Performance comparison between open-loop and closed-loop uplink power control in UTRAN LTE networks

Abstract

Uplink power control in 3GPP UTRAN Long Term Evolution networks supports an optional closed-loop component around an open-loop point of operation. In this study the performance difference between pure open-loop and combined open-and closed-loop power control has been evaluated using a full blown system level simulation model. The interworking between power control, adaptive transmission bandwidth, and adaptive modulation and coding has been thoroughly analyzed and the resulting performance differences depending on the users' locations within the cells are demonstrated by two-dimensional network plots. A deep inhomogeneous throughput distribution throughout the deployment area has been observed for pure openloop power control. Enabling the closed-loop component results in a more homogeneous performance albeit at lower mean throughput. Significant impact is given by the selected quality and level targets for the closed-loop component. The benefit of closed-loop power control is the higher homogeneity in terms of throughput across the entire cell area and its ability to adjust the transmission power according to the desired quality and level targets. Hence the network performance is stabilized in various cell environments.

Load adaptive power control in LTE Uplink

“…The standardization of Release 8 of LTE E-UTRA has been completed with the aim of achieving a 2 to 4 times higher spectral efficiency gain over HSPA UTRA [15]. The main features include reduced latency in user data transmission, the possibility of having scalable bandwidth up to 20MHz and support for packet-switched domain only.…”

“…The present paper will focus on the impact of the Adaptive Transmission Bandwidth (ATB) algorithm (described in [15] and in which UEs are not allocated more bandwidth than their power capabilities allow) on the optimal power control settings. The algorithm proposed in this contribution is based on the observed dependency of the optimal settings on the allocated bandwidth.…”

How to set the fractional power control compensation factor in LTE ?

“…Authors of [3], [4] compare the pure open loop power control scheme with a combination of open and closed loop algorithms. They study the influence of the maximum terminal power and of the dynamic Radio Blocks (RB) allocation.…”

“…They study the influence of the maximum terminal power and of the dynamic Radio Blocks (RB) allocation. Performances are obtained through extensive simulations for some combinations of P 0 and α in [3] and a joint optimization of these two parameters is performed in [4].…”