Effect of Outdated CSI on Handover Decisions in Dense Networks

We consider an ultra-dense network where each mobile is attached to the access point, which provides the best reference signal received power considering both path-loss and small-scale fading. In order to evaluate the effect of outdated channel state information (CSI) brought by feedback delay, we first derive the estimated and accurate handover probability according to outdated and perfect CSI, respectively. Furthermore, two metrics are proposed to measure the handover failure, i.e., false handover probability and miss handover probability. Simulations show that in sparse or ultra-dense networks, the imperfection of CSI is acceptable for handover decisions; however, in between, i.e., dense networks (medium-size networks), handover decisions are very sensitive to the user velocity and CSI imperfection.