Quasi-Cylic LDPC Codes and Its Application for Compass

Jiuchao Qian, Rendong Ying, Kai Chen, Peilin Liu, Wenxian Yu

Abstract:	As one of the key technologies of global satellite navigation system designing, signal structure is at an important position in the process of GPS modernization, as well as the system designing of Compass and other navigation systems. Satellite navigation signal is liable to be interfered and failed by different kinds of jamming. Although we can suppress the jamming to some extent using dispreading technology, it is still not enough for the application of satellite navigation, as the received navigation signal is too weak. On the other hand, the performance of the navigation system is eventually constrained by navigation signals themselves regardless of advanced receiver technologies. However, there is a more effective way to utilize channel coding technology with powerful error correction capacity, which can protect the transmit data and improve interference tolerance meanwhile. This paper mainly puts emphasis on the performance evaluation of a novel navigation signal scheme using a kind of particularly attractive channel code called quasi-cyclic low density parity check (QC-LDPC) code. This code demonstrates the important characteristics and high performance for GNSS. Compare with other traditional codes, QC-LDPC codes have higher coding gain, and can enhance the robustness of navigation signal with decoding algorithm of low complexity, which make them become a kind of constructed LDPC code of great concern for navigation signal structure designing. First of all, this paper focuses on the topics of the construction of QC-LDPC. Then, the performance of QC-LDPC codes influenced by different factors is analyzed and evaluated, such as various girths of the Tanner graphs, unequal information sequence length, and different numbers of iterations and so on. Finally, the proposed codes are applied in Compass signal structure design. The simulation results show that QC-LDPC codes can achieve superior performance and they are worthy of further exploration for GNSS modernization and application.
Published in:	Proceedings of the 25th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2012) September 17 - 21, 2012 Nashville Convention Center, Nashville, Tennessee Nashville, TN
Pages:	3606 - 3612
Cite this article:	Qian, Jiuchao, Ying, Rendong, Chen, Kai, Liu, Peilin, Yu, Wenxian, "Quasi-Cylic LDPC Codes and Its Application for Compass," Proceedings of the 25th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2012), Nashville, TN, September 2012, pp. 3606-3612.
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