Recent Advances in Indoor Localization: A Survey on Theoretical Approaches and Applications

Nowadays, the availability of the location information becomes a key factor in today’s communications systems for allowing location based services. In outdoor scenarios, the Mobile Terminal (MT) position is obtained with high accuracy thanks to the Global Positioning System (GPS) or to the standalone cellular systems. However, the main problem of GPS or cellular systems resides in the indoor environment and in scenarios with deep shadowing effect where the satellite or cellular signals are broken. In this paper, we will present a review over different technologies and concepts used to improve indoor localization. Additionally, we will discuss different applications based on different localization approaches. Finally, comprehensive challenges in terms of accuracy, cost, complexity, security, scalability, etc. are presente

Context-aware Self-Optimization in Small-Cell Networks

Most mobile communications take place at indoor environments, especially in commercial and corporate scenarios. These places normally present coverage and capacity issues due to the poor signal quality, which degrade the end-user Quality of Experience (QoE). In these cases, mobile operators are offering small cells to overcome the indoor issues, being femtocells the main deployed base stations. Femtocell networks provide significant benefits to mobile operators and their clients. However, the massive integration and the particularities of femtocells, make the maintenance of these infrastructures a challenge for engineers. In this sense, Self-Organizing Networks (SON) techniques play an important role. These techniques are a key feature to intelligently automate network operation, administration and management procedures. SON mechanisms are based on the analysis of the mobile network alarms, counters and indicators. In parallel, electronics, sensors and software applications evolve rapidly and are everywhere. Thanks to this, valuable context information can be gathered, which properly managed can improve SON techniques performance. Within possible context data, one of the most active topics is the indoor positioning due to the immediate interest on indoor location-based services (LBS). At indoor commercial and corporate environments, user densities and traffic vary in spatial and temporal domain. These situations lead to degrade cellular network performance, being temporary traffic fluctuations and focused congestions one of the most common issues. Load balancing techniques, which have been identified as a use case in self-optimization paradigm for Long Term Evolution (LTE), can alleviate these congestion problems. This use case has been widely studied in macrocellular networks and outdoor scenarios. However, the particularities of femtocells, the characteristics of indoor scenarios and the influence of users’ mobility pattern justify the development of new solutions. The goal of this PhD thesis is to design and develop novel and automatic solutions for temporary traffic fluctuations and focused network congestion issues in commercial and corporate femtocell environments. For that purpose, the implementation of an efficient management architecture to integrate context data into the mobile network and SON mechanisms is required. Afterwards, an accurate indoor positioning system is developed, as a possible inexpensive solution for context-aware SON. Finally, advanced self-optimization methods to shift users from overloaded cells to other cells with spare resources are designed. These methods tune femtocell configuration parameters based on network information, such as ratio of active users, and context information, such as users’ position. All these methods are evaluated in both a dynamic LTE system-level simulator and in a field-trial

An innovative intelligent system for child care & safety applications using ZigBee Wireless Sensing Networks

The focus of this paper is to outline the research undertaken of Wireless Sensor Net-works and how they can be used to assist in home health and safety applications. The particular area of interest is a computer controlled system that tracks a wireless sensor attached to a child indoors for the purpose of alarming when the child enters a prede-termined unsafe area. The system must also define boundaries and have the ability to alert a parent/guardian in the case of the boundaries being breached. A thorough review of the available literature was undertaken which gave the author background information as to techniques for localisation and their suitability in indoor applications. An empirical approach to localisation using the Profiling/Fingerprinting method was used. A centralised system design was implemented and an application called Adapt-able Infant Monitoring System was written and tested to perform the localisation and boundary alarming and to provide the ability for remote location retrieval via storing relevant data in a database. Algorithms were proposed to reduce the localisation error. These algorithms have been rigorously tested in two scenarios. A baseline test was applied to create a benchmark, then testing was applied to a real residential situation. The results are analysed and discussed. The results concluded that localisation using the specified hardware and the finger-printing technique was inadequate for the application domain. Factors attributing to the localisation error have been discussed including irregular radio signal propogation which has been earmarked for further work. The localisation accuracy does not render the research work invalid. Providing an omni-directional radio signal and additional research and testing will see the full potential of the system design. The system proposed in this research allows for user-defined boundaries to be set for the alarming mechanism. This feature alone provides, versatility and expandability which is one of a kind and has potiential to enter the market-place covering unlimited application scenarios