ITR: Cross-Layer Design of Ad-Hoc Wireless Networks for Real-Time Media

安德烈·斯坦福大学戈德史密斯：临时无线网络是一组可能的移动无线节点，无需任何已建立的基础设施即可自行配置以形成网络。对于通信基础设施部署成本太高、无法快速部署或根本不可行的应用来说，基础设施的缺乏是非常紧迫的。这些应用从多跳无线宽带互联网接入到传感器网络，到建筑或高速公路自动化，再到语音、图像和视频通信，以应对紧急情况，这是我们社会迫切需要的一种拯救生命的能力。自组织无线网络的性质使得对语音和视频等延迟关键型应用的支持非常具有挑战性。在这个项目中，研究人员研究了一种新的自组织无线网络设计框架，以支持这种延迟关键型应用。该框架包括动态分配网络资源以支持媒体需求，对网络中的变化和不确定性具有健壮性的协议，以及即使在网络条件较差时也能保持端到端网络连通性的自适应媒体压缩技术。该项目的结果预计将对未来无线网络的发展和关键应用的实现产生重大影响。正在开发的框架基于跨网络协议栈的跨层设计，以支持自组织无线网络中的延迟关键应用。该设计包含跨多协议层的适配，包括应用层、传输层、网络层和链路层。在此框架下，研究人员开发了一套新的技术来平衡网络拥塞和实时媒体流的失真，通过联合优化容错信源编码、分组调度、基于流的路由、链路容量分配和自适应链路层技术。所有节点基于链路状态通信动态地进行优化，以不断适应不断变化的链路和跟踪条件，本研究项目系统地研究了这些新思想，并最终在小型试验床上进行了演示。

ABSTRACT0325639Goldsmith, AndreaStanford UniversityAn ad-hoc wireless network is a collection of possibly mobile wireless nodes that self-configure to form anetwork without the aid of any established infrastructure. The lack of infrastructure is extremely compellingfor applications where a communications infrastructure is too expensive to deploy, cannot be deployedquickly, or is simply not feasible. Such applications range from multi-hop wireless broadband Internetaccess to sensor networks to building or highway automation to voice, image, and video communication foremergency response, a life-saving capability urgently needed by our society. The nature of ad-hoc wirelessnetworks makes support of delay-critical applications such as voice and video quite challenging. In thisproject the investigators study a new framework for ad-hoc wireless network design to support such delay-critical applications. The framework includes dynamic allocation of network resources to support mediarequirements, protocols that are robust to variations and uncertainties in the network, and adaptive mediacompression techniques that preserve end-to-end network connectivity even when network conditions arepoor. The results of the project are expected to have a significant impact on the development of futurewireless networks and the enabling of critical applications.The framework being developed to support delay-critical applications in ad-hoc wireless networks is basedon cross-layer design across the network protocol stack. The design incorporates adaptation across multipleprotocol layers, including the application, transport, network, and link layers. Within this framework, theinvestigators develop a suite of new techniques to balance network congestion and distortion of real-timemedia streams by jointly optimizing error-resilient source coding, packet scheduling, stream-based routing, link capacity assignment, and adaptive link layer techniques. The optimization is carried out dynamically by all nodes, based on link state communication, to continuously adapt to changing link and trac conditions.The research project systematically investigates these new ideas and ultimately demonstrates them in a smalltestbed.