Ulrich Türke

Cell outage management in LTE networks

Cell outage management is a functionality aiming to automatically detect and mitigate outages that occur in radio networks due to unexpected failures. We envisage that future radio networks autonomously detect an outage based on measurements, from e.g., user equipment and base stations, and alter the configuration of surrounding radio base stations in order to compensate for the outage-induced coverage and service quality degradations and satisfy the operator-specified performance requirements as much as possible. In this paper we present a framework for cell outage management and outline the key components necessary to detect and compensate outages as well as to develop and evaluate the required algorithms.

HSDPA performance analysis in UMTS radio network planning simulations

Whereas high speed downlink packet access (HSDPA) channel performance has been investigated to some extent, its impact on the planning process has hardly been addressed at all. In order to allow a fast HSDPA performance analysis in everyday planning purposes, a novel two-staged process is introduced. It builds on snapshot based simulations, but introduces a dynamic analysis of the HSDPA channel with scalable increase in computational effort of the network analysis. The method includes very detailed modeling of the RSDPA channel, including a time varying fading environment. Different traffic models and scheduling schemes can easily be integrated. The application of the approach is illustrated for a realistic planning scenario, where different HSDPA configurations are compared.

An advanced approach for QoS analysis in UMTS radio network planning

This paper presents a novel analysis concept for UMTS radio network performance evaluation. In particular a mix of multi-rate circuit switched (CS) and packet switched (PS) service types is considered. A flexible way of modeling different Quality of Service (QoS) policies taking costs for bit-rate adaptation into account is introduced. All constraints and limits important with regard to network performance are considered. The simulation is based on the “Monte-Carlo Method”. Fast evaluation of individual snap-shots of the system is achieved by carrying out calculations on cell basis. This leads to a considerably higher rate of convergence and also a lower computational effort per iteration compared to state-of-the-art computations on connection basis. Furthermore, an additional gain is achieved by a highly linear modeling of the system.

Public UMTS radio network evaluation and planning scenarios

A library of three public and realistic scenarios for UMTS radio networks was compiled within the EU-funded project MOMENTUM. We illustrate the contents of these scenarios and demonstrate the importance for detailed data by some cross-checks with common simpler models from the literature. The scenarios are valuable to research for several reasons. Being public, the datasets can be used freely in the scientific community. In similar situations, the availability of public benchmark data has stimulated research over years and has significantly contributed to the reproducibility and comparability of computational results. Being realistic, the scenarios are far more detailed than those typically used for publications; they help scientists to better establish or to improve on the practical relevance of their results.

Short term dynamic system level simulation concepts for UMTS network planning

Universal Mobile Telecommunication System (UMTS) network simulation focused on network planning requires simulation concepts capable of providing reliable results especially on Quality of Service aspects. In simulations, there is always a tradeoff between a reasonable maximum simulation time, and the system complexity resp. the evaluated level of detail. Three simulation concepts, namely static, short term dynamic, and dynamic, are briefly introduced and compared qualitatively with respect to their suitability to network planning. They differ in how detailed the dynamic system aspects, mainly user mobility and session details, are considered. The focus is on the short term dynamic (STD) simulation concept which combines advantages of the static and dynamic concepts. The evaluated system parameters are provided, and simulation results are shown. Performance issues are discussed and first improvements are applied and investigated. The STD simulation concept is a reasonable combination of the static and dynamic concepts, providing abilities to evaluate dynamic system aspects. First speed-up approaches save over 85% run time, and further methods have been identified for investigation.

A generic approach for including live measurements and traffic forecasts in the generation of realistic traffic scenarios in mobile radio networks

This paper presents a generic approach for including live measurements from 2G or 3G networks into the planning and optimisation process of UMTS networks. Network planning is done under the assumption of traffic predictions. The proposed method yields increased planning accuracy by exploiting existing knowledge on traffic distribution. This novel mapping of live measurement data takes into account the subscriber specific behaviour in different environments and clutters, the radio conditions of the cells where the traffic is measured, and extrapolation and smoothing methods based on radio conditions and clutter specifics. As result, a generic methodology is designed which is able to handle arbitrary planning scenarios. The overall approach is illustrated at a large scale network example of the city of Shanghai.

Policy-Based SON Management Demonstrator

A Self-Organising Network (SON) represents an approach where the optimisation of a mobile radio network is automated through a set of independently operating SON functions. These SON functions, however, require to be configured in order to allow for an optimised network performance with respect to technical objectives defined by the network operator. The SEMAFOUR demonstrator shows a concept for SON management based on operator objectives, where the SON function configuration is performed in an automated way. The demonstrator illustrates the different aspects and complexity of the management of SON in a heterogeneous network.

Demonstrator for objective driven SON operation

The demonstrator shows a self-management system for heterogeneous mobile wireless networks that uses context-specific and weighted Key Performance Indicator (KPI) target values defined by the operator to automatically and autonomously configure and control the operation of Self-Organising Network (SON) functions such that they contribute to achieving these KPI targets by appropriately optimising the network configuration. Changing KPI targets, context or weights leads to an automatic re-configuration of the SON functions by using a policy system, and the impact of the changes to the policy and the network configuration can be seen and traced in the demonstrators realistic network scenario and KPI charts.