Moonas Ahmad

Power amplifier architecture for mmWave communications

The next generation of communication systems will make use of mm-Wave spectrum to achieve high data rate demands due to crowding of frequency bands below 6 GHz. Multiple mm-wave frequency bands are being allocated for future communications (e.g., 24/28/37/39 GHz). To achieve Gb/s data rates, mm-Wave communication systems will use spectrum-efficient modulation schemes (e.g., 64- and 256-QAM) and MIMO techniques. High order QAMs scheme waveforms have high peak-to-average power ratios (PAPRs) thus putting strict linearity requirement on power amplifier. Also, mm-Wave devices should be energy efficient in power back-off (PBO) to extend the battery life. This means that power amplifiers (PA) for mm-Wave application should be both linear and energy efficient which is hard to achieve due to trade-off between these two parameters.

But Gb/s data rates and >400MHz bandwidth target for mm-Wave communication entails additional challenges for PA design techniques. The signal processing for Digital Predistortion (DPD) will be complex and consume high dc power. Envelope tracking (ET) PAs will require high-speed supply modulators with wide dynamic range. Outphasing PAs require the generation of highspeed outphasing signals, demanding significant baseband overhead. Instead PA architecture such as Stacked-transistor, Doherty and switch-mode seems more suited for mm-wave system. Thus, the design approach will be to utilise Doherty PA architecture where Stacked-FETs will be used to implement main and auxiliary PAs to enhance efficiency and DPD techniques will be employed to increase linearity.

Faya Algahtani

Micro-*countermeasures for severely constrained IoT wireless embedded devices

In the Internet of Things (IoT), resource-limited devices are connected to the untrusted Internet using IPv6 and 6LoWPAN networks. Despite message security via cryptography, these devices are vulnerable to both to attacks from within the 6LoWPAN network and the Internet. Since these attacks may succeed, security countermeasures mechanisms such as firewalls, intrusion detection systems, and intrusion prevention systems are essential. Currently, security countermeasures that meet the requirements of the 6LoWPAN are either customized for wireless sensor networks or the conventional Internet. In this research project, the necessary background theory is considered as well as a review, comparison, and evaluation of current algorithms suitable for battery-powered devices with severe computation and communication constraints. Potential ideas on how to devise novel algorithms for security countermeasures for severely constrained IoT devices are also considered.

Obada Alia

Physical layer network security for the future internet

With the improvement of quantum computers, the current public encryption algorithms will be considered outdated; hence a new technology is required to secure the internet. Quantum Key Distribution (QKD) provides an unconditional secrecy based on the principles of quantum mechanics, and found to be the essential element in many cryptography applications. QKD protocols are divided into continuous-variable QKD (CV-QKD) and discrete-variable QKD (DV-QKD) protocols and a comparison in terms of performance, applications, and limitation is made. Two of the main limitations of QKD are that fact that the current available protocols only support end-end transmission and the relatively short effective range of transmission comparing to other security methods. Integrating QKD with the classical channels (co-existence) in a mesh-topology network is proposed with which to enhance the quality of the transmission and to provide a multi-hop connectivity using trusted nodes. The proposed solution has been integrated into a fully meshed metro network where a dynamic quantum channel is co-existed with four classical channels in the 5GUK Test Network. The results show the possibility of having such a network revealing the resource allocation and rerouting advantages for QKD networking.

Sebastian Kudera

Atmospheric ducting and over the horizon propagation

Atmospheric ducts, which are caused by the rapid decrease in the refractive index of the lower atmosphere, can trap the propagating signals. The atmospheric duct trapping effects can be used as a means of communication for links beyond-line-of-sight (b-LoS). In this work, the effects of atmospheric ducts on RF propagation when it takes place over water in the context of developing Smart City infrastructure are studied. Main characteristics of ducts are analysed, and it is found that due to its high rate of occurrence and strength the most promising type of duct is evaporation duct. Even the strongest ducts trap radiowaves at propagation angles only to within 1°. Drawbacks of atmospheric duct are overviewed. Ducting is found to create radar holes, inter-symbol interference and co-channel interference. To overcome those problems, optimal transmit and receive beam patterns should be designed and orthogonal frequency division multiplexing (OFDM) can be promising for the ducting layer if the channel creates high delay spreads. This work introduces the state-of-the-art methods for wave propagation modelling, the Parabolic Equation (PE) method, and the Ray-Optics (RO) method. The assumptions of the derivation, the advantages, and drawbacks of the PE and RO methods are discussed. A basic limitation of the RO model is that it assumes a horizontally homogeneous refractive environment and must be used over a flat surface, while parabolic methods cannot be used in estimating delay spreads and angle of arrivals. Therefore, characteristics of the channel can be estimated with hybrid models. Deep learning methods look promising for refractivity profile modelling.

