Microwave filters are essential components in many wireless systems from mobile base stations to satellites. They are used to select useful signals while rejecting unwanted interferences or spurious signals. The most widely used microwave filters are formed of resonators that are electromagnetically coupled together to generate the required transmission responses between the two ports - input and output. The properties of the resonators and the couplings between them can be mathematically represented by a so-called 'coupling matrix'. Such a matrix may be found - synthesised - from the required frequency response. The synthesis of two-port filters is an established art. Recently this coupling matrix approach has been extended from two-port filters to multi-port filtering networks (MPFNs). The fundamental difference between a filter and a MPFN is the 'junction resonators', introduced to route the signal to different ports. Such resonators serve not only as resonant poles as in a filter, but also as splitters of the signal which are traditionally achieved by non-resonant transmission lines. One of the microwave circuits that benefit most from the MPFN concept is a multiplexer, also known as a combiner or a filter bank. It basically contains multiple interconnected filters, used to combine multiple channels and feed to one antenna for transmission or reception. It is one of the most complex passive circuits in wireless base stations and satellite payloads. Conventionally all the channel filters are connected to the common port through a signal distribution network based on transmission lines. Using the MPFN concept, the transmission line network can be replaced with resonators. This significantly increases the selectivity of the multiplexer without sacrificing the circuit size, which is highly desired by industrial applications. This means the multiplexer, usually a large component, can be reduced in size and mass for a more contact system. In the case of satellites, this can be translated to a significant cost reduction. The exclusive use of resonators in a microwave circuit also enables integrating filtering function into traditional non-filtering circuit. For instance, common microwave power dividers and couplers are transmission-line based with very limited selectivity. By using the MPFN concept, all-resonator-based power dividers and couplers can be realised with embedding filtering functions. This means two circuit functions are merged into one circuit. This approach is known as 'co-design'. Despite the significant increase in the usage of the MPFN concept and co-design approach in microwave circuit design, there are still significant challenges associated with the technique. The synthesis of the MPFNs is much more demanding than the filters. It requires a new understanding of the coupling characteristics around the junction resonators. The currently inaccessible synthesis technique impedes the take-up of the MPFN concept by microwave engineers. Also there are concerns with the bandwidth and power handling capability of the MPFN-enable devices, as the junction resonator is narrowband in nature and may be a concentration of power. This project aims to develop a robust, more accessible and applicable synthesis technique for MPFNs and to address the practical challenges in bandwidth and power handling by proposing novel junction resonators. The research will help to release the full potentials of MPFNs for industrial applications. There is no doubt the MPFN concept will lead to more innovations in microwave circuits. Built on from the synthesis technique, the project will investigate two new circuit concepts. It is expected new research directions on novel microwave circuits, opportunities for further development and commercial exploration will be generated from this project.

