Due to major differences with respect to its counterpart in infrastructure networks, the handoff problem in ad hoc networks needs to be treated through an integrated multi-layer approach. In this paper, an integrated framework through cross layer approach is presented to deal with the handoff problem in heterogeneous wireless networks with multiple interfaces. Further, extensive study has been conducted to evaluate our proposed handoff solution, through simulation, real wireless-hardware-in-the-loop (WHIL) emulation, as well as hardware experiments using Android phones and GSM base station systems. It has been shown through study that transparent user application can be achieved using our handoff approach with low latency, minimum packet losses and only necessary control overhead.