Adaptive iterative receiver in low density parity-check code and continuous phase modulation system

Abstract

The invention provides an adaptive iterative receiver in a low-density parity check code and continuous phase modulation system. The adaptive iterative receiver comprises a receiving antenna (8), a CPM (continuous phase modulation) demodulator (9), a CPM soft-input and soft-output module (10), a random deinterleaver (11), a weighted processing module (12), an LDPC (low density parity check) code soft-input and soft-output module (13), a random interleaver (2), a sign change rate judging module (14), a switching circuit (15) and a bit decision device (16). The weighted processing module (12) and the sign change rate judging module (14) are introduced and used together. Iterative times are adaptively set by the receiver according to change conditions of a Rayleigh fading channel, an iterative process is prevented from entering a positive feedback state, iterative detection is automatically stopped at a position with a small bit error rate, average iterative times are reduced, iterative detection time is saved, and convergence, reliability and instantaneity of a system are improved. In addition, the adaptive iterative receiver has the advantages of reliable performance, low complexity, easiness in maintenance and the like, and has popularization and application values in satellite communication, deep space communication and the like.

Description

technical field [0001] The present invention relates to an adaptive iterative detection receiver applied to a low density parity check (Low Density Parity Check Code, LDPC) code and continuous phase modulation (Continuous Phase Modulation, CPM) serial cascading system, especially to a An iterative processing receiver that can improve signal detection convergence, reliability, and real-time performance in Rayleigh fading channels. Background technique [0002] The business of satellite communication is becoming more and more busy, and the communication capacity is increasing rapidly, resulting in very crowded radio frequency spectrum and increasingly tight bandwidth resources. Therefore, it is necessary to adopt an efficient modulation method to improve the utilization rate of the system bandwidth. CPM is a type of advanced modulation technology that can meet the above requirements. It has efficient frequency band and power utilization. It is a modulation method with memory,...

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Problems solved by technology

The "Iterative Stopping Algorithm Based on Average Outer Information Exchange in SCCPM" published in "Journal of Xidian University" introduced the average outer information exchange method into the SCCPM system and achieved similar gain effects, but the problem of excessive decoding delay still not resolved

[0005] The above solutions are all proposed based on Additive White Gaussion Noise (AWGN). The effect in Rayleigh fading channel is not as obvious as in AWGN. From the impact of the number of iterations on the bit error rate, it is absolutely Most frames can be decoded correctly with a small number of iterations. When the number of iterations is large, it will not only increase the decoding delay, but also cause positive feedback

Although the weighted external information exchange method and the average external information exchange method can reduce the occurrence of positive feedback, they cannot completely eliminate positive feedback

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