Optimization of Delay Constrained Wireless Communication Networks

传统上，为了解决通信中出现的许多复杂问题， 网络，采取了"分层”的方法。 不同的层通常被分配不同的“职责”，这样一般的网络设计问题就可以分解成更简单、更易于管理的问题。 然而，不同层的独立设计-忽略了它们相互作用的详细性质，共享约束以及对网络整体性能的累积影响-可能导致效率低下。 未来的无线通信网络需要为产生突发多媒体信息的移动的用户提供宽覆盖和高容量。这种异构业务将对网络的时变服务质量（QoS）的约束。由于许多多媒体应用程序具有延迟敏感的信息与不同的可靠性要求，如数字数据，语音和视频，该项目将采取端到端的延迟和数据完整性作为其主要的系统约束。 从最广泛的意义上讲，该项目的目标是对端到端性能进行更全面的了解，更好地理解各层之间的交互，开发通过联合优化各层来提高系统性能的技术，并在端到端延迟约束的背景下这样做。 该提案的一个关键主题涉及在多个用户的情况下优化系统性能，特别是在不采用蜂窝型架构的系统中。这就需要开发技术，一方面，解决多用户干扰在物理层的有害影响，但也纳入端到端的QoS目标，特别是延迟，就像路由和调度算法的发展。另一个主要的主题将是确定的最佳分布和实时动态的错误控制功能，在网络的层，受指定的最终用户的要求。这需要调查的错误率和解码延迟的FEC采用在物理层之间的固有的权衡，以及错误控制功能，包括重传策略，调用在更高的水平之间的相互作用。

Traditionally, in order to address the many complex issues that arise in communication networks, a ``layered" approach has been taken. The different layers are typically assigned different ``responsibilities," so that the general network design problem can be decomposed into simpler, more manageable problems. However, the independent design of the different layers - which ignores the detailed nature of their mutual interactions, shared constraints, and cumulative impact on the network's overall performance - can lead to inefficiencies. Future wireless communication networks will be required to provide wide coverage and high capacity to mobile users generating bursty multi-media information. This heterogeneous traffic will impose upon the network time-varying quality of service (QoS) constraints. Since many multi-media applications have delay-sensitive information with varying reliability requirements, such as numerical data, voice, and video, the project will take end-to-end delay and data integrity as its dominant system constraints. The goal of this project is, in the broadest sense, to take a more global view of end-to-end performance, to better understand the interactions among the layers, to develop techniques that improve system performance through joint optimization over the various layers and to do so in the context of a end-to-end delay constraint. One key theme of the proposal involves the optimization of system performance in the context of multiple users, particularly in a system which does not employ a cellular-type architecture. This requires the development of techniques that, on the one hand, address the deleterious effects of multiple-user interference at the physical layer, yet also incorporate end-to-end QoS objectives, especially delay, just as with the development of routing and scheduling algorithms. Another major theme will be the determination of the optimal distribution and the real-time dynamics of error control functions implemented across t he layers of the network, subject to specified end-user requirements. This requires investigation of inherent tradeoffs between error-rate and decoding delay of FEC employed at the physical layer, as well as the interactions among error control functions, including retransmission strategies, invoked at higher levels.