线性调频多载波系统抗多普勒性能

Performance of Linear FM Multi-carrier System against Doppler Frequency Shift

针对OFDM系统对多普勒频偏的敏感性,在介绍广义多载波系统的基础上,为了进一步改善多普勒频偏下的系统性能,利用线性调频形式的正交信号基代替原有的指数信号基,构成了基于线性调频基的广义多载波通信系统,并给出了各子载波线性调频基的表达式、发射机输出信号和接收机接收信号的表达式。在六径信道模型下,设定多普勒频移为55 Hz,225 Hz和450 Hz,进行了通信系统数字仿真。结果表明,基于线性调频基的广义多载波通信系统具有较好的误码率性能。

Because of sensitivity of OFDM system with Doppler frequency shift, generalized multi-carrier （GMC） commu- nication system is introduced. In order to improve the performance of the system with Doppler frequency shift, the ortho-go-nal basis of the chirp type signal is used to substitute the original exponential type signal. The GMC communication system based on the chirp type basis is presented. Moreover, the expressions of chirp type basis, the output of transmitter and the in-put of receiver based on chirp basis are derived. Under the condition of the channel model with six paths and the Doppler frequency shift of 55 Hz,225 Hz,450 Hz, the digital simulation for communication systems is finished. Simulation results show that the GMC communication system based on chirp basis has lower error rate.