Spectrum Allocation for Cognitive Radio Networks with Non-Deterministic Bandwidth of Spectrum Hole

The spectrum allocation for cognitive radio networks(CRNs) has received considerable studies under the assumption that the bandwidth of spectrum holes is static. However, in practice, the bandwidth of spectrum holes is time-varied due to primary user/secondary user(PU/SU) activity and mobility, which result in non-determinacy. This paper studies the spectrum allocation for CRNs with non-deterministic bandwidth of spectrum holes. We present a novel probability density function(PDF) through order statistics as well as its simplified form to describe the statistical properties of spectrum holes, with which a statistical spectrum allocation model based on stochastic multiple knapsack problem(MKP) is formulated for spectrum allocation with non-deterministic bandwidth of spectrum holes. To reduce the computational complexity, we transform this stochastic programming problem into a constant MKP through exploiting the properties of cumulative distribution function(CDF), which can be solved via MTHG algorithm by using auxiliary variables. Simulation results illustrate that the proposed statistical spectrum allocation algorithm can achieve better performance compared with the existing algorithms when the bandwidth of spectrum holes is time-varied.

Spatial-temporal spectrum hole discovery:a hybrid spectrum sensing and geolocation database framework

A hybrid spectrum sensing and geolocation database framework is proposed to tackle the discovery of spatial-temporal spectrum hole in cognitive radio networks.We first analyze the advantages and disadvantages of spectrum sensing-based and geolocation database-based approaches respectively,which motivate us to further propose a hybrid protocol framework by effectively integrating the benefits of both spectrum sensing and geolocation database.Specifically,in the proposed hybrid approach,the goal is to maximize the utilization of spatialtemporal spectrum hole while satisfying the protection constraints for the primary users.Analytical and numerical results demonstrate the superior performance of the proposed hybrid approach over the existing spectrum sensing only and geolocation database only approaches,in terms of interference-free throughput.This article serves as a fundamental framework for advancing the design of hybrid approaches for spatial-temporal spectrum hole discovery.

Area spectrum of the three-dimensional Godel black hole

The aim of this paper is to investigate the area spectrum of the three-dimensional Godel black hole by using two different methods. The result shows that the area spectrum of the black hole is △A = 8πl2p, which confirms the initial proposal of Bekenstein that the area spectrum is independent of black hole parameters and the spacing is 8πl2p.

Area Spectrum of D-Dimensional Large Schwarzschild-AdS Black Hole from Asymptotic Quasinormal Modes

我们调查 D 维的大 Schwarzschild 黑洞的区域和熵系列。由利用我们发现那的 quasinormal 模式频率的新物理解释，一个大 Schwarzschild 广告黑洞有一同等地 spaced 区域光谱和一个等距离的熵系列；两个依赖于 spacetime 尺寸。

Concrete quantum tunneling spectrum of Schwarzschild black holes

In this paper,a canonical ensemble model for black hole quantum tunneling radiation is introduced.We find that the probability distribution function is the same as the emission rate of a spherical shell in the Parikh-Wilczek tunneling framework.With this model,the probability distribution function corresponding to the emission shell system is calculated.Therefore,the concrete quantum tunneling spectrum of the Schwarzschild black hole is obtained.

Throughput Analysis of Dynamic Spectrum Anti-Jamming Multiple-Access in HF Communication Systems

A multiple-access networking scheme based on the new dynamic spectrum anti-jamming system is proposed in this paper. The network consists of a center node and multiple user nodes. The center node detects spectrum holes in the operation band periodically according to the user performance target. Detected spectrum holes are allocated to users who request communication. Throughput of this networking scheme is analyzed over a high-frequency(HF) interference channel. The effect of error correction coding and spectrum hole information transmission error is discussed. Throughput of this scheme and conventional frequency-hopping multiple-access(FHMA) scheme are compared. Results show that user performance increase leads to throughput decrease, which can be offset by error correction coding. If spectrum hole information transmission is in error, the throughput is not affected much as long as the bit error rate is below 10-2. Furthermore, throughput of this scheme is obviously superior to the throughput of FHMA scheme.

