Next wireless network aims to integrate heterogeneous wireless access networks by sharing wireless resource.The spectral bandwidth mapping concept is proposed to uniformly describe the resource in heterogeneous wirele...Next wireless network aims to integrate heterogeneous wireless access networks by sharing wireless resource.The spectral bandwidth mapping concept is proposed to uniformly describe the resource in heterogeneous wireless networks.The resources of codes and power levels in WCDMA system as well as statistical time slots in WLAN are mapped into equivalent bandwidth which can be allocated in different networks and layers.The equivalent bandwidth is jointly distributed in call admission and vertical handoff control process in an integrated WLAN/WCDMA system to optimize the network utility and guarantee the heterogeneous QoS required by calls.Numerical results show that,when the incoming traffic is moderate,the proposed scheme could receive 5%-10% increase of system revenue compared to the MDP based algorithms.展开更多
In Light of the analysis of the physical implication and underlying assumption of the bandwidth parameter epsilon of wave spectrum, a time-averaging method is used to evaluate epsilon of the JONSWAP spectrum for diffe...In Light of the analysis of the physical implication and underlying assumption of the bandwidth parameter epsilon of wave spectrum, a time-averaging method is used to evaluate epsilon of the JONSWAP spectrum for different sea states. The resulting values of epsilon, which vary from 0.44 to 0.53 depending on the dimensionless fetch, are physically meaningful and reasonable. The same method is also used to compute epsilon from wind-wave records measured in a flume under different wind speeds at different fetches. The computed values of epsilon, which vary with wind fetches and speeds too, are compared with those evaluated for the JONSWAP spectrum.展开更多
The spectral resolution is a main index of evaluating the performance of the designed acousto-optic tunable filter (AOTF). In this letter, an accurate expression of the spectral resolution is presented by considering ...The spectral resolution is a main index of evaluating the performance of the designed acousto-optic tunable filter (AOTF). In this letter, an accurate expression of the spectral resolution is presented by considering both the birefringence and the rotatory property of TeO2 crystal. The deduced expression is significant in improving the accuracy of the design of an AOTF and pushing the development of the high-performance AOTF.展开更多
Spectral bandwidth is a relevant parameter of water wave evolution and is commonly used to represent the number of wave components involved in wave-wave interactions.However,whether these two parameters are equivalent...Spectral bandwidth is a relevant parameter of water wave evolution and is commonly used to represent the number of wave components involved in wave-wave interactions.However,whether these two parameters are equivalent is an open question.Following the high-order spectral method and taking the weakly modulated Stokes wave train as the initial condition,the relationship between the spectral bandwidth and the number of wave components is investigated in this work.The results showed that the number of wave components can vary with the same spectral bandwidth and that distinct wave profiles emerge from different numbers of wave components.With a new definition of significant wave components,the characteristics of this parameter in the long-time wave evolution are discussed,along with its relationship with common parameters,including the wave surface maximum and the wave height.The results reveal that the wave surface evolution trend of different numbers of significant wave components(Ns)is the same from a holistic perspective,while the difference between them also exists,mainly in locations where extreme waves occur.Furthermore,there is a negative correlation between r(aj/a_(0))and wave surface maximum(η_(max)/a_(0))and wave height(H_(max)and Hs).The evolution trends of the relative errors(RE)ofη_(max)/a_(0),H_(max),and Hs of different Ns show the periodic recurrence of modulation and demodulation in the early stage when the Benjamin-Feir instability is dominated.The difference is that in the later stage,the RE ofη_(max)/a_(0)and H_(max)is chaotic and irregular,while those of Hs gradually stabilize near an equilibrium value.Furthermore,we discuss the relationship between the mean relative error(MRE)and r.Forη_(max)/a_(0),MRE and r show a logarithmic relationship,while for H_(max)and Hs,a quadratic relationship exists between them.Therefore,the choice of Ns is also important for extreme waves and is particularly meaningful for wave generation experiments in the wave flume.展开更多
对超奈奎斯特(faster than Nyquist,FTN)和奈奎斯特系统的频谱效率进行了对比分析。在绝对带宽的前提下,首先证明了基于根升余弦函数脉冲的单载波FTN可达速率大于奈奎斯特可达速率,并推导了有子载波间干扰的多载波FTN的频谱效率公式。...对超奈奎斯特(faster than Nyquist,FTN)和奈奎斯特系统的频谱效率进行了对比分析。在绝对带宽的前提下,首先证明了基于根升余弦函数脉冲的单载波FTN可达速率大于奈奎斯特可达速率,并推导了有子载波间干扰的多载波FTN的频谱效率公式。本文证明了单载波FTN的频谱效率大于奈奎斯特系统的频谱效率,并且证明了单载波FTN的频谱效率随着滚降因子的减小而增大。基于频谱效率公式和数值仿真,本文给出了多载波FTN对于不同滚降因子的最优子载波间隔。结果表明,即使存在子载波间干扰,基于最优子载波间隔的多载波FTN频谱效率也高于正交系统(奈奎斯特)的频谱效率。展开更多
基金Supported by the National Natural Science Foundation of China (No. 60772061)the Research Achievements Industrialization Project (No. JHB2011-10)
文摘Next wireless network aims to integrate heterogeneous wireless access networks by sharing wireless resource.The spectral bandwidth mapping concept is proposed to uniformly describe the resource in heterogeneous wireless networks.The resources of codes and power levels in WCDMA system as well as statistical time slots in WLAN are mapped into equivalent bandwidth which can be allocated in different networks and layers.The equivalent bandwidth is jointly distributed in call admission and vertical handoff control process in an integrated WLAN/WCDMA system to optimize the network utility and guarantee the heterogeneous QoS required by calls.Numerical results show that,when the incoming traffic is moderate,the proposed scheme could receive 5%-10% increase of system revenue compared to the MDP based algorithms.
