Uplink Pilot-to-Data Power Ratio Design Based on User Joint Optimization Algorithm in Multi-cell Massive MIMO System

In multi-cell massive multiple-input multiple-output (MIMO) systems, the reasonable design of user uplink pilot power and data power is the key to improving system performance. This paper aims to maximize the target cell's sum achievable uplink rate, and users' uplink pilot-to-data power ratio (PDPR) in this cell is designed in the presence of pilot contamination (PC). The optimal uplink PDPR under the condition of the lower bound of the sum achievable uplink rate is calculated. Based on this optimal uplink PDPR, the user joint optimization algorithm (UJOA) is proposed to design uplink PDPR in the target cell. To achieving the purpose of jointly optimizing the uplink PDPR, we use the error factor controlling the uplink PDPR and gradually approach the optimal uplink PDPR of each user in the target cell. Numerical results show that the UJOA scheme is better than the same ratio (SR) scheme in the design of uplink PDPR. We can achieve the better sum achievable uplink rate in the target cell and have a large gain in the system performance when using the uplink PDPR which designed by UJOA.