基于Manchester-PAM4调制的无源光网络平滑升级

为了消除新加入无源光网络（PON）线路对旧有PON线路的干扰，实现新旧PON线路的共存，提出基于Manchester-PAM4调制的PON平滑升级方案. 方案分别测试NRZ、Manchester、PAM4、Manchester-PAM4调制格式的新旧PON信号共存时的眼图和误码率. 测试结果表明，Manchester-PAM4信号减少了与Manchester信号几乎相同的串扰，但提供了双倍的比特率；与消光比减小的NRZ信号相比，Manchester-PAM4信号具有更好的串扰抑制效果. Manchester-PAM4调制的新PON信号不仅抑制了对于旧PON信号的干扰，而且保持了100%的编码效率. 在渐进且“无痕迹”的平滑升级后，Manchester-PAM4能够通过软件操作更改为PAM4，以提供双倍的比特速率.

Smooth migration for passive optical networks based on Manchester-PAM4 modulation

A smooth passive optical network (PON) migration based on Manchester-PAM4 modulation was proposed, in order to eliminate the crosstalk from the newly added PON link to the old PON link and realize the coexistence of the two PON links. The eye diagrams and bit error rates were tested when the new PON signal coexisting with the old one in modulation formats of NRZ, Manchester code, PAM4, and Manchester-PAM4, respectively. Test results showed that the Manchester-PAM4 signal reduced almost the same crosstalk as the Manchester code signal, but provided double bit rate, and the Manchester-PAM4 signal showed better crosstalk suppression than the NRZ signal of reduced extinction ratio. The new PON signal in Manchester-PAM4 not only suppressed the crosstalk to the old one, but also maintained 100% coding efficiency. After gradual and "traceless" smooth upgrade, Manchester-PAM4 can be changed to PAM4 through software operation to provide double bit rate.