This application note is written for people who need to understand the
configuration and testing of ultra-wideband (UWB) devices, and some of the
issues surrounding their use. A broad range of topics is addressed in this
paper, including practical test techniques. Further details on many of them
may found in the references in Appendix B.
The basic concepts behind UWB signals are not new, but the radios are
becoming more sophisticated. The signals are split into three main groups,
depending on the signal generation technique: baseband-pulsed, pulse-
modulated RF, and orthogonal frequency division multiplexing (OFDM).
Pulsed signals have been used in air and ground-penetrating RADAR
systems of various forms for many years. Ultra-wideband OFDM involves
adapting standard OFDM principles to meet the regulatory requirements of
an underlay technology.
RADAR and position location in the form of radio frequency identification
(RFID) tags are good applications of UWB, but it is the application to short
range, very high speed data transfer that has recently triggered increased
interest, and is the main focus of this application note. Communications
applications like streaming video can make use of the latest mixed signal IC
technology to provide viably-priced consumer devices.
Spectrum allocation is the key to new radio development. In 2002 the FCC
in the United States allocated 3.1 to 10.6 GHz for use with unlicensed UWB
signals as an underlay technology. It has stimulated many proposals to meet
the specific requirements of the ruling. The IEEE 802.15.3a Working Group
is one of the bodies looking to develop a standard that can be used generally
by the industry for high-speed communication. Similar to Bluetooth?, the
Multi-Band OFDM Alliance Special Interest Group has been established to
promote an open OFDM standard. Other groups in Europe, Japan, and
Asia are also showing interest, but do not currently have definite spectrum
allocation rules with which to work.??