Design of DL-based certificateless digital signatures

Public-key cryptosystems without requiring digital certificates are very attractive in wireless communications due to limitations imposed by communication bandwidth and computational resource of the mobile wireless communication devices. To eliminate public-key digital certificate, Shamir introduced the concept of the identity-based (ID-based) cryptosystem. The main advantage of the ID-based cryptosystem is that instead of using a random integer as each user’s public key as in the traditional public-key systems, the user’s real identity, such as user’s name or email address, becomes the user’s public key. However, all identity-based signature (IBS) schemes have the inherent key escrow problem, that is private key generator (PKG) knows the private key of each user. As a result, the PKG is able to sign any message on the users’ behalf. This nature violates the “non-repudiation” requirement of digital signatures. To solve the key escrow problem of the IBS while still taking advantage of the benefits of the IBS, certificateless digital signature (CDS) was introduced. In this paper, we propose a generalized approach to construct CDS schemes. In our proposed CDS scheme, the user’s private key is known only to the user himself, therefore, it can eliminate the key escrow problem from the PKG. The proposed construction can be applied to all Discrete Logarithm (DL)-based signature schemes to convert a digital signature scheme into a CDS scheme. The proposed CDS scheme is secure against adaptive chosen-message attack in the random oracle model. In addition, it is also efficient in signature generation and verification.     

Design of Semipersistent Resource Allocation in LTE-V Network

Radio network access technology currently used in 4G/5G is Long Term Evolution-Advanced (LTE-A), which was developed by 3rd Generation Partnership Project (3GPP). Device-to-device (D2D) communication is a technology enabling direct communications among wireless devices without forwarding through an evolved Node B (eNB). Moreover, D2D transmission can support vehicles as a vehicle-to-vehicle (V2V) environment. It is possible to avoid accidents via exchanging movement-related information among vehicles and effectively increase driving safety (and efficiency). However, radio resources are limited in radio networks. A vehicle transmits through D2D in Long Term Evolution-Vehicle (LTE-V) mode-3 standard, and an eNB can allocate the same spectrum radio resources for cellular and V2V links simultaneously. When using the same radio resources, the probability of interference may increase. This study designed a semipersistent resource allocation algorithm based on different cycles in an LTE-V network. Moreover, resource allocation under different cycles was analyzed, and a scheme for resource selection is proposed based on cycle size. The proposed Semi Persistent Gain Aware Resource Allocation (SP-GARA) scheme selects resources based on the expected sum rate of the cycle size and analyzes and discusses the results of the total sum rate at different cycles and speeds for an improved performance.     

基于软件无线电的无线频谱测量接收机设计

无线频谱测量接收机要求具有对宽带频谱的快速扫描功能,和对特定目标信号的实时高分辨率频谱分析能力;采用软件无线电的设计思想,通过分离的数字下变频通道分别处理扫频信号和谱分析目标信号,达到了11GHz/s的扫频速度和0.2Hz的频谱分辨率;给出了实用的接收机实现方案,并通过实现结果验证了方案的有效性.     

Call admission control policies in cellular wireless networks with spectrum renting

Radio spectrum is scarce and precious resource in wireless networks. To efficiently utilize radio spectrum, a wireless network can rent radio channels from another wireless network and returns back the rented channels when the rented channels are required to be withdrawn. The rental and withdrawal of radio channels result in two phenomena: (i) variable number of radio channels in a wireless network and (ii) call dropping due to the channel withdrawal. Call admission control aims to provide good quality-of-services for mobile users while efficiently utilize radio channels. Many call admission control policies in the previous literatures were studied without the two phenomena. In this paper, we study three call admission control policies, namely, fixed-reservation policy, single-threshold policy and multiple-threshold policy in a wireless network which rents channels from another wireless network. We develop numerical analyses to analyze and compare the performances of the three call admission control policies. Numerical results show that the multiple-threshold policy produces higher throughput than the single-threshold and fixed-reservation policies under the same constraint of quality-of-services.     

A distributed-request-based CDMA CAC for DiffServ multimedia services in wireless cellular mobile networks

In this paper, a distributed-request-based CDMA DiffServ (differentiated service) call admission control (CAC) scheme is proposed to provide various multimedia services seamlessly in wireless mobile Internet. Conventional CDMA CAC schemes cannot fully support DiffServ QoS (Quality of Service) and seamless handoff due to lack of consideration on service priority and seamless mobility. Therefore, in order to achieve QoS guarantee for each service class, seamless fast-handoff, and high utilization of the scarce wireless resource, we define a code assignment policy and an adaptive access permission scheme taking each user’s service priority and mobility into consideration. For that purpose, in the proposed scheme, the DQRUMA/CDMA is combined with the new code assignment scheme and the adaptive access permission probability (APP). Numerical examples show that the forced termination ratio of handoff calls is guaranteed to be much less than the blocking ratio of new calls for a seamless fast-handoff while proposed scheme provides QoS guarantee for each service class efficiently.     

