关键词: 低信噪比, LDPC码, 编码辅助, 深空通信, 提前停止判决, 相位噪声

Abstract: In order to solve the high complexity and high latency problem in current code-aided carrier synchronization scheme, a new code-aided carrier synchronization scheme which induces an early stopping mechanism is proposed. On the basis of the existing code-aided carrier synchronization structure, the proposed scheme makes decision of the loop signal to noise ratio (SNR) on the fly. The code-aided carrier synchronization will stop after the loop SNR exceeds a predetermined criterion with no performance degradation. With the improved phase estimation method, a carrier signal phase with phase noise can be estimated while the loop SNR also increases. Using 1/2 low density parity check (LDPC) code in simulation, the results show that the number of iteration in the proposed code-aided carrier synchronization decreases by about 50% when the bit error rate is 10^-5; with phase noise signals, the performance degradation is less than 0.15 dB as compared with the ideal decoding performance.

Key words: low signal to noise ratio, LDPC code, code-aided, deep space communications, early stopping decision, phase noise