Mobility Load Balancing Scheme based on Cell Reselection

Mobility Load Balancing (MLB) is one of the most important functions of Self-Organizing Networks (SON) in Long Term Evolution (LTE). The conventional MLB schemes based on handover (HO) conflict with Mobility Robustness Optimization (MRO) because both operations adjust the same HO parameters. The simulation results show that the conventional MLB scheme cannot achieve load balancing gain without some degradation in HO performance. In order to solve the conflict problem, this paper proposes an MLB scheme based on cell reselection (CR) that works in coordination with MRO. The proposed scheme adjusts the CR parameters and not the HO parameters, and never conflicts with MRO. Through computer simulations, it is shown that the proposed scheme can realize effective load balancing on a par with conventional schemes without any degradation in HO performance. The simulation results show that the proposed scheme is especially effective in an environment where a lot of small-size data packets are transmitted by a large number of users, which is highly applicable to current mobile networks with explosive diffusion of smart phones. In such case, more than 10% and 90% gains can be obtained in the total throughput and 5 percentile user throughput, respectively.