Heterogeneous Network Handover Mechanism Based On The Position Prediction

The development of wireless networks let mobile terminals have more connection choices, but it also brings more difficulty for the handover decisions. Thus the emerging of handover technologies and their optimization have become a key researching point of modern wireless communication fields. Terminals would make inaccurate and frequent handovers due to the variations of the speed and direction. It may affect terminals' communication performance. What's more, it would make damages to terminals. As a result, it brings poor experiences for users. So this thesis focus on how to reduce the handover times and the handover latency.Combining with the dwell time algorithm and the straight highway scenario, this paper proposed a speed-based handover prediction algorithm. In this algorithm, speed matrices and the corresponding weight matrices were created. Then the speeds and next interval position of terminals would be determined. Finally terminals made a handover decision combined with the dwell time algorithm. The simulations results indicated that, the proposed algorithm would slightly increase handover times, but reduce handover latency with sufficient RSS guaranteed in communication, comparing to the traditional dwell time algorithm.On the basis of preliminary research and the promise that communication quality is guaranteed, a vertical handover algorithm is proposed which based on acceleration prediction in order to reduce the handover times further. The algorithm predicts the RSS(Received Signal Strength) of WIMAX and LTE networks in the next time based on the velocity obtained by APA(Acceleration Prediction Algorithm). Then velocities multiply their timeslots to get moving distance respectively. Then current positions were added with moving distances, thus to get next time's positions. Finally distance between AP (Access Point) and MN (Moving Node) were calculated by the relationship between distance and present RSS. In the end, the next time's RSS are predicted. Then an effective handover algorithm was proposed based on the predicted RSS aiming to reduce the handover times and shorten handover latency. The simulations results indicated that, the proposed algorithm could reduce about 10% handover times and reduce handover latency with sufficient RSS was guaranteed in communication, comparing to the traditional dwell time algorithm.