Heterogeneous wireless access technologies will coexist in next generation wireless networks.These technologies form integrated networks,and these networks support multiple services with high quality level.Various acc...Heterogeneous wireless access technologies will coexist in next generation wireless networks.These technologies form integrated networks,and these networks support multiple services with high quality level.Various access technologies allow users to select the best available access network to meet the requirements of each type of communication service.Being always best connected anytime and anywhere is a major concern in a heterogeneous wireless networks environment.Always best connected enables network selection mechanisms to keep mobile users always connected to the best network.We present an overview of the network selection and prediction problems and challenges.In addition,we discuss a comprehensive classification of related theoretic approaches,and also study the integration between these methods,finding the best solution of network selection and prediction problems.The optimal solution can fulfill the requirements of the next generation wireless networks.展开更多
A new vertical handoff decision algorithm is proposed to maximize the system benefit in heterogeneous wireless networks which comprise cellular networks and wireless local area networks （WLANs）. Firstly the block pr...A new vertical handoff decision algorithm is proposed to maximize the system benefit in heterogeneous wireless networks which comprise cellular networks and wireless local area networks （WLANs）. Firstly the block probability, the drop probability and the number of users in the heterogeneous networks are calculated in the channel-guard call admission method, and a function of the system benefit which is based on the new call arrival rate and the handoff call arrival rate is proposed. Then the optimal radius of WLAN is obtained by using simulation annealing （SA） method to maximize the benefit. All the nodes should handoff from cellular network to WLAN if they enter WLAN＇s scope and handoff from WLAN to cellular network if they leave the scope. Finally, the algorithm in different new call arrival rates and handoff call arrival rates is analyzed and results show that it can achieve good effects.展开更多
虚拟电厂(virtual power plant,VPP)可利用异构网络实现分布式新能源聚合调度,实现综合效益提升。为了提高VPP在不同网络下的丢包与时延等非理想传输能力,提出面向异构通信网络的设备接入优化算法。首先,分析总结了VPP设备充放电容量、...虚拟电厂(virtual power plant,VPP)可利用异构网络实现分布式新能源聚合调度,实现综合效益提升。为了提高VPP在不同网络下的丢包与时延等非理想传输能力,提出面向异构通信网络的设备接入优化算法。首先,分析总结了VPP设备充放电容量、出力特性、接入网络时延、网络承载能力等约束条件,考虑异构网络下设备接入的丢包率和时延理论性能构建了以收益损失最小化为目标的优化模型。然后,利用分层求解和贪婪算法进行模型求解,获得设备的接入方式。最后,仿真验证了所提模型和算法的有效性和可靠性。结果表明,所提算法可提高网络接入容量并降低系统收益损失,实现收益最大化。展开更多
海上异构无线网络覆盖下的业务需求和节点多种多样,这就要求网络资源在分配时需要兼顾匹配性和网络性能。相邻多节点在选择无线网络时,易产生策略冲突并大量接入同一网络,进而导致网络负载不均衡、接入阻塞率高和服务质量(quality of se...海上异构无线网络覆盖下的业务需求和节点多种多样,这就要求网络资源在分配时需要兼顾匹配性和网络性能。相邻多节点在选择无线网络时,易产生策略冲突并大量接入同一网络,进而导致网络负载不均衡、接入阻塞率高和服务质量(quality of service,Qos)降低。针对以上问题提出一种基于网络评价和时隙分配的网络接入选择算法,设计网络评价模块、时隙分配模块和接入决策模块,通过业务评价和阻塞率估计对可选网络进行综合评价以提高匹配性,根据节点执行业务的优先级对多节点进行时隙分配,依序优化网络接入策略。仿真结果表明,相对于负载均衡和多属性决策算法,所提算法的节点平均接入阻塞率降低了32.09%,20.87%,节点平均吞吐量提升了76.90%,33.25%,网络的负载均衡性和传输效率均得到有效提升。展开更多
