The most challenging technical problem associated with using UWB, is finding
ways to prevent other emitters from interfering with UWB devices. Other radio
systems have a strong advantage in this area. All other systems are fitted with
a front-end filter, which prevents interference from transmitters operating
outside of their reception bands. Unfortunately, a UWB receiver needs to have
an open front-end filter, to allow for a broad spectrum of frequencies,
including signals from potential sources of interference. The ability to
overcome this impediment, which is sometimes referred to as jamming resistance,
is a key attribute of a well-designed UWB receiver. One approach to improving
jamming resistance is to install notch filters, which attenuate the narrow
parts of the spectrum, where interference is likely to occur. Another solution
is to use automatic notch filters, which seek out and diminish the signals of
particularly strong sources of narrowband interference.
Multipath
Interference
Multipath interference, as discussed in Module 4, is also
an issue. However, clever design can permit UWB systems to take advantage of
this phenomenon. The narrow pulses of UWB make it possible for some receivers
to resolve the separate multipath streams and simultaneously lock onto the
various reflected signals. Then a comparison in near real-time determines if a
received bit is a one or a zero. This bit-checking function actually improves
the performance of the receiver.