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The paradigm of cognitive radio recently received considerable interest to address the so called ‘spectrum scarcity’ problem. In the USA, the Federal Communications Commission issued the regulatory for the use of cognitive radio in the TV white space spectrum. The primary objective is the design of cognitive devices able to combine the use of spectrum sensing and GEO-location information with the concept of the cognitive control channel to manage the cognitive devices. The recent standard ECMA-392 defines physical layer techniques and medium access control protocols to enable a cognitive network managed in a fully distributed fashion. In this work, we pursue the design of an efficient medium access control protocol for the cognitive control channel to flexibly and reliably exchange messages inside the cognitive radio network. In particular, we explore how the cognitive devices can raise their awareness of spectrum vacancies of spectrum vacancies by means of sensing when the distributed beaconing defined by ECMA-392 is used. Our main contributions are the following: (1) we propose a proprietary medium access control protocol based on the Standard ECMA-392; (2) we model the behavior of the cognitive radio network by means of an innovative urn model approach, (3) we investigate the access of the cognitive devices to the frequency channels with and without spoofing attacks and (4) we investigate the ability of the cognitive devices to identify frequency holes accounting for perfect and imperfect spectrum sensing, as well as we study the network throughput. 相似文献
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Cognitive radio is an intelligent technology designed to help secondary users (SUs) increase their opportunity to access unused spectrum channels while avoiding interference with the primary users. In cognitive radio networks (CRNs), to find the available channels, SUs execute cooperative spectrum sensing and exchange channels-related control information, namely an available channels list (ACL), on a common control channel (CCC) before determining which channels they may transmit. However, some SUs, defined as attackers, could create a security issue by sharing false ACL information with other SUs to increase their own utilization of the available channels, which significantly decreases the performance of CRNs. In this paper, we propose an efficient detection scheme for CCC security to identify any attacker among the cooperating SUs. In the proposed scheme, all SUs share their ACL information on the CCC, with an associated reputation, which is updated according to its own behavior in each cooperation round, to cooperatively identify attackers. An attacker will be excluded from cooperating group with the result that its updated reputation value exceeds a certain threshold. Simulation results show how to further improve the performance of the proposed scheme by choosing optimized thresholds. In addition, we also illustrate that the proposed scheme can achieve considerable performance improvement compared with a attack detection technique COOPON for secure ACL information exchange. 相似文献
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Wireless Personal Communications - The common control channel (CCC) design plays a pivotal role in achieving the desired quality of service in cognitive radio (CR) technology. Various schemes of... 相似文献
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认知无线电网络的MAC层关键技术 总被引:2,自引:0,他引:2
认知无线电作为一种智能的频谱共享技术,已成为无线通信领域的研究热点。为达到在不干扰授权用户的条件下有效地实现机会式频谱利用,认知无线电网络的媒体接入控制(MAC)层不仅需要提供传统的服务,还要求能支持一套全新的功能。频谱检测管理通过对检测模式的选取、检测周期及检测时长的设置、检测信道的选取和检测静默期的设置等实现检测策略和参数的选取及优化。接入控制主要采用与授权用户协调接入和透明接入两种方式避免与授权用户的接入产生碰撞。动态频谱分配针对二进制干扰模型和累积干扰模型进行不确定频谱资源的优化分配。安全机制通过增加MAC帧的认证和保密以防御MAC层的安全攻击。跨层设计结合物理层和网络层、传输层等上层信息设计和实现全局优化的MAC层技术。 相似文献
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Cooperative Communications for Cognitive Radio Networks 总被引:4,自引:0,他引:4
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Clustering is an efficient tool to improve the routing and data transmission performance in large scale networks. However, in cognitive radio ad hoc networks (CRAHNs), clustering design is challenging due to the dynamic spectrum access and the blind information environment. In this paper, we propose a novel distributed clustering algorithm for CRAHNs, where neither a dedicated common control channel (CCC) nor prior topology information is required. First, a neighbor discovery protocol without relying on CCC is proposed to construct the local topology. Then, we model the network as a undirected graph and formulate the clustering process as a graph cut problem. We design a mincut based heuristic algorithm to approximate the optimal clustering solution. After this, we also present a synchronize protocol to achieve the global consistency of cluster memberships. Finally, we propose a proactive cluster maintenance mechanism to reduce the interferences caused by PU activities. We validate our work through comparisons with other clustering methods. The simulation results show that, by adjusting the cluster structure according to the changing spectrum, the proposed method reduces the interference and improves the network efficiency. 相似文献
