Wireless indoor positioning systems have become very popular in recent years. These systems have been successfully used in many applications such as asset tracking and inventory management. This paper provides an overview of the existing wireless indoor positioning solutions and attempts to classify different techniques and systems. Three typical location estimation schemes of triangulation, scene analysis, and proximity are analyzed. We also discuss location fingerprinting in detail since it is used in most current system or solutions. We then examine a set of properties by which location systems are evaluated, and apply this evaluation method to survey a number of existing systems. Comprehensive performance comparisons including accuracy, precision, complexity, scalability, robustness, and cost are presented.

Survey of Wireless Indoor Positioning Techniques and Systems

A framework for positioning, navigation, and tracking problems using particle filters (sequential Monte Carlo methods) is developed. It consists of a class of motion models and a general nonlinear measurement equation in position. A general algorithm is presented, which is parsimonious with the particle dimension. It is based on marginalization, enabling a Kalman filter to estimate all position derivatives, and the particle filter becomes low dimensional. This is of utmost importance for high-performance real-time applications. Automotive and airborne applications illustrate numerically the advantage over classical Kalman filter-based algorithms. Here, the use of nonlinear models and non-Gaussian noise is the main explanation for the improvement in accuracy. More specifically, we describe how the technique of map matching is used to match an aircraft's elevation profile to a digital elevation map and a car's horizontal driven path to a street map. In both cases, real-time implementations are available, and tests have shown that the accuracy in both cases is comparable with satellite navigation (as GPS) but with higher integrity. Based on simulations, we also argue how the particle filter can be used for positioning based on cellular phone measurements, for integrated navigation in aircraft, and for target tracking in aircraft and cars. Finally, the particle filter enables a promising solution to the combined task of navigation and tracking, with possible application to airborne hunting and collision avoidance systems in cars.

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Particle filters for positioning, navigation, and tracking

A system for integrating video programming with the vast information resources of the Internet. A computer-based system receives a video program with embedded uniform resource locators (URLs). The URLs, the effective addresses of locations or Web sites on the Internet, are interpreted by the system and direct the system to the Web site locations to retrieve related Web pages. Upon receipt of the Web pages by the system, the Web pages are synchronized to the video content for display. The video program signal can be displayed on a video window on a conventional personal computer screen. The actual retrieved Web pages are time stamped to also be displayed, on another portion of the display screen, when predetermined related video content is displayed in the video window. As an alternative, the computer-based system receives the URLs directly through an Internet connection, at times specified by TV broadcasters in advance. The system interprets the URLs and retrieves the appropriate Web pages. The Web pages are synchronized to the video content for display in conjunction with a television program being broadcast to the user at that time. This alternative system allows the URLs to be entered for live transmission to the user.

Enhanced video programming system and method for incorporating and displaying retrieved integrated Internet information segments

Location-aware technologies will revolutionize many aspects of commercial, public service, and military sectors, and are expected to spawn numerous unforeseen applications. A new era of highly accurate ubiquitous location-awareness is on the horizon, enabled by a paradigm of cooperation between nodes. In this paper, we give an overview of cooperative localization approaches and apply them to ultrawide bandwidth (UWB) wireless networks. UWB transmission technology is particularly attractive for short- to medium-range localization, especially in GPS-denied environments: wide transmission bandwidths enable robust communication in dense multipath scenarios, and the ability to resolve subnanosecond delays results in centimeter-level distance resolution. We will describe several cooperative localization algorithms and quantify their performance, based on realistic UWB ranging models developed through an extensive measurement campaign using FCC-compliant UWB radios. We will also present a powerful localization algorithm by mapping a graphical model for statistical inference onto the network topology, which results in a net-factor graph, and by developing a suitable net-message passing schedule. The resulting algorithm (SPAWN) is fully distributed, can cope with a wide variety of scenarios, and requires little communication overhead to achieve accurate and robust localization.

