Electronic Theses and Dissertations

Date

2024

Document Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Electrical & Computer Engineering

Committee Chair

Aaron Robinson

Committee Member

Madhusudhanan Balasubramanian

Committee Member

Peter Lau

Committee Member

Xing Gao

Abstract

In recent years, the amount of data required and consumed by users of internet applications has exponentially increased. Wireless networks play a main role in the data distribution associated with these internet networks as a substantial portion of the data is delivered to mobile clients. As the demand for wireless content delivery continues to increase, significant amounts of wireless network research effort now focus on latency reduction and methods to increase network reliability. In this dissertation, we will work in both directions, reducing latency and increasing reliability. In case of reducing latency, we will work in what is called in the literature as a “Femotcell”. Femtocells are a dense collection of small cells arranged in a manner such that overlap exists between each cell’s coverage. The overlap allows users to have simultaneous access to more than one small cell. These small cells are equipped with large cheap memory and expensive low backhaul links. The idea behind the large cheap memory is to bring the content from the internet and make it closer to users by storing the most valued items. In cases where the requested content is not available in the small cell cache memory, the small cell then uses the expensive backhaul link to fetch the content from the original source and deliver it to the user. The problem of determining which portion of which file should be cached in cache memory to reduce the usage of the backhaul link is defined as the content placement problem. The dissertation will also include results regarding the efficacy of Massive MIMO (Multiple Input Multiple Output) system design strategies as one of the most promising approaches to addressing wireless network issues. MIMO systems have two or more transmitter antennas and one or more receiver antennas to send and receive more data or to improve transmission reliability. MIMO codes are developed to increase the data rate or improve network reliability. Along these lines, we proposed a new Quasi-OSTBC (Orthogonal Space Time Block Code) with the goal of improving system reliability. The basic theory required to support the conclusion, the development of the experiments used to verify results, and the detailed discussion of the implications of the results produced in this dissertation will also be included in the following sections. As such, the contribution of the work completed in this dissertation can be summarized as follows: 1. A novel method to reduce latency in wireless networks considering multi-connectivity where users have access to multiple small cells. 2. Formulation and development of an optimal solution to the content placement problem considering user mobility where user connection to individual small cells changes as a function of time. 3. Development of a technique to improve connection reliability between the network base station and users by decreasing the bit error rate using MIMO system.

Comments

Data is provided by the student.

Library Comment

Dissertation or thesis originally submitted to ProQuest.

Notes

Embargoed until 10-29-2026

Available for download on Thursday, October 29, 2026

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