基于冲突指示和分组隐藏节点冲突解析策略*

摘要

Hidden node problem is an important factor in performance degradation of IEEE 802.15.4 protocol. This paper presents a resolution strategy of hidden collision based on collision indication and grouping. The new strategy, named Hidden Node Collision Detection and Avoidance Strategy (HNCDAS), uses grouping method to divide the CFP of IEEE 802.15.4 protocol into several equal slot cycles and extract the hidden node address information from some damaged frame caused by the hidden conflict. The strategy dynamically adjusts nodes to different competition groups based on currently obtained hidden relationship. The nodes within competitive groups still competitively send messages in accordance with the binary back method in the same period, while different competitive groups send messages in different time slots. As a result, the strategy completely solves the hidden conflict problem. Compared with other hidden node collision resolution strategies, HNCDAS has certain advantages such as less overhead and dynamic adjustment capability. The convergence of the strategy and the maximum time of resolution strategies are also demonstrated in theory. Experimental results show that HNCDAS can significantly improve data transmission rate, throughput and energy efficiency.%隐藏节点问题是导致IEEE 802.15.4协议性能下降的一个重要因素,而在IEEE 802.15.4中没有给出解决该类问题的具体方案.提出一种基于冲突指示和分组的隐藏冲突避免策略(hidden node collision detection and avoid strategy,简称HNCDAS),该策略采用分组方法将IEEE 802.15.4的CAP周期划分为多个等分时隙,从隐藏冲突导致的部分破损帧中提取出隐藏节点地址信息,依据当前获得的隐藏关系动态地将节点调整到相应的竞争组,竞争组内的节点在同一周期内仍按照二进制后退方法竞争发送消息,不同的竞争组在不同的时隙发送消息,从而彻底解决隐藏冲突问题.与其他隐藏冲突解析策略相比,HNCDAS 具有额外开销少和动态调整等优点.从理论上证明了该策略的收敛性和解析策略时间的上限,实验结果表明,HNCDAS在数据传递率、吞吐率和能量利用率等方面都有明显的提高.