网格编码调制在无线信道下的应用

网格调制编码是将编码与调制相结合,利用信号集的冗余度来获取纠错能力.它通过增加系统设备复杂度解决了在不增加信道带宽、不降低有效信息传输速率的情况下获得明显的编码增益的问题,同时使系统的频带和功率利用率达到最佳.在无线信道下,对网格编码调制技术进行了研究,提出了基于无线信道的非对称调制信号集设计方案以及信号映射规则,进行了仿真.结果表明:在对称调制信号上,调制方式分别为4PSK和8PSK模式,编码器状态数增加相对于未编码时的BPSK和QPSK编码增益可以得到提高;非对称调制信号集相对于对称调制信号集可进一步改善编码增益.因此,网格编码技术可以在功率和频率受限的通信系统中得广泛的应用.

Simulation of TCM Based on Wireless Channel

Trellis Coded Modulation combins encoding with modulation and uses the redundancy degree of signal sets to get the capacity of error corretion.TCM increases the complexity of the system to get an obvious gain after coding without increasing the channel band and reducing the information rate at the same time.The frequency band of the system and the utility of the power will be optimal.The TCM coding method applied in wireless channel is described.The method of designing asymmetric partition based on the wireless channel is presented here,and the its performance is simulated.Simulation results of symmetric QPSK/8PSK modulated signals show that increasing the number of states of the coder will improve the coding gain in comparison with uncoded one.Simulation also shows that the asymmetric partition scheme can bring a better coding gain than the symmetric scheme.This will improve the error bit correction in the system.So it can be used widely in the channel in which power and bandwidth are limited.