协作D2D通信技术是M2M应用的一种通信手段。目前，协作D2D通信网络的研究主要聚焦于用户完全协作的模式，即用户以完全无私的方式帮助其它用户转发消息，而很少考虑真实世界中用户关系对协作模式的影响。本项目的目标是面向用户关系的协作D2D通信网络性能评估与增强技术研究。研究面向用户关系的协作D2D通信网络容量性能评估理论；针对不同应用对通信实时性和可靠性的不同需求，研究时延和中断受限的协作D2D通信网络容量，以及协作D2D通信网络容量、时延和中断之间的折衷关系，并通过开发新的中继机制，实现这三者之间的自适应调整；联合物理层串行干扰消除、网络层编码和路由进行跨层组合传输模式设计，在有限频谱资源约束下，增强协作D2D通信网络容量。本项目预期建立一套面向用户关系的协作D2D通信网络性能评估与增强方法，为协作D2D通信网络的设计和优化提供支撑，促进D2D通信网络的广泛应用。

Cooperative D2D communication technology is a means of communication for M2M applications. At present, the research of cooperative D2D communication network mainly focuses on the mode of user complete collaboration, in other words, users help other users to forward messages in a completely selfless way, which ignored the impact of user relationship on collaborative mode in the real world. The goal of this project is to study the performance evaluation and enhancement technology of cooperative D2D communication network oriented to user relationship. This project studies the capacity performance evaluation theory of cooperative D2D communication network based on user relationship, studies the capacity of cooperative D2D communication network with limited delay and interruption, and the trade-off among capacity, delay and interruption of cooperative D2D communication network, aiming at the different requirements of real-time and reliability of communication for different applications, and realizes the adaptive tuning among these three by developing a new relay mechanism. Combining physical layer serial interference cancellation, network layer coding and routing, cross-layer combined transmission mode is designed to enhance the capacity of cooperative D2D communication network under the constraints of limited spectrum resources. This project expects to establish a set of user-relationship-oriented performance evaluation and enhancement methods for collaborative D2D communication network, which will provide support for the design and optimization of collaborative D2D communication network, promote the wide application of D2D communication network.