用软件无线电实现MPSK自适应调制

自适应调制能够根据信道的时变性达到很高的传输速率和进行合理的功率分配.同时,它需要自适应调整调制模式级别M.采用软件方式在DSP板上能够实现MPSK的调制、解调功能和调制模式M的识别,替代在硬件之间进行切换的繁琐模式.调制器根据星座图和已知的调制级别在己存储的波形中挑选对应的调制波形,解调器在信号同步的情况下通过使用最小均方进行解调,同时进行M模式识别.模拟结果显示用软件无线电方式实现MPSK自适应调制是一条简捷快速的途径.特别在自适应调制中加入LDPC(低密度校验码)编码和一种新的结合BP和list-based SI HO解码后,系统性能更为优异.

MPSK Adaptive Modulation by Using Software Radio

Adaptive modulation can reach a high transmission rate and appropriate power allocation according to channel variation,and it needs adaptive selection of modulation level in the meantime.Instead of the conventional complicated hardware implementations,which have different modulation-demodulation levels,it is proposed a software solution which realizes MPSK modulator and demodulator by using DSP.The modulator selects one of the stored waveforms according to constellation and modulation level,and the demodulator is a least square detector which compares the stored waveform with input symbol.The modulation level recognition is also accomplished by least square method which compares waveforms.Simulation results show that the proposed MPSK software solution is a quick and convenient tool.Especially when LDPC channel coding and decoding combining BP with list-based SIHO are used,the system is able to yield a superior performance.