An optimized Chord protocol is proposed to solve the convergence problem for separated Chord rings over mobile Ad-hoc networks （MANETs）. This protocol exploits the information of topological neighbors in routing lay...An optimized Chord protocol is proposed to solve the convergence problem for separated Chord rings over mobile Ad-hoc networks （MANETs）. This protocol exploits the information of topological neighbors in routing layer by utilizing a cross-layer design, and periodically detects whether there is any neighbor node that belongs to an alien Chord ring by sending detecting packets. The detection will be confirmed and then the corresponding predecessor node will be found out to initialize convergence of the Chord rings. Theoretical analysis and experiment results show that the proposed algorithm can detect separated Chord rings and implement the convergence process efficiently, and that a significant improvement in the successful lookup ratio is also achieved at an acceptable overhead for the system maintenance. Moreover, the proposed protocol can ensure the stability and scalability of the system.展开更多
移动Ad hoc网自组织、移动性等特性为组网带来便利的同时也增加了路由管理的难度.针对现有可靠路由算法解决问题具有局限性以及获取链路评价信息低效等问题,在DSR(dynamic source routing)协议基础上提出了基于本地信任系统的可靠路由协...移动Ad hoc网自组织、移动性等特性为组网带来便利的同时也增加了路由管理的难度.针对现有可靠路由算法解决问题具有局限性以及获取链路评价信息低效等问题,在DSR(dynamic source routing)协议基础上提出了基于本地信任系统的可靠路由协议(reliable routing protocol based on local trust system,简称TR-DSR).TR-DSR协议选择路由时,综合考虑路由上各节点和各链路的可靠信任度,并在路由建立过程中利用这些信息,在确保找到可靠路由的基础上降低寻路开销.同时,为了防止自私节点对信任系统评价正确性的影响,提出了基于GTFT(generous tit for tat)策略的激励节点推荐响应行为的DFR(decide forwarding recommendation)算法.仿真实验结果表明,在节点频繁移动和存在大量自私节点的网络中,该协议的性能优势明显,验证了TR-DSR协议的可靠性.展开更多
The mobile nature of the nodes in a wireless mobile ad-hoc network(MANET) and the error prone link connectivity between nodes pose many challenges. These include frequent route changes, high packet loss, etc. Such pro...The mobile nature of the nodes in a wireless mobile ad-hoc network(MANET) and the error prone link connectivity between nodes pose many challenges. These include frequent route changes, high packet loss, etc. Such problems increase the end-toend delay and decrease the throughput. This paper proposes two adaptive priority packet scheduling algorithms for MANET based on Mamdani and Sugeno fuzzy inference system. The fuzzy systems consist of three input variables: data rate, signal-to-noise ratio(SNR) and queue size. The fuzzy decision system has been optimised to improve its efficiency. Both fuzzy systems were verified using the Matlab fuzzy toolbox and the performance of both algorithms were evaluated using the riverbed modeler(formally known as OPNET modeler). The results were compared to an existing fuzzy scheduler under various network loads, for constant-bit-rate(CBR) and variable-bit-rate(VBR) traffic. The measuring metrics which form the basis for performance evaluation are end-to-end delay, throughput and packet delivery ratio. The proposed Mamdani and Sugeno scheduler perform better than the existing scheduler for CBR traffic. The end-to-end delay for Mamdani and Sugeno scheduler was reduced by an average of 52 % and 54 %, respectively.The performance of the throughput and packet delivery ratio for CBR traffic are very similar to the existing scheduler because of the characteristic of the traffic. The network was also at full capacity. The proposed schedulers also showed a better performance for VBR traffic. The end-to-end delay was reduced by an average of 38 % and 52 %, respectively. Both the throughput and packet delivery ratio(PDR) increased by an average of 53 % and 47 %, respectively. The Mamdani scheduler is more computationally complex than the Sugeno scheduler, even though they both showed similar network performance. Thus, the Sugeno scheduler is more suitable for real-time applications.展开更多
基金supported by the National Natural Science Foundation of China (60672124)the Hi-Tech Research and Development Program of China (2007AA01Z221)
文摘An optimized Chord protocol is proposed to solve the convergence problem for separated Chord rings over mobile Ad-hoc networks （MANETs）. This protocol exploits the information of topological neighbors in routing layer by utilizing a cross-layer design, and periodically detects whether there is any neighbor node that belongs to an alien Chord ring by sending detecting packets. The detection will be confirmed and then the corresponding predecessor node will be found out to initialize convergence of the Chord rings. Theoretical analysis and experiment results show that the proposed algorithm can detect separated Chord rings and implement the convergence process efficiently, and that a significant improvement in the successful lookup ratio is also achieved at an acceptable overhead for the system maintenance. Moreover, the proposed protocol can ensure the stability and scalability of the system.
文摘移动Ad hoc网自组织、移动性等特性为组网带来便利的同时也增加了路由管理的难度.针对现有可靠路由算法解决问题具有局限性以及获取链路评价信息低效等问题,在DSR(dynamic source routing)协议基础上提出了基于本地信任系统的可靠路由协议(reliable routing protocol based on local trust system,简称TR-DSR).TR-DSR协议选择路由时,综合考虑路由上各节点和各链路的可靠信任度,并在路由建立过程中利用这些信息,在确保找到可靠路由的基础上降低寻路开销.同时,为了防止自私节点对信任系统评价正确性的影响,提出了基于GTFT(generous tit for tat)策略的激励节点推荐响应行为的DFR(decide forwarding recommendation)算法.仿真实验结果表明,在节点频繁移动和存在大量自私节点的网络中,该协议的性能优势明显,验证了TR-DSR协议的可靠性.
文摘The mobile nature of the nodes in a wireless mobile ad-hoc network(MANET) and the error prone link connectivity between nodes pose many challenges. These include frequent route changes, high packet loss, etc. Such problems increase the end-toend delay and decrease the throughput. This paper proposes two adaptive priority packet scheduling algorithms for MANET based on Mamdani and Sugeno fuzzy inference system. The fuzzy systems consist of three input variables: data rate, signal-to-noise ratio(SNR) and queue size. The fuzzy decision system has been optimised to improve its efficiency. Both fuzzy systems were verified using the Matlab fuzzy toolbox and the performance of both algorithms were evaluated using the riverbed modeler(formally known as OPNET modeler). The results were compared to an existing fuzzy scheduler under various network loads, for constant-bit-rate(CBR) and variable-bit-rate(VBR) traffic. The measuring metrics which form the basis for performance evaluation are end-to-end delay, throughput and packet delivery ratio. The proposed Mamdani and Sugeno scheduler perform better than the existing scheduler for CBR traffic. The end-to-end delay for Mamdani and Sugeno scheduler was reduced by an average of 52 % and 54 %, respectively.The performance of the throughput and packet delivery ratio for CBR traffic are very similar to the existing scheduler because of the characteristic of the traffic. The network was also at full capacity. The proposed schedulers also showed a better performance for VBR traffic. The end-to-end delay was reduced by an average of 38 % and 52 %, respectively. Both the throughput and packet delivery ratio(PDR) increased by an average of 53 % and 47 %, respectively. The Mamdani scheduler is more computationally complex than the Sugeno scheduler, even though they both showed similar network performance. Thus, the Sugeno scheduler is more suitable for real-time applications.
