On Cross-Layer Design and Resource Scheduling in Wireless Networks
On Cross-Layer Design and Resource Scheduling in Wireless Networks
复制标题
DOI：
--
复制
发表时间：
2009
期刊：
影响因子：
--
通讯作者：
Pablo Soldati
中科院分区：
文献类型：
--
作者：
Pablo Soldati
无线技术已经彻底改变了通信世界，使无处不在的连接成为可能，每年都有数十亿用户接受一些新的应用和服务。为了满足对高数据速率无线服务日益增长的需求，标准化机构和供应商发布了新一代基于标准的设备，能够提供广域高速和高质量的无线覆盖。最近，无线传感器网络（wsn）引起了工业社会的关注，将传统有线工业基础设施的大部分转移到无线技术上。尽管人们对无线服务的需求越来越大，但这些系统的基本物理资源——带宽——是有限的。因此，设计有效的网络控制机制以优化复杂网络的功能已成为网络中越来越重要的一个方面。在本文中，我们探讨了优化技术在无线系统资源分配中的应用。我们将最优网络运行表述为网络效用最大化问题的解决方案，该问题强调了如何通过联合优化传统分离的网络层来提高系统性能。这种跨层优化的优势是双重的：首先，跨层的联合优化揭示了实际协议可以实现的真实性能限制，因此对网络设计或性能分析很有用；其次，分布式优化技术可以用于系统地设计协议和信令方案，以确保系统的全局最优运行。在这个框架内，我们考虑了几个具有挑战性的问题。第一部分考虑了多跳无线网络中功率和端到端速率联合最优分配方案的设计，该方案遵循传输和物理层机制的自然时间尺度，并施加有限的信令开销。为了验证理论发展，我们在网络模拟器ns-2中详细实现了DS-CDMA自组织网络的跨层网络堆栈。这个实现练习揭示了在实践中出现的几个关键问题，但在理论协议设计中通常被忽略。其次，我们考虑了在数据链路层采用资源调度的网络，并为实现最优网络效用的联合端到端通信速率选择、多时隙传输调度和功率分配开发了详细的分布式解决方案。我们通过实例展示了如何将数学框架应用于优化空间复用时分多址（S-TDMA）网络和正交频分多址（OFDMA）网络中的资源分配。然后，我们稍微转移了焦点，并考虑离线跨层优化来研究多跳网络中各种路由策略的好处，并将这些结果应用于蜂窝中继网络的技术经济可行性研究。最后，我们考虑了无线传感器网络中受时限限制的实时流量的有效资源调度方案的设计。具体而言，我们根据最新的无线HART标准开发了网络时间和信道最优调度的理论和算法。
Wireless technology has revolutionized the world of communications, enabling ubiquitous connectivity and leading every year to several new applications and services embraced by billions of users. To meet the increasing demand for high data-rate wireless services, standardization bodies and vendors released a new generation of standard-based devices capable to offer wide area high-speed and high-quality wireless coverage. More recently, wireless sensor networks (WSNs) have captured the attention of the industry society to migrate substantial parts of the traditionally wired industrial infrastructure to wireless technologies. Despite the increasing appetite for wireless services, the basic physical resource of these systems, the bandwidth, is limited. Therefore, the design of efficient network control mechanisms for optimizing the capabilities of complex networks is becoming an increasingly critical aspect in networking. In this thesis, we explore the application of optimization techniques to resource allocation in wireless systems. We formulate the optimal network operation as the solution to a network utility maximization problem, which highlights how system performance can be improved if the traditionally separated network layers are jointly optimized. The advantage of such cross-layer optimization is twofold: firstly, joint optimization across layers reveals the true performance limits that can be achieved by practical protocols, and is hence useful for network design or performance analysis; secondly, distributed optimization techniques can be used to systematically engineer protocols and signalling schemes that ensure the globally optimal system operation. Within this framework, we consider several challenging problems. The first one considers the design of jointly optimal power and end-to-end rate allocation schemes in multi-hop wireless networks that adhere to the natural time-scales of transport and physical layer mechanisms and impose limited signalling overhead. To validate the theoretical development, we present a detailed implementation of a cross-layer networking stack for DS-CDMA ad-hoc networks in the network simulator ns-2. This implementation exercise reveals several critical issues that arise in practice, but are typically neglected in the theoretical protocol design. Second, we consider networks employing resource scheduling at the data link layer, and we develop detailed distributed solutions for joint end-to-end communication rate selection, multiple time-slot transmission scheduling and power allocation that achieve the optimal network utility. We show with examples how the mathematical framework can be applied to optimize the resource allocation in spatial-reuse time division multiple access (S-TDMA) networks and orthogonal frequency division multiple access (OFDMA) networks. We then make a slight shift in focus, and consider off-line cross-layer optimization to investigate the benefits of various routing strategies in multi-hop networks, and apply these results to a techno-economical feasibility study of cellular relaying networks. Finally, we consider the design of efficient resource scheduling schemes for deadline-constrained real-time traffic in wireless sensor networks. Specifically, we develop theory and algorithms for time- and channel-optimal scheduling of networks operating according to the recent Wireless HART standard.