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文中以认知无线电技术(cognitive Radio, CR)为基础,提出了一种基于CR的小卫星群通信动态频谱分配MAC方案.该方案允许未授权用户自适应地选取可用带宽,实现了动态频谱接入,有效地提高了频谱利用率.提出一种动态信道的跳预约多址接入(DC-HRMA)协议,在不需要公共信道的情况下,解决了信道有效接入与退让问题.仿真结果表明,该协议性能和主次用户数目的合理搭配相关. 相似文献
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基于固定长度的EPON帧结构和MAC协议设计 总被引:2,自引:0,他引:2
以太无源光网络(EPON)已成为国内外接入网技术的最新研究热点,而EPON标准正在制定。针对EPON系统的核心关键技术之一的上行信道带宽动态分配问题,参照APON的G.983建议,提出了一种基于固定长度的EPON上下行传输帧结构和媒质接入控制(MAC)协议。该方案以APON为借鉴,将EPON中以太网帧长度固定下来;考虑到实时业务对时延敏感,MAC协议对实时业务实行优先带宽分配,对其他类型业务则采用动态带宽分配方案。最后通过建模防真分析了协议的信元时延(CD)特性。 相似文献
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结合配电通信网通信距离远且分布分散的特点以及各种业务对带宽和时延的要求,首先从经典TDM-PON即EPON系统最基本的带宽分配算法---自适应周期的交替轮询算法(IPACT)出发,根据不同的授权服务机制产生的不同授权窗口大小,改进了三种授权服务机制下数据包的平均时延和轮询周期的数学分析,使其更适合配电通信网LR-PON带宽分配,并通过OPNET仿真比较了改进后的三种授权服务机制在平均包时延和轮询周期方面的优越性。最后对改进后的IPACT算法和经典IPACT算法的带宽利用率进行仿真比较,结果表明当网络负载超过50%时,改进后的IPACT算法的带宽利用率要明显提高。 相似文献
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EPON系统中MAC算法的仿真设计 总被引:1,自引:0,他引:1
在分析EPON系统中MAC协议和算法的基础上进行了数学建模及仿真实验,提出了基于OLT的带宽分配算法.该算法可充分使用EPON的带宽资源,为在EPON的MAC层设计上提供了参考. 相似文献
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提出了一种基于等效带宽分配的媒质接入控制(MAC)方法,它针对CDMA系统是“误码率受限”型系统这一特点,将多媒体业务不同的误码率要求映射为等效带宽。系统根据流量动态地将等效带宽分配给不同业务。仿真结果表明,相比与已有的CDMA系统的MAC方法,本方法具有更好的吞吐量性能。 相似文献
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《电子科技文摘》1999,(5)
Y98-61391-302 9906640高速无线网络的已有 MAC 协议的述评=A review ofproposed MAC protocols for high-speed wireless networks[会,英]/Renaud,A.& Blight,D.//1997 IEEE Con-ference on Communications,Power and Computing-Wescanex.—302~305(MaG)本文在媒体接入控制(MAC)协议的介绍和简单综述之后,对有关高速无线系统的 MAC 协议和带宽分配策略方面的现有文献进行了述评。评述了从简单Aloba 型算法到相当复杂的轮询方案的四种协议。还试图对这些协议在它们的技术性能的基础上进行比较。参4 相似文献
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Diameter协议用于IP多媒体子系统(IMS),实现认证、授权和计费功能。Diameter协议包含基础协议、传送协议和不同的应用扩展。介绍了Diameter在IMS中的接口关系,对Diameter协议进行了分析,提出了Diameter基础协议和Cx接口应用协议的软件设计流程,并介绍了最终实现的成果—能力交换、位置管理和用户数据处理。 相似文献
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Threshold proxy re-encryption( PRE) authorizes the data access right of data subject to multiple proxies, who authorize the right again to delegatee to accomplish the end-to-end data encryption process from storage to authorization. Based on threshold PRE algorithm, in order to build a complete trusted data storage and authorization system, the four protocols, which are data access protocol, authorization proxy protocol, authorization proxy cancellation protocol and data reading authorization protocol, are defined completely. On that basis, an efficient data searching method is constructed by specifying the data delegatee. At last, to ensure the right to know of data, the audit log is processed with trusted data right confirmation based on distributed ledger technology. Meanwhile, a parallel data right confirmation processing method is defined based on hierarchical derivation algorithm of public and private key. In the end, the performance evaluation analysis of the protocol are given. Trusted data access and authorization protocol is convenient to build a complete data processing system on the premise of protecting data privacy based on public cloud storage system or distributed storage system. 相似文献
