GNSS is in a class of its own and the positioning/navigation/timing (PNT) technology of choice for most applications. Why wouldn’t we always use it?
It is affordable, it is a mature technology with many form factors, and its level of performance spans several orders of magnitude — millimeters to meters. There are a bewildering number of permutations of user equipment, augmentation solutions, processing algorithms, and operational procedures to choose from.
However. . . .
A number of well-known environments and operational scenarios exist in which GNSS signals cannot be tracked reliably. And these environments or scenarios are attracting the attention of those wishing to develop alternatives and backups to GNSS.
Conditions that are difficult or impossible for GNSS operations are experienced indoors or other occluded environments where the low-powered satellite signals are blocked or unreliable. Moreover, jamming and interference can degrade these signals and represent a continuing threat, given the widespread availability of so-called personal privacy devices (PPDs).
As PNT applications continue to expand strongly in consumer and commercial segments, demand is also growing for uninterrupted, ubiquitous, and seamless access to position/location information.
In this context, “seamless” refers to an ideal situation in which PNT capability is continuously available in all environments, indoors and outdoors. Achieving this will necessarily require a PNT technology mix that may be characterized as GNSS+.
To help us explore this issue further and assess the progress being made toward achieving ubiquitous positioning, we called on Dr. Chris Rizos, the head of the School of Surveying & Geospatial Engineering at the University of New South Wales, Australia. In the early 1990s Rizos established the Satellite Navigation and Positioning Lab at UNSW, an R&D group that focuses on GNSS and wireless positioning technology and applications.
Rizos’s current research includes new positioning technologies and he has written and spoken widely on the subject of ubiquitous positioning.