John Turk

Handover Parameter Optimization in LTE Self-Organizing Networks

This paper presents a self-optimizing algorithm that tunes the handover (HO) parameters of a LTE (Long-Term Evolution) base station in order to improve the overall network performance and diminish negative effects (call dropping , HO failures). The proposed algorithm picks the best hysteresis and time-to-trigger combination for the current network status. We examined the effects of this self-optimizing algorithm in a realistic scenario setting and the results show an improvement from the static value settings.

A coordination framework for self-organisation in LTE networks

Self-organising Networks (SON) as introduced for 3G Long Term Evolution (LTE) will typically involve several different SON functions. These functions are not necessarily aware of each other and may have complex relations and interdependencies, for example, conflicting parameter settings, depending on their design and approach. Coordination of SON functions may become necessary in order to harmonise the actions of SON functions and allow for a stable and reliable behaviour of the SON system. This paper describes different conflict types, harmonisation approaches to avoid and resolve conflicts, and a functional framework with different roles to achieve harmonisation. An exemplary case study is given. The paper concludes that, in case several conflicting SON functions are implemented in a network, a SON Coordinator may be beneficial to prevent from network instabilities and/or to improve the performance.

Embedding Multiple Self-Organisation Functionalities in Future Radio Access Networks

Wireless network operators today allocate considerable manual effort in managing their networks. A viable solution for lowering the manual effort is to introduce self-organisation functionalities. In this paper we discuss the challenges that are encountered when embedding multiple self-organisation functionalities into an overall self-organisation concept for future wireless networks. We foresee that there will most likely be a need of a rather complex coordination mechanism for handling multiple self-organisation functionalities in future wireless access networks.

On the quest for new KPIs in mobile networks: The impact of throughput fluctuations on QoE

Downlink throughput is the most widely used and accepted Quality of Service (QoS) related feature within the networking community, specially in the operational field. Current quality monitoring and reporting systems as well as quality benchmarking campaigns use the Average Downlink Throughput (ADT) as metric to assess the performance of the network. For example, flow-based monitoring systems normally report the per flow ADT as a throughput-based Key Performance Indicator (KPI), which is then aggregated at different temporal (e.g., 15 minutes), geographical (e.g., per radio cell) and/or logical (e.g., per service) scales to reflect the health of the network. A similar direction is currently followed within the Quality of Experience (QoE) research domain, where ADT is translated into a measure of user satisfaction for bandwidth-sensitive services (e.g., video streaming, file sharing, etc.). We claim that the ADT is not always an accurate KPI in terms of QoE for bandwidth-sensitive services, and present results showing that the variation of downlink throughput can actually have a major impact on the perceived quality of the end user. In this paper we present a complete study of the QoE undergone by 52 mobile users in controlled subjective lab tests, using different mobile applications such as YouTube, Facebook and Gmaps. By shaping the traffic of the users through multiple bandwidth fluctuation patterns, we conclude that novel downlink-throughput related KPIs must be defined for QoE-based traffic analysis in mobile networks. Based on this observation, we propose some very first simple throughput fluctuation models to define such KPIs.

A case study on estimating future radio network energy consumption and CO 2 emissions

In this paper we examine the potential impact on total network energy consumption and CO2 emissions when LTE is introduced into an existing cellular network. We note that by replacing existing 2G or 3G hardware with modern equipment the energy consumption per node can be reduced by approximately 50% already today. Furthermore, based on power models from the EARTH project, we predict that this potential gain will continue to increase year by year. In the paper we show that it is possible to reduce the total network energy consumption by approximately 60% by 2020 compared to today, despite deploying LTE, if we modernize the existing legacy hardware at the same pace as LTE is rolled out. Vodafone has a CO2 reduction target of reducing emissions by 50% in the mature market by 2020 compared to the reference year 2006/07, and this target appears to be realistic to reach.