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诊断主体授权问题是车辆远程故障诊断中的关键问题。针对当前车辆远程诊断授权协议(PVAUDS)中存在的问题,提出了新的车辆远程诊断授权协议(PVAUDS+)。在保证原协议安全目标的前提下,为诊断主体提供双向认证和票据新鲜性验证,并保证发送票据的可信第三方能够有效抵御拒绝服务攻击。使用安全协议证明工具ProVerif对PVAUDS+协议的安全属性进行自动化证明,通过增加发起代价的机制解决对可信第三方的拒绝服务攻击问题,从而说明PVAUSD+协议能够满足提出的安全目标。定量分析结果说明本协议具有较好的可行性。 相似文献
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本文提出了一种基于电子现金的新型支付协议,该协议通过第三方实时核算客户拥有的电子现金,但不进行实时转账。协议模型较好地克服了现有在线支付的交易瓶颈问题以及离线支付中电子现金容易被重用、伪造或篡改的问题,在交易过程中有效地保证了安全性,并且实现了电子现金的原子性、匿名性、可分割性和可验证性。 相似文献
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针对人们对无线通信网络的功能和安全越来越高的要求,提出基于EC_DH交换密钥和基于RSA交换密钥的扩展WTLS(Wireless Transport Layer Security)协议。首先分析WAP安全架构中WTLS的安全性问题,然后根据数据的机密性、完整性以及在移动电话和其它无线终端中完成授权鉴定,在此基础上针对漏洞提出解决方案,改进后的协议增加了一个颁发证书的过程。最后通过案例证明本协议的安全性。结果表明,WTLS协议是一个更高安全性的协议,在无线通信网络中有着重要的价值和研究意义。 相似文献
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OAuth2.0 protocol has been widely adopted to simplify user login to third-party applications,at the same time,existing risk of leaking user privacy data,what even worse,causing user accounts to be hijacked.An account hijacking attack model around authorization code was built by analyzing the vulnerabilities of the OAuth2.0 protocol.A vulnerable API identification method based on differential traffic analysis and an account hijacking verification method based on authorized authentication traffic monitoring was proposed.An account hijacking attack threat detection framework OScan for OAuth2.0 authorization API was designed and implemented.Through a large-scale detection of the 3 853 authorization APIs deployed on the Alexa top 10 000 websites,360 vulnerable APIs were discovered.The further verification showed that 80 websites were found to have threat of account hijacking attack.Compared with similar tools,OScan has significant advantages in covering the number of identity provider,the number of detected relying party,as well as the integrity of risk detection. 相似文献
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Zoltán Faigl 《Wireless Networks》2015,21(2):531-555
This paper evaluates the performance overheads of two Host Identity Protocol-based signalling schemes controlling internet protocol connectivity establishment and handover procedures in distributed mobile networks. The paper proves using an analytical model that the Ultra Flat Architecture has significant performance gains on user side, in the access networks and at the rendezvous service over the terminal-based architecture due to the application of delegation of signalling rights. On the other hand, the former architecture results in greater overhead in the transport network connecting the gateways and at the gateways. The results also provide guidance on the optimal setting of protocol lifetime parameters, maximum delegation authorization certificate chain length and distribution level of gateways in both schemes. 相似文献