Box 1000, 02044 Espoo, Finland  
S. Ruponen  
VIT Technical Research Centre of Finland Ltd., P.O. Box 1000, 02044 Espoo, Finland  
S. Ruponen  
VIT Technical Research Centre of Finland Ltd., P.O. Box 1000, 02044 Espoo, Finland  
S. Ruponen  
VIT Technical Research Centre of Finland Ltd., P.O. Box 1000, 02044 Espoo, Finland  
S. Ruponen  
VIT Technical Research Centre of Finland Ltd., P.O. Box 1000, 020444 Espoo, Finland  
S. Ruponen  
VIT Technical Research Centre of Finland Ltd., P.O. Box 1000, 02044 Espoo, Finland  
S. Ruponen  
VIT Technical Research Centre of Finland Ltd., P.O. Box 1000, 02044 Espoo, Finland  
S. Ruponen  
VIT Technical Research Centre of Finland Ltd., P.O. Box 1000, 020444 Espoo, Finland
General compendiums on the positioning systems, methods, and technologies for indoor and outdoor use are described in [5; 6; 7; 8; 9; 10; 11; 12; 13; 14; 15]. In the context of this work, we will primarily cover indoor positioning systems, although the approach to be described can be implemented for outdoor use-cases as well. Among the different positioning methods and technologies for indoor positioning, we will discuss fingerprinting-based positioning. It is outside of our scope to argue for the benefits and drawbacks of each positioning method and technology, as these have been widely discussed in the literature. In our view, each positioning method and technology has its merits, problems, and an associated cost-performance or cost-benefit. Here, we focus on enhancing fingerprinting-based positioning. Fingerprinting-based positioning uses the magnitudes of signals that vary as function of position, called fingerprints, so that these can be mapped to an approximate position estimate. Fingerprinting-based positioning can be used (1) as a positioning method alone; (2) to complement other positioning methods in a so-called hybrid positioning system; (3) to act as a secondary positioning system to back up a primary positioning system; (4) to make an assessment or evaluate the trustworthiness of the position reported by a primary positioning system; or (5) as part of a collaborative positioning system [16]. A common metric of performance used in positioning systems is the _positioning error_ referred to as the _distance error_ or _error distance_. In the context of our work, the positioning error is defined as the Euclidean distance measured from the position reported by a positioning device to a known ground truth reference position. An ideal positioning system would be one in which the positioning error is minimized to zero. However, in practice, the minimization of the positioning error has an associated complexity and cost. The costs in positioning systems primarily comprise the capital and maintenance costs of the core infrastructure and positioning devices. In addition, there are costs associated with the time required to install and configure a positioning system, the data post-processing time, and the computing time. Some of the costs involved in a positioning system are discussed in [17]. All of these costs are summarized in some contexts as the total cost of ownership. Among different positioning methods, fingerprinting-based positioning is generally regarded as an economical option. Its low cost can be attributed to different reasons. One reason is the possibility of relying on signals, or any other distinctive characteristic of the environment, which can be repurposed as fingerprints for positioning when these are available in the area where the positioning is needed (e.g., magnetic fields, sounds, radio signals, etc.). Another reason is the fact that this method does not require knowledge of the position of the sources that generate the fingerprints. This fact minimizes the costs of infrastructure and the coordination to set up the positioning system. The sources that generate the fingerprints can be managed or unmanaged.