As one of the key technologies of global satellitenavigation system designing, signal structure is at animportant position in the process of GPS modernization,as well as the system designing of Compass and othernavigation systems. Satellite navigation signal is liable tobe interfered and failed by different kinds of jamming.Although we can suppress the jamming to some extentusing dispreading technology, it is still not enough for theapplication of satellite navigation, as the receivednavigation signal is too weak. On the other hand, theperformance of the navigation system is eventuallyconstrained by navigation signals themselves regardlessof advanced receiver technologies. However, there is amore effective way to utilize channel coding technologywith powerful error correction capacity, which can protectthe transmit data and improve interference tolerancemeanwhile.This paper mainly puts emphasis on the performanceevaluation of a novel navigation signal scheme using akind of particularly attractive channel code called quasicycliclow density parity check (QC-LDPC) code. Thiscode demonstrates the important characteristics and highperformance for GNSS. Compare with other traditionalcodes, QC-LDPC codes have higher coding gain, and canenhance the robustness of navigation signal with decodingalgorithm of low complexity, which make them become akind of constructed LDPC code of great concern fornavigation signal structure designing.First of all, this paper focuses on the topics of theconstruction of QC-LDPC. Then, the performance of QCLDPCcodes influenced by different factors is analyzedand evaluated, such as various girths of the Tanner graphs,unequal information sequence length, and differentnumbers of iterations and so on. Finally, the proposedcodes are applied in Compass signal structure design. Thesimulation results show that QC-LDPC codes can achievesuperior performance and they are worthy of furtherexploration for GNSS modernization and application.
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