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Increasing the capacity of 5G networks using mobile-cells : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Engineering at Massey University, New Zealand
(Massey University, 2019) Jaffry, Shan
Recently, the exponential growth in mobile data demand, fuelled by novel use-cases, such as high- definition video streaming, etc., has caused massive strain on cellular networks. As a solution, the fifth generation (5G) of cellular technology has been introduced to improve network performance through various innovative features, such as millimeter-wave spectrum, device-centric communication, and heterogeneous networks (HetNet). The HetNets will comprise of several small-cells underlaid within macro-cell to serve densely populated regions, like stadiums, malls, etc. On the other hand, due to the constant rise in the use of mobile phones while traveling, the concept of mobile-cells has emerged. Mobile-cells may well be defined as public transport vehicles (e.g., buses or trains etc.) equipped with in- vehicle cellular antenna to serve commuters. The argument for using mobile-cell is based on the observation that commuters often experience poor quality of service (QoS) due to vehicular penetration loss (VPL). Mobile-cell will decouple commuters from the core network, thus eliminating VPL, along with relieving base station off large number of users. Mobile-cells will contain multiple wireless links. Commuters will be served over access link (AL), while the communication with the core network will occur over the backhaul link (BL). On the other hand, neighboring mobile-cells will mutually exchange data over sidehaul links (SLs). Like any other device-centric communication, mobile-cells need to ‘discover’ their neighbors before establishing SLs. Neighborhood discovery is challenging for mobile-cells. Relevant literature on this topic has only focused on static devices, and discovery for mobile devices has not been investigated in detail. Hence, as our first research problem in this thesis, we have focused on the autonomous discovery by a mobile-cell. In general, due to randomness involved in an autonomous process, neighborhood discovery often fails due to collision and half-duplexing effects. This thesis focuses on mitigating these effects. Firstly, we have proposed a modified time-frequency frame structure to subside the collision and half-duplexing effects. Later on, we have presented a more reliable solution that utilizes proximity awareness to adapt transmission probability of individual devices. This scheme has resulted in a drastic increase in the probability of successful discovery as compared to the conventional approaches. On the other hand, actual data exchange via mobile-cell’s links requires interference-free resource allocation for each link. Mobile-cells’ wireless links will cause severe interference to the out-of-vehicle cellular users. Few researchers have assigned separate bands for in-vehicle and out-of-vehicle links. However, given the scarcity of spectral resources, these methods are practically inefficient. Thus, we have addressed the issue of resource allocation as the second research problem in this thesis. Instead of assigning individual resources to each link, we have focused on resource sharing between multiple wireless links. To achieve this goal, we have exploited VPL and utilized successive interference cancellation. Our results have shown high QoS at each individual link. We have also demonstrated the effect of mobility on the proposed resource sharing schemes. The schemes proposed in this thesis will ensure that the mobile-cell increases the capacity of 5G networks through aggressive resource sharing such that more links will use available spectral resources.
Effective relaying mechanisms in future device to device communication : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in School of Food and Advanced Technology at Massey University, Palmerston North, New Zealand
(Massey University, 2020) Zaidi, Syeda Kanwal
Future wireless networks embrace a large number of assorted network-enabled devices such as mobile phones, sensor nodes, drones, smart gears, etc., with different applications and purpose, but they all share one common characteristic which is the dependence on strong network connectivity. Growing demand of internet-connected devices and data applications is burdensome for the currently deployed cellular wireless networks. For this reason, future networks are likely to embrace cutting-edge technological advancements in network infrastructure such as, small cells, device-to-device communication, non-orthogonal multiple access scheme (NOMA), multiple-input-multiple out, etc., to increase spectral efficiency, improve network coverage, and reduce network latency. Individual devices acquire network connectivity by accessing radio resources in orthogonal manner which limits spectrum utilisation resulting in data congestion and latency in dense cellular networks. NOMA is a prominent scheme in which multiple users are paired together and access radio resources by slicing the power domain. While several research works study power control mechanisms by base station to communicate with NOMA users, it is equally important to maintain distinction between the users in uplink communication. Furthermore, these users in a NOMA pair are able to perform cooperative relaying where one device assists another device in a NOMA pair to increase signal diversity. However, the benefits of using a NOMA pair in improving network coverage is still overlooked. With a varierty of cellular connected devices, use of NOMA is studied on devices with similar channel characteristics and the need of adopting NOMA for aerial devices has not been investigated. Therefore, this research establishes a novel mechanism to offer distinction in uplink communication for NOMA pair, a relaying scheme to extend the coverage of a base station by utilising NOMA pair and a ranking scheme for ground and aerial devices to access radio resources by NOMA.
