具有约束条件的认知无线电网络最优频谱价格函数

保证主用户的QoS是认知无线电网络中必须遵循的原则之一.本文利用伺机频谱共享方式中的实际约束条件,求解出既能保证主用户的QoS,又能使主业务运营商获得较大利润的最优频谱价格函数.该价格函数能反映实际的通信环境(如信道质量、业务动态性)对频谱价格的影响,同时在动态环境下,通过迭代可以使频谱价格收敛到最优价格.仿真结果表明...     

基于OFDM协作中继的机会主义频谱共享协议及其最优资源分配

提出了一种基于OFDM协作中继的机会主义频谱共享协议。当主用户信道不好,不能达到其要求速率时,如果认知用户能够协作帮助主用户达到其要求速率,则该认知用户就可以以协作的方式接入主用户的频谱。在该接入方式中,认知用户利用接入频谱中的一部分子载波放大转发主用户的信息,帮助主用户达到其要求速率。然后可以利用剩余的子载波发送自己的信息。对这种接入方式中的资源分配进行了分析,利用对偶算法,提出了一种以最大化认知用户速率,保证主用户速率达到要求速率为原则的最优资源分配算法。如果认知用户不能够协作帮助主用户达到要求速率,为了有效地利用频谱资源,认知用户以非协作的方式接入主用户的频谱,利用接入的全部频谱来发送自己的信息。仿真结果验证了所提频谱共享协议的有效性,同时说明了主用户和认知用户都能够从该协议中获得好处。     

基于强化学习的合作频谱分配算法

为了解决认知无线电网络中的频谱分配问题,提出了一种基于用户体验质量的合作强化学习频谱分配算法,将认知网络中的次用户模拟为强化学习中的智能体,并在次用户间引入合作机制,新加入用户可以吸收借鉴其他用户的强化学习经验,能够以更快的速度获得最佳的频谱分配方案;并且在频谱分配过程中引入了主用户和次用户之间的价格博弈因素,允许主用...     

认知无线网络中一种新的频谱共享方法

频谱共享是认知无线网络关键技术之一。为消除认知无线网络中频率选择性信道下授权主用户与认知用户间的相互干扰,本文提出了一种新的频谱共享方法。该方法充分利用了无线通信系统中由信道的频率选择性衰落导致的不同用户信道的不相关性,通过求解矩阵方程获得预处理矩阵的通解,并在主用户和认知用户发射端分别进行预处理。从而实现认知系统中主用户与认知用户之间的相互零干扰,并使每个用户都可有效地传输数据。理论推导及系统仿真均表明,新方法可以有效地消除授权主用户与认知用户之间的双向干扰,实现不同用户平等地共享无线频谱资源。新方法可以提高频谱的利用率,一定程度上缓解无线频谱资源在当前及未来无线通信领域日益紧缺的矛盾。而且新方法也同样适用于不同认知用户之间共享频谱。      

一种认知无线电周期数据传输优化机制

如何合理选择频谱感知时间和数据传输时间使系统传输效率最大化是认知无线电研究的一个重要方向,具有极其广泛的应用背景。针对该问题,该文提出一种认知无线电周期数据传输优化机制,并分别给出频谱感知时间、信道搜索时间以及数据传输时间的优化计算方法。从数值及仿真结果可知,在不同的主用户到达强度的情况下,所得到的最优频谱感知时间、最优信道搜索时间和最优数据传输时间能够确保对主用户的保护性并有效降低数据传输延迟。     

一种分布式认知MANET功率控制算法

对认知MANET的研究涉及到许多方面,其中认知MANET中的功率控制算法设计是目前的一个研究热点.为了实现认知MANET中的次用户网络和主用户网络频谱共享,从而提高频谱利用率,即次用户网络中的次用户可以机会接入授权主用户所在的频谱,且同时保证主用户和次用户的QoS需求.本文认知MANET中功率控制的目的就是在满足QoS...     

非理想频谱检测对主用户干扰的性能分析

实际中认知中继网络的频谱检测不可能完全正确检测频谱状态,次级用户传输会对主用户传输产生干扰。在分布式协作频谱检测和集中式协作频谱检测情况下,研究了认知中继网络中非理想频谱检测对主用户干扰性能的影响。在瑞利信道下推导了非理想频谱检测条件下主用户干扰概率的数学表达式。最后,仿真结果证明了理论分析的合理性,并表明非理想频谱检测会对主用户产生较大干扰,而中继节点数目的增加可以明显降低干扰概率。     

