Abstract: Effective and timely Link Going Down (LGD) trigger mechanisms are critical to handover performance. Firstly, this paper introduced IEEE 802.21 MIH standard, and the required handover time was estimated using the information service provided by Media Independent Handover (MIH). Then, a LGD trigger mechanism based on grey prediction was proposed. It established grey prediction model by the required handover time, and the trigger time can be dynamically determined by the predictive Received Signal Strength (RSS) of mobile terminal. Furthermore, in order to reduce the prediction costs, a grey prediction modeling method based on signal decay detection was proposed. The simulation results show that this algorithm achieves the goal of effective and timely LGD trigger, and can reduce unnecessary prediction costs and avoid the waste of terminal resources.

Key words: Link Going Down (LGD), Media Independent Handover (MIH), grey prediction, signal decay detection, prediction costs

摘要： 及时有效的链路即将中断(LGD)触发机制对网络切换的性能有重要的影响。首先引入IEEE 802.21介质独立切换(MIH)标准，利用MIH提供的信息服务估计出网络切换所需时间，然后提出了一种基于灰色预测的LGD触发机制，通过估计的切换时间建立灰色预测模型，预测出终端的接收信号强度，动态确定触发时刻。并且为了降低预测开销，提出了基于信号衰减检测的灰色预测建模方法。仿真结果表明，算法实现了LGD及时有效地触发，而且可以减少不必要的预测开销，避免了终端资源的浪费。

关键词: 链路即将中断触发, 介质独立切换, 灰色预测, 信号衰减检测, 预测开销