Performance improvements to the AODV routing protocol and multiple hop wireless routes : a thesis presented in partial fulfilment of the requirements for the degree of Masters of Engineering in Computer Systems Engineering at Massey University, Palmerston North, New Zealand
(Massey University, 2005) Sinclair, Matthew Kersley
This research focused on improving the performance of the Ad-hoc On-demand Distance Vector (AODV) routing protocol over multiple hop routes. The two specific areas that this research addressed were the dramatic decrease in throughput over multiple hop IEEE 802.11 wireless routes and the problems caused by the use of hello messages by AODV implementations to detect broken routes. To help ensure that this research was suitable for real world scenarios, only off-the-shelf software and hardware was used for both the implementations and the tests. This thesis firstly presents an overview of IEEE 802.11 based wireless networking and the AODV protocol, along with wireless networking and networking in general within the Linux operating system. The thesis then presents the problems caused by hello messages and shows how the IEEE 802.11 wireless standard contributes to the dramatic decrease in throughput over multiple hop routes. To overcome the hello message problems, an AODV implementation was developed which used existing mechanisms on the data link layer, specifically the transmit retry limit, rather then hello messages to detect broken links. To address the multiple hop route throughput problem, the use of two and four IEEE 802.11 based wireless network interfaces per node were investigated, rather than using just a single wireless interface per node. These proposed solutions, and the AODV implementation that was developed as part of this research, were then tested in the areas of functionality and throughput performance improvements. The thesis concludes by presenting the performance improvements resulting from using multiple interfaces per node and the non hello message based AODV implementation along with outlining possible future research in this area.
Performance improvements to the 802.11 wireless network medium access control sub-layer : a thesis presented in partial fulfilment of the requirements for the degree of Master of Engineering in Computer Systems Engineering at Massey University
(Massey University, 2005) Morrison, Michael Philip
This thesis presents the outcome into the research and development of improvements to the 802.11 wireless networking medium access control (MAC) sublayer. The main products of the research are three types of improvement that increase the efficiency and throughput of the 802.11 protocol. Beginning with an overview of the original 802.11 physical layer and MAC sub-layer standard, the introductory chapters then cover the many supplements to the original standard (including a brief on the future 802.11n supplement). The current state of the 802.11 MAC sub-layer is presented along with an assessment of the realistic performance available from 802.11. Lastly, the motivations for improving the MAC sub-layer are explained along with a summary of existing research into this area. The main improvement presented within the thesis is that of packet aggregation. The operation of aggregation is explained in detail, along with the reasons for the significant available throughput increase to 802.11 from aggregation. Aggregation is then developed to produce even higher throughput, and to be a more robust mechanism. Additionally, aggregation is formally described in the form of an update to the existing 802.11 standard. Following this, two more improvements are shown that can be used either with or without the aggregation mechanism. Stored frame headers are designed to reduce repetition of control data, and combined acknowledgements are an expansion of the block acknowledgement system introduced in the 802.11e supplement. This is followed by a description of the simulation environment used to test the three improvements presented, such as the settings used and metrics created. The results of the simulations of the improvements are presented along with the discussion. The developments to the basic improvements are also simulated and discussed in the same way. Finally, conclusions about the improvements detailed and the results shown in the simulations are drawn. Also at the end of the thesis, the possible future direction of research into the improvements is given, as well as the aspects and issues of implementing aggregation on a personal computer based platform.
Multi-carrier cooperative wireless communication : performance analysis and resource allocation : a thesis presented in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Electrical Engineering at Massey University, New Zealand
(Massey University, 2013) Abrar, Muhammad
Relay-based cooperative wireless communication is emerging as the major candidate technology for the next generation wireless cellular networks that will support significantly higher data rates than the recent systems. The combination of cooperative relaying with Orthogonal Frequency Division Multiplexing (OFDM) is a very promising design for next generation of wireless networks with increased system throughput and spectral efficiency. The success of this combination, like other wireless networks, relies on the efficient utilization of limited radio resources such as relays, power, subcarriers and antennas. In this research, resource allocation problems are examined with different relaying techniques and protocols and computationally efficient resource allocation algorithms are proposed. The general objective is to device resource allocation schemes in relay-based cellular networks that maximize the system throughput under different constraints. The main goal of our research is to develop efficient resource allocation algorithms for two different relaying models, namely; one-way relaying and two-way relaying in realistic scenarios for the Third Generation Partnership Project (3GPP) Long Term Evolution Advanced (LTE-Advanced) cellular standard. Performance of the proposed algorithms will be evaluated in terms of not only the throughput but also the computational complexity. In particular, in this thesis we present low-complexity efficient schemes for jointly deciding the selection of relays and subcarriers for the users. Two types of fairness among users, namely; minimum rate proportional fairness and access proportional fairness, are also considered in assigning subcarriers to users in relay networks. A new low-complexity iterative resource block (RB)-pairing and allocation algorithm is also investigated in relay networks. Finally, we present a brief analysis of inter-cell interference in relay networks. Both theoretical analysis and computer simulations are performed in the performance evaluation of the proposed algorithms. Furthermore, practical implementation issues are also addressed.
