Uplink Power Control in LTE - Overview and Performance, Subtitle: Principles and Benefits of Utilizing rather than Compensating for SINR Variations

Uplink power control is a key radio resource management function. It is typically used to maximize the power of the desired received signals while limiting the generated interference. This paper presents the 3GPP long term evolution (LTE) power control mechanism, and compares its performance to two reference mechanisms. The LTE power control mechanism constitutes of a closed loop component operating around an open loop point of operation. Specifically, the open loop component has a parameterized fractional path loss compensation factor, enabling a trade-off between cell edge bitrate and cell capacity. The closed-loop component can be limited to compensate for long-term variations, enabling fast channel quality variations to be utilized by scheduling and link adaptation. Simulation results indicate that the LTE power control mechanism is advantageous compared to reference mechanisms using full path loss compensation and SINR balancing. The fractional pathless compensation can improve the cell-edge bitrate and/or the capacity with up to 20% while at the same time battery life time is improved. The fast SINR balancing closed loop mechanism performs poorly at high load since it does not utilize the link adaptation and the full link performance capability in LTE.