基金National Natural Science Foundation of China(Grant No.49676277)
文摘In Light of the analysis of the physical implication and underlying assumption of the bandwidth parameter epsilon of wave spectrum, a time-averaging method is used to evaluate epsilon of the JONSWAP spectrum for different sea states. The resulting values of epsilon, which vary from 0.44 to 0.53 depending on the dimensionless fetch, are physically meaningful and reasonable. The same method is also used to compute epsilon from wind-wave records measured in a flume under different wind speeds at different fetches. The computed values of epsilon, which vary with wind fetches and speeds too, are compared with those evaluated for the JONSWAP spectrum.
文摘The spectral resolution is a main index of evaluating the performance of the designed acousto-optic tunable filter (AOTF). In this letter, an accurate expression of the spectral resolution is presented by considering both the birefringence and the rotatory property of TeO2 crystal. The deduced expression is significant in improving the accuracy of the design of an AOTF and pushing the development of the high-performance AOTF.
基金the National Key Research and Development Program of China(Grant No.2022YFE0104500)the National Natural Science Foundation of China(Grant No.52271271)the Major Science and Technology Project of the Ministry of Water Resources of the People’s Republic of China(Grant No.SKS-2022025).
文摘Spectral bandwidth is a relevant parameter of water wave evolution and is commonly used to represent the number of wave components involved in wave-wave interactions.However,whether these two parameters are equivalent is an open question.Following the high-order spectral method and taking the weakly modulated Stokes wave train as the initial condition,the relationship between the spectral bandwidth and the number of wave components is investigated in this work.The results showed that the number of wave components can vary with the same spectral bandwidth and that distinct wave profiles emerge from different numbers of wave components.With a new definition of significant wave components,the characteristics of this parameter in the long-time wave evolution are discussed,along with its relationship with common parameters,including the wave surface maximum and the wave height.The results reveal that the wave surface evolution trend of different numbers of significant wave components(Ns)is the same from a holistic perspective,while the difference between them also exists,mainly in locations where extreme waves occur.Furthermore,there is a negative correlation between r(aj/a_(0))and wave surface maximum(η_(max)/a_(0))and wave height(H_(max)and Hs).The evolution trends of the relative errors(RE)ofη_(max)/a_(0),H_(max),and Hs of different Ns show the periodic recurrence of modulation and demodulation in the early stage when the Benjamin-Feir instability is dominated.The difference is that in the later stage,the RE ofη_(max)/a_(0)and H_(max)is chaotic and irregular,while those of Hs gradually stabilize near an equilibrium value.Furthermore,we discuss the relationship between the mean relative error(MRE)and r.Forη_(max)/a_(0),MRE and r show a logarithmic relationship,while for H_(max)and Hs,a quadratic relationship exists between them.Therefore,the choice of Ns is also important for extreme waves and is particularly meaningful for wave generation experiments in the wave flume.
文摘对超奈奎斯特(faster than Nyquist,FTN)和奈奎斯特系统的频谱效率进行了对比分析。在绝对带宽的前提下,首先证明了基于根升余弦函数脉冲的单载波FTN可达速率大于奈奎斯特可达速率,并推导了有子载波间干扰的多载波FTN的频谱效率公式。本文证明了单载波FTN的频谱效率大于奈奎斯特系统的频谱效率,并且证明了单载波FTN的频谱效率随着滚降因子的减小而增大。基于频谱效率公式和数值仿真,本文给出了多载波FTN对于不同滚降因子的最优子载波间隔。结果表明,即使存在子载波间干扰,基于最优子载波间隔的多载波FTN频谱效率也高于正交系统(奈奎斯特)的频谱效率。
