针对无线传感器网络能量有限的问题,基于瑞利衰落信道及无线链路,建立了一种跨越物理层与媒质接入层的能耗模型,并针对IEEE 802.11 DCF和时隙ALOHA协议进行了具体的能耗分析.考虑到无线信道的多变特点与信道饱和度的情况,以及用户对信道质量的要求与接入方式,对网络工作过程中的能量消耗进行了理论分析,并对节点平均功耗、净荷能耗率及发送功率与传输速率的变化对能耗的影响进行了仿真.结果表明：给出的能耗模型的理论分析结果与仿真值吻合良好;发送功率与传输速率过大、过小都不利于节约能耗;联合控制更易于降低能耗.

By considering the energy limitation of wireless sensor networks（WSNs）,an energy consumption model crossing both the physical layer and the medium access layer is proposed based on Rayleigh fading channels and wireless links.Then,a concrete energy consumption analysis is performed for IEEE802.11 DCF and slotted ALOHA protocols.Moreover,according to the variance and saturation of wireless channels,the requirements of users for channel quality and the access control mode,the energy consumption in the working process of WSNs is theore-tically analyzed.Finally,the average power consumption,the net load energy consumption rate,and the influences of transmission power and rate variance on energy consumption are discussed by simulation.It is found that the theoretical results accord well with the simulated ones,that too large or too small transmission power and rate are unprofitable to the energy consumption,and that a combined control of transmission power and rate may benefit the decrease in energy consumption.