improved by 31.9% compared with the constant coding modulation (CCM) transmission system

and the power consumption of the encoder was reduced by 21.7%.