Move a Bezier curve node using keyboard

How can I move a Bezier curve node using keyboard? If I press arrow keys, the whole figure is moved even if one node is selected.

I assume you are already in point editing mode. Press Ctrl+Tab. Now one point is blinking. This point you can move now by the arrow keys. Press Ctrl+Tab again to switch to the next point. So you can traverse all points. Use Ctrl+Shift+Tab to traverse backwards. Press Esc to leave point selection mode.