Position and time are some of the most vital pieces of information for convenience, security, and safety in our daily lives and have enabled innovative advancements in many science and engineering fields. Since Global Positioning System (GPS) became available to the public, GPS has been applied not only to smartphones and vehicular navigation systems that we use every day, but also to diverse areas such as Internet-of-Things (IOT), synchronization, cellular communications, military, geodesy, agriculture, mining, construction, remote sensing and more. However, the legacy GPS has only been successful in outdoor and open-sky applications, and the demand for positioning and navigation in indoor and urban street environments has been rapidly growing. A number of countries are carrying out their own plans to build advanced satellite-based navigation systems, called global navigation satellite systems (GNSS), with initial operation capability planned around 2020. GNSS will provide a number of new wideband signals with encoded data at multiple frequencies for the enhancement of accuracy, robustness, and signal availability in the GPS-denied environments, such as dense urban streets and indoor environments, as well as in the presence of cyber-attacks. On the other hand, there have been research activities around the world to develop indoor positioning and navigation technologies in diverse directions. One conventional approach is to use radio signals from wireless infrastructure such as WiFi, UWB, and LTE (i.e., cellular signals), and the other is to utilize non-radio signal measurements such as camera-vision, in-building magnetic anomaly, and inertial measurements.