Sarmad Ozan

Frequency agile and resilient RF technologies

Millions of devices are susceptible to cyber-attacks due to the vulnerabilities in the Radio Frequency (RF) technologies used. Nowadays, society rely primarily on services provided by the Critical Infrastructures (CIs) such as health, transportation and public safety which can severely be affected in terms of functionality and stability if an adversary intends to degrade wireless connectivity by some means such as jamming. Furthermore, coverage of a multi-band multi-standard by a single transceiver architecture is highly desirable for the wireless communications industry. Spectrum sharing is a promising technique to optimise the use of the spectrum by giving access to underutilised spectrum such as TV white space. Also, using hybrid spectrum sharing to exploit different bands for the same user as Mobile Network Operators (MNOs) try to meet the high data rate and low latency requirements with cost-effective solutions. Carrier aggregation (CA) is a known technique to combine multiple component carriers (CCs) across the accessible spectrum, to improve network performance, but is problematic in implementation. This project addresses how wireless communication transceiver RF technologies works and how it can be made resilient to attack by reviewing the advances in RF technologies including amplifiers, filters, duplexers. Further, these devices need to be tuneable in frequency thus offering agility in the RF front-end making it adapt quickly to any blocking signal and allow multiband simultaneous receive/ transmit. Today’s challenges are presented in terms of secure RF design with a connection to the spectrum allocations and regulations, and how the RF technologies can comply with these regulations.

Ioannis Papoutsidakis

Towards massive, ultra reliable and low-latency wireless communications

At the moment, the 5th generation of wireless networks (5G) is deployed around the world and several limitations of the system are exposed. For instance, only one of the three designated service classes are implemented and ready to be used. These shortcoming result to an emerging interest for the future wireless networks that must be innovative and at the same time cover the weaknesses of previous generations. In this work, a vision for the 6th Generation (6G) wireless networks is presented based on new technological trends and applications. The potential service classes for 6G, that can accommodate new applications, are presented and open research problems are discussed. We focus, especially, at a service class that connects 5G and 6G research, namely Ultrareliable and Low-Latency Communications (URLLC). The fundamental tradeoffs between rate, reliability, and latency are considered in the context of short packet communications and a new upper bound to the non-asymptotic capacity of erasure channels is developed. This bound can be used as a benchmark of channel coding for arbitrary channels.

Simon Wilson

Secure dynamic spectrum access

“Secure By Design” initiatives are intended to ensure that wireless systems are built on secure foundations and include the ability to field-update the radio physical layer. Such security and agility will enable spectrum allocation through Dynamic Spectrum Access (DSA), a technique for improving spectrum usage based on instantaneous need in space and time, rather than fixed licensing. DSA has attracted much attention, with many administrations keen to promote its development and uptake, but will require secure sharing protocols and flexible, agile radios as well as robust detection mechanisms to identify unused spectrum. It is therefore timely to extend further wireless physical layer security research, to identify threats and find solutions that can be retrospectively applied to existing systems, and to influence the next generation of wireless standards, all the while raising awareness of potential problems. The initial approach to be taken in the Secure DSA project will be to: understand the vulnerabilities of sharing protocols by analysis of current and potential dynamic access protocols; identify the key features of robust detection mechanisms to identify unused spectrum; evaluate the security of protocols employed to manage spectrum sharing; establish a novel methodology to synthesize attacks, vectored through the radio interface; develop a range of testing protocols; and undertake a cost-benefit analysis of DSA protocols.