Advanced handover scheme considering downlink and uplink service traffic in asymmetric channel

We study an application of link asymmetry between downlink and uplink in orthogonal frequency division multiple access (OFDMA) systems. In our previous works, we investigated downlink and uplink asymmetry and showed the advantages of utilizing the link asymmetry in link management. In this paper, we propose an advanced handover scheme that exploits multiple-criteria decision-making (MCDM) considering the asymmetric channel quality. The advanced handover scheme consists of the uplink estimation method and two handover target cell selection schemes. The uplink estimation method does not require additional radio resources to obtain uplink channel quality of neighbor cells, and the target cell selection schemes select an optimal target cell on the basis of the technique for ordering by similarity to the ideal solution (TOPSIS) algorithm with the downlink and uplink signal-to-interference-plus-noise ratio (SINR). The advanced handover scheme can be exploited to achieve two different purposes. First, the proposed scheme maximizes throughput on a network by determining weights on the basis of the downlink and uplink traffic load in a network. Second, the proposed scheme maximizes the quality of experience (QoE) from a user perspective by determining weights on the basis of the downlink and uplink traffic load ratio of a used service in a mobile device. We evaluate the performances of the proposed schemes from the perspectives of the network and a user by simulation. According to the results, we show that the proposed scheme outperforms previous studies in terms of network throughput, mean opinion score (MOS), and the number of calls dropped.