N-class replacement policy for resolving mobility database overflow

Visitor location register (VLR) may overflow due to the limited capacity. By replacing an existing record, the overflow users can still receive services. The most-idle replacement (MR) policy was proposed to improve the performance of the random replacement (RR) policy. The MR policy seems to be optimum and outperforms the RR policy significantly. However, the MR policy has potential limitations. Accordingly, we propose the N-class replacement (NR) policy to overcome the drawbacks. Moreover the simulation results show that the NR policy outperforms the MR policy in most scenarios investigated in our study. As N increases, the improvement becomes more considerable.