In multi-tier cellular networks, user performance is largely a ected by the varying
transmit powers, distances, and non-uniform tra c loads of di erent base stations
(BSs) in both the downlink (DL) and uplink (UL) directions of transmission. In
presence of such heterogeneity, decoupled UL-DL user association (DUDe), which
allows users to associate with di erent BSs for UL and DL transmissions, can be
used to optimize network performance. Again, in-band full-duplex (FD) communi-
cation is considered as a promising technique to improve the spectral e ciency of
future multi-tier fth generation (5G) cellular networks. Nonetheless, due to severe
UL-to-DL and DL-to-UL interference issues arising due to FD communications, the
performance gains of DUDe in FD multi-tier networks are inconspicuous. To this end,
this thesis develops a comprehensive framework to analyze the usefulness of DUDe in
a full-duplex multi-tier cellular network. We rst formulate a joint UL and DL user
association problem (with the provision of decoupled association) that maximizes the
sum-rate for UL and DL transmission of all users. Since the formulated problem
is a mixed-integer non-linear programming (MINLP) problem, we invoke approxi-
mations and binary constraint relaxations to convert the problem into a Geometric
Programming (GP) problem that is solved using Karush-Kuhn-Tucker (KKT) opti-
mality conditions. Given the centralized nature and complexity of the GP problem,
the solution of which serves as the upper bound for any sub-optimal solution, we
formulate a distributed two-sided iterative matching game and develop a solution to
obtain the solution of the game. In this game, the users and BSs rank one another
using preference metrics that are subject to the externalities (i.e., dynamic interfer-
ence conditions). The solution of the game is guaranteed to converge and provides
Pareto-e cient stable associations. Finally, we derive e cient light-weight versions
of the iterative matching solution, i.e., non-iterative matching and sequential UL-DL
matching algorithms. The performances of all the solutions are critically evaluated
in terms of aggregate UL and DL rates of all users, the number of unassociated users,
and the number of coupled/decoupled associations. Simulation results demonstrate
the e cacy of the proposed algorithms over the centralized GP solution as well as
traditional coupled and decoupled user association schemes. / October 2016
| Identifer | oai:union.ndltd.org:MANITOBA/oai:mspace.lib.umanitoba.ca:1993/31621 |
| Date | January 1900 |
| Creators | Sekander, Silvia |
| Contributors | Hossain, Ekram (Electrical and Computer Engineering), Cai, Jun (Electrical and Computer Engineering) Wang, Yang (Computer Science) |
| Source Sets | University of Manitoba Canada |
| Detected Language | English |
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