Half-duplex Two-way Networks: Bounds and Protocols

无线网络的操作频谱效率通常远低于底层物理层的频谱效率。这种频谱效率的降低主要是由于协议开销，它由不依赖于物理层和网络层的信息位的传输组成。然而，我们的分析模型都不允许对系统中的协议开销进行一致和完整的计算。利用网络协议管理时变未知数的观点，本研究正在开发从根本上考虑无线网络中所有资源消耗的新方法。关键的创新是使用双向通道公式来解释所有资源的使用，无论是用于反馈，状态估计还是数据传输。在双向表述中，每个节点都有系统中其他节点的数据，因此所有节点都是接收方和发送方。通过每个节点的双向结构，数据独立传输与数据相关传输被联合编码，从而允许对有限的、有噪声的侧信息传输进行编码理论分析。研究人员研究了衰落信道和突发源，并推导出新的性能边界和协议类。新的协议类可以用来推导实际的协议，从而大大减少实际无线系统的开销。

The operational spectral efficiency of wireless networks is typically far lower than the spectral efficiency of underlying physical layers. This reduced spectral efficiency is primarily due to protocol overhead, which consists of transmissions that do not depend on information bits, in both physical and network layers. However, none of our analytical models allow a coherent and complete accounting for protocol overheads in the system. Using the viewpoint that network protocols manage time-varying unknowns, this research is developing fundamentally new methods to account for all resource consumption in wireless networks. The key innovation is the use of a two-way channel formulation to account for all resource usage, whether it is for feedback, state estimation or transmission of data. In the two-way formulation, each node has data for other nodes in the system, and hence all nodes are both receivers and transmitters. With the two-way structure at every node, data-independent transmissions are jointly coded with the data-dependent transmissions to allow a coding-theoretic analysis of finite, noisy side-information transmission. The investigators study both fading channels and bursty sources, and derive new performance bounds and protocol classes.The new protocols classes can then be used to derive practical protocols which dramatically reduce overhead in real wireless systems.