In visible light communication systems, the intensity modulation/direct
detection channel inherently restricts the transmitted signal to be unipolar
(nonnegative only) and incoherent. Those restrictions limit the types of
transceivers that can be used in visible light communication systems; indeed,
the intensity modulation/direct detection transceivers can be readily
utilized, whereas classic radio frequency methods (e.g., schemes such as
pulse amplitude modulation, quadrature amplitude modulation and orthogonal
frequency division multiplexing) require adjustments that reduce their
conventional efficiency. A continuous effort has been made to adapt radio
frequency transceiver techniques to visible light communication; however, up
to date, the proposed solutions came at the expense of the energy efficiency
of the systems. In turn, it severely affects the bit error rate performance
of the system. In light of this, the topic of this thesis is to design energy
efficient transmission schemes to expand the set of legacy radio frequency
modulation methods that can be efficiently used in visible light communication
systems. Thus, the first contribution of this dissertation is a unipolar
transmission technique that allows conveying bipolar symbols through the
intensity modulation/direct detection channel without severely consuming
the amount of transmit power. The second contribution is proposing a
new technique to simultaneously transmit the two parts of two-dimensional
signals over the intensity modulation/direct detection channel. The schemes
are proposed with the objective of minimizing the transmitted power and
reducing the direct current component of two-dimensional transmit signals
by relying on multi-waveform transmission techniques, and, in turn,
providing a high-energy efficient transmission scheme for two-dimensional
signals. The third contribution is a low complex multi-input multi-output
system capable of transmitting unipolar two-dimensional signals. Finally,
the error rate expressions of our proposed transceivers in this work are
derived, and the performance gains of the proposed schemes are evaluated
through Monte-Carlo simulations. The findings show that our schemes
could enhance the energy efficiency of the existing transmission techniques
in visible light communication systems.