A Numerical Study of Scheduling Power Efficiency Gain for MIMO-OFDM Networks

Though previous studies have proven that the spectral efficiency of wireless channels can be significantly improved by employing time-domain power allocation schedulers, it is not clear whether the benefits from scheduling techniques are still remarkable in complex multi-user wireless systems, particularly the ones under rate constraints. In this study, we focus on multi-user multiple-input multiple-output orthogonal frequency division multiplexing (MU-MIMO-OFDM) networks, which are considered as the standard configurations of future wireless networks. Specifically, we study and analyze the performance gain brought by time-domain schedulers in terms of power efficiency gain (PEG) in MU-MIMO-OFDM wireless networks with rate constraints. To enable the evaluation of PEG in such a complex channel model, a fast approximation method is proposed to efficiently obtain an approximated PEG which is shown to be an accurate surrogate. With the proposed method, the approximated PEG is numerically simulated in the 3rd generation partnership project spatial channel extended model (SCME). Simulation results show that the approximated PEG is generally insignificant under most practical outdoor wireless environments defined in the SCME, e.g., Less than 1.5dB for a 1-second scheduling period. The approximated PEG further reduces as the numbers of users and equipped antennas increase. This study indicates that it should be reconsidered when employing traditional time-domain scheduling techniques in the rate-constrained MU-MIMO-OFDM networks.