If you mean simmulation, you can use anynetwork simulators, such as, NS2. However, you have to start from zero. Mininet is the formal SDN simulator. However, it will not help you with handoff. However, if you modify the clients code and you used Ryu controller you can do it
Check this article: Survey of software components to emulate OpenFlow protocol as an SDN implementation (2014) Mohammed Basheer Al-Somaidai, Estabrak Bassam Yahya, American Journal of Software Engineering and Applications