Channel Prediction-Based Adaptive Power Control for Dynamic Wireless Communications

In order to improve the transmit power efficiency at the Mobile Station (MS), the transmit power is usually adjusted based on feedback information from the Base Station (BS) or Channel State Information (CSI) estimated at the MS. In fast-varying channels, because of the propagation and estimation delays, and the short channel coherence time, both the feedback information and the estimated CSI may become outdated at the transmit instant, leading to a reduction in power control performance. In this paper, a new channel prediction-based adaptive power control technique is proposed for uplink transmission in Time Division Duplex (TDD) Orthogonal Frequency Division Multiplexing (OFDM) systems. Based on the predicted Channel Impulse Responses (CIRs) provided by a cluster-based time- domain channel predictor, the transmit power is allocated to each OFDM subcarrier and then, a global gain is applied to compensate for the propagation path loss. In doing this, the power control process does not rely on the feedback information from the BS nor the estimated CSI at the MS and thus, the system responsiveness, adaptivity, and power savings are improved.