中文摘要：

实验测量发现WSNs的底层通信链路存在着丢失、非对称等特性；该文针对传统链路层可靠机制运用于无线传感器网络中存在着路径效率低，能量开销大的缺点，提出了一种面向效率的链路层组确认机制，并就路径效率、缓存需求、时间开销等指标进行了理论分析；最后，与传统链路层可靠传输机制在MicaZ平台上分别加以实现。测试结果表明该文提出的组确认机制的路径效率高、缓存需求固定，特别适合于高可靠，低实时要求的一类应用。

英文摘要：

Firstly, it is found that the physical communication link of WSNs takes on lost, asymmetric characteristics according to experimental measurements. Secondly, some typical reliable transmission mechanisms of link layer provide a certain degree of reliability, but low path efficiency and high energy costs. Therefore, an efficiency-centric link Group-based Acknowledgement Mechanism（GAM） is presented in the paper, and its performance is analyzed theoretically based on the evaluation metrics, such as path efficiency, buffer requirements, and etc. Finally, the results compared with traditional reliable transmission mechanisms based on the existing MicaZ platform show that the GAM presented in the paper particularly meets the requirements of the high reliability, low real-time applications of WSNs for its high path efficiency and constant cache occupation.