应用于中继卫星通信系统的16QAM-TCM技术研究

16QAM-TCM Technology Research Applied in Relay Satellite Communication System

摘要:

网格编码调制技术可以在不改变信息传输频谱带宽的条件下，改善信噪比，减少发射功率，降低误码率，其实现的方法是分割星座图形成子集，逐步增大星座图中信号点之间的最小欧氏距离。本论文在项目组自研的中继卫星通信系统仿真平台上，仿真了8PSK与16QAM-TCM两种调制技术的解调性能，仿真曲线反映了误比特率需求与所需信噪比之间的关系。仿真结果表明：① 在理想信道条件、I/Q（Inphase/Quadrature， 同相/正交）幅相不平衡、幅频特性、群时延、相位噪声、功率放大器饱和点条件下，假设误比特率需求为1E-7，16QAM-TCM技术的信噪比需求与8PSK调制技术的信噪比需求相比，分别可节省8.85 dB、9.04 dB、8.45 dB、10.2 dB、8.5 dB、14.6 dB的信噪比；② 在非线性信道条件下，当信噪比增大时，8PSK调制技术的误比特率在1E-3数量级附近波动，不再变化；③ 假设需求的误比特率为1E-7，16QAM-TCM调制技术非线性信道信噪比仿真值与理想信道信噪比仿真值相比，损失了4.8 dB。

Abstract:

Trellis coding modulation technology can improve the signal-to-noise ratio, reduce the transmission power, and lower the bit error rate without changing the bandwidth of the information transmission spectrum. The realization method is to divide the constellation map to form a subset and gradually increase the minimum Euclidean distance between the signal points in the constellation map. In this paper, the demodulation performance of 8PSK and 16QAM-TCM modulation techniques is simulated on the simulation platform of a relay satellite communication system developed by the project team. The simulation curve shows the relationship between the required bit error rate and signal-to-noise ratio. The simulation results demonstrate: ① under the channel conditions of an ideal channel, I/Q amplitude and phase imbalance, amplitude and frequency characteristics, group delay, phase noise, power amplifier saturation, if the required BER is 1E-7, compared to 8PSK modulation technology, the signal-to-noise ratio of 16QAM-TCM technology saves 8.85 dB, 9.04 dB, 8.45 dB, 10.2 dB, 8.5 dB, and 14.6 dB, respectively; ② under the channel conditions of non-linear, correspondingly along with increasing of the signal-to-noise ratio, the BER of 8PSK modulation technology fluctuates around the order of 1E-3; ③ if the required BER is 1E-7, compared with the ideal channel SNR simulation result, the non-linear channel SNR simulation result of 16QAM-TCM technology loses 4.8 dB.