The localization of wireless devices, e.g. mobile phones, laptops, and handheld GPS receivers, has gained much interest due to the benefits it provides, including quicker emergency personnel dispatch, location-aided routing, as well as commercial revenue opportunities through location based services.  GPS is the dominant position location system in operation, with 31 operational satellites producing eight line of sight satellites available to users at all times making it very favorable for system implementation in all wireless networks.  Unfortunately when a GPS receiver is in a challenging environment, such as an urban or indoor scenario, the signal quality often degrades causing poor accuracy in the position estimate or failure to localize altogether due to satellite availability. Our goal is to introduce a new solution that has the ability to overcome this limitation by improving the accuracy and availability of a GPS receiver when in a challenging environment.  To test this theory we created a simulated GPS receiver using a MATLAB simulation to mimic a standard GPS receiver with all 31 operational satellites.  Here we are able to alter the environment of the user and examine the errors that occur due to noise and limited satellite availability.  Then we introduce additional user(s) to the GPS solution with the knowledge (or estimate) of the distances between the users.  The new solutions use inter-receiver distances along with pseudoranges to cooperatively determine all receiver location estimates simultaneously, resulting in improvement in both the accuracy of the position estimate and availability. / Master of Science

Denna kandidatuppsats utforskar hur ifyllandet av reseräkningar efter tjänsteresor kan förenklas. Det kan hända att en anställd efter en resa har svårt att minnas detaljerade uppgifter om antal körda mil, besökta platser och genomförda aktiviteter. Detta kan leda till att ifyllandet av en reseräkning blir en tidskrävande process. Som en potentiell lösning utvecklades en applikation som använder platsspårning för att automatiskt fylla i relevant information till ett företags "Tjänsteresa"-tjänst som används för att generera reseräkningar. För att få en djupare förståelse för hur “Tjänsteresa”-tjänstens kunder använder applikationen och vanliga problem de kan möta, utfördes en semi-strukturerad intervju med produktägaren för “Tjänsteresa”-tjänsten på företaget som detta arbete utfördes i samarbete med. Vidare genomfördes en enkätundersökning med 25 deltagare, som besvarade frågor om den potentiella användbarheten av detta arbetes applikation och om de tidigare hade upplevt svårigheter vid ifyllandet av reseräkningar. Deltagarna gav också sin syn på platsspårning. Applikationens platsspårning testades också genom flera användartester där deltagarna åkte på tjänsteresor. Vid två av testerna jämfördes applikationens inhämtade information med deltagarnas inskickade reseräkningar. Resultatet av användartesterna visar att den nya applikationen kan redovisa för 8 av 11 punkter av information till en reseräkning, vilket tyder på en förbättring av processen. Enligt enkäten och den semi-strukturerade intervjun visades det att applikationen har potential att förbättra potentiella användares upplevelse genom att spara tid och förenkla processen. Majoriteten av deltagarna uttryckte inte några farhågor kring platsspårning. För dem som hade invändningar, minskade oron om garantier kunde ges att endast den genererade reseräkningen, och inte den specifika reseinformationen, var tillgänglig för medarbetare och chefer.

Miniature air vehicles (MAVs) have attracted a large amount of interest recently both from the research community and from the public. New battery technologies as well as rapid developments in embedded processing and MEMS sensor technologies have greatly increased the potential of these vehicles. MAVs have been envisioned playing significant roles in both civil and military applications. Examples include: fire monitoring, search and rescue, traffic monitoring, crop monitoring, convoy protection, border surveillance, troop support, law enforcement, natural disaster relief, and aerial photography. The application of MAVs tends to center on the ability of the MAV to collect and deliver visual information to the user. In many applications it is important to be able to accurately geolocate items of interest in the visual data. However, the inaccuracies associated with MAV platforms have led to relatively large errors in previous attempts at geolocation. The first half of this thesis focuses on increasing the accuracy of geolocation estimates achievable using a hand-launchable MAV. To accomplish this, methods are presented for bias estimation, wind estimation, recursive least squares filtering, and optimal flight path generation. Hardware results are presented which demonstrate the ability to consistently localize targets to within 5 m regardless of wind conditions. The second half of this thesis focuses on using the high accuracy geolocation estimates to complete a search and engage mission. This is a mission in which the MAV not only locates the target, but also accurately delivers a payload to the target site. The focus is on delivering an attached payload via accurate landing at the target site. A vision-based landing approach is presented which is robust to both wind and moving targets. Simulation results are presented which demonstrate the effectiveness of the control.

