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，到2020年，预计将有500亿台设备通过移动网络连接。为了满足不断增长的移动数据业务需求，需要多种方法的组合，即显著提高频谱效率，将可用频谱扩展到更高的频段，以及使用小小区进行网络致密化。设计新的无线接入技术是以经济有效的方式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为多个用户提供同时接入和共享无线电资源的手段的正交多址方案，例如，频分多址(FDMA)、时分多址(TDMA)、码分多址(CDMA)和正交FDMA(OFDMA)。以3GPP-LTE使用的OFDMA为例的正交多址(OMA)方案的关键问题之一是，当诸如副载波信道的一些带宽资源被分配给具有较差信道条件的用户时，其导致较低的频谱效率。受OMA技术频谱效率低下的激励，非正交多址(NOMA)技术最近被认为是一种很有前途的多址技术，可以显著提高频谱效率，并被展望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或码域NOMA。在功率域NOMA中，用户根据其信道条件被分配不同的功率等级，以获得最大的系统性能增益；而在码域NOMA中，不同的用户被分配不同的码，然后在相同的时频资源上被多路复用。然而，NOMA技术仍然面临着一些关键的挑战，如对NOMA的性能极限缺乏深入的了解，以及在单天线/多天线、单/多小区情况下对NOMA收发信机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，以实现单天线/多天线、单/多小区方案中的NOMA概念。该项目的创新之处在于a)具有实际约束的信息理论分析，b)电力域和码域NOMA的低计算复杂度的收发信机设计，c)单小区和多小区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，以及e)下一代移动网络场景中的系统级性能评估。该项目将与未来移动网络研究和标准化(三星、诺基亚贝尔实验室、MobileVCE)以及国防和紧急服务(QinetiQ)领域的领导者合作实施。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出色的记录，拥有理论和实践技能的恰当组合。鉴于本课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，并使业界对下一代移动网络中基于NOMA的无线电接入的发展有一个新的和及时的见解，从而提升英国在世界上的无线通信研究形象。人们进一步相信，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性变化，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.