Minimum-Risk Layer 2 Trigger Levels for Proactive Media-Independent Handovers

Anticipated handovers that use Link Going Down (LGD) and Link Down (LD) trigger events require the network operator to set the LGD trigger high enough that the handover completes before the LD trigger event. However, setting the LGD trigger too high can result in frequent handovers by mobile nodes, leading to high signaling overhead. We propose a mechanism for balancing these requirements using a risk function. The function expresses the risk with respect to the probability that the LD event falls within a range of times with respect to handover completion. The risk function can be used with weights that allow the network operator to set the relative importance of the early handover completion requirement and the requirement that the LGD trigger not be too sensitive. Because the risk is expressed using the characteristic function of the handover time, we can easily use it to set the LGD trigger for any mobility management protocol.