No description available.

Recently, there are great interests in the location-based applications and the location-awareness of mobile wireless systems in indoor areas, which require accurate location estimation in indoor environments. The traditional geolocation systems such as the GPS are not designed for indoor applications, and cannot provide accurate location estimation in indoor environments. Therefore, there is a need for new location finding techniques and systems for indoor geolocation applications. In this thesis, a wide variety of technical aspects and challenging issues involved in the design and performance evaluation of indoor geolocation systems are presented first. Then the TOA estimation techniques are studied in details for use in indoor multipath channels, including the maximum-likelihood technique, the MUSIC super-resolution technique, and diversity techniques as well as various issues involved in the practical implementation. It is shown that due to the complexity of indoor radio propagation channels, dramatically large estimation errors may occur with the traditional techniques, and the super-resolution techniques can significantly improve the performance of the TOA estimation in indoor environments. Also, diversity techniques, especially the frequency-diversity with the CMDCS, can further improve the performance of the super-resolution techniques.

In spite of major research initiatives by DARPA and other research organizations, precise indoor geolocation still remains as a challenge facing the research community. The core of this challenge is to understand the cause of large ranging errors in estimating the time of arrival (TOA) of the direct path between the transmitter and the receiver. Results of wideband measurement in variety of indoor areas reveal that large ranging errors are caused by severe multipath conditions and frequent occurrence of undetected direct path (UDP) situations. Empirical models for the behavior of the ranging error, which we refer to as the distance measurement error (DME), its relation to the distance between the transmitter and the receiver and the bandwidth of the system is needed for development of localization algorithms for precise indoor geolocation. The main objective of this dissertation is to design a direct empirical model for the behavior of the DME. In order to achieve this objective we provide a framework for modeling of DME, which relates the error to the distance between the transmitter and the receiver and bandwidth of the system. Using this framework we first designed a set of preliminary models for the behavior of the DME based on the CWINS proprietary measurement calibrated ray-tracing simulation tool. Then, we collected a database of 2934 UWB channel impulse response measurements at 3-8GHz in four different buildings to incorporate a variety of building materials and architectures. This database was used for the design of more in depth and realistic models for the behavior of the DME. The DME is divided into two components, Multipath-DME (MDME) and UDP-DME (UDME). Based on the empirical data, models for the behavior of each of these components are developed. These models reflect the sensitivity to bandwidth and show that by increasing the bandwidth MDME decreases. However in UDME the behavior is complicated. At first it reduces as we increase the bandwidth but after a certain bandwidth it starts to increase. In addition to these models through an analysis on direct path power versus the total power the average probability of having a UDP was calculated.

Recently, there has been an enormous growth of interests in geolocation applications that demand an accurate estimation of the user’s location in indoor areas. The traditional geolocation system, GPS, which was designed for being used in outdoor environments, does not perform well in indoor areas, causing frequent inaccuracies in location estimation. Therefore the need for more accurate positioning systems and even positioning techniques is a motivation for researchers to turn their attention into indoor positioning systems. In this thesis we present a unique testbed for indoor geolocation system’s real-time performance evaluation. Then we present a real-time performance evaluation of a sample indoor positioning system. We make a comparison between the simulated results of the performance evaluation of the positioning engine and the real-time performance evaluation of the positioning system. Finally, we perform a sensitivity analysis for Ekahauâ„¢ indoor positioning engine. We show that the simulation with the introduced testbed yields the same results as one would obtain by evaluating the performance of the positioning system by means of massive measurement campaigns. Running the testbed for several measurement campaigns for different scenarios enabled us to compare the results and study the effect of selected parameters on the performance of the positioning system. We also perform primitive error analysis in terms of distance error to verify the validity of the result obtained with the testbed. We show that under the same configuration both real-time performance evaluation and simulated performance evaluation will yield same result with respect to position error. We also use error modeling to determine which error model is best matched to the observed indoor positioning error. Amongst all of the possibilities of choosing methods of positioning, we focused on the Received Signal Strength (RSS) based method along with fingerprinting. Briefly said, profiles previously gathered by measurement or simulation will decide on the location of mobile terminal if a new profile comes in. It is worth mentioning that previous work similar to this testbed has been done for outdoor areas according to Ekahau's white paper. Their work is mainly focused on outdoor environment, in which multipath does not exist. In this research effort we tried to analyze the effect of different parameters on sensitivity of indoor positioning systems who suffer from multipath. Different setups for simulating real-time radio channels have been studied in literature, but still not focused on indoor areas.

