Intermodulation Distortion in Switched Multibeam
Antennas for Cellular Radio Systems
11th IEEE International Symposium on Personal, Indoor and Mobile Radio Communication (PIMRC'2000).
London, UK, September 18-21, 2000.
© 2000 IEEE
entry in list of publications
The performance of switched multibeam antennas for cellular radio
systems is investigated when the transmit amplifier is of a
multicarrier (MCPA) type. The MCPA nonlinearity generates
intermodulation distortion in the transmitted signal that is spatially filtered by the array
radiation pattern. Hence, the intermodulation distortion becomes
direction-dependent, and the direction of the generated
intermodulation products of any order is derived.
It is shown by using Monte Carlo simulations how the downlink
carrier to interference ratio depends on the frequency reuse distance
and on the MCPA linearity measured as its noise power ratio (NPR). For
reuse factor one systems, which is made possible by use of multibeam
antennas, the linear co-channel interference dominates the interference. On the contrary, for a reuse factor
seven system it is shown that a weak nonlinearity directly gives a degradation in
carrier to interference ratio (CIR) due to intermodulation distortion.
However the reuse factor seven system has a large CIR overhead due to
the increase in CIR using a multibeam antenna, and the outage
probability is thereby only slightly affected.
Wireless 99 paper Investigation of nonlinearites an adaptive antenna arrays (no switched beams)
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