Abstract: Energy efficiency is an important metric in wireless Ad Hoc networks. Until now, there is no universally accepted definition of energy efficiency, and the related results are asymptotic or qualitative, which has limited its applicability. By regarding a bit as a physical particle with one unit of mass, the authors assumed that a bit in transmission possessed a certain amount of kinetic information energy. As a result, the energy efficiency of wireless transmission was defined as the ratio of information energy to physical energy. A quantitative analysis on energy efficiency in wireless transmission was carried out and meaningful results were obtained. It is concluded that the energy efficiency changes non-monotonously with the transmission power, and there is an optimal transmission power, with which the maximum energy efficiency will be acquired. The optimal transmission power was given to help the protocol design. Based on the theoretical results, a practical solution for transmission power control was proposed, and an extensive experimental study of it was given on the CC2420 radio. The results show the effectiveness of the proposed transmission power control scheme.

Key words: wireless transmission, energy efficiency, quantitative analysis, power control

摘要： 能量效率是无线自组织网络中非常重要的性能指标。到目前为止，自组织网络的能量效率还没有一个普遍接受的定义，且得出的结论多数是渐近的或定性的，其实用性非常有限。将比特看作质量为1的物理粒子，假设其在传输过程中携带了一定的信息动能，并将能量效率定义为物理能量转化为信息能量的比率，然后从信息论的角度定量地研究了无线传输的能量效率。通过理论分析，得出如下结论：能量效率随发送功率的增加非单调变化，且存在一个最优发送功率，使得能量效率取得最大值;给出了相应的最优发送功率，这将为协议设计提供最直接的帮助。根据得出的理论结果，提出了一种基于参数估计的功率控制的方法，并在Micaz传感器节点上进行了相关的实验。实验结果证明了此功率控制方法的有效性。

关键词: 无线传输, 能量效率, 定量分析, 功率控制