一种低复杂度的Multi-h CPM相干解调算法及FPGA实现

A low-complexity coherent demodulation algorithm of Multi-h CPM and its FPGA implementation

摘要:

多调制指数连续相位调制（Multi-h Continuous Phase Modulation，Multi-h CPM）是一种恒包络调制，具有多个周期出现的调制指数，因此其频谱效率和功率效率比单调制指数CPM更高，但其接收机的复杂度也随之增加。本文在倾斜相位（Tilted Phase，TP）的基础上采用频率脉冲截断（Frequency Pulse Truncation，FPT）和状态空间分割（State Space Partition，SSP）相结合的方法来降低多调制指数连续相位调制的复杂度，使相位状态由512降低到16，理论损耗约为0.8 dB。同时，对降低复杂度的解调算法在现场可编程门阵列（Field Programmable Gate Arrays， FPGA）上进行了验证。仿真和在线测试的误码率曲线接近理论分析曲线，和常用的128状态解调算法相比，资源消耗降低了约59%。

Abstract:

Multi-h Continuous Phase Modulation (CPM) has a constant envelope with periodical modulation indices, and its spectral efficiency and power efficiency are higher than single-h CPM. However, the receiver complexity also increases exponentially. In this paper, a combination of Tilde Phase, Frequency Pulse Truncation, and State Space Partition is proposed to reduce the complexity of Multi-h CPM, which reduces the phase state from 512 to 16 with a theoretical loss of about 0.8dB. Meanwhile, the reduced-complexity demodulation algorithm is verified on FPGA. The simulated and online BER results are close to the theoretical analysis curve, and the implementation resource usage is reduced by 59% compared to the conventional 128 states demodulation algorithm.