Dealing with indoor localization and navigation is an interdisciplinary problem. Particular views are distributed into 11 chapters. Even if some of them may seem less interesting than others, I encourage reading all of them; on the other hand, most of them can be skipped without losing much of the context for the rest. Each chapter contains a list of references to a wealth of relevant sources.
The first chapter describes how researchers began working on this problem over 30 years ago. It is fascinating to read that some of the historic approaches can bring some added value even to recent research endeavors.
Chapter 2 describes an experiment in a virtual building. Participants were given various tasks to move from one certain place to another. Their movement was recorded and evaluated (for example, by mean travel time or absolute and averaged wrong turns per route). Results of course depend on various conditions, for example, number of turns, participant’s familiarity, and motivation. This can help navigation designers have a better idea about the behavior/movement of people in an indoor space.
Chapter 3 gives an overview of existing technologies for indoor localization, such as radio frequency based (cellular, Wi-Fi, Bluetooth, RFID), acoustic, dead reckoning, signage and maps, hybrid, and other methods based on proximity, time of arrival (TOA), direction of arrival (DOA), and those that employ location fingerprinting (see Figure 3.1). Subchapters describe advantages and disadvantages of these technologies one by one, including their accuracy--mostly of the order of tens of centimeters.
Chapter 4 deals with a system based on magnetic field sensing (magnetic indoor local positioning system, MILPS). This requires placing coils and sensors that can measure the strength of the magnetic field--usually only in smaller rooms such as 3x3 meters, with resulting accuracy in centimeters. The larger the area, the bigger the localization error, which is quite clearly illustrated in Figure 4.15. One can use also the built-in sensors of smartphones--experiment results are worse by only about one order.
Chapter 5 makes readers think about localization in atypical conditions such as high temperature or high humidity, difficult access to the area, and thus the inability to install any additional equipment. Such tough conditions are precisely found at CERN (the European Organization for Nuclear Research). The chapter contains a description of the whole design and measurement results of their system, which is based on received signal strength indicator (RSSI) fingerprinting over a leaky coaxial cable.
Chapter 6 is essential--it presents another view on localization and navigation. For successful localization, it is necessary to have a map. A system can have the map in advance (infrastructure-based approaches) or the map is unknown and thus the system has to reconstruct it by itself (infrastructure-free approaches). If the map is known, the system calculates position using trilateration, otherwise fingerprinting is often used (for example, radio maps, magnetic field maps). When visitors have motion sensors installed, the system can provide simultaneous localization and mapping (SLAM). This requires a motion model (MM, the chapter lists at least 13 of them), usually based on probability, for example, described system FootSLAM (later FeetSLAM with crowdsourced mapping and Wi-Fi enriched version WiSLAM), accompanied by an experiment and its results.
The next four chapters are dedicated to the navigation of visually impaired and/or blind people. Chapter 7 explains how people with such disabilities perceive the world, how they navigate, what helps them and what does not, and how their world works. This chapter will greatly help those who could not imagine this world. In particular, it helps correct many naive but false assumptions regarding the visually impaired. Chapter 8 pays more attention to navigation aids. Specifically, it shows how visually impaired people use mobile phones or other devices, and how to combine all these aids so that users will be satisfied. Chapter 9 is dedicated to NavPal, where the rules and steps that should be followed by all navigation systems designed for this group of people are summarized. Chapter 10 is devoted to the future of indoor navigation for blind travelers from both short and longer-term visions, which already include assistive robots, smart cities, and smart buildings.
The last chapter is dedicated to privacy in location-based services (LBS). It deals with the risks of such systems and mentions four types of attacks on LBS. Two basic approaches are described in more detail: mixed-zone based and anonymity based (location-based cloaking techniques). At the end of the chapter, the authors also mention other approaches, with short descriptions.
Everyone who is involved in indoor navigation development of any kind would definitely like to read this book. It is not a textbook; however, my graduate students, for example, appreciated it very much when researching thesis projects. It broadened their views on the topic, deepened their technical knowledge, and gave many hints for further study.