Future wireless systems are expected to constitute an ultra dense wireless network, which supports billions of smart wireless devices (or machines) to provide a wide varieties of services for smart homes, smart cities, smart transportation systems, smart healthcare, and smart environments, etc., in addition to supporting conventional human-initiated mobile communications. Therefore, the communication technologies employed in future wireless communication systems are expected to be capable of coping with highly diverse service requirements and communication environments, both of which also have time-varying nature. However, the legacy wireless systems, such as LTE/LTE-A, have been primarily designed for human-initiated mobile communications, which rely on strict synchronisation guaranteed by a substantial signalling overhead. Explicitly, due to this overhead legacy systems are inefficient for device-centric mMTC. Furthermore, they are unable to support the massive connectivity required by the future mMTC networks, where devices heavily contend for the limited resources available for communications. This project is proposed at the time, when myriads of smart wireless devices of different types are being deployed and connected via the Internet, which is expected to be the next revolution in the mobile ecosystem. To fulfil these objectives, a new design paradigm is required for supporting the massive number of wireless devices having diverse service requirements and unique traffic characteristics. In this project, we propose to meet the challenges of future mMTC by investigating and designing novel non-orthogonal multiple access, flexible duplexing, and adaptive coherent-noncoherent transmission schemes, as well as new waveforms that are tailored for the future mMTC systems. We aim for alleviating the strict synchronism demanded by the legacy wireless systems, and for significantly improving their capabilities, network performance as well as the lifetime of autonomous mMTC nodes. The novelties of this project are summarized as follows. 1. New non-orthogonal sparse code multiple access (SCMA) schemes will be developed for mMTC systems, where the number of devices exceeds the number of available resource-slots, resulting in an over-loaded or a generalized rank-deficient condition. 2. Novel multicarrier waveforms will be designed for future mMTC in order to maximize spectrum efficiency by minimizing the overhead for achieving synchronisation as well as for reducing the out-of-band radiation. 3. By jointly exploiting the resources available in the time, frequency and spatial domains, we will design noncoherent, partially-coherent and adaptive coherent-noncoherent transmission schemes, in order to strike the best possible trade-off among overhead reduction, energy and spectral efficiency, latency and implementation complexity in practical mMTC scenarios. 4. We will investigate the full potential of the multicarrier-division duplex (MDD) scheme and, especially, its applications to future mMTC by synergistically combining it with novel multicarrier waveforms, non-orthogonal SCMA techniques and other high-efficiency transmission schemes developed within the project. 5. Furthermore, the key techniques developed in the project will be prototyped and integrated into the 5G Innovation Centre (5GIC) test bed facilities at the University of Surrey. This will allow us to demonstrate the viability of our new design approaches, as well as to accelerate knowledge transfer and commercialisation. The proposed research will be conducted jointly by the 5GIC at the University of Surrey and Southampton Wireless (SW) at the University of Southampton, led by Xiao, Tafazolli, Yang & Hanzo. The research and commercial exploitation of the project will be further consolidated by our partnership with experienced academic and industrial partners.

Three-dimensional (3D) printing, also known as additive manufacturing, is now common place in many industries and is used widely. Some types of 3D printers are available for home use at modest cost. However, detailed work, together with demonstrator devices, is still in the very early stages in relation to the manufacture of microwave and terahertz circuits. These requires a level of precision and materials very different from the consumer products. This proposal is to evaluate and improve the performance of 3D printing for microwave and terahertz passive and diode circuits through measurement, design and demonstration. These high frequencies, from 10 GHz to 1000 GHz, are used for free space communications, security sensing and remote monitoring of the Earth's atmosphere. The focus will be on evaluation of 3D printed circuits at frequencies above about 50 GHz, the small feature sizes required for these frequencies allows only the best printing process to compete; enabling the project to evaluate the most advanced 3D printing approaches. This exciting project will be the most comprehensive academic study worldwide to date. A strong, experienced, national team, at the University of Birmingham and the STFC Rutherford Appleton Laboratory (RAL) will conduct the research in collaboration with several UK and international industry partners. The Communications and Sensing research group at Birmingham University have already demonstrated significant research in this area, with 3D printed devices published covering the frequency range 0.5 GHz to 100 GHz. The importance of this work has been recognised externally through prizes, invited international presentations and refereed academic publications. Birmingham's partners, the Millimetre Wave Technology Group in the RAL Space department, bring extensive expertise in precision manufacturing of conventional devices for these high frequencies, and knowledge of the demanding space and other requirements that the new 3D circuits must fulfil. RAL staff will conduct post processing of the 3D printed circuits and perform accelerated lifetime measurements under conditions of elevated temperature and humidity. 3D printed microwave and terahertz circuits will have an important beneficial economic impact on UK industry, not only because complex circuits become possible at low cost, but because new design approaches emerge because of the unique manufacturing. The applicants will both work on their own ideas, and closely with industrial partners, during the project. There are a number of hurdles to overcome before the technology becomes mainstream: this proposal tackles these challenges. The advantages of 3D printing include the availability to rapidly generate novel circuits with complex shapes and multiple functions using low material volumes in a lightweight form. This enables reliable, low cost, superior performance circuits with less waste and reductions in lead time. Considerations to be addressed include the metal coating of polymer circuits which adds an extra step in the production, as well as potentially lower thermal stability and power handling of such circuits. If the polymer is used as a microwave dielectric, power loss may be a problem. For metal 3D printed circuits, power handling and thermal stability is good, but surface roughness may reduce device performance. These problems and others are addressed in the proposal with a methodical investigation based on the measurement of resonant waveguide cavities, the microwave equivalent of a tuning fork. Changes to the frequency and decay time indicate the quality of manufacture. The project will inform industry and academia through a widely distributed technology development roadmap and external collaborative projects, as well as the provision of advice and guidance. Our finding will also be communicated to national and international colleagues through academic publications, and presentations at relevant conferences.

