Mención Internacional en el título de doctorCooperative short-range communication schemes provide powerful tools to solve interference
and resource shortage problems in wireless access networks. With such schemes, a mobile node
with excellent cellular connectivity can momentarily accept to relay traffic for its neighbors experiencing
poor radio conditions and use Device-to-Device (D2D) communications to accomplish
the task. This thesis provides a novel and comprehensive analytical framework that allows evaluating
the effects of D2D communications in access networks in terms of spectrum and energy
efficiency. The analysis covers the cases in which D2D communications use the same bandwidth
of legacy cellular users (in-band D2D) or a different one (out-band D2D) and leverages on the
characterization of underlying queueing systems and protocols to capture the complex intertwining
of short-range and legacy WiFi and cellular communications.
The analysis also unveils how D2D affects the use and scope of other optimization techniques
used for, e.g., interference coordination and fairness in resource distribution. Indeed, characterizing
the performance of D2D-enabled wireless access networks plays an essential role in the optimization
of system operation and, as a consequence, permits to assess the general applicability of
D2D solutions. With such characterization, we were able to design several mechanisms that improve
system capabilities. Specifically, we propose bandwidth resource management techniques
for controlling interference when cellular users and D2D pairs share the same spectrum, we design
advanced and energy-aware access selection mechanisms, we show how to adopt D2D communications
in conjunction with interference coordination schemes to achieve high and fair throughputs,
and we discuss on end-to-end fairness—beyond the use of access network resources—when
D2D communications is adopted in C-RAN. The results reported in this thesis show that identifying
performance bottlenecks is key to properly control network operation, and, interestingly,
bottlenecks may not be represented just by wireless resources when end-to-end fairness is of
concern.Programa Oficial de Doctorado en Ingeniería TelemáticaPresidente: Marco Ajmone Marsan.- Secretario: Miquel Payaró Llisterri.- Vocal: Omer Gurewit