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文章提出了基于认知无线电的光纤无线通信系统-无源光网络(ROF-PON)光无线接入网络系统结构。该方案光纤中直接传输射频信号。光层可采用波分复用-无源光网络(WDM-PON)技术(也可以是一个定制的光接入层)。远端的光网络单元(ONU)将得到的传感信息回传到中心局(CO),应用认知无线电技术进行处理。频谱感知和信道接入等都在CO处理,降低了整个系统的复杂度,发挥了光纤无线通信系统(ROF)的优势,也发挥了认知无线电在管理频谱方面的特长。 相似文献
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Mahassin Mohamed Sharifah Kamilah Syed Yusof NikNoordini NikAbdMalik Suleiman Zubair 《电子科技学刊:英文版》2016,14(2):145-151
The absence of network infrastructure and opportunistic spectrum access in cognitive radio ad hoc networks (CRAHNs) results in connectivity and stability problems. Clustering is known as an effective technique to overcome this problem. Clustering improves network performance by implementing a logical network backbone. Therefore, how to efficiently construct this backbone among CRAHNs is of interest. In this paper, we propose a new clustering algorithm for CRAHNs. Moreover, we model a novel cluster head selection function based on the channel heterogeneity in term of transmission ranges. To the best of our knowledge, this is the first attempt to model the channel heterogeneity into the clustering formation in cognitive radio networks. Simulation results show that the performance of clustering is significantly improved by the channel heterogeneity considerations. 相似文献
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Yinglei Teng F. Richard Yu Ke Han Yifei Wei Yong Zhang 《Wireless Personal Communications》2013,69(2):771-791
In cognitive radio networks, an important issue is to share the detected available spectrum among different secondary users to improve the network performance. Although some work has been done for dynamic spectrum access, the learning capability of cognitive radio networks is largely ignored in the previous work. In this paper, we propose a reinforcement-learning-based double auction algorithm aiming to improve the performance of dynamic spectrum access in cognitive radio networks. The dynamic spectrum access process is modeled as a double auction game. Based on the spectrum access history information, both primary users and secondary users can estimate the impact on their future rewards and then adapt their spectrum access or release strategies effectively to compete for channel opportunities. Simulation results show that the proposed reinforcement-learning-based double auction algorithm can significantly improve secondary users’ performance in terms of packet loss, bidding efficiency and transmission rate or opportunity access. 相似文献
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Cross-Layer Based Opportunistic MAC Protocols for QoS Provisionings Over Cognitive Radio Wireless Networks 总被引:6,自引:0,他引:6
Hang Su Xi Zhang 《Selected Areas in Communications, IEEE Journal on》2008,26(1):118-129
We propose the cross-layer based opportunistic multi-channel medium access control (MAC) protocols, which integrate the spectrum sensing at physical (PHY) layer with the packet scheduling at MAC layer, for the wireless ad hoc networks. Specifically, the MAC protocols enable the secondary users to identify and utilize the leftover frequency spectrum in a way that constrains the level of interference to the primary users. In our proposed protocols, each secondary user is equipped with two transceivers. One transceiver is tuned to the dedicated control channel, while the other is designed specifically as a cognitive radio that can periodically sense and dynamically use the identified un-used channels. To obtain the channel state accurately, we propose two collaborative channel spectrum-sensing policies, namely, the random sensing policy and the negotiation-based sensing policy, to help the MAC protocols detect the availability of leftover channels. Under the random sensing policy, each secondary user just randomly selects one of the channels for sensing. On the other hand, under the negotiation-based sensing policy, different secondary users attempt to select the distinct channels to sense by overhearing the control packets over the control channel. We develop the Markov chain model and the M/GY/1-based queueing model to characterize the performance of our proposed multi-channel MAC protocols under the two types of channel-sensing policies for the saturation network and the non-saturation network scenarios, respectively. In the non-saturation network case, we quantitatively identify the tradeoff between the aggregate traffic throughput and the packet transmission delay, which can provide the insightful guidelines to improve the delay-QoS provisionings over cognitive radio wireless networks. 相似文献