Understanding the behaviour of the Internet with its inherent complexity and scale is essential when designing new Internet systems and applications. Simulation, emulation, and test-bed experiments are important techniques for investigating large-scale complex Internet systems. It is now widely recognised that classical theoretical/simulation scalability studies for Internet research are unreliable without relevant and representative supporting experimental evidence. This is increasingly important with the emergence of 5G, cloud services and IoT, which lead to at least 2 orders increase in connection capacity requirements and 3 orders of additional devices that require Internet connectivity. Great progress has been made in the UK over the years on the development of communications laboratories infrastructure in ICT domains such as optical & wireless, signal processing, networks and distributed systems, where the UK is internationally leading. However, UK telecommunications research remains largely segregated in independent optical, wireless or computer network research labs, so researchers very rarely have the opportunity to experiment across the boundaries between these disciplines. Due to the limitations of performing research in discipline-specific facilities, the current UK ICT research output does not address realistic end-to-end Internet systems INITIATE will create a new, specialist distributed test-bed to facilitate the increasingly large and complex experimentation required for future Internet research. This will be achieved by interconnecting operational, state-of-the-art operational laboratories at the Universities of Bristol, Lancaster (UoLan), Edinburgh (UoEd) and Kings College London (KCL). These laboratories will contribute many key capabilities for Internet research including optical networks, wireless/RF communications, the Internet of Things (IoT), Software Defined Networking (SDN), Network Function Virtualisation (NFV) and cloud computing. Therefore INITIATE will offer the combined capability to the UK Internet research and innovation communities as a single distributed test-bed able to support the increasingly complex experimentation required for future Internet research. For example, INITIATE will enable for the first time experimentally driven research addressing the integration of multi-domain and multi-technology 5G and IoT access platforms with high-speed optical transport and investigate full system optimization strategies. Uniquely, INITIATE will also be able to integrate end-users as part of the experimental process and support user driven scenarios such as mobile edge computing, data visualization and autonomous mobility. The applicants have an outstanding worldwide reputation for creating, maintaining and operating research test-beds. They have repeatedly enabled remote access to their laboratories for experimenters and they have worked in multiple initiatives involving interconnection of research test-beds either locally, across the consortium partners or at a regional, national and international scale. Examples are: Bristol Is Open (UoB), TOUCAN (EPSRC involving UoB, UoEd, UoLan), NDFIS (UoB, UCL, SOTON, Cambridge), wireless mesh networks for rural communities (UoLan) and the Ofcom whitespace trial environment (KCL), among others. Internationally, the partners have been involved in numerous Future Internet infrastructure projects such as OFELIA & Fed4FIRE (EU FIRE), FIBRE & FUTEBOL (EU-Brazil), STRAUSS (EU-Japan) and GEANT, where they have delivered test-bed infrastructure, developed experimental control and federation tools and supported user experiments. INITIATE will create an environment for delivering excellence in Internet research, educational and industrial innovation and cross-discipline interaction through experimentally driven national collaboration. The project will also support academia as well as industry and SMEs and will deliver a sustainable engagement model.