Mobile ad hoc networks （MANETs） are a kind of very complex distributed communication systems with wireless mobile nodes that can be freely and dynamically self-organized into arbitrary and temporary network topologi...Mobile ad hoc networks （MANETs） are a kind of very complex distributed communication systems with wireless mobile nodes that can be freely and dynamically self-organized into arbitrary and temporary network topologies. MANETs inherit several limitations of wireless networks, meanwhile make new challenges arising from the specificity of MANETs, such as route failures, hidden terminals and exposed terminals. When TCP is applied in a MANET environment, a number of tough problems have to be dealt with. In this paper, a comprehensive survey on this dynamic field is given. Specifically, for the first time all factors impairing TCP performance are identified based on network protocol hierarchy, i.e., lossy wireless channel at the physical layer; excessive contention and unfair access at the MAC layer; frail routing protocol at the network layer, the MAC layer and the network layer related mobile node; unfit congestion window size at the transport layer and the transport layer related asymmetric path. How these factors degrade TCP performance is clearly explained. Then, based on how to alleviate the impact of each of these factors listed above, the existing solutions are collected as comprehensively as possible and classified into a number of categories, and their advantages and limitations are discussed. Based on the limitations of these solutions, a set of open problems for designing more robust solutions is suggested.展开更多
低功耗设计是MANET(Mobile Ad Hoc Network)研究中面临的一个挑战性问题。根据跨层设计思想,提出了一种基于能量约束的MANET路由算法。利用MAC层反馈信息,以分组交付所需的发送次数作为选路标准,提高分组发送的成功率,减少竞争和重传造...低功耗设计是MANET(Mobile Ad Hoc Network)研究中面临的一个挑战性问题。根据跨层设计思想,提出了一种基于能量约束的MANET路由算法。利用MAC层反馈信息,以分组交付所需的发送次数作为选路标准,提高分组发送的成功率,减少竞争和重传造成的功耗,从而优化网络性能。并具体结合AODV路由协议,通过仿真分析对该方案的可行性进行了评估。展开更多
由于严格分层的协议无法很好地适应移动自组织网络(Mobile Ad hoc Network,MANET)的动态变化,交叉层设计与优化近年来成为MANET的一个研究热点。针对802.11b标准支持的多速率通信,分别在网络层和MAC层实现了两种多速率控制方案,并通过...由于严格分层的协议无法很好地适应移动自组织网络(Mobile Ad hoc Network,MANET)的动态变化,交叉层设计与优化近年来成为MANET的一个研究热点。针对802.11b标准支持的多速率通信,分别在网络层和MAC层实现了两种多速率控制方案,并通过仿真实验详细分析了这两种速率控制方案的性能。实验结果表明,在网络层引入物理层提供的多速率信息作为路由选取标准,可有效提高网络吞吐率,降低端到端延迟;同时,在MAC层使用高速率转发中继,对网络层路由进行局部优化,可以进一步改善对拓扑动态变化的适应性。展开更多
文摘Mobile ad hoc networks （MANETs） are a kind of very complex distributed communication systems with wireless mobile nodes that can be freely and dynamically self-organized into arbitrary and temporary network topologies. MANETs inherit several limitations of wireless networks, meanwhile make new challenges arising from the specificity of MANETs, such as route failures, hidden terminals and exposed terminals. When TCP is applied in a MANET environment, a number of tough problems have to be dealt with. In this paper, a comprehensive survey on this dynamic field is given. Specifically, for the first time all factors impairing TCP performance are identified based on network protocol hierarchy, i.e., lossy wireless channel at the physical layer; excessive contention and unfair access at the MAC layer; frail routing protocol at the network layer, the MAC layer and the network layer related mobile node; unfit congestion window size at the transport layer and the transport layer related asymmetric path. How these factors degrade TCP performance is clearly explained. Then, based on how to alleviate the impact of each of these factors listed above, the existing solutions are collected as comprehensively as possible and classified into a number of categories, and their advantages and limitations are discussed. Based on the limitations of these solutions, a set of open problems for designing more robust solutions is suggested.
文摘低功耗设计是MANET(Mobile Ad Hoc Network)研究中面临的一个挑战性问题。根据跨层设计思想,提出了一种基于能量约束的MANET路由算法。利用MAC层反馈信息,以分组交付所需的发送次数作为选路标准,提高分组发送的成功率,减少竞争和重传造成的功耗,从而优化网络性能。并具体结合AODV路由协议,通过仿真分析对该方案的可行性进行了评估。
文摘由于严格分层的协议无法很好地适应移动自组织网络(Mobile Ad hoc Network,MANET)的动态变化,交叉层设计与优化近年来成为MANET的一个研究热点。针对802.11b标准支持的多速率通信,分别在网络层和MAC层实现了两种多速率控制方案,并通过仿真实验详细分析了这两种速率控制方案的性能。实验结果表明,在网络层引入物理层提供的多速率信息作为路由选取标准,可有效提高网络吞吐率,降低端到端延迟;同时,在MAC层使用高速率转发中继,对网络层路由进行局部优化,可以进一步改善对拓扑动态变化的适应性。