基于合约制的认知网络协作频谱共享模型

为了提高认知无线电网络中主用户的能效和谱效,提出了一种基于合约制的协作频谱共享新模型。在该模型中,当主用户信道质量差时,次用户为其提供中继服务;作为回报,在主用户信道质量好时,次用户可以在一定的干扰约束下以underlay的模式和主用户共享频谱。在此框架下引入经济学中的合约理论,将主次用户间的协作问题建模为合约设计问题,并建立了主次用户评价合约收益的效用函数,将提高主用户的能效和谱效问题转变为设计合约使主用户获得最大效用的优化问题,并利用差分进化算法对该问题求解。最后,在不同的环境下,将主用户协作与不协作获得的效用进行对比,结果表明,主用户在没有额外投入频谱资源的条件下,不仅节省了发送功率,而且有效地提高了数据传输速率,进而提高了能效和谱效。     

认知中继网络中认知用户基于频谱感知机会中继的中断性能分析

认知无线电中继网络中,认知用户需要成功感知到其所在簇内的主用户频谱空穴后才能成为认知中继节点,且各认知中继节点发射功率受到各自主用户干扰温度限制(ITC)。该文对认知中继节点采用分布式空时编码和解码转发协议时认知用户的中断性能进行了分析;给出了认知用户在干扰温度限制下中断概率的上下界,得出中断概率的上下界在不同干扰温度限下与认知用户归一化数据速率、中继数量和其对主用户检测概率的关系。给出了源节点和频谱感知中继节点在相同干扰温度限下的数值仿真,并对仿真结果进行了分析。     

基于稳定匹配的认知无线网络协作物理层安全机制

在Underlay认知无线网络中,次用户被允许在主用户进行数据发送时接入主用户的频谱.此时,主用户将对次用户和窃听者造成干扰.利用协作干扰技术,主用户产生的干扰可以被用来改善次用户的物理层安全.基于此,本文针对包含多个主次用户的Underlay认知无线网络,提出了一种新的协作物理层安全机制.为了在保证主用户通信质量的前提下,最大化网络中次用户的总的安全容量,该机制将对次用户进行合理的频谱接入选择和功率控制.另外,考虑到个体理性和自私性对于频谱接入稳定性的影响,该机制利用稳定匹配理论将频谱接入选择问题建模为一对一的双边匹配问题,通过构建主次用户之间的稳定匹配来保证频谱接入的稳定性.仿真结果表明,使用本文所提安全机制,可以在保证主用户通信质量的前提下,稳定而又有效地改善网络中次用户获得的总的安全容量.     

基于拍卖的认知无线电频谱分配研究

分析了认知无线电中基于拍卖的频谱分配的特点,给出了认知无线电系统中的频谱拍卖模型,并讨论了第一价格和第二价格密封拍卖机制在认知无线电频谱分配上的应用,研究了认知无线电中频谱拍卖问题的最优价格、保留底价等问题。最后还给出了简单情形下的仿真,结果表明,基于拍卖的频谱分配在吞吐量和丢包率等性能上较随机分配方案有明显改善。     

国际数字红利发展移动宽带业务的经济价值分析

广播电视经过模数转换后带来数字红利频段。分析了数字红利频段的传播特性和发射功率覆盖效率。使用700 MHz建设移动通信网络,在相同覆盖条件下,建设成本约为2.6 GHz频段的1/8。通过研究国外数字红利频段的规划,对比数字红利频段与其他频段的拍卖和收益情况,数字红利频段的拍卖价格为2.6 GHz等高频的30~40倍,带来的巨大经济收益也是广播电视业务的5~10倍。将数字红利频段应用于宽带移动业务将产生的巨大社会影响和经济收益,对我国数字红利频段的规划和使用起到参考作用。     

Spectrum pricing for cognitive radio networks with user’s stochastic distribution

Wireless Networks - Amid the dynamic spectrum access in cognitive radio networks, when complex spectrum conditions should be taken into account, how to price the spectrum in order to benefit...     

Game-theoretic spectrum sharing for cognitive radio based on the expectation of primary users

Cognitive radio is a new intelligent wireless communication technique for remedying the shortage of spectrum resource in recent years. Secondary users have to pay when they share available spectrum with primary users while price is an important factor in the spectrum allocation. Based on the game theory, an improved pricing function is proposed by considering the expectation of primary users. In this article, expectation represents the positivity of sharing spectrum with primary users. By introducing the positivity, price not only becomes different for different secondary users, but also can be adjusted according to the positivity. It is proved that the Nash Equilibrium of the new utility function exists. The simulation results show that spectrum sharing can not only be determined by the channel quality of secondary users, but also can be adapted according to the expectation of primary users. Besides, the proposed algorithm improves the fairness of sharing.     