Cognitive radio network security: A survey

Recent advancements in wireless communication are creating a spectrum shortage problem on a daily basis. Recently, Cognitive Radio (CR), a novel technology, has attempted to minimize this problem by dynamically using the free spectrum in wireless communications and mobile computing. Cognitive radio networks (CRNs) can be formed using cognitive radios by extending the radio link features to network layer functions. The objective of CRN architecture is to improve the whole network operation to fulfil the user's demands anytime and anywhere, through accessing CRNs in a more efficient way, rather than by just linking spectral efficiency. CRNs are more flexible and exposed to wireless networks compared with other traditional radio networks. Hence, there are many security threats to CRNs, more so than other traditional radio environments. The unique characteristics of CRNs make security more challenging. Several crucial issues have not yet been investigated in the area of security for CRNs. A typical public key infrastructure (PKI) scheme which achieves secure routing and other purposes in typical ad hoc networks is not enough to guarantee the security of CRNs under limited communication and computation resources. However, there has been increasing research attention on security threats caused specifically by CR techniques and special characteristics of CR in CRNs. Therefore, in this research, a survey of CRNs and their architectures and security issues has been carried out in a broad way in this paper.     

A uplink radio resource allocation scheme for localized SC-FDMA transmission in LTE network

The radio resource allocation is one of the most important issues to achieve effective wireless communication. In Long Term Evolution (LTE) network, single carrier frequency division multiple access (SC-FDMA) is applied as the transmission technology for uplink traffic. Most researches focus on maximizing the system throughput of SC-FDMA under changeable channel condition. However, users may require different quality of services (QoS) for different applications. This paper studies radio resource allocation for QoS users in localized SC-FDMA system. The proposed scheme divides allocation process into matching algorithm and radio resource assignment algorithm. The Gale–Shapley algorithm is applied to find the optimal matching between resource blocks (RB) and user equipment (UE) by considering channel conditions and the desired QoS. Then the resource assignment algorithm heuristically allocates bandwidth to UE by referring the matched RB under the constraint of carrier continuity. This paper modified the Recursive Maximum Expansion (RME) algorithm to effectively assign radio resource for UEs with different bandwidth demands. The performance of our proposed scheme is compared with the modified RME scheme through exhaustive simulations. The video streaming, VoIP, and FTP traffic types were adopted for simulations. Our simulation results show that the proposed scheme achieves better QoS satisfaction and system throughput than the RME-modified scheme.     

认知无线电网络组播路由算法和协议综述

认知无线电网络（CRN）在实现更好的无线带宽利用率和提高无线应用质量方面发挥着至关重要的作用。由于认知用户可用频谱机会的动态特性,认知无线电网络中的组播是一个具有挑战性的问题。研究者们已经提出了多种在认知无线电网络中进行有效组播的方案,包括基于优化理论、网络编码、机器学习、博弈论的方案等。总结了解决组播问题有效的算法和技术,并对已有的无线电网络中的组播协议进行了全面的综述,最后给出了未来的研究方向。     

认知无线电网络双天线多信道MAC协议

在认知无线电网络中,媒体接入控制(MAC)协议的主要功能包括信道感知、选择和接入控制,其中感知时间和传输时间的长度对网络的性能有着重要的影响。在动态无线网络环境下,如何合理分配感知时间和传输时间是个挑战性问题。提出了一种双天线多信道分布式认知无线电MAC（TM-MAC）协议,不需要在传输之前对信道进行感知。节点可以在其它节点传输数据的同时对频谱资源进行检测,然后利用空闲的频谱资源通信。建立了数学模型分析在饱和网络状况下MAC协议的吞吐量。仿真分析表明TM-MAC协议能够有效提高网络的吞吐量。     

针对不确定流量的多收发机无线网络资源优化研究

多收发机无线网络具有多接口多信道多跳的特点,是今后无线网络发展的趋势。该网络中信道与链路的资源分配,涉及路由、信道分配以及链路调度的联合优化。在以往的研究中通常对网络流量模型进行简化,假设其是确定且相对稳定的。考虑到实际网络中流量不确定性的特征,以网络吞吐量最大化为目标,提出传输流约束、信道资源约束以及干扰约束条件下的资源分配联合优化模型,以及基于不确定流量条件下资源分配最优解的链路调度策略。仿真实验结果证明所提出的路由、信道分配及链路调度方案能够更好地适应变化的网络流量需求。     

