Max-Life Power Schedule for Connectivity and Biconnectivity in Wireless Ad Hoc Networks

Given the initial energy supplies and the maximal transmission power of the individual nodes in a wireless ad hoc network, a power schedule of duration t for a specified topological property is a scheduling of the transmission powers of the individual nodes over the period [0, t] such that (1) the total amount of energy consumed by each node during the period [0, t] does not exceed its initial energy supply, (2) the transmission power of each node at any moment in the period [0, t] does not exceed its maximal transmission power, and (3) the produced network topology at any moment in the period [0, t] satisfies the property . The problem Max-Life Power Schedule for seeks a power schedule of the maximal duration for . Let g be the golden ratio , and ε be an arbitrarily positive constant less than one. In this paper, we present a -approximation algorithm for Max-Life Power Schedule for Connectivity, a -approximation algorithm for Max-Life Power Schedule for 2-Node-Connectivity, and a -approximation algorithm for Max-Life Power Schedule for 2-Edge-Connectivity. This work is supported in part by Research Grants Council of Hong Kong under grant number CityU 9041040. Peng-Jun Wan received his Ph.D. degree from University of Minnesota, MS degree from The Chinese Academy of Science, and BS degree from Tsinghua University. He is currently an Associate Professor in Computer Science at Illinois Institute of Technology, and at City University of Hong Kong. His research interests include wireless networks, optical networks, and algorithm design and analysis. Chih-Wei Yi received his M.S. and B.S. degrees from National Taiwan University. He is currently a Ph.D. candidate at the Illinois Institute of Technology. His dissertational research focuses on wireless ad hoc networks. He is expected to graduate in 2005.     

ad hoc网络组播对于DoS攻击畦抵抗策略分析

与固定有线网络相比,无线ad hoc网络动态的拓扑结构、脆弱的无线信道、网络有限的通信带宽以及节点兼备主机和路由功能等特点,使得网络容易遭受拒绝服务（DOS）攻击。文章针对ad hoc网络的组播应用在抵御DoS攻击方面的不足,提出外部和内部两种组播DoS泛洪攻击模型,同时针对ad hoc网络组播组内的攻击提出相应的两种抵抗策略和具体实现步骤。     

多跳Ad Hoc网络中支持MIMO的分布式拓扑未知时分多址接入协议的研究与分析

针对Ad Hoc网络和MIMO的有效结合,提出了适于多跳Ad Hoc网络的支持MIMO的分布式拓扑未知时分多址接入协议.该协议通过有限域无线网络设计算法在每帧给每个节点分配时隙且无需知道全网拓扑信息,这极大地减小了收集全网拓扑信息的开销.通过预约,每个节点在其分配的无干扰时隙并行发送MIMO链路的所有数据流,并在与其他节点共享的时隙发送MIMO链路的一部份数据流来解决传输冲突.同时推导出保证通过率和最佳帧长.结果显示动态分配MIMO的传输容量和抗干扰能力会极大地提高通过率.