Low density parity check (LDPC) encoder and encoding method of China mobile multimedia broadcasting (CMMB) based on piece line circulation

Abstract

The invention provides an encoding scheme of low density parity check (LDPC) codes with two code rates of a China mobile multimedia broadcasting (CMMB) system. The encoding scheme of the LDPC codes with the two code rates of the CMMB system is characterized in that the LDPC encoder of the system is mainly formed by a controller, a vector quantity memorizer, a destination address table, a high density matrix table, a matrix line mapping table, a first piece line expanding table, an address generator, a rearrangement unit, a lateral accumulation unit and a parallel accumulation unit. The encoder is strong in the consistency of encoding steps, and is easy to achieve. The encoding scheme of the LDPC code with the two code rates of the CMMB system simplifies a backward recurrence arithmetic, and removes the complex operation of reading-operating-writing back, and therefore encoding time is shortened. The encoding scheme fully uses the characteristic that the piece line circulation features and the line weights of the check matrix are identical, can obviously improve encoding speed and effectively reduce the demands of memorizers and logical resources at the same time, and has the advantages of being high in handling capacity, low in cost, and small in power consumption.

Description

technical field [0001] The invention relates to the field of mobile multimedia broadcasting, in particular to an efficient implementation method of an LDPC encoder in a CMMB system. Background technique [0002] Since various distortions and noises in the transmission channel will interfere with the transmitted signal, bit errors in the digital signal will inevitably occur at the receiving end. In order to reduce the bit error rate, channel coding technology needs to be adopted. Low-Density Parity-Check (Low-Density Parity-Check, LDPC) codes have become a research hotspot in the field of channel coding because of their excellent performance close to the Shannon limit and high-speed parallel decoding. [0003] The CMMB standard adopts binary LDPC regular codes with two code rates of 1 / 2 and 3 / 4. They are all systematic codes, but the information vectors are not concentrated in the first half or the second half of the codeword intact, but are scattered in the codeword. The ...

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Problems solved by technology

[0004] Existing CMMB LDPC coders generally use the LU decomposition coding algorithm or RU coding algorithm (also known as the approximate lower triangular coding algorithm) suitable for general LDPC codes, which divides H into multiple isolated sub-matrices, which is not reasonable Using H's block row cycle characteristics and the same characteristics of row weight, and involving complex backward recursive operations, resulting in long encoding time, large storage capacity, high cost, and high power consumption

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