Design of Sustainable Cloud Radio Access Networks

无线数据流量以及移动设备数量的指数增长预计将继续下去。例如，根据思科的预测，到2021年，移动设备的人均数量将达到1.5台；包括机器到机器模块在内的移动连接设备将达到116亿台。2016至2021年间，全球移动数据流量将增长七倍。另一方面，全球蜂窝网络每年的能耗约为600亿千瓦时，预计在未来几年内将翻一番。具体地说，蜂窝网络使用的电力的很大一部分(80%)由基站消耗，每年排放超过1亿吨二氧化碳。结合对高无线数据速率的需求、电价的上涨以及日益加剧的环境担忧，蜂窝网络提供商正面临着独特的挑战，导致资本和运营支出大幅增加。因此，以可持续的方式满足日益增长的无线数据需求的无线网络的需求比以往任何时候都更加迫切。为了实现可持续的能量和频谱高效的无线网络，大规模多输入多输出(MIMO)、毫米波通信、网络加密和能量收集等几项有前途的技术正在研究中。云无线接入网络(CRAN)被认为是实现网络增密化的一种潜在解决方案，因此将以一种成本和能源高效的方式满足无线网络流量的指数增长。CRAN有助于提高网络容量和能效，同时减少网络资本支出和运营费用。然而，我们坚信CRAN的潜力仍未得到充分开发，通过采用大规模MIMO和能量收集等新技术，可以显著提高其性能。该项目的目的是设计可持续的高能量和高频谱效率的克朗。这个项目的新奇之处在于，我们提出并优化了一个新的CRAN架构，其中包括一个庞大的MIMO中央单元和配备混合能源(即具有能量收集能力并连接到电网)的远程无线电头(RRH)，以进一步提高无线网络的能源和频谱效率，同时实现可持续发展。为达致这项计划的目标，我们会考虑对拟议的CRAN架构进行长期和短期的性能优化。在长远表现方面，鉴于使用无线前线通道可灵活安置残疾人士院舍，我们建议优化安置残疾人士院舍的安排。在短期性能方面，我们建议设计一种低复杂度的信道估计方法，并联合设计前端链路和接入链路。新CRAN架构的优化设计将带来可持续的能源和频谱效率提高的无线网络。

The exponential growth in terms of wireless data traffic along with the number of mobile devices is expected to continue. For example, according to Cisco, it is predicted that the number of mobile devices will reach 1.5 per capita in 2021; there will be 11.6 billion mobile-connected devices including machine-to-machine modules. Global mobile data traffic will increase sevenfold between 2016 and 2021. On the other hand, the energy consumption of cellular networks world-wide per year is around 60 billion kWh and is expected to double within the next few years. Specifically, the large portion (80%) of electricity used in cellular networks is consumed by base stations, emitting over a hundred million tons of carbon dioxide annually. Combining the need for high wireless data rates, the increase in power prices and the raising environmental concerns, cellular network providers are facing unique challenges leading to huge increases in capital and operating expenditures. As a result, the need for wireless networks meeting the ever increasing demand in wireless data in a sustainable way is more pressing than ever.To achieve sustainable energy and spectrally efficient wireless networks, several promising technologies, such as massive multiple-input multiple-output (MIMO), millimetre wave communication, network densification and energy harvesting, are under investigation. Cloud radio access network (CRAN) is considered as a potential solution to achieve network densification, and hence will meet the exponential growth in wireless network traffic, in a cost and energy efficient manner. CRANs facilitate increase in network capacity and energy efficiency while reducing both network capital expenditure and operating expense. However, we strongly believe that the potential of CRANs is still not fully exploited and their performance can significantly be improved via incorporating new technologies such as massive MIMO and energy harvesting. The aim of this project is to design sustainable high energy and spectral efficiency CRANs. The novelty of this project is that we propose and optimise a new CRAN architecture incorporating a massive MIMO central unit and remote radio heads (RRHs) equipped with hybrid energy sources (i.e., with energy harvesting capability and connection to the power grid) to further improve the energy and spectral efficiencies of wireless networks while being sustainable. To achieve the goal of this project, we will consider both long-term and short-term performance optimisation of the proposed CRAN architecture. In terms of long-term performance, given the flexibility in placing the RRHs offered by using wireless fronthaul, we propose to optimise the placement of the RRHs. In terms of short-term performance, we propose to design a low complexity channel estimation method and to jointly design the fronthaul and access links. The optimised design of the new CRAN architecture will lead to sustainable and improved energy and spectral efficiency wireless networks.