I have submitted a manuscript in springer journal circuit,systems and signal processing. Its status is "Editor Assigned" for more than a month. what does it means?

I have submitted a manuscript in springer journal circuit,systems and signal processing on 10 october 2017. after 10 days the status has changed to "Editor Assigned". but know its more than a month, that this status is not changing. what does it means? because this status shows that my manuscript is not under review. why it is taking such a long time with editor? i have never experienced this much time for this stage in previous.