Cooperative Localization in Wireless Networks

Positioning in wireless networks is mainly used for safety, gaming, and commercial services It is expected to increase in popularity when emergency call services become mandatory as well as with the advent of more advanced location-based services and mobile gaming In this article, we discuss and illustrate the possibilities and fundamental limitations associated with mobile positioning based on available wireless network measurements The possibilities include a sensor fusion approach and model-based filtering, while the fundamental limitations provide hard bounds on the accuracy of position estimates, given the information in the measurements in the most favorable situation The focus of this article is to illustrate the relation between performance requirements, such as those stated by the Federal Communications Commission (FCC), and the available measurements Specific issues on accuracy limitation in each measurement, such as synchronization and multipath problems, are briefly commented upon A geometrical example, as well as a realistic example adopted from a cell planning tool, are used for illustration

Mobile positioning using wireless networks: possibilities and fundamental limitations based on available wireless network measurements

Due to the FCC requirement that operators of mobile communications networks be able to accurately locate mobile callers requesting emergency assistance via 911 by the year 2001, there has been a lot of activity among cellular and PCS providers to examine cellular positioning options. This article examines positioning solutions for the GSM group of standards. Worldwide deployment of GSM systems is well underway, and the positioning characteristics of the various systems are similar. The authors examine the ability to derive position information from GSM signals, based on their May 1996 achievement of accurate position measurements using GSM. Features of GSM signals relevant to positioning are analyzed as well as results achieved and the authors' ongoing positioning trials. Finally, other issues related to GSM positioning and mobile phone positioning in general are covered.

Positioning GSM telephones

The invention concerns a method of finding the position of a mobile radio-frequency transceiver in a communications system. A network of at least two unsynchronized base stations arranged to transmit/receive signals to at least one mobile-radio frequency transceiver; a reference receiver located at a known distance from the base stations and including measuring means to measure the times of arrival of signals transmitted from the base stations; determination means to use the known distances and measured times to determine the relative time offsets of transmissions from each base station; and location means to use the determined relative time offsets to calculate the position of a mobile transceiver in the network area using hyperbolic positioning techniques. A number of other enhancements to positioning systems relating to the usage of Doppler, carrier information, direction of arrival to improve the performance of mobile telephone-based positioning systems are also described.

Location and tracking system

The invention described relates to a radio positioning system primarily for a mobile telephone network, in which a list of offsets in time, phase, frequency, or derivatives thereof, or their equivalents expressed as offsets in distance or derivatives thereof, of a plurality of transmission source signals, received at a given location, relative to a common reference are generated. Data is acquired from one or more receivers, the positions of which may be known or determined. Such data are offsets in time, phase, frequency, or derivatives thereof, respectively of signals received from the transmission sources relative to a reference source in each receiver or to each other. The acquired data is combined for calculating the list of offsets relative to the common reference.

Radio positioning systems.

Systems, methods and devices for monitoring the location of mobile radio terminal users for the purpose of detecting when they approach within range of one or more target locations in order to trigger voice and/or data communications to or from the network or other mobile radio terminals.

Systems and methods for triggering location based voice and/or data communications to or from mobile radio terminals

Methods, systems, processor-readable media, and devices for collecting information pertaining to the configuration of one or more wireless networks and using this information in turn to estimate the location of mobile wireless devices associated with those networks are disclosed. Also disclosed are methods, systems, processor-readable media, and devices for discovering and/or maintaining wireless transmitter characteristics corresponding to one or more wireless networks. Also disclosed are methods, systems, processor-readable media, and devices for aggregating wireless network transmitter characteristics from a plurality of wireless network transmitters. The present disclosure can be used across multiple networks, without requiring information from the operators of those networks, in which the information concerning those networks is collected and maintained in a current state efficiently and with rapid response to changes in the network configuration.

Malcolm David Macnaughtan

Papers

Positioning GSM telephones

Location and tracking system

Radio positioning systems.

Systems and methods for triggering location based voice and/or data communications to or from mobile radio terminals

Location of wireless mobile terminals