Optimization of downlink power control based on LTE

This paper presents a downlink power optimization scheme to improve LTE system performance in accordance with UE speed. Especially in railway wireless communication system, the speed of UE is very important factor because trains move so fast over 300km/h that usually downlink performance should be degraded. So the additional requirements for the high-speed railway mobile communication system besides commercial LTE system are needed. At the LTE Femtocell test-bed including HeNB, UE, fading simulator and some test equipment, downlink performance is tested with the P_A parameter of downlink power control for several cases of UE speed. By analysis of the test result the optimum P_A parameter can be found regarding UE speed. An adaptive downlink power control scheme is introduced to improve downlink performance in high speed mobile condition. According to the simulation result for the proposed scheme downlink throughput is increased by 6.2% in mobile environment considering LTE railway communication service.