Interference Management in a Class of Multi User Networks
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Date
2014-03-13
Authors
Mahboubi, Seyyed Hassan
Journal Title
Journal ISSN
Volume Title
Publisher
University of Waterloo
Abstract
Spectrum sharing is known as a key solution to accommodate the increasing number of users
and the growing demand for throughput in wireless networks. Interference is the primary barrier
to enhancing the overall throughput of the network, especially in the medium and high signal to
noise ratios (SNRs). Managing interference to overcome this barrier has emerged as a crucial
step in developing efficient wireless networks.
An interference management strategy, named interference Alignment, is investigated. It is observed
that a single strategy is not able to achieve the maximum throughput in all possible
scenarios, and in fact, a careful design is required to fully exploit all available resources in each
realization of the system.
In this dissertation, the impact of interference on the capacity of X networks with multiple
antennas is investigated. Degrees of freedom (DoF) are used as a figure of merit to evaluate the
performance improvement due to the interference management schemes. A new interference
alignment technique called layered interference alignment, which enjoys the combined benefits
of both vector and real alignment is introduced in this thesis. This technique, which uses a
type of Diophantine approximation theorems first introduced by the author, is deployed and
was proved to enable the possibility of joint decoding among the antennas of a receiver. With
a careful transmitter signal design, this method characterizes the total DoF of multiple-input
multiple-output (MIMO) X channels. Then, this result is used to determine the total DoF of two
families of MIMO X channels. The Diophantine approximation theorem is also extended to the
field of complex numbers to accommodate the complex channel realizations as well.