A novel joint optimization strategy for the secondary user( SU) was proposed to consider the short-term and long-term video transmissions over distributed cognitive radio networks( DCRNs).Since the long-term video tra...A novel joint optimization strategy for the secondary user( SU) was proposed to consider the short-term and long-term video transmissions over distributed cognitive radio networks( DCRNs).Since the long-term video transmission consisted of a series of shortterm transmissions, the optimization problem in the video transmission was a composite optimization process. Firstly,considering some factors like primary user's( PU's) collision limitations,non-synchronization between SU and PU,and SU's limited buffer size, the short-term optimization problem was formulated as a mixed integer non-linear program( MINLP) to minimize the block probability of video packets. Secondly,combining the minimum packet block probability obtained in shortterm optimization and SU's constraint on hardware complexity,the partially observable Markov decision process( POMDP) framework was proposed to learn PU's statistic information over DCRNs.Moreover,based on the proposed framework,joint optimization strategy was designed to obtain the minimum packet loss rate in long-term video transmission. Numerical simulation results were provided to demonstrate validity of our strategies.展开更多
We investigate the approximating capability of Markov modulated Poisson processes (MMPP) for modeling multifractal Internet traffic. The choice of MMPP is motivated by its ability to capture the variability and correl...We investigate the approximating capability of Markov modulated Poisson processes (MMPP) for modeling multifractal Internet traffic. The choice of MMPP is motivated by its ability to capture the variability and correlation in moderate time scales while being analytically tractable. Important statistics of traffic burstiness are described and a customized moment-based fitting procedure of MMPP to traffic traces is presented. Our methodology of doing this is to examine whether the MMPP can be used to predict the performance of a queue to which MMPP sample paths and measured traffic traces are fed for comparison respectively, in addition to the goodness-of-fit test of MMPP. Numerical results and simulations show that the fitted MMPP can approximate multifractal traffic quite well, i.e. accurately predict the queueing performance.展开更多
随着分布式新能源渗透率不断提高,智能配电网电力电子化趋势明显,电气参数更加复杂,亟需研究适用于配电网的同步相量测量装置(Synchrophasor measurement unit for distribution network,D-PMU)。然而,现有通信协议与条件无法满足D-PMU...随着分布式新能源渗透率不断提高,智能配电网电力电子化趋势明显,电气参数更加复杂,亟需研究适用于配电网的同步相量测量装置(Synchrophasor measurement unit for distribution network,D-PMU)。然而,现有通信协议与条件无法满足D-PMU的接入需求。针对该问题,该文设计一种适用于D-PMU的基频相量、谐波/间谐波同步测量、异步传输的结构框架,提出一种谐波/间谐波的数据传输协议,减少了通信负担。在上述框架的条件下,分析网络通信延时与丢包率的影响因素,搭建通信性能测试平台,进行通信性能实际测试,验证所提通信方法的可行性,并根据测试结果提出一种D-PMU通信接入参数的设置方法。展开更多
基金National Natural Science Foundation of China(No.61301101)
文摘A novel joint optimization strategy for the secondary user( SU) was proposed to consider the short-term and long-term video transmissions over distributed cognitive radio networks( DCRNs).Since the long-term video transmission consisted of a series of shortterm transmissions, the optimization problem in the video transmission was a composite optimization process. Firstly,considering some factors like primary user's( PU's) collision limitations,non-synchronization between SU and PU,and SU's limited buffer size, the short-term optimization problem was formulated as a mixed integer non-linear program( MINLP) to minimize the block probability of video packets. Secondly,combining the minimum packet block probability obtained in shortterm optimization and SU's constraint on hardware complexity,the partially observable Markov decision process( POMDP) framework was proposed to learn PU's statistic information over DCRNs.Moreover,based on the proposed framework,joint optimization strategy was designed to obtain the minimum packet loss rate in long-term video transmission. Numerical simulation results were provided to demonstrate validity of our strategies.
文摘We investigate the approximating capability of Markov modulated Poisson processes (MMPP) for modeling multifractal Internet traffic. The choice of MMPP is motivated by its ability to capture the variability and correlation in moderate time scales while being analytically tractable. Important statistics of traffic burstiness are described and a customized moment-based fitting procedure of MMPP to traffic traces is presented. Our methodology of doing this is to examine whether the MMPP can be used to predict the performance of a queue to which MMPP sample paths and measured traffic traces are fed for comparison respectively, in addition to the goodness-of-fit test of MMPP. Numerical results and simulations show that the fitted MMPP can approximate multifractal traffic quite well, i.e. accurately predict the queueing performance.
文摘随着分布式新能源渗透率不断提高,智能配电网电力电子化趋势明显,电气参数更加复杂,亟需研究适用于配电网的同步相量测量装置(Synchrophasor measurement unit for distribution network,D-PMU)。然而,现有通信协议与条件无法满足D-PMU的接入需求。针对该问题,该文设计一种适用于D-PMU的基频相量、谐波/间谐波同步测量、异步传输的结构框架,提出一种谐波/间谐波的数据传输协议,减少了通信负担。在上述框架的条件下,分析网络通信延时与丢包率的影响因素,搭建通信性能测试平台,进行通信性能实际测试,验证所提通信方法的可行性,并根据测试结果提出一种D-PMU通信接入参数的设置方法。