Generalized Drazin spectrum of operator matrices

Let A ∈ B（X） and B ∈ B（Y）, Me be an operator on Banach space X ＋ Y given by Mc =（A C 0 B）A generalized Drazin spectrum defined by σgD（T） = {λ∈C ： T-λI is not generalized Drazin invertible} is considered in this paper. It is shown that

Analysis of Coverage and Area Spectrum Efficiency of UDN with Inter-Tier Dependence

Stochastic geometry is widely employed to model cellular network. But in most existing works, base stations(BSs) are modelled following a homogeneous Poisson point process(PPP) for one-tier network, or several independent homogeneous PPP for multi-tier network, which ignore the dependence among BSs. In this paper, a three-tier UDN(Ultra dense network) with Macrocell BSs(MBS) for basic coverage, Picocell BSs(PBSs) deployed outside the coverage area of MBSs for compensating coverage holes, and Femtocell BSs(FBSs) surrounding MBSs for capacity improvement modelled by point process with inter-tier dependence is proposed. The tier association probability, the coverage probability and area spectrum efficiency(ASE) are derived. Simulation results validate our derivation, and results show that the proposed network model has 25%-45% performance gain in ASE.

Persistent Spectral Hole Burning of Eu^3＋ Doped Y2SiO5 Crystal at 579.62 nm

By using an Ar^＋ ion laser, a tunable Rh6G dye laser（linewidth： 0.5 cm^-1） pumped by the second harmonic of a YAG：Nd laser and an 899-21 dye laser as light sources and using a monochromator, a phase-locking amplifier and a computer as the data detecting system, the spectra and spectral hole burning of Eu^3＋：Y2SiO5 crystal were researched in this paper.Photoluminescence excitation spectrum and site selective fluorescence spectrum were detected at room temperature and 77 K. Hole burning experiments were reached at 16 K. A spectral hole with hole width of about 80 MHz were detected and it could be kept for 10 h.

Area and entropy spectra of black holes via an adiabatic invariant

By considering and using an adiabatic invariant for black holes, the area and entropy spectra of static spherically- symmetric black holes are investigated. Without using quasi-normal modes of black holes, equally-spaced area and entropy spectra are derived by only utilizing the adiabatic invariant. The spectra for non-charged and charged black holes are calculated, respectively. All these results are consistent with the original Bekenstein spectra.

Tunnelling effect of the non-stationary Kerr black hole

Extending Parikh and Wilczek＇s work to the non-stationary black hole, we study the Hawking radiation of the non-stationary Kerr black hole by the Hamilto-Jacobi method. The result shows that the radiation spectrum is not purely thermal and the tunnelling probability is related to the change of Bekenstein Hawking entropy, which gives a correction to the Hawking thermal radiation of the black hole.

露天矿电子雷管与普通雷管爆破振动对比试验研究

为研究电子雷管相比于普通塑料导爆管雷管在爆破振动控制方面的优势,在爆破参数以及岩体条件一致的情况下,开展了电子雷管起爆和普通雷管起爆的对比试验研究,结果表明:相同爆心距条件下,电子雷管的峰值质点振动速度比普通雷管的小,电子雷管的爆破振动主频比普通雷管的高,电子雷管爆破振动能量集中分布,主要分布于40~60 Hz和80~200 Hz频带,普通雷管爆破振动能量分布较电子雷管均匀,主要分布于低频频带。电子雷管不仅振动幅值小,且主频及能量占比高的频带均较普通雷管高,对保护建(构)筑物有利。

认知无线电网络中频谱感知性能分析

分析了认知无线电网络中使用能量检测器进行频谱检测的性能。仿真结果表明,衰落会使认知无线电用户检测性能下降,采用硬合并协作方案的合作频谱检测可以提高认知无线电系统的检测概率,但认知无线电系统的虚警概率也会随着参与协作的用户数的增多而上升,特别是控制信道不理想时,协作检测会导致虚警概率下限的出现,造成频谱利用率达不到预期的目标。

