Jakob Belschner

A measurement-based study of handover improvement through range expansion and interference coordination

Although the range expansion and inter-cell interference coordination ICIC have been shown to successfully enhance the capacity and load balancing in the Heterogeneous Network, their impacts on the handover HO performance are not fully understood in existing studies. In this paper, a novel measurement-based approach is adopted to investigate these issues, where the real measured data of the reference signal received power in a macro-pico co-channel deployment are collected. Then the mobility performance in terms of the HO failure rate and ping-pong rate is simulated with various ICIC schemes in the same reality environment. This has been made possible by modeling the possible HO failure events based on evaluating the downlink received signal-to-interference-plus-noise ratio from reference signal received power. The simulation results indicate that range expansion together with ICIC can have positive or negative influences on macro-to-pico, pico-to-macro, pico-to-pico and macro-to-macro HOs in the Heterogeneous Network. The existing static ICIC or mobility-based ICIC cannot handle the intra-layer pico-to-pico and macro-to-macro interference, thus limiting their abilities to improve the mobility performance. Motivated by this, a dynamic-ICIC-aided HO procedure is proposed. The proposed HO enhancement method is more flexible and effective in mitigating both the inter-layer and intra-layer interference, outperforming the existing methods significantly. Copyright

Optimisation of Radio Access Network Operation Introducing Self-x Functions: Use Cases, Algorithms, Expected Efficiency Gains

With the deployment of next generation (4G) mobile radio systems an additional radio access network is established. A variety of different Radio Access Technologies (RATs) will be operated in parallel. In this framework, the Long Term Evolution (LTE) system, specified by 3GPP, will have to co-exist with WiMAX, mobile 2G/3G networks and Wireless Local Area Networks (WLANs). To cope with this increasing diversity and complexity mechanisms for self-optimisation, self-organisation, self-healing, self-configuration (self-x) are essential to guarantee cost efficient and high quality network operation. Within the project E³ (1) self-x functionalities for different use cases and different elements of a mobile radio access network are developed. Aim of this paper is to give and overview about the interworking of different self-x functionalities and to present three exemplary use cases. I. INTRODUCTION Evolution of mobile radio networks is driven by the demand for new, high bit rate consuming applications and services. The technical answer is the development of new and more powerful radio technologies and integration into existing mobile radio networks. This leads to significantly higher complexity and heterogeneity while pressure for maintaining manageability and cost efficiency of the networks is continuously increasing. E³ answer is introduction of solutions for obtaining higher flexibility and efficiency in usage of radio, hardware and computational resources by cognition, self- organisation and self-optimisation. This paper presents the interworking of cognitive radio self-x functions in E³ environments and hereafter three exemplary self-x use cases namely Handover Parameter Optimisation, Protocol Stack Self- Configuration & Topology Self-Organisation and Knowledge- based Proactive Context Handling.

Agile resource management for 5G: A METIS-II perspective

An explosive growth in the demand for higher data rates and capacity along with diverse requirements set by massive and ultra-reliable machine-type communications are the main drivers behind the development on new access technologies as part of the fifth generation (5G) networks. Currently, different air interface (AIF) and/or AIF variants, optimized based on the frequency band of operation and use case, are envisioned for such a network. Developing an agile resource management framework for 5G networks is one of the main goals of the METIS-II project. The METIS-II project builds strongly upon the EU flagship project METIS, which has laid the foundation of 5G. This framework will take into account the multi-link and multi-layer constraints currently envisioned for 5G. In this paper, we provide our first insights into agile resource management and the associated synchronous control functions. We will discuss the essential building blocks in terms of technology enablers and their mapping to 5G services and deployments. The introduced agile resource management framework for 5G is expected to enable enhanced interference management, dynamic traffic steering, fast radio access network (RAN) moderation, efficient context management, and optimized integration with legacy networks.

Performance Measurement Results Obtained in a Heterogeneous LTE Field Trial Network

In order to get practical experience with heterogeneous LTE networks Deutsche Telekom and Huawei built up a field trial network consisting of one macro site and eight pico sites which are spatially spread in different environments to cover many pico site deployment scenarios. The main performance results obtained in the field trial are presented for both relevant deployment aspects: Either macro and pico cells are running on the same frequency or the pico cell layer uses an individual carrier frequency. Outdoor as well as indoor conditions are covered in the paper. As the measure for the pico cell size we introduce a coverage radius based on a minimum throughput threshold. For the best performing scenario - outdoor condition and different frequencies for macro and pico cells - the mean throughput ranges between 40-65 Mb/s for most pico cells and the coverage radius exceeds 200m. For the other scenarios the performance measures are partly significantly lower.

