How to develop the handoff function by Openwrt

How to develop the handoff roaming function by Openwrt? It can't be developed by QSDK.
Handoff and roaming function is that the board can defect the many signals and choose the strongest one the connect automatically when the module moves from one place to another one.
Let's discuss this technical issues.

Feel free to discuss this roaming technical issues.

Isn't that already working in Openwrt? I think DAWN project is the way (my opinion).... Hostapd already has full support for roaming and handoff in wireless....