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In LTE Uplink, the slow varying pathgain and shadowing are compensated by the standardized open loop power control (OLPC) which is based on a power density offset and a compensating factor for the pathloss experienced by the users. The optimization of those parameters reveals a dependency on the allocated bandwidth. A Load Adaptive Power Control (LAPC) algorithm is proposed to handle the bandwidth variations and ensure optimal system performance. In this contribution it is shown that using closed loop power control commands to adapt the transmission power density to the used bandwidth, it is possible to achieve coverage gains up to 60% while maintaining a cell throughput comparable to the reference case.

SUMMARYUplink power control in 3GPP UTRAN long term evolution (LTE) networks consists of a closed-loop scheme around an open-loop point of operation. The uplink performance of the network is decisively influenced by power control. This paper provides insight into the uplink power control procedure and its interworking with adaptive transmission bandwidth (ATB) as well as adaptive modulation and coding (AMC). A detailed performance evaluation is presented based on system level simulations. In the first step, the performance of pure open-loop power control (OLPC) was analysed and the impact of parameter settings on resource allocation, utilisation of specific modulation and coding schemes (MCS), re-transmission rate, and resulting throughput was determined. A two-dimensional parameter optimisation for full path-loss (PL) compensation and fractional power control (FPC) was performed to conclude the best strategy for the trade-off between network capacity and coverage. In the second step, the impact of traffic load on the interaction between the different LTE radio resource management algorithms was analysed. A novel strategy is presented which introduces traffic load dependent decisions for the closed-loop power control (CLPC) component to optimise the uplink throughput. This solution provides an automatic configuration for LTE networks without further intervention by the operator.

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