软件定义无线网络(Software Defined Wireless Network,SDWN)中,终端在无线接入点(Access Point,AP)切换时容易造成网络中断以及待切换无线接入点选择不当等问题,从而导致实时应用服务质量下降。为了解决这一问题,文中提出了一种基于双...软件定义无线网络(Software Defined Wireless Network,SDWN)中,终端在无线接入点(Access Point,AP)切换时容易造成网络中断以及待切换无线接入点选择不当等问题,从而导致实时应用服务质量下降。为了解决这一问题,文中提出了一种基于双网络通道互备的AP切换方案。该方案首先利用双网络通道互备机制在链路层实现先连后断的软切换,并进一步利用SDWN中网络地址映射机制实现网络层的无缝切换。依据基于综合评价法(Technique for Order Preference by Similarity to an Ideal Solution,TOPSIS)的思想,设计实现了高性能AP选择算法。该算法中根据待切换AP的信号强度、负载、传输带宽和当前连接数构造待评价对象,并依据待评价对象与理想对象的接近程度进行待切换AP选择。通过NS-3网络模拟器仿真实验表明:相较于基于RSSI的切换方案,所提方案中实时应用的传输时延降低了85.29%,丢包率降低了14.11%,吞吐量提升了8.94%。提出的双网络通道切换方案能够明显改善单网络通道切换方案因AP切换造成的网络中断问题,更好地保障实时应用的服务质量。展开更多
To the existing spectrum sharing schemes in wireless-powered cognitive wireless sensor networks,the protocols are limited to either separate the primary and the secondary transmission or allow the secondary user to tr...To the existing spectrum sharing schemes in wireless-powered cognitive wireless sensor networks,the protocols are limited to either separate the primary and the secondary transmission or allow the secondary user to transmit signals in a time slot when it forwards the primary signal.In order to address this limitation,a novel cooperative spectrum sharing scheme is proposed,where the secondary transmission is multiplexed with both the primary transmission and the relay transmission.Specifically,the process of transmission is on a three-phase time-switching relaying basis.In the first phase,a cognitive sensor node SU1 scavenges energy from the primary transmission.In the second phase,another sensor node SU2 and primary transmitter simultaneously transmit signals to the SU1.In the third phase,the node SU1 can assist the primary transmission to acquire the opportunity of spectrum sharing.Joint decoding and interference cancellation technique is adopted at the receivers to retrieve the desired signals.We further derive the closed-form expressions for the outage probabilities of both the primary and secondary systems.Moreover,we address optimization of energy harvesting duration and power allocation coefficient strategy under performance criteria.An effective algorithm is then presented to solve the optimization problem.Simulation results demonstrate that with the optimized solutions,the sensor nodes with the proposed cooperative spectrum sharing scheme can utilize the spectrum in a more efficient manner without deteriorating the performance of the primary transmission,as compared with the existing one-directional scheme in the literature.展开更多
文摘软件定义无线网络(Software Defined Wireless Network,SDWN)中,终端在无线接入点(Access Point,AP)切换时容易造成网络中断以及待切换无线接入点选择不当等问题,从而导致实时应用服务质量下降。为了解决这一问题,文中提出了一种基于双网络通道互备的AP切换方案。该方案首先利用双网络通道互备机制在链路层实现先连后断的软切换,并进一步利用SDWN中网络地址映射机制实现网络层的无缝切换。依据基于综合评价法(Technique for Order Preference by Similarity to an Ideal Solution,TOPSIS)的思想,设计实现了高性能AP选择算法。该算法中根据待切换AP的信号强度、负载、传输带宽和当前连接数构造待评价对象,并依据待评价对象与理想对象的接近程度进行待切换AP选择。通过NS-3网络模拟器仿真实验表明:相较于基于RSSI的切换方案,所提方案中实时应用的传输时延降低了85.29%,丢包率降低了14.11%,吞吐量提升了8.94%。提出的双网络通道切换方案能够明显改善单网络通道切换方案因AP切换造成的网络中断问题,更好地保障实时应用的服务质量。
基金Project (61201086) supported by the National Natural Science Foundation of ChinaProject (201506375060) supported by the China Scholarship Council+2 种基金Project (2013B090500007) supported by Guangdong Provincial Science and Technology Project,ChinaProject (2014509102205) supported by the Dongguan Municipal Project on the Integration of Industry,Education and Research,ChinaProject (2017GK5019) supported by 2017 Hunan-Tech&Innovation Investment Project,China
文摘To the existing spectrum sharing schemes in wireless-powered cognitive wireless sensor networks,the protocols are limited to either separate the primary and the secondary transmission or allow the secondary user to transmit signals in a time slot when it forwards the primary signal.In order to address this limitation,a novel cooperative spectrum sharing scheme is proposed,where the secondary transmission is multiplexed with both the primary transmission and the relay transmission.Specifically,the process of transmission is on a three-phase time-switching relaying basis.In the first phase,a cognitive sensor node SU1 scavenges energy from the primary transmission.In the second phase,another sensor node SU2 and primary transmitter simultaneously transmit signals to the SU1.In the third phase,the node SU1 can assist the primary transmission to acquire the opportunity of spectrum sharing.Joint decoding and interference cancellation technique is adopted at the receivers to retrieve the desired signals.We further derive the closed-form expressions for the outage probabilities of both the primary and secondary systems.Moreover,we address optimization of energy harvesting duration and power allocation coefficient strategy under performance criteria.An effective algorithm is then presented to solve the optimization problem.Simulation results demonstrate that with the optimized solutions,the sensor nodes with the proposed cooperative spectrum sharing scheme can utilize the spectrum in a more efficient manner without deteriorating the performance of the primary transmission,as compared with the existing one-directional scheme in the literature.