Immune optimization algorithm for solving joint call admission control problem in next-generation wireless network

The integration of radio access networks with different radio access technologies (RATs) is one of the remarkable characteristics of the next-generation wireless networks (NGWNs). In NGWN, the users with multi-network interface terminals should be able to select independently radio access network to obtain the best service. Therefore, joint call admission control (JCAC) schemes are required to select the most appropriate radio access network (RAN) for incoming calls. We propose an immune algorithm-based JCAC (IA-JCAC) scheme with users centric in order to enhance user's satisfaction. However, JCAC algorithms with users centric can lead to highly unbalanced traffic load among the available RANs in NGWN because users act independently, and most of them may prefer to be connected through a particular RAN. Highly unbalanced traffic load in NGWN will result in high overall call blocking/dropping probability and poor radio result utilization. To solve this problem, we employ dynamic pricing for balancing traffic load among available RANs in heterogeneous wireless networks where users' preferences are considered in decision-making on RAT selection. The proposed IA-based JCAC scheme is compared with another scheme that does not use the dynamic pricing on the performance. The simulation result shows the effectiveness of the proposed IA-JCAC scheme is improved significantly.     

大规模认知无线电网络的时延分析

时延作为无线网络的最基本的性能之一,对网络信息分发、路由协议设计、节点部署等都具有重要意义。与传统的无线网络不同,认知无线电网络的频谱资源具有动态变化性,该特性会对网络时延产生极大的影响。因此,如何对动态频谱环境下的大规模认知无线电网络进行时延分析,是一项很具挑战性的课题。为此,首先对动态频谱环境进行建模,将认知用户的频谱接入过程建模为一个连续时间的马尔可夫链,并建立认知用户的生存函数来量化授权用户活动以及信道数量对频谱环境的影响;其次,将上述模型与首次通过渗流理论结合起来,研究了大规模认知无线电网络时延的伸缩规律,并获取了更为精确的时延与距离比的上限值。理论分析及仿真结果表明,动态频谱环境与密度一样会对时延产生极大影响。研究结论对认知无线电网络的设计具有重要的指导意义。     

基于非合作博弈的变电站无线网络资源研究

无线资源管理对实现资源的有效利用起着至关重要的作用.针对变电站中无线网络资源分配问题,提出了基于非合作博弈的变电站无线网络资源的优化管理算法,解决了全双工系统的无线电资源分配问题.将下行链路与上行链路的联合速率最大化问题建模成为上下行链路信道之间的非合作博弈,提出了基于非合作博弈的迭代算法.该算法有效的实现最佳上行链路与下行链路的资源分配,直到达到纳什均衡.仿真结果表明,该算法实现了快速收敛,与同等资源分配方法相比,可以显著提高全双工的性能.     

基于局部信息交互的博弈学习算法

博弈理论在无线通信领域的应用愈加广泛并逐渐成为解决无线频谱资源分配的重要方法之一。论文关注5G通信系统中的异构信道选择问题,针对该问题传统集中式优化机制系统效率较优但优化开销大,而传统分布式优化机制优化开销较少但系统效率受限。为实现系统效率与优化开销的有效折衷,论文将问题建模为局部合作博弈,提出基于局部信息交互的博弈学习算法,实现了系统在分布式优化机制下达到最优性能。仿真结果验证了算法的最优性,收敛性和稳健性。     

Efficiency-based multi-item bargaining design in cognitive radio networks with spectrum coordination

This paper studies the spectrum sharing problem with coordination-generated wireless resource for cooperative cognitive radio networks. A new alternating-offer spectrum bargaining framework is introduced with asymmetrically bilaterial wireless resource, in terms of sequential bargaining equilibria for frequency bands for high efficiency or approximate efficiency. In the proposed framework, the role of spectrum bargaining with user diversity can constrain many items with private information for spectrum allocation, thereby aggregating to a current frequency band surplus with spectrum trading to exchange the use in the reform of spectrum regulatory practice. While the users have an incentive in agreeing on a division of resource, they also have an interest in maximizing the amount of resource that it received. Furthermore, we develop an efficiency-based algorithm to explain why spectrum bargaining based on asymmetrical resource information can get little deviation from the first best resource utilization for high efficiency consideration. Simulation results show that the proposed multi-item spectrum bargaining scheme significantly outperforms the existing schemes.     

