Indoor Localization Using Barely Perceptible Audio Signals

This paper presents a new approach to an audio-based indoor localization system. By using audio signals emitted by a public address sound system, mobile devices may globally localize themselves in an indoor environment where global navigation satellite systems are not viable or reliable. The use of data hiding techniques such as spread spectrum coding or echo hiding has allowed to convey information to a receiver avoiding people’s perception of the added audio content. Results demonstrate a relatively quite good localization with centimetre accuracy and precision and successful data transmission using barely perceptible audio signals

Localization of Wi-Fi Devices

Cílem této bakalářské práce bylo navržení způsobu lokalizace a jeho implementace. V teoretické části práce je nejdříve popsaná technologie Wi-Fi a následně jsou popsané různé metody lokalizace pomocí technologie Wi-Fi. S ohledem na předpokládané podmínky je vyvozen návrh lokalizačního systému založeného na kombinaci metody AoA a metody využívající RSSI. Pro srovnání je dále navržen a implementován druhý lokalizační systém, vyúžívající čistě RSSI s metodou laterace. Závěrem se práce zaměří na testování obou systémů a diskutuje jejich možné použití pro vyhledávání osob.The goal of this bachelor thesis was to design a method of localization and its implementation. In the theoretical part of the thesis, the Wi-Fi technology and different methods of locating via Wi-Fi are described. Given the anticipated conditions a design of positioning system based on a combination of the AoA method and the RSSI based method was designed. For comparsion, one more positioning system, based on lateration with RSSI method only was designed and implemented. Last part of the thesis is focused on the testing of both systems. In conclusion, the paper discuss the potential future systems usage for finding people.

Understanding mobile network quality and infrastructure with user-side measurements

Measurement collection is a primary step towards analyzing and optimizing performance of a telecommunication service. With an Mobile Broadband (MBB) network, the measurement process has not only to track the network’s Quality of Service (QoS) features but also to asses a user’s perspective about its service performance. The later requirement leads to “user-side measurements” which assist in discovery of performance issues that makes a user of a service unsatisfied and finally switch to another network. User-side measurements also serve as first-hand survey of the problem domain. In this thesis, we exhibit the potential in the measurements collected at network edge by considering two well-known approaches namely crowdsourced and distributed testbed-based measurements. Primary focus is on exploiting crowdsourced measurements while dealing with the challenges associated with it. These challenges consist of differences in sampling densities at different parts of the region, skewed and non-uniform measurement layouts, inaccuracy in sampling locations, differences in RSS readings due to device-diversity and other non-ideal measurement sampling characteristics. In presence of heterogeneous characteristics of the user-side measurements we propose how to accurately detect mobile coverage holes, to devise sample selection process so to generate a reliable radio map with reduced sample cost, and to identify cellular infrastructure at places where the information is not public. Finally, the thesis unveils potential of a distributed measurement test-bed in retrieving performance features from domains including user’s context, service content and network features, and understanding impact from these features upon the MBB service at the application layer. By taking web-browsing as a case study, it further presents an objective web-browsing Quality of Experience (QoE) model