The backhaul of tens and hundreds of light fidelity (LiFi)-enabled luminaires constitutes a major
challenge. The problem of backhauling for optical attocell networks has been approached by
a number of wired solutions such as in-building power line communication (PLC), Ethernet and
optical fiber. In this work, an alternative solution is proposed based on wireless optical communication
in visible light (VL) and infrared (IR) bands. The proposed solution is thoroughly
elaborated using a system level methodology. For a multi-user optical attocell network based
on direct current biased optical orthogonal frequency division multiplexing (DCO-OFDM) and
decode-and-forward (DF) relaying, detailed modeling and analysis of signal-to-interference-plus-
noise (SINR) and end-to-end sum rate are presented, taking into account the effects of
inter-backhaul and backhaul-to-access interferences.
Inspired by concepts developed for radio frequency (RF) cellular networks, full-reuse visible
light (FR-VL) and in-band visible light (IB-VL) bandwidth allocation policies are proposed to
realize backhauling in the VL band. The transmission power is opportunistically minimized to
enhance the backhaul power efficiency. For a two-tier FR-VL network, there is a technological
challenge due to the limited capacity of the bottleneck backhaul link. The IR band is employed
to add an extra degree of freedom for the backhaul capacity. For the IR backhaul system,
a power-bandwidth tradeoff formulation is presented and closed form analytical expressions
are derived for the corresponding power control coefficients. The sum rate performance of the
network is studied using extensive Monte Carlo simulations. In addition, the effect of imperfect
alignment in backhaul links is studied by using Monte Carlo simulation techniques.
The emission semi-angle of backhaul LEDs is identified as a determining factor for the network
performance. With the assumption that the access and backhaul systems share the same propagation
medium, a large semi-angle of backhaul LEDs results in a substantial degradation in
performance especially under FR-VL backhauling. However, it is shown both theoretically and
by simulations that by choosing a sufficiently small semi-angle value, the adverse effect of the
backhaul interference is entirely eliminated. By employing a narrow light beam in the back-haul
system, the application of wireless optical backhauling is extended to multi-tier optical
attocell networks. As a result of multi-hop backhauling with a tree topology, new challenges
arise concerning optimal scheduling of finite bandwidth and power resources of the bottleneck
backhaul link, i.e., optimal bandwidth sharing and opportunistic power minimization. To tackle
the former challenge, optimal user-based and cell-based scheduling algorithms are developed.
The latter challenge is addressed by introducing novel adaptive power control (APC) and fixed
power control (FPC) schemes. The proposed bandwidth scheduling policies and power control
schemes are supported by an analysis of their corresponding power control coefficients.
Furthermore, another possible application of wireless optical backhauling for indoor networks
is in downlink base station (BS) cooperation. More specifically, novel cooperative transmission
schemes of non-orthogonal DF (NDF) and joint transmission with DF (JDF) in conjunction
with fractional frequency reuse (FFR) partitioning are proposed for an optical attocell downlink.
Their performance gains over baseline scenarios are assessed using Monte Carlo simulations
