Self-optimization of handover parameters for dynamic small-cell networks

Seamless is an essential feature of cellular networks. For small-cell networks, effective becomes particularly challenging. If some cells may be activated and deactivated dynamically, effective handling will become even more difficult. A key factor of good performance is handover timing, that is, making decision at a right time. If is executed too early or too late, users will experience temporary link disconnection, called radio link failure RLF. Handover timing is controlled by parameters, which are set by the network. RLF prevention is directly related to the proper configuration of these parameters. In this paper, we propose a self-optimization scheme that adjusts the parameters to minimize RLFs for dynamic small-cell networks. Our scheme first detects the types of RLF and then adjusts the parameters according to the types of RLF. Unlike most existing schemes, our scheme adjusts both system common parameters and cell-specific parameters together. In certain situations, such as when two adjacent cells do not have sufficient coverage overlap, RLFs may not be reduced to a satisfactory level by the parameter adjustment alone. To deal with such a case, our scheme adjusts the cell coverage in conjunction with the parameter optimization. The simulation results show that the proposed scheme can virtually eliminate RLFs.