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Our research: wireless networking

Architecture, design and wireless communications systems for IoT

We pursue breakthrough research and development for 5G mobile communications networks and cooperative wireless heterogeneous systems.

Wireless networking refers to the method by which homes, telecommunications networks and business installations avoid the introduction of cables onto their premises or as a connection between various equipment locations.

We pursue breakthrough research and development for 5G mobile communications networks and cooperative wireless heterogeneous systems by using the latest specialised hardware and software equipment, including cache-enabled ultra-dense networks, energy harvesting techniques for the Internet of Things (IoT), wireless powered communications, network visualisation and software-defined networks, public safety communications and IoT security.

Our ongoing recent research projects apply to both mobile terrestrial and aerial communications, revolving around architecture design and wireless communications techniques as well as securing the mobile network and bringing the infrastructure-based networks and the infrastructure-less networks into a mutual agreement under cooperative communications.

4G+/5G Mobile networks architecture

Our experts: Professor Abbas Jamalipour, Ms Parisa Ramezani

Energy limitation has always been a major concern for long-term operation of wireless networks. With today's exponential growth of wireless technologies and the rapid movement towards IoT, the need for a reliable energy supply is more tangible than ever. Energy harvesting is one potentially sustainable solution for prolonging the lifetime of wireless networks, particularly harvesting energy from radio frequency (RF) signals.

The integration of RF energy transfer with wireless communication networks has led to the emergence of the research area known as wireless powered communication network (WPCN). In this network, users are powered by a hybrid access point (HAP) which transfers wireless energy to the users in addition to serving the functionalities of a conventional access point.

Our research has extended the baseline model of WPCN to a dual-hop WPCN (DH-WPCN) in which a number of energy-limited relays are in charge of assisting the information exchange between energy-stable users and the HAP. We studied uplink and downlink information transmission in the DH-WPCN and designed algorithms for optimising the performance of the network in both directions. We also tackled the doubly near-far problem – which occurs due to unequal distance of the relays from the HAP – by proposing a fairness enhancement mechanism that guarantees throughput fairness among all users.

Our experts: Professor Abbas Jamalipour, Mr Muntadher Ali

Cellular networks such as long-term evolution (LTE) are suffering from bandwidth starvation due to the ever-increasing growth in traffic demands. The third generation partnership project (3GPP) has proposed sharing the unlicensed spectrum (5 GHz) of wi-fi by LTE to alleviate this starvation. Augmenting the licensed spectrum with unlicensed band for LTE is potentially the key enabler to improve the quality of service (QoS) of LTE; however unfair-coexistence issues arise for wi-fi. Almost all existing approaches harness carrier sensing for both LTE and wi-fi to share the unlicensed spectrum. These solutions are not perfectly viable due to the lack of global visibility on the unlicensed spectrum usage of LTE and wi-fi. Software-Defined Networking (SDN) separates the control plane from the data plane so that the controller gains global networking view.

We propose a resources management framework to allocate unlicensed spectrum to LTE and wi-fi in an SDN environment leveraging the controller’s global view to determine the spectrum/traffic conditions of LTE and wi-fi. Furthermore, traffic engineering (TE) is harnessed where bandwidth chunks correspond to paths in wire networks. The system model combines SDN, cloud, and network function virtualisation (NFV) in a wireless environment. Mechanisms for admission control (AC), classification, monitoring and optimisation are included in the design.

We establish, for the purpose of analysis, a thorough mathematical model employing several concepts including queuing theory. The implementation comprises theoretical and practical evaluations via numerical examples, ns-3, etc. Device-to-device (D2D) communication and cognitive radio are under consideration for inclusion in our project.

Our experts: Professor Abbas Jamalipour, Mr Md. Sazzad Hossen

The aim of this project is to develop a universal traffic steering framework for the next generation software defined networking (SDN)-based cellular network. The framework will consider the current user condition and demand as well as the candidate network's status. With the help of SDN, a feedback mechanism will be introduced in order to make real-time dynamic decisions for steering the traffic/user. On the top, an operator-defined traffic steering policy will assist the traffic steering functionalities.

Our experts: Professor Abbas Jamalipour, Dr Aroba Khan

The goal of this project was to develop a cellular network model that could provide realistic performance evaluation of the network by including the scope for cooperative communication. The effect of cooperative communication via low-power base stations was included in the performance evaluation and compared with a non-cooperative scenario. Analysis showed that the location of cooperating low-power base stations played an important role in user performance.

This project also investigated the impact of moving relays mounted on top of public transports travelling in cells. Testing demonstrated that the cooperative communication range for a moving relay depends upon its transmission power and the direction of travel. Moving relays improve the performance of vehicular users as well as boundary non-vehicular users depending on availability. As a result, a significant improvement in the overall network performance is achieved through the proposed network model.