Smart power monitoring utility system using wireless sensor networks : a project report submitted in partial fulfilment of the requirements for the degree of Master of Engineering in Electronics and Electrical Engineering
(Massey University, 2013) Gill, Satinder Pal Singh
The design and development of a Wireless Sensor Networks based Smart Grid for home utility system for power utility has been presented in this thesis. The system utilises wireless power monitoring devices and control units. The electronic wireless power monitoring devices have been designed to monitor electrical parameters such as voltage, current and power of the household appliances. The measured electrical parameters are transmitted to a central controller via the ZigBee node. The central coordinator has been configured around a laptop computer and receives all the transmitted data from different nodes. The computer stores the measured data and analyses them. The computer is also connected to internet and the website of the electrical power supply company is accessed. The real-time electricity tariff is available to the controller. Based on the tariff condition the controller can determine the off-peak and peak-electricity rate. The controller can decide to switch off the unimportant electrical loads at peak-tariff situation. This is implemented by sending the necessary command to the zigbee node connected to the appropriate load. The zigbee node can then switch off the load by sending an off-command to the triac which is used as the control device. The user has the options of controlling the electrical appliances in different modes. If the users would like to continue the load to be on during the peak-tariff condition, the option of a manual switch can be used to bypass the triac. The appropriate electrical loads can be monitored as well as controlled using the developed GUI available at the laptop. The complete information of the system is also available through a website and appropriate control action can be implemented through a secured access. The objective of the research is to lower the consumption of power during the peak-tariff condition and thereby saves electricity cost. A prototype has been designed, developed and extensively tested. This Thesis presents the current work, experimental results and concludes with possible future research opportunities.
Wireless data acquisition and monitoring for healthcare services systems : a thesis in the partial fulfillment of the requirement for the Masters of Engineering (Electronics and Computer Systems), Massey University, Palmerston North, New Zealand
(Massey University, 2011) Kioumars, Amir Hoshang
The aging population brings challenges to healthcare systems. To cope with the high demand on health professionals and services, the feasible solution is to engage modern technologies. Wireless communication, service robots and information technology have become the active research areas for future healthcare systems. In the field of human health, collecting and analysing the real-time data is vital. New facilities and advanced tools give health service providers and their patients more choices to readily access and use health information and collect and store real-time health data. Information technology (IT) has the potential to improve the quality, safety, and efficiency of healthcare. IT allows healthcare providers to collect, store, retrieve and transfer information electronically. Together with modern communication technologies and intelligent systems, patients are able to monitor their own vital health signs from home and communicate the results to their health providers wirelessly. This will increase the ability to address a problem before a patient requires acute care. The ability to remotely monitor vital signs of a patient in real-time using a simple, low-cost and compact device with a minimum training time is highly desirable in a society with an increasing aging population. This research outlines the design and development of a cost effective and reliable wireless sensing device for collecting real-time health vital signs such as human body temperature and heart rate. A software system is also developed to provide two-way communications with the remote sensor device in order to receive and store the collected data by the sensor device in a central database. The literature review led to the use of ATmega micro-controller, ZigBee technology for wireless communication and the development of highly adaptable, flexible and intelligent software written in Microsoft C-Sharp (C#). A unique communication data packet is also developed and implemented to overcome the micro-controller memory limitations, improving the reliability of the communication and increasing the security of data as well as saving power. The system is able to communicate with service robots and host computers via the network of XBees. The proposed hardware device is able to collect the human heart rate and body temperature in real-time. It is light-weight, low-cost, power efficient and maintainable. It can be wrapped around the wrist and carried with the person. It transmits the data when it is needed and stays on sleep mode to save power. The developed software system (T-HBR, stands for temperature-heart beat rate) is capable of receiving the data from the remote device and storing the data to a central database. T-HBR allows health professionals such as general practitioners (GPs), nurses and healthcare providers to be able to collect the real-time data, see the patient‟s history, issue a new prescription and send it to the patient, other GPs or nurses by e-mails or text messages. The software can be a component of an individual system or can be used within a network connected to a central database. The software system supports a high level of security by using ten different types of encryption algorithms and is also able to import data from other T-HBR software and merge them into the existing database. It is component-based software with a three-layer architecture, which allows each component of the system to be replaced separately. Such a design approach reduces the cost of maintenance and enables more functionality to be added easily.
