| Summary: | In this thesis, we propose a novel architecture for hybrid radio frequency
(RF)/free–space optics (FSO) wireless systems. Hybrid RF/FSO systems
are attractive since the RF and FSO sub–systems are affected differently by
weather and fading phenomena. We give a thorough introduction to the RF
and FSO technology, respectively. The state of the art of hybrid RF/FSO systems
is reviewed. We show that a hybrid system robust to different weather
conditions is obtained by joint bit–interleaved coded modulation (BICM) of the
bit streams transmitted over the RF and FSO sub–channels. An asymptotic
performance analysis reveals that a properly designed convolutional code can
exploit the diversity offered by the independent sub–channels. Furthermore,
we develop code design and power assignment criteria and provide an efficient
code search procedure. The cut–off rate of the proposed hybrid system is also
derived and compared to that of hybrid systems with perfect channel state
information at the transmitter. Simulation results show that hybrid RF/FSO
systems with BICM outperform previously proposed hybrid systems employing
a simple repetition code and selection diversity.
|
|---|
