Protograph code for deep space optical communication system

Abstract

The invention discloses a protograph code for a deep space optical communication system. A code rate of the protograph code is 1/2, and a corresponding protograph contains four variable nodes, two check nodes and ten edges. The four variable nodes do not contain slotting nodes. A parity check matrix of the protograph code has a quasi-cyclic structure, and the parity check matrix is obtained by a two-step expansion: a first expansion is that an improved progressive edge growth algorithm is used to obtain the parity check matrix corresponding to a derived diagram; a second expansion is that a zero matrix, and a cyclic shift array of a unit matrix are used to replace 0 and 1 in the parity check matrix corresponding to the derived diagram; and a final parity check matrix is obtained. In the invention, provided is the protograph code for the deep space optical communication system; the protograph code is new for the deep space optical communication system; through the adoption of the encoded BICM-ID (Bit interleaved coded modulation-iterative decoding) solution in the invention, the excellent bit error rate performance is achieved in the deep space optical channel.

Description

technical field [0001] The invention relates to a prototype image code suitable for a deep-space optical communication system, which belongs to the coding technology. Background technique [0002] Communication over deep space distances is extremely difficult due to the huge power loss caused by beam spreading, and the difficulty of communication grows quadratically as the distance increases. Therefore, the joint design of power efficient pulse position (PPM) modulation and channel coding has been favored by people in deep space optical communication. The powerful error correction ability of LDPC codes makes them be applied in PPM modulated optical communication systems. Bit Interleaved Coded Modulation-Iterative Decoding (BICM-ID) can achieve excellent performance in additive white Gaussian noise (AWGN) channels and Rayleigh fading channels. [0003] figure 1 A block diagram of an LDPC-encoded BICM-ID system is given. As shown in the figure, the LDPC encoder first encod...

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Problems solved by technology

However, the research in this literature also shows that when considering BICM-ID, the original model image codes optimized under the AWGN channel may not be able to maintain their excellent performance under the Poisson PPM channel

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