A Unified Multiple Access Framework for Next Generation Mobile Networks By Removing Orthogonality (MANGO)

An 8-fold increase in global mobile data traffic is predicted from 2015 to 2020, and it is expected that 50 billion devices will be connected through the mobile networks by 2020, given the expected surge in mobile connectivity and Internet of Things (IoT) applications. A combination of multiple approaches would be required to satisfy ever-growing demand of mobile data traffic, i.e., significant enhancement in spectrum efficiency, extension of available spectrum to higher frequency bands, and network densification using small cells.

The design of novel radio access technologies is an important aspect in improving spectrum efficiency in a cost-effective manner for future mobile networks. Radio access technologies are typically characterised by orthogonal multiple access schemes, e.g., frequency division multiple access (FDMA), time division multiple access (TDMA), code division multiple access (CDMA), and orthogonal FDMA (OFDMA) that provide the means for multiple users to access and share the radio resources simultaneously. One of the key issues with the orthogonal multiple access (OMA) schemes, for example, OFDMA used by 3GPP-LTE, is that when some bandwidth resources, such as subcarrier channels, are allocated to users with poor channel condition, it results in lower spectrum efficiency.

Motivated by the spectral inefficiency of OMA techniques, non-orthogonal multiple access (NOMA) has been recognised recently as a promising multiple access technique to significantly enhance the spectral efficiency and is envisioned to be a key component of the next generation mobile networks. The dominant NOMA schemes are grouped in two categories: power-domain or code-domain NOMA. In power-domain NOMA, users are allocated different power levels according to their channel conditions to obtain the maximum gain in system performance whereas in code-domain NOMA, different users are assigned different codes, and are then multiplexed over the same time-frequency resources. However, NOMA techniques still involve several critical challenges such as lack of insightful understanding of the performance limits of NOMA and a large gap in the performance evaluation of NOMA transceivers under single-/multiple antennas, single-/multi-cell cases, which makes their immediate deployment prohibitive.

This visionary project tackles the issue of NOMA techniques' deployment in next generation mobile networks by establishing a unified theoretical framework and developing sophisticated digital signal processing algorithms to realise the concept of NOMA in single-/multiple antenna, single-/multi-cell scenarios. The novelty of this project lies in a) information theoretical analysis with practical constraints, b) less-computationally complex transceiver design for power-domain and code-domain NOMA c) joint precoding design for single- and multi-cell NOMA networks, d) NOMA applications in cognitive radio and IoT systems and e) system level performance evaluations in next generation mobile network scenarios.

The project will be performed in partnership with leaders in future mobile network research and standardisation (Samsung, Nokia Bell Labs, MobileVCE) and in defence and emergency services (QinetiQ). The project consortium maintains a very strong track record in wireless communications, MIMO signal processing, and information theory with a right mix of theoretical and practical skills. Given the novelty and originality of the topic, the research outcomes will be of considerable value to transform the future of mobile networks and give the industry a fresh and timely insight into the development of NOMA based radio access in next generation mobile networks, advancing UK's research profile of wireless communication in the world. It is further believed that the successful completion of this project will lead to radically changes in the design of the physical layer of wireless communication systems and have a tremendous impact on standardisation.

The recent spectrum and energy crisis and the predicted saturation of the ICT sector profits are imposing a rethink of the mobile network design and business models. Presently, the focus is turning to the design of next generation mobile networks that would provide 10-100x data rate, 1000x capacity per unit area, 10-100x connected devices, round-trip latency (< 1ms), 10x spectrum efficiency and energy efficiency as well as the support for Internet of Things (IoT) applications. One of the major focuses of the next generation network design is on developing new radio access technologies to achieve much higher spectrum efficiencies than available today. Non-orthogonal multiple access (NOMA) technology provides a new way of achieving such demanding requirements by successfully overcoming the long-held principle of orthogonality in time/frequency/code domain.

Commercial and societal impact: Firstly, by exploitation of the NOMA technology, MANGO project will deliver significantly enhanced spectrum efficiency (3x compared to 4G-LTE systems) to achieve the next generation mobile networks targets. Secondly, by utilising NOMA, this project will deliver the much-needed balance between system throughput and user fairness in next generation mobile networks. By using the NOMA to achieve significantly higher spectrum efficiency in next generation mobile networks, the project's outcome will boost the diminishing profits for the ICT industry and re-define the operators' business models. At the same time, by delivering higher data rates, the proposed work will contribute in improving the quality of service and user experience with cheaper mobile devices, thus enhancing the penetration of the ICT industry in current and new markets. The overall advancement of the mobile communication technology through MANGO project will impact the associated environmental, healthcare, security and industrial applications. Therefore, MANGO project aligns with the EPSRC portfolio of research in the themes of ICT, Digital Economy, and Energy, as detailed in the National Importance section, and will contribute to the economic competitiveness of the UK and enhance quality of life.

Academic impact: The vast impact of the work in the broader research communities, detailed in the academic beneficiaries section, will boost the profile of the communications groups in HWU, LU, and UoE and enhance the UK research impact in these areas by citations of the proposed work and international exposure. The creation of new knowledge in the above fields within MANGO project, and the inclusion of this in the educational curricula will further establish the UK as a world leader in technological and applied state-of-the-art knowledge transfer. Apart from the performance limits of NOMA systems that will set the benchmarks for the system performance, the practical design on implementing NOMA with single-/multiple antennas in single-/multi cell scenarios will attract commercial interests, stimulate industrial research and encourage joint academic-industrial collaboration on the field. This will further augment the research income for HWU, LU and UoE through follow-on research projects and industrial consultancy. The adoption of the proposed techniques by global communication standards will further establish the UK as a leader in communication standardisation. The protection of the created intellectual property and the commercialisation of the NOMA signal processing solutions will improve the penetration of the UK sector in the multibillion-pounds ICT industry.

New experts: The research training within the project will develop the research profile, expertise and manpower of the world class research groups in HWU, LU and UoE and establish an inter-institutional team with excellence in next generation mobile networks, by producing new experts in the field of NOMA, transceiver design, interference management and wireless communications in general.