Self-optimization of uplink power control in LTE.

Abstract

In today’s heterogeneous communication networks, where different technologies such as Global System for Mobile communication (GSM)/Universal Mobile Telecommunications System (UMTS)/Long Term Evolution (LTE)/ New Radio (NR) coexist, the ability to self-manage and automate the maximum number of processes is essential. Only in this way, a better network performance can be achieved while reducing operational costs (OPEX, Operating Expenses). This was the reason why the concept of Self-Organizing Networks (SON) emerged, which includes the functionalities of self-configuration, self-optimization and self-healing.

Self-optimization consists of the automatic adjustment of network parameters, whose settings are dynamically updated whenever there is a change in user traffic and mobility trends, or new equipment or functionality is introduced into the network. Examples of optimization use cases are the updating of neighbor cell list, or capacity and coverage optimization through procedures such as Remote Electrical Tilt (RET) or UpLink Power Control (ULPC).

The first tests carried out in live networks showed that in LTE the UpLink (UL) is much more restrictive than the DownLink (DL). This is due to the limited power of user terminals and the interference that exists in this link, coming from a large number of User Equipments (UE) in neighbor cells. To alleviate this effect, a possible strategy would be to adjust the UL nominal power (P0), i.e., the transmit power of each UE.

In this thesis, a preliminary analysis shows the impact of P0 changes in ULPC on network performance indicators. The sensitivity analysis of said parameter is carried out in a commercial LTE network, and the acquired knowledge is the starting point for designing the optimization methods presented in this work. Once the impact of P0 parameter is understood, a model is devised to accurately determine the neighbor cells that cause the highest UL interference on the cell under study.