Heterogeneous network is a type of network, where several computers or devices with different protocols are connected together, for e.g. WLAN-WiMAX or WiFi-3G. Due to the advancement of technology, there is a need for mobility and uninterrupted connection. Vertical Handover Mechanism helps to have a seamless communication and mobility between these networks. The existing work defines the Admission Control (AC) and Wiener Process (WP) based prediction algorithms, but AC cannot be used directly in WiMAX, because some MSs may be served by two ASN GWs, which results in delay. So, in this paper, authors have used a WLAN-WiMAX interworking network, and in order to reduce the time delay, an architecture for Gateway Relocation is proposed. The evaluation of the proposed architecture can be seen in the simulated graphs, which comprises of many parameters like handover delay, packet Loss etc. Hence, from the proposed architecture of the heterogeneous networks, better performance can be obtained.