The goal of this thesis is to investigate the W3C Geolocation API from a developer’s perspective, focused on whether it makes development of location-based applications more accessible to developers. This has been investigated by looking at available ways to locate, possible uses, the functionality offered, the necessary level of prior knowledge needed for a developer and requirements on developer tools. This has been achieved through studies in relevant areas, a thorough introduction to W3C Geolocation API functionality, and by using the API to develop two different location-based applications as a demonstration. Testing of applications, on different platforms and in different environments, in conjunction with investigation of the rest of the material has shown that W3C Geolocation API in many ways actually makes development of location-based applications more accessible for developers. The API also provides fully adequate functionality and quality to meet the requirements for development of both simple and very advanced location-based applications. Målet med denna uppsats är att undersöka W3C Geolocation API ur ett utvecklarperspektiv, fokuserat på om den gör utveckling av positionsbaserade applikationer mer tillgänglig för utvecklare. Detta har undersökts genom att titta på vilka positioneringstekniker som är tillgängliga, vilka användningsområden som är möjliga, vilka funktioner som erbjuds och vilka krav som ställs på utvecklaren i form av kunskap och utvecklingsverktyg. Detta har åstadkommits genom studier på relevanta områden, en genomgående introducering av vad W3C Geolocation API har att erbjuda för funktioner, samt användning av API:n i form av två egenutvecklade applikationer. Tester av applikationerna, på olika plattformar och i olika miljöer, har sedan tillsammans med utredning av resten av materialet visat på att W3C Geolocation API på många sätt gör utveckling av positionsbaserade applikationer mer tillgänglig för utvecklare samt erbjuder fullt tillräcklig funktionalitet och kvalitet för att tillgodose de krav som ställs för önskvärda användningsområden.

Dissertation thesis deals with methods for finding the location of the device in the Internet, based on knowledge of the IP address. The process is called IP geolocation and is currently solved by geolocation databases or by measurement of network properties to the IP address. The disadvantage of nowadays geolocation databases is an incorrect information about some locations, because they can be in large distance from correct position. The aim of the thesis is to develop a method for verification of a position from geolocation database using delay measurement. Because of it, there is a detail analysis of influence of partial delays on the distance estimation accuracy, calculated using measured delay between the landmark and the target IP address. For the same reason, long-term delay measurement was performed, where the IP geolocation accuracy was compared using calibration data from previous measurements. On this background, Cable Length Based Geolocalisation (CLBG) method is proposed. Principle of this method is built on the properties of partial delays, which depend on the length of transport media. Firstly, the method measures round trip time (rtt), which is subsequently lowered by intermediate devices and end stations delay. The geographical distance is estimated using signal speed in the transport media. Further, the winding media parameter is established, which is used to determine a constraint around the landmark. The intersection of all constraints defines the area, where the target IP is. The IP geolocation using CLBG gives better results than simpler methods (ShortestPing, GeoPing and SOI), in comparison with more advanced methods (CBG and Octant) the accuracy is similar. The disadvantage of the CLBG method is the size of region, where the target lies, but this is due to its purpose. The position found in geolocation database can be checked by evaluation if it lies in the region.

Frequency domain techniques have been widely used in indoor radio propagation measurements and modeling for telecommunication applications. This work addresses measurement of the time of arrival (TOA) of the first path for geolocation applications using results of frequency domain channel measurements. First, we analyze the effect upon TOA measurement accuracy due to: sampling period of the radio channel in the frequency domain, sampling period in the time domain used for detection of the TOA and the windowing filter used before transformation to the time domain. Then, we provide some results of measurement made in line of sight (LOS) and Obstructed LOS (OLOS) indoor environments in order to compare the characteristics of the measured TOA in these two important scenarios for indoor geolocation applications. Finally, we compare the measurement results with the ray tracing based model that had been developed previously for indoor geolocation applications.