A study of handover techniques used in heterogeneous networks using LTE and WLAN

Recently, smart phones have proliferated considerably into the global market and millions of multimedia applications have been newly introduced. Consequently, demands for wireless communications with high data rates has increased considerably. Many cellular service providers are hard-pressed to satisfy the ever-increasing demand for the wireless communication resources. In order to reduce the heavy load and increase overall capacity of cellular networks, internetworking between Wireless Local Area Networks (WLANs) and cellular networks has being considered. In the internetworking of cellular networks and WLANs, since performance of overall networks is closely related with the execution timing of vertical handover, an efficient vertical handover technique is required. In general, IEEE 802.11WLAN can offer higher data rate to users than cellular networks, while its service coverage is relatively small and it does not support mobility in general. On the other hand compared with WLAN, cellular networks cover large area and support users with higher mobility but only at a relatively lower data rates than WLAN. Therefore, if WLAN and cellular networks can be integrated effectively, both users and wireless service providers can take advantage of those networks’ complementarities. Especially, cellular networks can accommodate more users with high data rates by sharing its traffic loads with WLANs. In conventional networks, since information which a Mobile Node (MN) can acquire in wireless environments is limited, many handover triggering mechanisms are based on the Received Signal Strength (RSS) which can be easily measured by the MN. The objective of research reported in this work is to study the vertical handover techniques which have been developed for Long-Term Evolution (LTE) networks, and for WLANs. Based on this study a new technique for efficient vertical handover between LTE networks and WLANs has been proposed. The advantages and disadvantages of the proposed approach have been discussed