WiFiUS: Ubiquitous Video over Dynamic Spectrum

移动的电话和平板电脑是当今最广泛使用的无线通信设备。视频已经代表了移动的流量的大部分，预计在未来几年将大幅增长。尽管有更新的蜂窝通信技术可用，但网络运营商已经面临支持如此大量的业务的带宽短缺。认知无线电网络（CRN）是提高无线通信技术可用性和效率的一种解决方案。通过自适应通信协议，CRN具有感测大范围频谱的能力和动态利用可用资源的灵活性。因此，它们可以回收未使用的频谱（即，空白空间）用于无线通信，同时避免许可和未许可用户之间的干扰。然而，在CRNs上的视频传输提出了一些挑战，涉及到信道的高度变化的性质，行为不端的用户的存在，以及异构资源的动态可用性。该研究采取了灵活的方法，适用于跨越国界的各种法规，并专门针对移动的设备。它有助于创造一个认知电话，即，具有认知无线电功能的智能手机，以弥合CRN背后的技术和真实的应用之间的差距。该项目建立在两个主要的研究重点之上。首先，它采用频谱人群感知作为一种手段，在多个尺度上对空白频段的可用性进行建模，并支持长期通信。这种方法使得新的解决方案能够准确地表征信道并执行由通信当局建立的策略。其次，它利用自适应机制作为基础，有效地向最终用户提供视频流。这些机制通过网络基础设施中的流协议和组件来实现，这些流协议和组件提供具有目标体验质量的视频内容。该项目还整合了美国和芬兰在教育、产业合作和创业方面的协同活动。

Mobile phones and tablets are the most widely-used wireless communication devices nowadays. Video already represents the majority of mobile traffic and is expected to grow significantly in the coming years. Network operators are already facing shortage of bandwidth to support such a huge amount of traffic, despite the availability of newer cellular communication technologies. A solution to increase the availability and the efficiency of wireless communication technologies is given by cognitive radio networks (CRNs). Enabled by adaptive communication protocols, CRNs have the capability to sense a wide range of the spectrum and the agility to make use of the available resources dynamically. Accordingly, they can reclaim unused spectrum (i.e., whitespace) for wireless communications while avoiding interferences with between licensed and unlicensed users. However, video delivery over CRNs presents several challenges related to the highly-varying nature of the channel, the presence of misbehaving users, and the dynamic availability of heterogeneous resources.This project addresses such challenges and makes CRNs suitable as a platform to provide ubiquitous wireless video. The research takes a flexible approach that is applicable to diverse regulations across national boundaries and specifically targets mobile devices. It helps create a cognitive phone, i.e., a smartphone with cognitive radio capabilities, to bridge the gap between the technologies behind CRNs and real applications. The project builds on two major research thrusts. First, it adopts spectrum crowd-sensing as a means to model the availability of whitespace at multiple scales and support long-lived communications. Such an approach enables novel solutions to accurately characterize the channel and enforce the policies established by the communication authorities. Second, it leverages adaptive mechanisms as foundations to efficiently deliver video streams to end users. These mechanisms are implemented through streaming protocols and components in the network infrastructure that provide video content with a target quality of experience. The project also integrates synergistic activities between the United States and Finland in education, industry collaboration, and entrepreneurship.