A wireless communication network can be viewed as a collection of nodes, located in some domain, which
can in turn be transmitters or receivers (depending on the network considered, nodes may be mobile users,
base stations in a cellular network, access points of a WiFi mesh etc.). At a given time, several nodes
transmit simultaneously, each toward its own receiver. Each transmitter–receiver pair requires its own
wireless link. The signal received from the link transmitter may be jammed by the signals received from
the other transmitters. Even in the simplest model where the signal power radiated from a point decays in
an isotropic way with Euclidean distance, the geometry of the locations of the nodes plays a key role since
it determines the signal to interference and noise ratio (SINR) at each receiver and hence the possibility of
establishing simultaneously this collection of links at a given bit rate. The interference seen by a receiver is
the sum of the signal powers received from all transmitters, except its own transmitter.
An acronym for Multiple-In, Multiple-Out, MIMO communication sends the same data as several signals
simultaneously through multiple antennas, while still utilizing a single radio channel. This is a form of
antenna diversity, which uses multiple antennas to improve signal quality and strength of an RF link. The
data is split into multiple data streams at the transmission point and recombined on the receive side by
another MIMO radio configured with the same number of antennas. The receiver is designed to take
into account the slight time difference between receptions of each signal, any additional noise or
interference, and even lost signals.
Wavelength division multiplexing (WDM) refers to a multiplexing and transmission
scheme in optical telecommunications fibers where different wavelengths, typically
emitted by several lasers, are modulated independently (i.e., they carry independent
information from the transmitters to the receivers). These wavelengths are then
multiplexed in the transmitter by means of passive WDM filters, and likewise they
are separated or demultiplexed in the receiver by means of the same filters or
coherent detection that usually involves a tunable local oscillator (laser).
The advent of modern wireless devices, such as smart phones and MID 1 terminals,
has revolutionized the way people think of personal connectivity. Such devices
encompass multiple applications ranging from voice and video to high-speed data
transfer via wireless networks. The voracious appetite of twenty-first century users
for supporting more wireless applications on a single device is ever increasing.
These devices employ multiple radios and modems that cover multiple frequency
bands and multiple standards with a manifold of wireless applications often running
simultaneously.
This book is about global navigation satellite systems (GNSS), their two main instru-
ments, which are a receiver and a simulator, and their applications. The book is based on
an operational off-the-shelf real-time software GNSS receiver and off-the-shelf GNSS
signalsimulator.Theacademicversionsofthesetoolsarebundledwiththisbookandfree
for readers to use for study and research.
The purpose of this book is to present detailed fundamental information on a
global positioning system (GPS) receiver. Although GPS receivers are popu-
larly used in every-day life, their operation principles cannot be easily found
in one book. Most other types of receivers process the input signals to obtain
the necessary information easily, such as in amplitude modulation (AM) and
frequency modulation (FM) radios. In a GPS receiver the signal is processed
to obtain the required information, which in turn is used to calculate the user
position. Therefore, at least two areas of discipline, receiver technology and
navigation scheme, are employed in a GPS receiver. This book covers both
areas.
In this new edition of the book, only minor changes were made to the original
nine chapters but three new chapters treat topics of increasing interest to GPS
users and equipment developers. One topic, improving the GPS receiver sensi-
tivity may extend their operations into buildings, which is becoming important
for emergency rescue and urban warfare.
If one examines the current literature on GPS receiver design, most of it is quite a
bit above the level of the novice. It is taken for granted that the reader is already at a
fairly high level of understanding and proceeds from there. This text will be an
attempt to take the reader through the concepts and circuits needed to be able to
understand how a GPS receiver works from the antenna to the solution of user
position.
Many applications have required the positioning accuracy of a Global Navigation
Satellite System (GNSS). Some applications exist in environments that attenuate
GNSS signals, and, consequently, the received GNSS signals become very weak.
Examplesofsuchapplicationsarewirelessdevicepositioning,positioninginsensor
networks that detect natural disasters, and orbit determination of geostationary
and high earth orbit (HEO) satellites. Conventional GNSS receivers are not
designed to work with weak signals. This book presents novel GNSS receiver
algorithms that are designed to work with very weak signals.
