Research And FPGA Implementation Of LDPC Encoder In CMMB And T-MMB

Mobile TV has become a focus since its outstanding performance in the 2008 Beijing Olympic Games, it is considered the most promising and novel service in 3G era. The innovation of mobile phone functions becomes not only the focus of the enterprise to chase, but also the focus of consumer to concern. At present, the two most important standards for mobile TV are based on ground broadcasting technologies. One is China Mobile Multimedia Broadcasting (CMMB), the other is mobile multimedia broadcasting standard T-MMB proposed by Beijing Nufront Technology Co. Ltd. T-MMB was selected as the national mobile TV standard in April 2008, nonetheless, CMMB has already been into the business use, and broadcasted programs in the 2008 Beijing Olympic Games, it has been accepted by the public in no time.As one of the core technologies in mobile TV standard, the error-correcting code technology has become a hot topic in scientific research. And the corresponding codec chips have become the top priority, in which LDPC code has became the first channel coding schemes choice in many mobile TV standards for its excellent performance. CMMB adopted the concatenated codes make up of LDPC and RS code, and T-MMB adopted the concatenated codes make up of LDPC code and convolutional code.In this paper, we take LDPC code encoder in these two mobile TV standards as the breakthrough point, study the mobile TV channel coding method deeply, and a lot of work mainly in the algorithm improvement and analysis is done. For the LDPC encoder in CMMB, an improved algorithm using the idea of pipeline and parallel computing is proposed, which is based on the original encoding method by LU decomposition. As a result, its coding speed is improved, and the resouses is saved. Meanwhile, a new algorithm for RS encoder in CMMB is proposed, which make its encoding faster and can be applied in varied occasions. Since RS encoding and byte interleaving are working at the same time, the byte interleaving is implemented using SRAM in this paper, and finally the entire CMMB channel coding is implemented and tested in FPGA. For the LDPC encoder in T-MMB, according to the characteristics of the generator matrix, the encoding method based on quasi-cyclic code is adopted. Test results show that the chip logic function is correct, the speed and resource consumption are up to the standard requirements, and it has a certain business value.