Robust Design and Analysis of Cooperative Communication Systems

随着多媒体业务的快速增长，未来一代的无线通信需要更高的数据速率和更可靠的传输链路，同时保持令人满意的服务质量。协作无线通信是这些高数据速率多媒体应用(如移动数字电视)最有前景的使能技术之一。协作通信系统使用中继器来创建感兴趣信号的多个副本，并在此过程中提供分集、增加网络覆盖并增强对信道衰落的免疫力。然而，合作通信的许多方面都有待调查。目前提出的协作系统大多基于不可行的同步约束、不同节点的信道状态信息可获得性等理想假设，不适用于实际的衰落信道。此外，在不牺牲频谱效率(每单位带宽传输的数据量)和分集阶数(越高的分集阶数意味着更高的可靠性)的情况下，对于中继网络的最佳传输的严格研究在现有文献中仍然是缺乏的。“如何设计节能的协作无线网络？”这也是气候变化和环境问题时代需要回答的一个关键问题。因此，对协作分集系统的稳健高效设计进行基础性研究，以实现其在下一代无线网络中的巨大潜力是至关重要的。

With the rapid growth of multimedia services, future generations of wireless communications require higher data rates and a more reliable transmission link while keeping satisfactory quality of service. Cooperative wireless communication is one of the most promising enabling technologies for these high date rate multimedia applications (e.g. mobile digital TV). Cooperative communication systems employ relays to create multiple replicas of the signal of interest, and in the process provide diversity, increased network coverage, and enhanced immunity to channel fading. However, many aspects of cooperative communications are open for investigation. Most of the cooperative systems proposed so far are based on ideal assumptions, such as infeasible synchronization constraints, availability of channel state information at different nodes, and are not suitable for practical fading channels. Furthermore, a rigorous study of optimum transmission without sacrificing spectral efficiency (amount of data transmitted per unit bandwidth) and diversity order (higher diversity order implies higher reliability) for relay networks is still lacking in the existing literature. "How to design an energy efficient cooperative wireless network?" is also a key question that needs to be answered in an era of climate change and environmental concerns. Thus, fundamental research on the robust and efficient design of cooperative diversity systems to realize their great potential for next generation wireless networks is of paramount importance.