Optimization of handovers in present and future mobile communication networks.

摘要

In a mobile communication system a handover is defined seamless if the user is unaware that a handover has occurred, the handover process incurs low delay, and the data loss is kept to a minimum. We strive to solve some of the challenges involved in achieving a seamless handover in current and future wireless networks.;We explore the handover challenges involved in the Third Generation-Wireless LAN (3G-WLAN) integrated Internet Protocol version 6 (IPv6) network. We propose a handover scheme that utilizes the fast mobile IPv6 protocol with pre-authentication. Using this scheme we have reduced the authentication delay by more than 50% and eliminated packet loss by utilizing the fast mobile IPv6 protocol. Unlike the majority of the solutions to this problem, our solution does not require the mobile node to transmit and receive on the two radio interfaces of 3G and WLAN simultaneously. Such use of both interfaces would deplete the battery power of a mobile device considerably.;The most essential part in achieving a seamless handover is an early preparation. This can be achieved by an efficient prediction scheme. We present an adaptive prediction algorithm that adapts to the number of inputs available for prediction and the mobility pattern of mobile nodes. In 802.11 based wireless LANs the most delay in handover is due to the active scan procedure of scanning all available channels to find a new access point. We introduce WiMap, a new handover scheme that utilizes location knowledge of mobile nodes to improve the active scan delay and hence decrease the energy consumption of devices in 802.11 based wireless LANs. Our simulation results show an improvement of over 30% in active scan delay;Finally, we provide a generic framework for handover decision management in next generation networks. We show that any handover decision algorithm can utilize our framework. We show the feasibility of applying our framework through an implementation example. We present a novel handover decision algorithm that optimizes the quality of experience of the user. The simulation results show that our algorithm chooses the optimal network and is practical when the values offered by the different access networks have a vast deviation. Our proposed algorithm also avoids unnecessary handovers.