The Next generation mobile communication system called as 4G is expected to include heterogeneous wireless networks that will offer high data rate multimedia services to end users. In present wireless systems the capability of broader coverage is available but has the limitation of bandwidth and network cost. The proposed Seamless Media Independent Resilience Triggering (SMIRT) framework will provide decision based on soft-handover for Heterogeneous Networks like Wi-Fi, WiMAX and LTE. It will provide seamless roaming across the heterogeneous networks through the media independent handover framework without user intervention. This framework will be simulated by using NS3 and evaluate the increased performances like throughput, QoS, coverage and decreased performances like packet loss and delay.