Reputation-based collaborative spectrum sensing scheme in cognitive radio networks

Collaborative spectrum sensing is proposed to improve the detection performance in cognitive radio (CR) networks. However, most of the current collaborative sensing schemes are vulnerable to the interference of the malicious secondary users (SUs). In this paper we propose a reputation-based collaborative spectrum sensing scheme to improve the security of cooperative sensing by mitigating the impacts of misbehaviors. The fusion center calculates the reputation rating of each SU according to their history reports to weight their sensing results in the proposed scheme. We analyze and evaluate the performance of the proposed scheme and its advantages over previous schemes in expansibility and integrity. Simulation results show that the proposed scheme can minimize the harmful influence from malicious SUs.     

A selection scheme for optimum number of cooperative secondary users in spectrum sensing

An optimization scheme for choosing the optimum number of secondary users in cooperative spectrum sensing based on the cyclostationary feature detection with Neyman-Pearson criterion is proposed in this paper. The optimal soft combination test statistic for the cooperative spectrum sensing based on cyclostationary feature detection is derived according to the generalized likelihood ratio test and its corresponding detection performance is deduced. A target function, considering two important parameters as the resource use efficiency and the number of samples employed by each cooperative secondary user in the system design, is constructed to obtain the optimum number of cooperative secondary users. It can be found that the selection scheme is to make a tradeoff between the system complexity of the cognitive radio network and the global sensing performance of the cooperative spectrum sensing.     

海底搜寻“长尾鯊”

1963年4月10日,长尾鲨号在马萨诸塞州科德角海面上沉没,五角大楼震惊了。美国海军部迅速制订了寻找长尾鲨号的紧急计划,以便弄清失事的原因。     

基于矩阵分析的公共交通网络最优路径算法

为了更符合实际情况，即充分考虑换乘次数是乘客选择公共交通网络的决定因素，运行时问是其重要因素，分析了乘客心理特征，用CIS技术建立了公共交通网络模型，构建了适合公共交通分析的直达矩阵和最小换乘矩阵．在此基础上，结合路段、节点运行时间，提出了公共交通网络最优路径算法，并用一个简单的算例对算法进行了说明．     

基于停车特性因素的公共停车场停车需求预测

城市停车日益困难,而我国大部分城市停车设施建设不够完善。为了解决城市静态交通中存在的停车需求问题,基于传统方法,提出了一种适用于公共停车场的停车需求模型。以成都市温江区公共停车场中的大润发公共停车场建设项目为研究对象,通过对目标地点进行调查与分析,建立了基于停车特性因素的停车需求预测模型,并将计算需求量和现有实际数据对比分析,得出目标地点现有泊位可基本满足近期停车需求,但从长远考虑,该公共停车场的修建十分必要的结论。     

A HOS-based blind signal extraction method for chaotic MIMO systems

A novel method to extract multiple input and multiple output （MIMO） chaotic signals was proposed using the blind neural algorithm after transmitting in nonideal channel. The MIMO scheme with different chaotic signal generators was presented. In order to separate the chaotic source signals only by using the sensor signals at receivers, a blind neural extraction algorithm based on higher-order statistic （HOS） technique was used to recover the primary chaotic signals. Simulation results show that the proposed approach has good performance in separating the primary chaotic signals even under nonideal channel.     

海洋里的机器人

看了电影《未来世界》你—定为那些栩栩如生的机器人拍手叫绝。虽然现代科学技术已有实现这些幻想的可能,但兴奋之余,也不免令人感到这些都是假的。     

Robust digital audio watermarking scheme using blind source separation with global optimal property

The paper proposes a robust digital audio watermarking scheme using blind source separation(BSS) based on the global optimization of independency metric(IM),which is formulated as a generalized eigenvalue(GE) problem.Compared with traditional information-theoretical approaches used in digital audio watermarking,such as fast independent component analysis(FastICA),the proposed scheme has lower complexity without timeconsuming iteration steps used in FastICA.To make full use of the multiresolution characteris...     

交叉口信号协调控制适用性仿真分析

针对当前城市道路交通随着城市机动化的发展引起的交通阻塞问题,利用仿真技术对交通交叉口的信息控制进行模拟分析,通过仿真的结果对交叉口的信息控制-线控和面控进行比较,从而得出交叉口信号协调控制的适用性条件.     

Pre-emptive channel borrowing and traffic overflowing channel allocation scheme for multimedia overlay networks

This paper proposes a channel allocation scheme for multimedia wireless networks, in which a twolayer macro-cell or micro-cell architecture is considered. Macro-cells are used to access high-mobility services; while micro-cells, which are overlaid by the macro-cells, are used to cater low-mobility services. To analyze the scheme, a multidimensional Markov traffic model is firstly developed, in which traffic characteristic of two special periods of time is considered. And then, a pre-emptive channel-borrowing scheme combined with trafficoverflowing strategy for multimedia (voice, video or data) networks is proposed, in which handoff requests can not only borrow channels from adjacent homogenous cells, but also be overflowed to heterogeneous cells. Priority strategies are also dedicated to high-mobility services for they can pre-empt channels being used by low-mobility services in macro-cells. To meet the high quality of service (QoS) requirements of video services and increase the channel utilization ratio, video services can be transformed between real-time services and non-real-time services as necessary. Simulation results show that our schemes can decrease the blocking probabilities and improve the channel utilization.