Abstract: Sensor node energy is severely limited in medium and high rate sensor networks. The primary issue of MAC protocol is saving energy to prolong the network life. Constant duty-cycle of SMAC can not adapt to various rates in medium and high rate sensor network. This paper proposes an adaptive MAC named AMAC, which adopts adaptive rate mechanism and crisscross activation mechanism based on the cross-layer, can dynamically adjust the duty-cycle based on sensor node rate. Upper nodes activate relatively lower node after a delay. The simulation results show that AMAC reduces energy consumption using lower duty-cycle when node is in lower rate, and adjusts duty-cycle to reduce congestion. Especially, when the packets burst out, the new algorithm can improve throughput and reduce delay effectively．

Key words: adaptive rate, Sensor Media Access Control（SMAC）, medium and high rate sensor networks, duty cycle, crisscross awaken

摘要： 中高速传感器节点能量严重受限，节能是中高速传感器网络（Medium and High Rate Sensor Networks，MHWSN）中MAC协议设计的首要问题。针对SMAC协议固定占空比不能适应中高速网络中多种速率混合业务传输的特点，提出了一种适应于数据采集型应用的速率自适应的MAC协议（AMAC）。AMAC协议在SMAC基础上，采用了基于跨层的速率自适应机制和交错唤醒机制，根据节点速率动态调整占空比，上层节点较下层节点延迟一段时间后激活。仿真结果表明，在数据采集树中该算法节点速率较小时，可有效降低空闲节点的占空比、减少能量消耗，节点速率较大时，调整占空比大小，减少碰撞和阻塞发生的概率，尤其在多种速率任务突发的中高速传感器网络中，能有效提高节点的数据吞吐量并降低时延。

关键词: 速率自适应, 带周期性睡眠监听机制的低功耗传感器MAC协议（SMAC）, 中高速传感器网络, 占空比, 交错唤醒