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认知无线电的首要任务是动态、可靠地检测无线电频谱环境。因此,每个认知无线电终端必须具有频谱检测的功能。文章在简述认知无线电频谱检测技术的基础上,提出了基于滤波器组的频谱检测方案,详细描述了多相滤波器组的设计方法和功率谱估计算法,并在加性高斯白噪声环境下进行了仿真。仿真结果表明,在恰当设置判决门限的情况下基于滤波器组的认知无线电频谱检测具有良好的性能。 相似文献
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Signal Processing in Cognitive Radio 总被引:1,自引:0,他引:1
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认知无线电是在软件无线电的基础上发展而来的能够自适应外界环境变化的无线通信技术。认知无线电的网络结构有3种类型:集中式,分布式和集中 分布式。它通过频谱自适应技术来实现动态频谱分配,相关技术包括频谱检测技术,信道估计与预测技术、数据传输技术和多天线通信技术。随着认知无线电技术的发展,各国际标准组织和行业联盟纷纷开展相关的研究,并着手制定认知无线电的标准和协议。目前,认知无线电的推广仍面临着政策问题,但其市场需求日益扩大。总而言之,此技术的产业化发展还有很长的路需要走。 相似文献
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Spatiotemporal Sensing in Cognitive Radio Networks 总被引:7,自引:0,他引:7
Ganesan G. Ye Li Bing B. Shaoqian Li 《Selected Areas in Communications, IEEE Journal on》2008,26(1):5-12
Cognitive radio networks need to continuously monitor spectrum to detect the presence of the licensed users. In this paper, we have exploited spatial diversity in multiuser networks to improve the spectrum sensing capabilities of centralized cognitive radio (CR) networks. We develop a fixed and a variable relay sensing scheme. The fixed relay scheme employs a relay that has a fixed location to help the cognitive network base station detect the presence of the primary user. The variable relay sensing scheme employs cognitive users distributed at various locations as relays to sense data and to improve the detection capabilities. This effectively reduces the average detection time by exploiting spatial diversity inherent in multiuser networks. Finally, we study the network outage probabilities to compare the performances of the fixed and variable relay schemes. 相似文献
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?Cognitive radio? has emerged as a new design paradigm for next-generation wireless networks that aims to increase utilization of the scarce radio spectrum (both licensed and unlicensed). Learning and adaptation are two significant features of a cognitive radio transceiver. Intelligent algorithms are used to learn the surrounding environment, and the knowledge thus obtained is utilized by the transceiver to choose the frequency band (i.e., channel) of transmission as well as transmission parameters to achieve the best performance. In this article we first provide an overview of the different components to achieve adaptability in a cognitive radio transceiver and discuss the related approaches. A survey of the cognitive radio techniques used in the different wireless systems is then presented. To this end, a dynamic opportunistic channel selection scheme based on the cognitive radio concept is presented for an IEEE 802.11-based wireless mesh network. 相似文献
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Sedat Atmaca 《Wireless Personal Communications》2013,71(4):2417-2430
This paper aims to improve the spectrum efficiency of the licensed time division multiple access (TDMA) channel by exploiting the unused periods of primary users (PUs) in cognitive radio networks. A wireless network that consists of two classes of users, PUs and CR users, accessing a time slotted based common communication channel is considered. PUs employ TDMA and have always high priority over the CR users to access the channel. CR users utilize slotted Carrier Sense Multiple Access and can access the channel when it is not occupied by the PUs. New expressions for the throughput of both CR network and overall network have been derived in order to evaluate the channel utilization. Besides, an example network have been developed, modeled and simulated by using the OPNET Modeler simulation software with the purpose of verifying the analytical throughput results. The simulation results obtained under various network load conditions are consistent with the analytical results. This study has also proposed that the overall channel utilization can be improved by well exploiting the spectrum holes without interfering with the PU transmissions. 相似文献