Optimal Uplink Pilot-Data Power Allocation for Large-Scale Antenna Array-Aided OFDM Systems

The effective aggregate rate (AR) performance of large-scale multiple-input multiple-output aided orthogonal frequency division multiplexing systems based on time division duplexing protocol critically depends on uplink (UL) pilot-data power allocations for all users. We derive an asymptotic closed-form expression of the system's achievable AR for typical channel estimation schemes, which is a function of individual users' UL power allocation factors. We prove that the effective AR is a convex function of each UL power allocation factor, when all the other factors are given. The globally optimal UL pilot-data power allocation that maximizes the system's effective AR can easily be obtained using an iterative procedure, by solving an univariate convex optimization with the golden section method for individual UL power allocation factors one by one in each iteration. Owing to the piecewise convexity of the effective AR, this iterative algorithm guarantees to find the unique globally optimal solution with only one iteration. The simulation results confirm that the achievable effective AR is significantly enhanced through the proposed optimization of UL pilot-data power allocation.