中文摘要：

拥塞控制是无线传感器网络中的一个关键性问题,它不但影响传输可靠性,而且会浪费宝贵的能量资源.提出了一个全新的拥塞避免、检测与缓解策略,该策略主要包含两部分：拥塞避免（COTA）和拥塞检测及缓解（CODEM）.COTA从全网出发,基于路径的启发式信息分配流量,避免给潜在的热点区域分配过多负载.CODEM使用精确的拥塞度量来检测拥塞,并采取适当的措施来缓解拥塞,同时保证数据传输的可靠性.此外,还利用现有radio的多频特性有效地为控制报文进行拥塞隔离.详细的实验表明了COTA＋CODEM的优势.

英文摘要：

Congestion is an essential problem in wireless sensor networks. It occurs when the offered traffic load exceeds available capacity at any point in a network. Congestion causes overall channel quality to degrade and drop rates to rise. Furthermore, redundant transmissions are always adopted to guarantee reliable data delivery, which may deteriorate congestion since they bring about more contention and in return hampers the reliability. In this paper, a framework is proposed to avoid, detect and mitigate congestion effectively. Compared with previous works, this work doesn＇t control congestion at the cost of desired reliability, instead, both goals can be achieved. There are mainly two parts in this framework： congestion aware traffic allocation （COTA） and congestion detection and mitigation （CODEM）. COTA is used in muhipath routing to balance traffic around the whole network. COTA uses some heuristic information to analyze the potential congestion region and avoid traversing these regions. Once congestion happens inevitably, CODEM is presented to detect congestion using accurate metric and reallocate traffic among multiple paths to mitigate congestion. The multi-frequency characteristic of CC2420 radio is used to minimize contention between control packets and data packets. Comprehensive simulations validate the distinguished performance in several aspects of the framework.