In wireless networks during data transmission Mobile Nodes (MN's) seamless connectivity becomes a very challenging issue among heterogeneous wireless networks. When MN moves from home network to foreign network, it performs handover which is referred as vertical handover. Proxy MIPv6 (PMIPv6), a network-based mobility management protocol does not require the involvement of MN during handover. On behalf of the MN to perform the mobility-related signaling, network entities are allocated by the PMIPv6. In this paper, a new vertical handover decision algorithm is proposed to optimize the performance of the handover.