现代无线通信网络提供了广泛的信息服务，要实现高效可靠的信号传输，网络用户间的协作通信是一种必要的手段。多用户协作是一种灵活的通信机制，通过用户间的协作重传，实现信号的多路径传输，带来分集增益。协作通信使网络资源得到更充分的调配与共享，有效地提高了网络覆盖率，在民用通信、军事通信和应急救灾等方面发挥着积极的作用。然而，多用户协作通信是以影响用户的频谱效率、网络能耗和信号路由等问题为代价的。针对这些挑战，本项目将研究高谱效和高能效的多用户协作通信技术。项目将提出基于信息分段的协作通信和非正交机会式协作通信两种高谱效高能效的多用户协作机制，分析其理论性能、谱效增益和能效增益，提出能充分获取信道分集的纠错编码设计方案。为了提高网络吞吐量，项目还将研究网络-信道-编码调制的联合设计，实现在网络编码协作中的高谱效传输。本项目的研究为在下一代无线通信网络中实现高谱效和高能效的信号传输提供了关键的技术。

Modern wireless communication networks provide pervasive information services. Cooperative communication that motivates network users to collaborate for signal transmission is a crucial technology to realize reliable and efficient communications. It is a flexible communication mechanism, creating multi-path signal transmission and hence introducing diversity gains for the communication system. It also enables the network resources to be better utilized and improves the network coverage. Therefore, it plays an important role in many areas, including commercial and military communications and disaster managements. However, multi-user cooperative communication is at the expenses of spectral efficiency, energy consumption and information routing. Aiming to solve those challenges, this project investigates the spectrum and energy efficient communication technologies for multi-user cooperative networks. This project proposes the message partitioning based cooperative communications (MPBCC) and the nonorthogonal opportunistic cooperative communications (NOCC) schemes, both of which achieve a high spectrum efficiency and alleviate the energy consumption. Information theoretic performance of the two communication schemes will be analyzed as well as their spectrum and energy efficiencies. Design of channel codes for the cooperative channels will be proposed. In order to provide reliable communications, yet maintaining high throughput and spectral efficiency, this project will also investigate the design of network-channel-coded modulation (NCCM) scheme that integrates the network coding, channel coding and coded modulation as a single entity. Its applications for multi-user cooperative networks will be further explored. This research project can provide the key technologies for realizing spectrum and energy efficient signal transmission in the next generation wireless communication networks.