What is a cellphone? A tetradic odyssey : a study in media ecology : a thesis presented in partial fulfilment of the requirements for the degree of Master of Philosophy in Media Studies at Massey University, Manawatu, New Zealand
(Massey University, 2011) Palmer, Stephen Matthew; Palmer, Stephen Matthew
This study asks the question, “What is a cellphone?” Marshall McLuhan et al. jointly devised the tetrad as a method for revealing the hidden characteristics of any human medium or artefact. This study views a cellphone through the tetrad’s distinctive four-dimensional non-dialectical approach. In the process, many intriguing, surprising and even contradictory aspects come to light.
BER performance of MC-DS-CDMA systems in the presence of timing jitter : a thesis presented in partial fulfillment of the requirements for the degree of Master of Engineering in Information and Telecommunication Engineering at Massey University, Palmerston North, New Zealand
(Massey University, 2010) Xu, Lindong; Xu, Lindong
Multi-carrier direct-sequence code division multiple access (MC-DS-CDMA) technique, which is a combination of orthogonal frequency-division multiplexing (OFDM) and code division multiple accesses (CDMA), has been considered as an important technique for the future generation wireless systems due to its bandwidth efficiency, frequency diversity, and immunity to channel dispersion. OFDM has already been employed in many areas, such as digital audio and video broadcasting, wireless local/metropolitan area networks, and asynchronous digital subscriber lines (ADSL). Leveraging the multiple access capability of CDMA, the MC-DS-CDMA technique is an important enhancement to OFDM. Nevertheless, a major disadvantage of the MC-DS-CDMA systems is their high sensitivity to timing errors between transmitter and receiver due to the use of a large number of carriers and the superposition of signals of multiple users. In this thesis, we study the bit error rate (BER) performance of MC-DS-CDMA system under the effects of timing jitter in additive white Gaussian noise (AWGN) channel and multi-path Rayleigh fading channel, respectively. In particular, we have derived the analytical BER expressions for the MC-DS-CDMA signals in presence of white or colored timing jitters and verified the results via computer simulations.
Design and implementation of HTS technology for cellular base stations : an investigation into improving cellular communication : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Electrical Engineering at Massey University, Palmerston North, New Zealand, and James Cook University, Townsville, Australia
(Massey University, 2006) Knack, Adrian
When placed between the antenna and receiver electronics of a cellular base transceiver station, a Cryogenic Receiver Front End (CRFE), consisting of a High Temperature Superconducting (HTS) filter and modern Low Noise Amplifier (LNA), can significantly improve the base stations' coverage and capacity. Due to CRFEs being hurried to the telecommunications industry in a competitive market, the development of CRFEs and their performance have been classified. This left it to be pondered whether HTS filters could really have been beneficial or if they were always just of academic interest. It is the main objective of this thesis to investigate if and under what circumstances high temperature RF-superconductivity can prove to be an important technological contribution to current and future wireless communications. This dissertation presents the analysis of an existing CRFE developed by Cryoelectra GmbH and its performance characteristics measured in a field trial held in rural China. With the aid of a CDMA Uplink Model developed by the author, the data was analysed and several novel engineering improvements were made to create an advanced CRFE which was economical to deploy. The analysis of results from a field trial in Beijing city using the CDMA Uplink Model led to the exploration of alternative filter technologies which could achieve similar results to the HTS filter technology. This culminated in the development of dielectric resonators filters which could be used as an alternative and as a supplement to the HTS filters used in the CRFE. The design of two novel dielectric resonator duplexers and two advanced multioperator combiner antenna sharing solutions followed the successful implementation of a high performance dielectric resonator filter. The performed investigation and development described in this thesis suggest that HTS filter technology for terrestrial wireless communications can be beneficial in current cellular networks, but due to its high cost is economical for use only under certain conditions. However, HTS filter technology may be of great importance in the design and implementation of spectrum friendly wireless communications systems in the future.

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