Wireless communication systems -- Technological innovations

This study is a focused effort on elucidating the performance aspects of modern,
handheld wireless devices and associated mobile network services. Specifically addressed
thereof are: (i) Assessing the performance details on certain hardware sections of smart
handheld devices and (ii) determining the performance profile of market penetration
considerations vis-à-vis provisioning mobile networks. To meet the scope of this research,
the projected efforts are exercised in compiling relevant literature and deciding the said
hardware and technoeconomic performance issues. Hence, written in two parts, Part A is
devoted to hardware performance details of smart, handheld devices relevant to (a) delay
issues in PCB layouts; (b) crosstalk problems at the baseband level (audio/multimedia) using
EMI concepts and (c) ascertaining non-catastrophic EMP/EMI effects at the RF-sections so
as to implement protection strategies via compensating networks. Part B is concerned with the technoeconomics of wireless networks in supporting mobile (handheld devices).
Correspondingly, two market related considerations versus service performance details are
considered. The first one refers to deducing a relative performance index that includes
technology (mobile speed) details plus economics profiles of the users in the service area.
The second task refers to elucidating a performance index of such services in terms of
hedonic pricing heuristics.
The theoretical aspects of the test studies as above are supplemented with
experimental and/or simulation details as appropriate. Hence, the efficacy of performance
details are discussed in real-world applications.
Lastly, possible research items for future studies are identified as open-questions.

The growing demand for faster connection to the Internet service and wireless
multimedia applications has motivated the development of broadband wireless access
technologies in recent years. WiMAX has enabled convergence of mobile and fixed
broadband networks through a common wide-area radio-access technology and flexible
network architecture. Scheduling is a fundamental component in resource management in
WiMAX networks and plays the main role in meeting QoS requirements such as delay,
throughput and packet loss for different classes of service. In this dissertation work, the performance of uplink schedulers at the fixed WiMAX MAC layer has been considered, we proposed an Adaptive Hierarchical Weighted Fair Queuing Scheduling algorithm, the new scheduling algorithm adapts to changes in traffic, at the same time; it is able to heuristically enhance the performance of WiMAX network under most circumstances. The heuristic nature of this scheduling algorithm enables the MAC layer to meet the QoS requirements of the users. The performance of this adaptive WiMAX Uplink algorithm has been evaluated by simulation using MATLAB. Results indicate that the algorithm is efficient in scheduling the Base Stations’ traffic loads, and improves QoS. The utilization of relay stations is studied and simulation results are compared with the case without using relay stations. The results show that the proposed scheduling algorithm improves Quality of Service of WiMAX system.

To ensure that a system is robust and will continue operation even when facing
disruptive or traumatic events, we have created a methodology for system architects and
designers which may be used to locate risks and hazards in a design and enable the
development of more robust and resilient system architectures. It uncovers design
vulnerabilities by conducting a complete exploration of a systems’ component
operational state space by observing the system from multi-dimensional perspectives and
conducts a quantitative design space analysis by means of probabilistic risk assessment
using Bayesian Networks. Furthermore, we developed a tool which automated this
methodology and demonstrated its use in an assessment of the OCTT PHM communication system architecture. To boost the robustness of a wireless communication system and efficiently allocate bandwidth, manage throughput, and ensure quality of service on a wireless link, we created a wireless link management architecture which applies sensor fusion to gather and store platform networked sensor metrics, uses time series forecasting to predict the platform position, and manages data transmission for the links (class based, packet scheduling and capacity allocation). To validate our architecture, we developed a link management tool capable of forecasting the link quality and uses cross-layer scheduling and allocation to modify capacity allocation at the IP layer for various packet flows (HTTP, SSH, RTP) and prevent congestion and priority inversion. Wireless sensor networks (WSN) are vulnerable to a plethora of different fault types and external attacks after their deployment. To maintain trust in these systems and
increase WSN reliability in various scenarios, we developed a framework for node fault
detection and prediction in WSNs. Individual wireless sensor nodes sense characteristics
of an object or environment. After a smart device successfully connects to a WSN’s base
station, these sensed metrics are gathered, sent to and stored on the device from each
node in the network, in real time. The framework issues alerts identifying nodes which
are classified as faulty and when specific sensors exceed a percentage of a threshold
(normal range), it is capable of discerning between faulty sensor hardware and anomalous
sensed conditions. Furthermore we developed two proof of concept, prototype
applications based on this framework.