Pricing and power control for energy‐efficient radio resource management in cognitive femtocell networks

Cognitive femtocell has been considered as a promising technique that can improve the capacity and the utilization of spectrum efficiency in wireless networks because of the short transmission distance and low transmit power. In this paper, we study the win–win solution of energy‐efficient radio resource management in cognitive femtocell networks, where the macrocell tries to maximize its revenue by adjusting spectrum utilization price while the femtocells try to maximize their revenues by dynamically adjusting the transmit power. When the spectrum utilization price is given by macrocell, we formulate the power control problem of standalone femtocells as an optimization problem and introduce a low‐complexity iteration algorithm based on gradient‐assisted binary search algorithm to solve it. Besides, non‐cooperative game is used to formulate the power control problem between collocated femtocells in a collocated femtocell set, and then low complexity and widely used gradient‐based iteration algorithm is applied to obtain the Nash‐equilibrium solution. Specially, asymptotic analysis is applied to find the approximate spectrum utilization price in macrocell, which can greatly reduce the computational complexity of the proposed energy‐efficient radio resource management scheme. Finally, extensive simulation results are presented to verify our theoretical analysis and demonstrate the performance of the proposed scheme. Copyright © 2013 John Wiley & Sons, Ltd.     

Novel pricing model for spectrum leasing in secondary spectrum market

According to the property rights model of cognitive radio,primary users who own the spectral resource have the right to lease or trade part of it to secondary users in exchange for appropriate profit. In this paper,an implementation of this framework is investigated,where a primary link can lease the owned spectrum to secondary nodes in exchange for cooperation (relaying). A novel pricing model is proposed that enables the trading between spectrum and cooperation. Based on the demand of secondary nodes,the primary link attempts to maximize its quality of service (QoS) by setting the price of spectrum. Taking the price asked by primary link,the secondary nodes aim to obtain most profits by deciding the amount of spectrum to buy and then pay for it by cooperative transmission. The investigated model is conveniently cast in the framework of seller/buyer (Stackelberg) games. Analysis and numerical results show that our pricing model is effective and practical for spectrum leasing based on trading spectral resource for cooperation.     

Dynamic spectrum access in IEEE 802.22- based cognitive wireless networks: a game theoretic model for competitive spectrum bidding and pricing [accepted from open call]

The emerging IEEE 802.22-based wireless regional area network technology will use the same radio spectrum currently allocated for TV service. This standard will use the concept of cognitive radio based on dynamic spectrum access to provide wireless access services in a large coverage area. A brief overview of the current state of the IEEE 802.22 standard is provided with a particular emphasis on the spectrum management (i.e., spectrum sensing and dynamic spectrum access) in this standard. Key research issues related to spectrum trading among TV broadcasters, WRAN service providers, and IEEE 802.22-based cognitive radio users are identified. To this end, a hierarchical spectrum trading model is presented to analyze the interaction among WRAN service providers, TV broadcasters, and WRAN users. In this model a double auction is established among multiple TV broadcasters and WRAN service providers who sell and buy the radio spectrum (i.e., TV bands), respectively. Again, multiple WRAN service providers compete with each other by adjusting the service price charged to WRAN users. We propose a joint spectrum bidding and service pricing model for WRAN service providers to maximize their profits. A non-cooperative game is formulated to obtain the solution in terms of the number of TV bands and the service price of a service provider. Numerical results are presented on the performance of this joint spectrum bidding and pricing model.     

Dynamics of Multiple-Seller and Multiple-Buyer Spectrum Trading in Cognitive Radio Networks: A Game-Theoretic Modeling Approach

We consider the problem of spectrum trading with multiple licensed users (i.e., primary users) selling spectrum opportunities to multiple unlicensed users (i.e., secondary users). The secondary users can adapt the spectrum buying behavior (i.e., evolve) by observing the variations in price and quality of spectrum offered by the different primary users or primary service providers. The primary users or primary service providers can adjust their behavior in selling the spectrum opportunities to secondary users to achieve the highest utility. In this paper, we model the evolution and the dynamic behavior of secondary users using the theory of evolutionary game. An algorithm for the implementation of the evolution process of a secondary user is also presented. To model the competition among the primary users, a noncooperative game is formulated where the Nash equilibrium is considered as the solution (in terms of size of offered spectrum to the secondary users and spectrum price). For a primary user, an iterative algorithm for strategy adaptation to achieve the solution is presented. The proposed game-theoretic framework for modeling the interactions among multiple primary users (or service providers) and multiple secondary users is used to investigate network dynamics under different system parameter settings and under system perturbation.     

Economic Approaches for Cognitive Radio Networks: A Survey

Efficient resource allocation is one of the key concerns of implementing cognitive radio networks. Game theory has been extensively used to study the strategic interactions between primary and secondary users for effective resource allocation. The concept of spectrum trading has introduced a new direction for the coexistence of primary and secondary users through economic benefits to primary users. The use of price theory and market theory from economics has played a vital role to facilitate economic models for spectrum trading. So, it is important to understand the feasibility of using economic approaches as well as to realize the technical challenges associated with them for implementation of cognitive radio networks. With this motivation, we present an extensive summary of the related work that use economic approaches such as game theory and/or price theory/market theory to model the behavior of primary and secondary users for spectrum sharing and discuss the associated issues. We also propose some open directions for future research on economic aspects of spectrum sharing in cognitive radio networks.