RC3: Robust Cognitive Cooperative Communications

根据英国通信管理局2007年的《数字红利》报告，频谱之所以有限，只是因为由于管理僵化和效率低下，频谱严重未得到充分利用。据报道，超过90%的地点可以有大约100MHz的频谱用于其他业务。这些未充分利用或未使用的频谱空洞，也称为空白，主要是由于数字电视频带的交错频谱造成的。考虑到整个3G频谱只有75MHz的事实，这是一个不可接受的浪费。然而，与此同时，这为英国的移动运营商、宽带服务提供商和用户提供了千载千金的机会，他们可以利用频谱电视空白中的认知传输来改善个人通信的QoE。在这种情况下，英国电信致力于利用电视频谱的空白空间，利用认知无线电（CR）技术为农村地区的家庭提供无线宽带接入。据英国电信称，在农村地区有275万用户，被称为“无点”，听起来很荒谬，那里没有3G覆盖，互联网服务基本上仅限于通过住宅或商业电话线拨号接入。在“非盲点”中，服务速度低于每秒200万比特，但如果利用得当，电视频谱的空白空间有可能覆盖超过25%的“非盲点”，从而改善服务。这样做的机会在于，一个社区的家庭可以共享他们的天线和信号处理能力，从而在不额外成本的情况下，利用频谱空白空间提供更高的QoE。该项目采用了一种新颖的视角，通过用户合作（例如多户合作）来提高无线通信的能量和频谱效率，这种合作提供了通过在用户之间共享资源来改善信道的可能性。这一极具挑战性的目标有可能重新定义无线网络的架构，为扩展宽带通信的覆盖范围和提高QoE提供一种新颖的系统解决方案。在这个项目中，PI和BT（作为工业合作伙伴）将联手解决认知合作的优化问题。我们的目标是解决合作MIMO信道特有的基本技术挑战。例如，所需的优化将需要考虑到单个用户的需求、约束和公平性问题。此外，所提出的协作方案还要求对不完全通道状态信息（CSI）和协作节点的异步性具有鲁棒性，并以分布式方式实现。英国电信将是一个重要的合作伙伴，在实践层面上提供宝贵的投入，以确保项目的可交付成果是可利用的。拟议项目的最终成果将是自优化合作天线系统的技术，该技术可用于在电视频谱白色空间的无线上为“非斑点”区域提供宽带覆盖。

According to the Ofcom's Digital Dividend report in 2007, spectrum is limited only because they are seriously underutilised due to rigid and inefficient management. It was reported that over 90% of locations could have around 100MHz spectrum available for other services. These underutilised or unused spectrum holes, also known as white spaces, are mainly due to the interleaved spectrum for the digital TV band. Given the fact that the entire 3G spectrum is only 75MHz, this is an unacceptable wastage. At the same time, however, this gives golden opportunities for mobile operators, broadband service providers and users in the UK to improve the QoE for personal communications using cognitive transmission in the spectrum TV white spaces. In this context, BT is committed to exploiting the TV spectrum white spaces for providing wireless broadband access for homes in rural areas using cognitive radio (CR) technologies. According to BT, there are 2.75 million customers in rural areas, known as "not-spots" where, as ridiculous as it sounds, have no 3G coverage and Internet service is pretty much limited to dial-up access over residential or business telephone lines. In the "not-spots", the service is less than 2M bps but the TV spectrum white spaces, if utilised properly, can potentially cover more than 25% of the "not-spots" for improved services. The opportunity is that homes in a neighbourhood can share their antennas and signal processing capability to deliver much higher QoE using the spectrum white spaces at no extra cost.This project takes a novel perspective of enhancing the energy and spectrum efficiencies of wireless communications via user cooperation (e.g., multiple homes cooperation), which offers the possibility to improve the channel by sharing the resources between users. This exceptionally challenging objective has the potential to redefine the architecture of wireless networks, provide a novel system solution for extending the coverage and enhancing the QoE of broadband communications. In this project, the PI and BT (as the industrial partner) will join force to address the optimisation problem for cognitive cooperation. Our aim is to tackle the fundamental technical challenges specific to a cooperative MIMO channel. For instance, the required optimisation will need to take into account of individual users' requirements, constraints and fairness issues. Also, the proposed cooperative solution is also required to be robust to imperfect channel state information (CSI) and asynchronousity of the cooperating nodes, and be realised in a distributed manner. BT will be a key partner to provide invaluable inputs on the practical level to ensure that the project deliverables are exploitable. The final outcome of the proposed project will be the technologies for self-optimising cooperative antenna systems which can be used to provide broadband coverage for "not-spot" areas over wireless in the TV spectrum white spaces.