EVOLUTION OF VERTICAL HANDOFF TO VOICE OVER LTE VIA GENERIC ACCESS (VOLGA)

In Wireless Mobile Cellular Networks, users usually move between heterogeneous networks. In this type of environment, handoff procedure algorithm, handoff decision and its management is very important issue. Wireless Mobile Cellular Network supports the handoff process for users between various wireless technologies such as WLAN, CDMA and modern 3G networks. Heterogeneous networks are integrated in 4G wireless. To have seamless communication and mobility between these heterogeneous wireless access networks, support of vertical handoff (EVH) is required. Vertical handover is the convergence of heterogeneous networks for e.g.:- handover process between wireless cellular networks and WLAN. In this paper one of the handoff algorithms is discussed for different path loss models. Actually, the requirement to initiate handoff arises when the Received Signal Strength of the current base station falls below the threshold value. It adaptively controls the handoff according to the requirements of cells. The paper gives a theoretical overview and comparison of 3rd Generation Generic Access Networks with LTE's VoLGA. Migration towards Packet Switched Technology brought significant changes on Voice and Text services because of their circuit switched nature.