In converged heterogeneous wireless networks, vertical handoff is an important issue in radio resource management and occurs when an end user switches from one network to another （e.g., from wireless local area netwo...In converged heterogeneous wireless networks, vertical handoff is an important issue in radio resource management and occurs when an end user switches from one network to another （e.g., from wireless local area network to wideband code division multiple access）. Efficient vertical handoff should allocate network resources efficiently and maintain good quality of service （QoS） for the end users. The objective of this work is to determine conditions under which vertical handoff can be performed. The channel usage situation of each access network is formulated as a birth-death process with the objective of predicting the avaliable bandwidth and the blocking probability. A reward function is used to capture the network bandwidth and the blocking probability is expressed as a cost function. An end user will access the certain network which maximizes the total function defined as the combination of the reward fimction and the cost function. Simulation results show that the proposed algorithm can significantly improve the network performance, including higher bandwidth for end users and lower new call blocking and handoff call blocking probability for networks.展开更多
为了解决全双工(Full Duplex,FD)异构无线携能通信(Simultaneous Wireless Information and Power Transfer,SWIPT)网络中的传输安全问题,针对存在多个窃听者的通信场景,提出基于人工噪声(Artificial Noise,AN)辅助的FD异构SWIPT网络安...为了解决全双工(Full Duplex,FD)异构无线携能通信(Simultaneous Wireless Information and Power Transfer,SWIPT)网络中的传输安全问题,针对存在多个窃听者的通信场景,提出基于人工噪声(Artificial Noise,AN)辅助的FD异构SWIPT网络安全波束成形设计方案。该方案在满足安全发射功率阈值、最低安全速率以及收集能量等约束条件下,通过联合优化AN、信息信号波束成形矢量以及上行发射功率最大化安全能量效率(Secrecy Energy Efficiency,SEE)。针对安全能量效率优化问题的非凸性,提出一种基于Dinkelbach和连续凸近似的双层优化算法,通过半定松弛技术、泰勒级数展开、连续凸近似法将难以求解的非凸问题转化为凸问题,最后利用MATLAB软件中的凸优化工具箱CVX进行求解。仿真实验验证了波束成形设计方案能够实现安全传输,且对系统能效也有一定程度的提升。展开更多
基金funded by the University of Malaya, under Grant No.RG208-11AFR
文摘Heterogeneous wireless access technologies will coexist in next generation wireless networks.These technologies form integrated networks,and these networks support multiple services with high quality level.Various access technologies allow users to select the best available access network to meet the requirements of each type of communication service.Being always best connected anytime and anywhere is a major concern in a heterogeneous wireless networks environment.Always best connected enables network selection mechanisms to keep mobile users always connected to the best network.We present an overview of the network selection and prediction problems and challenges.In addition,we discuss a comprehensive classification of related theoretic approaches,and also study the integration between these methods,finding the best solution of network selection and prediction problems.The optimal solution can fulfill the requirements of the next generation wireless networks.
文摘A new vertical handoff decision algorithm is proposed to maximize the system benefit in heterogeneous wireless networks which comprise cellular networks and wireless local area networks （WLANs）. Firstly the block probability, the drop probability and the number of users in the heterogeneous networks are calculated in the channel-guard call admission method, and a function of the system benefit which is based on the new call arrival rate and the handoff call arrival rate is proposed. Then the optimal radius of WLAN is obtained by using simulation annealing （SA） method to maximize the benefit. All the nodes should handoff from cellular network to WLAN if they enter WLAN＇s scope and handoff from WLAN to cellular network if they leave the scope. Finally, the algorithm in different new call arrival rates and handoff call arrival rates is analyzed and results show that it can achieve good effects.
