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

预计从2015年到2020年，全球移动数据流量将增长8倍，鉴于移动连接和物联网（IoT）应用的预期激增，预计到2020年将有500亿台设备通过移动网络连接。需要多种方法的结合来满足不断增长的移动数据流量需求，即显著提高频谱效率，将可用频谱扩展到更高的频段，以及使用小型基站实现网络密度。新型无线接入技术的设计是提高未来移动网络频谱效率的一个重要方面。无线电接入技术的典型特征是正交多址方案，例如，频分多址（FDMA）、时分多址（TDMA）、码分多址（CDMA）和正交多址（OFDMA），它们为多个用户同时访问和共享无线电资源提供手段。3GPP-LTE使用的OFDMA等正交多址（OMA）方案的一个关键问题是，当将部分带宽资源（如子载波信道）分配给信道条件较差的用户时，会导致频谱效率较低。由于OMA技术的频谱效率低下，非正交多址（NOMA）最近被认为是一种有前途的多址技术，可以显著提高频谱效率，并被设想为下一代移动网络的关键组成部分。主要的NOMA方案分为两类：功率域NOMA和代码域NOMA。功率域NOMA是根据用户的信道条件分配不同的功率电平，以获得最大的系统性能增益；码域NOMA是为不同的用户分配不同的码，然后在相同的时频资源上复用。然而，NOMA技术仍然面临着一些关键的挑战，例如缺乏对NOMA性能限制的深刻理解，以及在单/多天线、单/多小区情况下NOMA收发器的性能评估存在很大差距，这使得它们无法立即部署。这个富有远见的项目通过建立统一的理论框架和开发复杂的数字信号处理算法来解决NOMA技术在下一代移动网络中的部署问题，以实现NOMA在单/多天线、单/多小区场景中的概念。该项目的新颖之处在于：a)具有实际约束的信息理论分析；b)功率域和码域NOMA的计算复杂度较低的收发器设计；c)单单元和多单元NOMA网络的联合预编码设计；d) NOMA在认知无线电和物联网系统中的应用；e)下一代移动网络场景下系统级性能评估。该项目将与未来移动网络研究和标准化领域的领导者（三星、诺基亚贝尔实验室、MobileVCE）以及国防和应急服务领域的领导者（QinetiQ）合作执行。该项目联盟在无线通信、MIMO信号处理和信息理论方面保持着非常强大的记录，并具有理论和实践技能的正确组合。鉴于该主题的新颖性和原创性，研究成果将对改变移动网络的未来具有相当大的价值，并为行业提供对下一代移动网络中基于NOMA的无线接入发展的新鲜和及时的见解，推进英国在世界无线通信领域的研究。进一步认为，该项目的成功完成将导致无线通信系统物理层设计的根本变化，并对标准化产生巨大影响。

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.