A Handover Mechanism Considering the Abstracted R-Factor

The user-perceived performance of voice services can be improved if the handover (HO) criterion is designed to consider the mean opinion score (MOS). However, this involves several problems, such as the measurement difficulty of the MOS, the detection difficulty of the MOS degradation factors, and the requirement of cross-layer design. To solve these problems, we propose an abstracted R-factor-based HO mechanism. The HO trigger used for this mechanism is derived by the optimization problem that considers the abstracted R-factor as the objective function. We first verify that the optimal HO trigger values exist for maximizing the R-factor by simulation. The derived HO trigger is similar to the optimal value extracted via simulation. The derived HO trigger is characterized by the linearization coefficients of the R-factor, the minimum required signal quality, the HO interruption time, and the variance of the average signal-to-interference-plus-noise ratio (SINR). These parameters can be easily obtained in the network. Therefore, the complexity of user equipment (UE) caused by the proposed HO mechanism is lower than that caused by the HO mechanisms that directly use the R-factor.