An Effective Secure MAC Protocol for Cognitive Radio Networks

The vast revolution in networking is increasing rapidly along with technology advancements, which requires more effort from all cyberspace professionals to cope with the challenges that come with advanced technology privileges and services. Hence, Cognitive Radio Network is one of the promising approaches that permit a dynamic type of smart network for improving the utilization of idle spectrum portions of wireless communications. However, it is vulnerable to security threats and attacks and demands security mechanisms to preserve and protect the cognitive radio networks for ensuring a secure communication environment. This paper presents an effective secure MAC protocol for cognitive radio networks, significantly enhancing the security level of the existing DSMCRN and SSMCRN protocols by eliminating the authentication server’s necessity, which can be a single point of failure to compromise the entire network communication. The proposed protocol has proven to be effective and reliable since it does not rely on a centralized entity for providing the required security for a single pair of cognitive users. The protocol also improves the performance in the context of fast switching to data channels leading to higher throughput is achieved compared to the benchmark protocols.     

Optimization algorithm of cognitive radio spectrum sensing based on quantum neural network

In recent years, with the development of mobile communications and Wireless Local Area Network (WLAN) as well as restrictions on limited spectrum resources, wireless spectrum resources are increasingly strained. Cognitive radio, put forward as a concept of dynamic use of spectrum, solved the problem of low spectrum utilization rate brought by the current static spectrum allocation scheme and greatly improved the utilization of the existing spectrum resources. In order to overcome the shortcomings of traditional spectrum sensing and improve spectrum detection performance under low signal-noise rate, this paper proposed a spectrum perception algorithm based on quantum neural network (QNN) and carried out an optimization study on the spectrum sensing algorithm of cognitive radio. Through the simulation experiment, we found that the improved QNN algorithm showed more excellent convergence performance and detection capability.     

Opportunistic sharing scheme for spectrum allocation in wireless virtualization

The past few decades have witnessed an increasing growth in mobile and wireless network, leading to a corresponding fast growth in mobile demands. However, the proliferating mobile demands compel wireless network to face several challenges, such as the conflict between spectrum crisis and low resource utilization ratio, and the poor quality of service and quality of experience. Wireless virtualization, enabling multiple concurrent virtual networks running on shared wireless substrate resource, has been proposed as a promising way to overcome the plights of the current mobile and wireless network. How to efficiently allocate the resource, especially the spectrum resource, of physical network to multiple virtual networks is one fundamental and important challenge in wireless virtualization. This paper rethinks the characteristics of virtual networks’ requirements, and then divides the requirement into a baseline part and a fluctuant part. Based on it, this paper introduces an opportunistic spectrum sharing approach, through which we formulate the spectrum resource allocation problem as an NP-Hard problem. Then, we propose our opportunistic spectrum resource allocation scheme for the wireless virtualization. Simulations validate the performance advantages of our approach and show that opportunistic spectrum sharing significantly improves the revenue, resource utilization and acceptance ratio of physical wireless network while decreasing the payments of virtual networks.     

关于安徽广播电视监测网网络安全的研究

安徽省广播电视监测台始建于1992年,其担负着对全省覆盖范围内的广播电视节目从播出到有线传输、无线发射、卫星频谱监测以及流动监测的多环节、全方位的监测任务,还担负着对全省广播电视节目安全播出的调度指挥任务.随着人民群众的精神文明生活的需求加大,监测工作的工作量也不断加大,这样也给监测网络的安全带来风险,对广播电视网络的性能提出了更高的要求.本文通过对监测网络的安全性和电视广播监测网的分析,提出了电视广播监测网络系统安全性对策.     

基于认知无线电技术的动态频谱分配方案研究

随着物联网的发展,人们能够更加方便快捷地利用智能终端,随时随地接入到无线网络中进行业务数据传输.然而,激增的移动用户数量和业务的带宽需求,使得无线频谱资源日益稀缺,现有固定式频谱分配方案面临巨大挑战.面向物联网发展,如何满足用户的高移动性和呈爆炸式增长的业务传输需求成为物联网研究的重点.认知无线电技术,一方面允许用户终端自适应感知所处环境的频谱资源空闲信息,为用户营造一个无缝的接入环境,保证用户的高移动性;另一方面通过动态频谱分配有效地解决了频谱资源稀缺和现有授权频谱资源利用率低的问题,为用户的海量数据传输提供保证.作者基于认知无线电技术,提出了一个用户终端和网络端共同参与决策的两级动态频谱分配框架结构,并提出了两级动态频谱分配方案.该方案设计包含:空闲频谱资源排序选择算法和集中式的联合优化匹配算法.通过用户终端和网络端的协同工作,文中所提出的两级动态频谱分配方案能够有效满足用户的高移动性和业务传输服务质量需求,实现空闲频谱资源利用率和频谱间切换概率的联合优化,为移动用户的海量数据传输提供保证.仿真实验结果表明,与传统图匹配方法相比较,该方案能够平均提高全网服务质量有效吞吐量70%,平均降低频谱间切换概率56%.