文摘虚拟电厂(virtual power plant,VPP)可利用异构网络实现分布式新能源聚合调度,实现综合效益提升。为了提高VPP在不同网络下的丢包与时延等非理想传输能力,提出面向异构通信网络的设备接入优化算法。首先,分析总结了VPP设备充放电容量、出力特性、接入网络时延、网络承载能力等约束条件,考虑异构网络下设备接入的丢包率和时延理论性能构建了以收益损失最小化为目标的优化模型。然后,利用分层求解和贪婪算法进行模型求解,获得设备的接入方式。最后,仿真验证了所提模型和算法的有效性和可靠性。结果表明,所提算法可提高网络接入容量并降低系统收益损失,实现收益最大化。
文摘海上异构无线网络覆盖下的业务需求和节点多种多样,这就要求网络资源在分配时需要兼顾匹配性和网络性能。相邻多节点在选择无线网络时,易产生策略冲突并大量接入同一网络,进而导致网络负载不均衡、接入阻塞率高和服务质量(quality of service,Qos)降低。针对以上问题提出一种基于网络评价和时隙分配的网络接入选择算法,设计网络评价模块、时隙分配模块和接入决策模块,通过业务评价和阻塞率估计对可选网络进行综合评价以提高匹配性,根据节点执行业务的优先级对多节点进行时隙分配,依序优化网络接入策略。仿真结果表明,相对于负载均衡和多属性决策算法,所提算法的节点平均接入阻塞率降低了32.09%,20.87%,节点平均吞吐量提升了76.90%,33.25%,网络的负载均衡性和传输效率均得到有效提升。
文摘针对异构无线网络(Heterogeneous Wireless Network,HWN)中多种无线接入技术(Radio Access Technology,RAT)间业务分组调度问题,提出一种基于介质独立切换(Media Independent Handover,MIH)的新型动态混合业务分组调度算法,用于长期演进技术(Long Term Evolution,LTE)蜂窝网、无线局域网(Wireless Local Area Network,WLAN)和无线mesh网络(WMN)之间的互联。利用MIH功能模块获得链路状态信息,并结合呼叫类型、业务类型和延迟约束来调度业务。其中,为具有最低剩余时间和最优信道质量的业务分配最高的优先级,从而确保延迟约束,并最大化资源利用率。仿真结果表明,该算法具有较低的分组丢包率、呼叫阻塞率和平均等待时间。
基金Project(20040533035) supported by the National Research Foundation for the Doctoral Program of Higher Education of ChinaProject (50275150) supported by the National Natural Science Foundation of China
文摘In converged heterogeneous wireless networks, vertical handoff is an important issue in radio resource management and occurs when an end user switches from one network to another （e.g., from wireless local area network to wideband code division multiple access）. Efficient vertical handoff should allocate network resources efficiently and maintain good quality of service （QoS） for the end users. The objective of this work is to determine conditions under which vertical handoff can be performed. The channel usage situation of each access network is formulated as a birth-death process with the objective of predicting the avaliable bandwidth and the blocking probability. A reward function is used to capture the network bandwidth and the blocking probability is expressed as a cost function. An end user will access the certain network which maximizes the total function defined as the combination of the reward fimction and the cost function. Simulation results show that the proposed algorithm can significantly improve the network performance, including higher bandwidth for end users and lower new call blocking and handoff call blocking probability for networks.
文摘为了解决全双工(Full Duplex,FD)异构无线携能通信(Simultaneous Wireless Information and Power Transfer,SWIPT)网络中的传输安全问题,针对存在多个窃听者的通信场景,提出基于人工噪声(Artificial Noise,AN)辅助的FD异构SWIPT网络安全波束成形设计方案。该方案在满足安全发射功率阈值、最低安全速率以及收集能量等约束条件下,通过联合优化AN、信息信号波束成形矢量以及上行发射功率最大化安全能量效率(Secrecy Energy Efficiency,SEE)。针对安全能量效率优化问题的非凸性,提出一种基于Dinkelbach和连续凸近似的双层优化算法,通过半定松弛技术、泰勒级数展开、连续凸近似法将难以求解的非凸问题转化为凸问题,最后利用MATLAB软件中的凸优化工具箱CVX进行求解。仿真实验验证了波束成形设计方案能够实现安全传输,且对系统能效也有一定程度的提升。