认知无线电网络中物理层频谱检测算法的研究

频谱检测是认知无线电网络(CRN)的关键技术之一,本文对认知无线电网络中物理层频谱检测的算法进行了研究。首先阐述了经典检测算法的应用场景、检测性能和设备实现复杂度,针对经典算法中的问题和不足,提出一系列改进型算法以及利用信号与噪声相关性差异的新型检测算法,并对各种检测算法进行了分类比较,在此基础上提出了结合不同检测算法优势的CRN检测策略,最后指出可能的研究方向。

认知无线电——智能的无线通信技术

认知无线电,以软件定义无线电为平台,是一种智能的无线通信技术;它能够感知周围的环境(外部世界),使用累积理解的方法从周围环境中逐步学习,根据射频输入激励的变化实时改变传输参数(如发射功率、载波频率、调制策略),使系统的通信规则与输入的射频激励相适应,确保无论何时何地都可以进行高度可靠的通信和无线电通信频谱的有效利用,并以更为灵活的方式来管理宝贵的频谱资源。

动态频谱抗干扰系统在部分频带干扰下的性能

为了评估动态频谱抗干扰新体制在抗干扰通信中的性能,采用理论分析与仿真相结合的方法,研究了动态频谱抗干扰系统在部分频带干扰下的信道容量及比特误码率,并将其与常规跳频系统在部分频带干扰下的信道容量及比特误码率进行了比较.结果表明:在很宽的部分频带干扰因子取值范围内,动态频谱抗干扰系统的信道容量均大于常规跳频系统的信道容量,即使动态频谱抗干扰系统无干扰状态信息,其信道容量也大于有干扰状态信息的常规跳频系统的信道容量;在中高信干比处,动态频谱抗干扰系统在最坏情况部分频带干扰下的比特误码率低于常规跳频系统;同时,纠错编码还可以为动态频谱抗干扰系统的性能带来进一步的改善.

认知无线电中基于循环统计量的频谱空穴检测方法

频谱空穴检测是认知无线电研究的关键技术。针对授权用户信号的循环平稳特性以及它和干扰信号、噪声的循环独立特性,提出了一种基于循环统计量的频谱空穴检测方案。构造了频谱空穴检测的二元假设检验模型,推导了相应的检验统计量。仿真结果表明,在低信噪比情况下,相比传统的能量检测法,该方法具有较优的检测性能,同时能有效地区分授权用户信号与同频干扰信号。

一种新型的认知无线电频谱空穴自适应检测算法

根据认知无线电实际频谱需求,通过对弱信号检测技术的研究,该文首次在认知无线电领域提出了一种基于三重矩阵累积估计的频谱空穴检测算法,该算法将频域块自适应滤波与矩阵重构、累积估计和频域平滑相结合实现弱信号检测。最后以QPSK调制信号为例进行了算法的计算机仿真,给出了性能分析。仿真结果表明该检测算法能够快速有效地实现弱信号检测并具有较高的检测概率,完全可以应用于认知无线电的频谱空穴检测。

业务类型感知的认知无线电动态频谱选择算法

在分析认知无线电的业务类型与主用户频谱空穴时长之间关系的基础上,提出一种认知业务类型感知的动态频谱选择算法.通过将认知业务接入到与其服务时长相近似的主用户频谱空闲时间隙中,结合认知用户的业务类型动态选择空闲信道,降低认知业务与主用户业务冲突的概率,增加主用户频谱空闲间隙的使用效率.模拟结果表明,本算法能够有效地降低认知用户的业务冲突率,进一步提高频谱资源的利用率.

卫星稀疏信道中频谱空穴的新型检测算法

面对宽带移动卫星通信中信道占用呈现的稀疏状态和时而存在的稀疏干扰,以低速率采样和运算是简化设备的必要途径。针对宽带频谱范围内稀疏信道信号和干扰信号的检测,提出了一种用于直接估计频谱空穴的压缩采样算法,以低速率对信号进行采样,通过相关向量机进行迭代优化,给出检测估计值。该算法基于最大似然贝叶斯估计,具有良好的抗噪性能,同时能够降低设备复杂度。仿真结果表明,其抗噪性能明显好于CVX方法而略逊于理想情况,而前端随机序列的相关性是影响检测性能的重要因素。