Green Heterogeneous Networks

移动网络的巨大发展使无处不在的通信成为可能，改变了人们相互联系的方式。随着快速可靠的信息交换，移动通信正在成为(如果还不是)日常必需品。然而，现有的移动网络并不“绿色”。尽管在探索移动电话的节能技术方面投入了大量精力，但基站和移动网络的情况并非如此。截至2008年，移动网络消耗了全球约0.5%的电力，对于一个特定的行业来说，这是一个相当大的数字。更糟糕的是，这种消费预计将在未来几年内增长200%。随着电价的上涨，这种高能耗将增加移动运营商的运营支出，从而导致更高的每兆字节成本。这将给移动运营商带来困难，也将影响消费者的定价。另一方面，能源消耗的增加会导致二氧化碳排放量的增加。考虑到全球气候变化的威胁，未来的移动网络非常希望更节能，从而更环保。同样重要的是，对更高数据速率移动通信的需求不断增加。首先，即使第三代(3G)移动网络的广泛发展，BBC最近的一项研究表明，25%的时间用户只能访问速度慢得多的第二代(2G)网络。这种缓慢的连接是真正无处不在的通信的瓶颈。因此，为了弥合数字鸿沟，政府、运营商和用户都强烈希望在任何地方都有高数据速率连接。其次，高质量多媒体和社交网络的显著增长已经将移动数据速率推到了极限，因此未来需要更快的网络。虽然3GPP LTE(长期演进)和802.16j(WiMax)将缓解部分压力，但仍需要先进的网络拓扑和技术。下一代移动网络IMT Advanced的研究工作已经开始。它的目标是实现1Gbps的峰值数据速率。最有希望实现IMT Advanced的方法是异质网络(HetNet)。它是在多层基站之间协作的高级网络拓扑，即宏基站、微基站、微微基站、毫微微基站和中继基站。通过智能干扰管理，HetNet最大限度地利用频率重用，并提供无处不在的高数据速率覆盖。然而，现有的HetNet研究大多集中在高数据速率方面，而对能量效率方面的研究很少。在这个项目中，高能量和频谱效率的目标将共同瞄准。特别是，我们将开发创新的技术来提供根本的改进，而不是渐进的增强。可以优化这些因素的自适应网络拓扑将被设计出来。将开发智能干扰管理和开发技术，以开发HetNet的潜力。网络MIMO、认知无线电和三维波束形成技术也将被开发出来，以实现适合未来的绿色HetNet。目标是开发能够在提供所需数据速率提升的同时降低能源消耗的新技术。

The tremendous development of mobile networks has enabled ubiquitous communication that has transformed the way people connect with each other. With fast and reliable information exchange, mobile communication is becoming (if not yet) a daily necessity. However, existing mobile networks are not "green". Although much efforts has been invested in exploring energy efficient techniques for mobile phones, this is not so for base stations and mobile networks. As of 2008, mobile networks consume around 0.5% of global electricity, which is a significant amount for one particular industry. To make matters worse, this consumption is expected to rise by 200% within the next few years. With increased electricity price, this high energy consumption will increase the operation expenditure for mobile operators, which results in higher cost-per-Mbyte. This will create difficulties for mobile operators, and will also impact on pricing for consumers. On the other hand, the increased energy consumption will lead to higher CO2 emission. Given the threats of global climate change, it is highly desirable for future mobile networks to be more energy efficient and thus more environmental friendly.Equally important, the need for higher data rate mobile communication is ever increasing. First of all, even with the extensive development of third generation (3G) mobile network, a recent study by the BBC shows that 25% of the time users will only able to access the much slower second generation (2G) network. This slow connection is a bottleneck for true ubiquitous communication. Therefore, to bridge the digital divide, there is a strong desire by the government, operator, and user to have high data rate connections everywhere. Secondly, the remarkable growth of high quality multimedia and social networks has pushed mobile data rates to the limit, and thus faster networks for the future are required. Although the 3GPP LTE (Long Term Evolution) and 802.16j (WiMax) will ease some of these pressures, advanced network topology and techniques are needed. Research work has already been started on IMT Advanced, which is the next generation mobile network. It aims to achieve a peak data rate of 1Gbps. The most promising approach for IMT Advanced is the Heterogeneous Network (HetNet). It is an advanced network topology that cooperates between multiple tiers of base stations, i.e., macro, micro, pico, femto and relay base stations. By intelligent interference management, HetNet exploits frequency reuse to its maximum, and provides high data rate coverage everywhere. However, existing research on HetNet has focused mostly on the high data rate aspects, but rarely on the energy efficiency aspects. In this project, both goals on high energy and spectral efficiency will be targeted jointly. In particular, we will develop innovative techniques to provide radical improvement, instead of incremental enhancement. Adaptive network topology that can optimise these factors will be devised. Smart interference management and exploitation techniques will be developed to exploit the potential of HetNet. Network MIMO, cognitive radio, and 3 dimensional beamforming techniques will also be developed to achieve a green HetNet that is suitable for the future. The goal is to develop new technologies that can reduce energy consumption while providing the required data rate increase.