Our experts: Professor Abbas Jamalipour, Mr Iwan Adhicandra

Worldwide mobile data usage has grown approximately 70 percent annually in recent years, requiring the mobile industry to provide high-performance mobile service to end users and create next-generation mobile technologies. Long-term evolution (LTE), as a popular cellular technology, has grown in importance due to its high data rate and better data access technique for mobile devices. However, LTE still may still be limited due to the existing spectrum insufficiency in licensed bands.

To sustain the possible growth in mobile capacity demand, the unlicensed band is being considered as a supplementary band for LTE and a favourable solution to increase the capacity of mobile systems. Based on the improvement of carrier aggregation, 3GPP has approved a study item that will support LTE by offloading mobile data in the unlicensed band. Hence, LTE will run on the spectrum that overlaps with wi-fi, which is another common unlicensed band technology. The concern is that LTE and wi-fi are unlikely to have mechanisms that directly coordinate with each other, considering dissimilar core networks, backhauls and deployment plans of LTE and wi-fi networks.

The goals of this project are to explore how LTE will influence wi-fi when both of them share the same channel and to develop a possible coexistence procedure to initiate the coexistence between LTE and wi-fi in the unlicensed band.

Our experts: Professor Abbas Jamalipour, Komal Khan

The increased interest in the use of traffic-intensive applications like high definition (HD) video, augmented reality, wearable devices and 3D visualisation is expected to result in a higher growth in network traffic. Video traffic – and particularly popular titles – account for a major proportion of this traffic, shifting the interest of researchers towards cooperative content caching in mobile networks and its services in terms of efficient cache placement. In such a caching scheme, both the mobile terminals and base stations cache content with cooperation, which overcomes the problem of redundant caching by getting rid of multiple and unnecessary copies of the same files in the network nodes.

In a cache-enabled D2D-underlaid cellular network, we aim to formulate cooperation-based caching that will further exploit the limited storage capacity and result in a more efficient wireless resource utilisation. Independent cache resources owned by mobile terminals can be jointly optimised with specific target files for a defined regime. This can be done by heterogeneously assigning correlated file groups to different clusters using stochastic geometry and optimisation theory methods. The spatial and temporal variation of data popularity provides significant information for designing an optimised model in this regard.

Our performance goal for such a model includes achieving a higher hit probability and throughput gain during peak hours, achieving a near optimal delay performance during localised D2D transmissions, and studying the effect of varying co-op devices in a given cluster.

Our experts: Professor Abbas Jamalipour

Our collaborators: Dr Kumudu Munasinghe (University of Canberra), Dr Md Farhad Hossain (Bangladesh University of Engineering and Technology)

Conventional conservative planning and optimisation of cellular mobile networks for supporting the peak-time user demand leads to substantial wastage of electrical energy. Infrastructure sharing among geographically collocated networks is considered promising for energy-efficient operation of future cellular systems. In this project we are developing a generalised energy-efficient cooperation framework for sharing base stations among the cellular radio-access networks (RANs) serving the same geographical area.

The cooperating base stations belonging to different RANs do not need to be collocated. Independent Poisson point process is used for modelling the near realistic random locations of both base systems and user equipment. Under the proposed framework, base stations belonging to different RANs dynamically share each other’s traffic and thus allow some base stations to switch into low power sleep mode for saving energy. During this base station switching through traffic sharing, connection continuity (no drop of the existing calls) is maintained throughout the network. A generalised optimisation problem for maximising energy savings is formulated.

Due to the high complexity of the optimisation problem, heuristically guided algorithms differing in BS selection and UE association policies are proposed. More specifically, two different BSs selection schemes and three separate UE association policies are integrated in the algorithms. Performance of the proposed inter-RAN cooperation framework is evaluated using extensive simulations demonstrating a substantial energy savings and gain in energy efficiency. Impact of different network parameters, such as BS selection and UE association policies, BS and UE densities, BS power profile and SINR requirements for connection continuity on the system performance is thoroughly investigated and analysed.

Mobile networks and IoT security

Our experts: Professor Abbas Jamalipour, Dr Ying Bi

Physical layer security (PLS) is an emerging technology exploiting the randomness and interference of fading channels. Its objective is to restrain the amount of information that can be gleaned at the bit level by eavesdroppers. The increasing research interest in PLS is due to its three main advantages: unlike classical cryptography, PLS makes confidential communication possible without the aid of an encryption key; it is rooted in information-theoretic principles presuming no computational restrictions on eavesdroppers; and it provides explicit performance metric to precisely quantify the security obtained at the physical layer.

This research project aims to develop novel PLS methods for wireless powered communication networks based on exploiting the coordination of cooperative jamming transmission and wireless power transfer. The secure transmission protocols that have been developed in this project can significantly improve the security performance. The analytical study and numerical results demonstrate that the proposed secure transmission protocols can help enhance PLS in wireless powered communication networks, compared to the existing works.

Our experts: Professor Abbas Jamalipour, Umair Nazim

We look at IoT security challenges in more detail and conduct contributed research in the domain of security aspect of machine-to-machine (M2M) communication. The goal of this research is to study approaches to security in IoT networks at TCP/IP layers to detect and prevent distributed denial of service attacks.

