同时在OFDM调制时可以采用M -QAM映射方式，提高短波跳频系统的信息传输速率。

At the same time, M-QAM mapping can be used in OFDM for improving data transportation speed.

youdao

基于OFDM(正交频分复用)系统，提出了一种新的空频时三维编码，将网格编码调制和差分空时分组码进行组合链接设计。

Based on OFDM system, a novel space-frequency-time code which combined trellis-coded modulation with differential space-time block code was proposed.

youdao

基于OFDM(正交频分复用)系统，提出了一种新的空频时三维编码，将网格编码调制和差分空时分组码进行组合链接设计。

Based on OFDM system, a novel space-frequency-time code which combined trellis-coded modulation with differential space-time block code was proposed.

youdao