OFDM无线多媒体系统中导频载波设计方法

A Design Method of Pilot Subcarrier in OFDM Wireless Multimedia System

提出了一种用于OFDM无线多媒体系统的导频符号设计方法,先根据系统性能要求确定信道估计误差方差的阈值;然后根据估计的导频载波信道增益和导频载波分布计算出数据载波的信道增益,并获得总载波信道估计误差方差;再比较该方差值与设定的门限值。通过随信道变化自适应调整导频载波,在信道深衰落时增加导频载波数,信道衰落低时减小导频载波数,既可保证业务传输质量的要求,又能提高系统频谱利用率。

A method for the selection of pilot subcarrier in OFDM system is presented in this paper. The key idea of this scheme is that the selection of different pilot subcarrier is based on channel quality for each frame. The implementation process is as follows. Firstly, based on current channel condition and bit error rate （BER） of system the threshold value of channel estimation error variance is determined. Then, pilot subcarriers are inserted into the OFDM subcarriers with equal space and pair-wise, and the channel estimation error variance is figured out. Finally, the variance is compared with the threshold value. By the channel variation and BER requirement of different service, the number of pilot subcarrier is selected adaptively, thus ensuring the quality of service and improving the spectral efficiency of the system.