在采用球填充理论生成八维调制格式的基础上,提出了一种基于八维调制格式的变速率方法。与当前变速率实现方法相比,该方法仅通过自适应地切换调制格式符号集即可实现更为精细的谱效率调整。仿真结果表明,这种基于八维调制格式的变速率方法可以自适应地实现谱效率的灵活切换,谱效率的调节粒度为0.25 bit。在符号速率为7 GBaud的条件下,比特速率的自适应范围为28~84 Gb·s ^-1。这种变速率方法可为弹性光网络提供精细的谱效率及比特速率的调整。

Using the sphere-packing theory to generate eight-dimensional modulation formats, we propose a rate-adaptive scheme based on eight-dimensional modulation formats. Compared with the existing rate-adaptive schemes, the proposed scheme can achieve a finer granularity in spectral efficiency only by adaptive switching of modulation alphabet. The simulation results show that the proposed rate-adaptive scheme can adaptively realize the flexible switching of spectral efficiency and the granularity of spectral efficiency is 0.25 bits. Moreover, the bit rate range is 28-84 Gb·s -1 at a fixed symbol rate of 7 GBaud. The proposed rate-adaptive scheme can be applied to the elastic optical network to provide a finer granularity in spectral efficiency and bit rate adjustment.