Assessment of future backhaul and fronthaul networks for HetNet architectures

Mobile traffic is heavily increasing in the last years and a massive continuous growth is forecasted for the next decade. To cope with this significant traffic increase in mobile networks and the further evolving competitive market situation, operators are looking for solutions to increase the capacity of their mobile networks, while keeping the cost low. Besides enhancements of mobile radio technology and adding new spectrum to the existing sites, densification of radio sites, by so called small cells, is considered as a very promising option to increase capacity. Adding small cells to the already existing macro cell layer lead to heterogeneous networks (HetNet). Because of the scarce radio spectrum it is most likely that the radio sites in HetNets will use the same frequencies and therefore create interferences. To mitigate this impact different coordination methods have been proposed creating new challenging requirements on the transport network compared to todays backhaul. Cost effective and scalable transport solutions are an important fundament for wide and successful deployment of HetNets. This paper investigates and assesses techno-economically different architectures for backhaul and fronthaul transport of existing and newly deployed radio sites in HetNet architectures taking requirements from interference co-ordination into account.

Centralized coordinated scheduling in LTE-Advanced networks

This work addresses the problem associated with coordinating scheduling decisions among multiple base stations in an LTE-Advanced downlink network in order to manage inter-cell interference with a centralized controller. To solve the coordinated scheduling problem, an integer non-linear program is formulated that, unlike most existing approaches, does not rely on exact channel state information but only makes use of the specific measurement reports defined in the 3GPP standard. An equivalent integer linear reformulation of the coordinated scheduling problem is proposed, which can be efficiently solved by commercial solvers. Extensive simulations of medium to large-size networks are carried out to analyze the performance of the proposed coordinated scheduling approaches, confirming available analytical results reporting fundamental limitations in the cooperation due to out-of-cluster interference. Nevertheless, the schemes proposed in this paper show important gains in average user throughput of the cell-edge users, especially in the case of heterogeneous networks.

5G radio access network architecture based on flexible functional control / user plane splits

5G networks are supposed to offer a high flexibility in a several ways. In this regard, a twofold split of the processing in the radio access network is under discussion: A control plane / user plane split to support the software defined networking principle and a radio protocol stack layer based split to allow a flexible placement of processing functions between a central and distributed units. In this work, the motivation and state of the art for both splits are described including a discussion of the advantages and disadvantages. It is followed by a description of a network architecture allowing a flexible implementation of these splits. This especially focuses on the required interfaces between control and user plane.

The effect of out of cluster interference on coordinated beamforming in LTE-A HetNets

Coordination is foreseen to be an important component of future mobile radio networks. It is especially relevant in heterogeneous networks, where high power base stations produce strong interference to an underlying layer of low power base stations. This work investigates the impact of the interference from base stations which are not part of the cooperation. This interference is called out of cluster interference. The practical implications of out of cluster interference are investigated in a realistic implementation of cooperation through coordinated beamforming. As a key result the relationship between the amount of out of cluster interference and the performance in the network is shown. Detailed simulation analysis is presented on a realistic network layout. Comprehensive system-level LTE-Advanced simulations were used to show which network layouts are suitable for the coordination.

Cost evaluation of small cell backhaul architectures

This study analyses and compares various small cell backhaul deployment scenarios considering different starting situations, backhaul technologies, and small cell locations.

5G Visualization: The METIS-II Project Approach

One of the main objectives of the METIS-II project was to enable 5G concepts to reach and convince a wide audience from technology experts to decision makers from non-ICT industries. To achieve this objective, it was necessary to provide easy-to-understand and insightful visualization of 5G. This paper presents the visualization platform developed in the METIS-II project as a joint work of researchers and artists, which is a 3D visualization tool that allows viewers to interact with 5G-enabled scenarios, while permitting simulation driven data to be intuitively evaluated. The platform is a game-based customizable tool that allows a rapid integration of new concepts, allows real-time interaction with remote 5G simulators, and provides a virtual reality-based immersive user experience. As a result, the METIS-II visualization platform has successfully contributed to the dissemination of 5G in different fora and its use will be continued after METIS-II.