The 6LoWPAN protocol is considered as one of the standard protocols supporting communications in the IoT wireless networks and supports large IP version six (IPv6) based networks, which operate with limited power and bandwidth. In our IoT AD-hoc wireless network we are researching utilising IPv6 and prevention and detection of distributed denial of service attacks in IoT networks with CoAP running DTLSv1.2 and 6LoWPAN over wi-fi.

Our experts: Professor Abbas Jamalipour, Dr Smitha Shivshankar

Vehicular ad hoc networks (VANET) employ a combination of vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications to provide drivers with advanced notification of traffic-related events. In V2V systems each vehicle is responsible for inferring the presence of an incident based on reports from other vehicles. Unfortunately, this invites a host of serious security attacks, possibly resulting in increased traffic congestion and a higher chance of severe accidents – a problem that has attracted a great deal of attention.

Vehicle manufacturers, government agencies and standardisation bodies have made significant efforts to improve safety and security. They include Networks-on-Wheels, the Car-2-Car Communication Consortium, the Vehicle Safety Communications Consortium, Honda’s Advanced Safety Vehicle Program and many others. In the past few years there has been a rapid convergence of intelligent transportation systems and VANET, leading to the emergence of Intelligent Vehicular Networks. These changes could revolutionise the way we drive by creating a safe, secure and robust ubiquitous computing environment.

There are a vast number of applications based on inter-vehicular communications that increase safety and information access for vehicle occupants. This project aims to find solutions to some of the most pressing safety and security problems for the current transportation network and future driverless cars.

Mobile networks applications

Our experts: Professor Abbas Jamalipour, Mr Robert Webster

Our collaborator: Associate Professor Kumudu Munasinghe (University of Canberra)

Seventy-five percent of the Earth’s surface is covered in water, yet a large proportion is unexplored. This is especially the case for deep oceanic waters, where it is extremely difficult and expensive for humans to explore. Being low cost, robust and relatively simply to deploy, wireless sensor networks (WSNs) have been touted as a potential solution to providing access to such uncharted waters.

Wireless sensor networks have capabilities defined by their individual nodes or sensors. In most cases, the sensors have low battery life (with the exception of power harvesting capabilities) and low memory and processing abilities.

Underwater wireless sensor networks (UWSNs) apply further constraints to an already constrained network and have limitations dependent on the communications technology used. For radio frequency communications, the signal is highly attenuated. For acoustic communications, signals are inhibited by high propagation delay and low bandwidth. This introduces high latency into the network, which for localisation and other applications would require each sensor to have a precise clock and is cost prohibitive.

Acoustic networks also require higher transmission power, which detracts from our power consumption constraint. Compounding issues further, lack of access to the global positioning system and the effect of passive node mobility created by underwater currents makes localisation and network organisation difficult.

Our research is based on the self-organisation of UWSN nodes into clusters determined by their mobility patterns. Neighbouring nodes with similar mobility patterns are clustered together, which ensures their spatial correlation over time. By doing so, we reduce the number of lost packets, which satisfies our battery constraint criteria and leads to improved network lifetimes.

Our experts: Professor Abbas Jamalipour, Mr Md Arafat Hossain

Our collaborators: Professor John Canning (University of Technology Sydney)

The Lab-in-a-Phone project demonstrates a smartphone-based IoT-compatible, low-cost optical sensing instrumentation for enabling ubiquitous detection and quality assessment of various biological, environmental and agricultural chemicals on spots. The technology can be applied across all agricultural food products including honey, milk, wine, meat and more.

In a previous demonstration, the technology has been used to measure drinking and environmental water quality from different locations across Sydney and produce a real-time map of water quality on a central computer via wireless data collection capabilities. This has heralded the potential of the smartphone technology in connecting the supply chain of many agricultural items into the global IoT network, which enables portable, easy and online assessment for rapid identification of any fraud item in the system and finally reporting to its immediate users as well as manufacturers.

Our experts: Professor Abbas Jamalipour, Dr Smitha Shivshankar

Vehicular networks are adopted for their characteristics of high mobility and self-organising nature. With the increasing demands in different applications and scenarios of information explosion, it requires a need for a framework for efficient communication among the vehicles in the network termed as vehicle-to-vehicle communication (V2V). Addressing such a communication in these networks has become a research challenge due its unique characteristics.

This work aims to develop a distributed and cooperative framework for efficient communication in such a highly-dynamic network. The framework applies cross-layer architecture by integrating the advantages of the application and network layers. It uses a publish/subscribe paradigm at the application layer, with content-based routing, and applies a multicast routing protocol at the network layer to perform network communication.

To enable successful communication it is important for the vehicles to cooperate with each other so that the information communicated over the network reaches the destined vehicles. Security and privacy also play a vital role accounting for the integrity and confidentiality of the information communicated. This is addressed by using cooperation techniques that apply game-theoretic models. The 'public goods game' from economics is applied to model group interactions in vehicular networks and analyses the extent of cooperation of the vehicles under different network conditions.