Design considerations and implementation of a RF front-end for CDMA adaptive array system.
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Date
2000
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Abstract
Recent studies have shown that considerable system capacity gains in mobile
communication systems can be obtained by exploiting the use of antenna arrays at the
base station. Unfortunately, these studies make little mention of practical issues
concerning implementation. It is thus one of the objectives of the Centre of Excellence
(CoE) in Radio Access Technologies at the University of Natal to investigate the
development of a widehand CDMA adaptive array transceiver using Alcatel software
radios as the transceiver platforms. Such a transceiver system can be subdivided into
three major sections: RF front-end, signal digitization and baseband processing stages.
Due to the enormity of such an undertaking, the research outlined in this thesis is focused
on (but not isolated to) some aspects of the RF front-end implementation for the proposed
system.
The work in this thesis can be catergorized into two sections. The first section focuses on
the theoretical and practical (or implementation) aspects of antenna arrays and
beamforming. In particular, it is evident that digital (rather than analogue) beamforming
in a multi user environment, is a more viable option from both a cost and implementation
standpoint. The second section evaluates the impact of RF component noise and local
oscillator generated phase noise in a DS-CDMA system. The implementation of a RP
front-end for a BPSK transceiver also forms part of the work in this section. LO phase
noise and Error Vector Magnitude (EVM) measurements are performed on this system to
support relevant theory. By use of the HP89410A phase noise measurement utility and
the phase noise theory developed in this thesis, a quantitative phase noise comparison
between two frequency sources used in the system were made. EVM measurement
results conclusively verified the importance of an LNA in the system. It has also been
shown that the DS-CDMA simulated system exhibits superior performance to the
implemented BPSK system. Furthermore, an EVM troubleshooting methodology is
introduced to identify possible impairments within the BPSK receiver RF front-end.
However, this thesis was written with the intention of bridging the gap between the theoretical and practical implementation aspects of RP wireless communication systems.
It is the author's opinion that this has been achieved to a certain extent.
Description
Thesis (M.Sc.Eng.)-University of Natal, Durban, 2000.
Keywords
Code division multiple access., Mobile communication systems., Adaptive antennas., Antenna arrays., Theses--Electronic engineering.