Novel techniques to enhance LTE and WiMAX throughput indoors and at the cell-edge for femtocells using MIMO
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Alshami2014.pdf (24.17Mb)
Date
30/06/2014Item status
Restricted AccessEmbargo end date
31/12/2100Author
Alshami, Mohamed Hassan Ahmed
Metadata
Abstract
Strong demand for wireless communications encourages academic research centres and
industrial electronics and communication companies to keep improving the performance,
increase the speed, extend the coverage area and enlarge the baud rate and capacity. LTE
(Long Term Evolution) and WiMAX (the Worldwide Interoperability Microwave Access)
are recent solutions for most wireless technologies.
LTE and WiMAX coverage range are one of the important factors that affect the quality of
broadband access services and mobile cellular systems in wireless communication.
Predicting and evaluating the path loss is essential in planning and designing cellular mobile
systems. This thesis presents a comprehensive study of path loss on LTE and mobile
WiMAX to achieve large throughputs and wide coverage at the Cell-edge. The thesis
introduces, analyzes and compares the path loss values, based on LTE and WiMAX standard
at one carrier frequency, namely 3.5GHz and a variation of distances in the range of 1 to 50
km, in flat rural, suburban and urban environments. The thesis discusses and implements the
Okumura, Hata, Cost-231, Ericsson, Erceg, Walfish, Ecc-33, Lee and the simplified free
space path loss models. The objectives of path loss evaluation results are to calculate the link
budget, the power outage and the base station cell coverage area for mobile cellular systems.
A femtocell (FMC) is a low cost low power cellular home base station, operating in licensed
spectrum. Because of the requirement for high data rates and improved coverage indoors,
FMC provides a solution to these requirements. FMC is deployed mainly indoors and
sometimes outdoors at the cell-edge to increase the area of coverage, capacity and in order to
enhance the received signal in the user’s premises. The thesis presents the interference,
SINR and the probability of connection for the downlink with different numbers of FMCs
based on LTE and WiMAX OFDMA. Moreover, comparisons of interference, SINR and
probability of connection for three different numbers of FMCs and for three different indoor
areas are presented. In addition, a comparison for the probability of connection with various
threshold values and numbers of FMCs is simulated and presented in 3-D. The probability of
connection for a varied number of FMCs is a guide study to find the appropriate number of
FMCs that could serve a specific indoor area and the proper number of UEs in the specified
area.
The thesis also presents the interference, SINR and the probability of connection at the
uplink for a user equipment device (UE) to an FMC with varied number of UEs based on
LTE and WiMAX OFDMA. Moreover, comparisons of the interference, SINR and
probability of connection for three different areas at the uplink are presented. Therefore,
analyzing probability of connection with varied number of UEs is a worthy study in order to
identify the appropriate number of UEs that could be served by a specific number of FMCs
at a specific indoor location.
The thesis presents and investigates the capacity of MIMO with the presence of FMCs to
perform cancellation of co-channel interference. The research introduces algorithms to
calculate the capacity of MIMO with the presence of FMCs by two models. The simulation
results show that the capacity equations of model-2 give better results than the capacity
equations of model-1. Therefore, model-2 is used for the interference cancellation of MIMO
in the presence of MIMO. Interference cancellation is performed at the downlink when the
signal is transmitted from FMC to UE by mitigating and cancelling the interference which
comes from the neighbouring FMCs to the target UE. The thesis introduces, explains and
applies a novel algorithm to calculate the capacity of MIMO at the presence of FMCs with
interference cancellation by these channel equalizers ZF, MMSE, VBLAST ZF, VBLAST
MMSE and VBLAST OFDM MMSE.