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认知无线电作为提高频谱使用效率的有效手段成为当前通信领域的研究热点。本文研究了单输入多输出的多用户认知无线网络,在主用户的干扰功率约束和认知用户的发射功率约束下,针对认知用户的信干噪比均衡问题,提出了一种低复杂度的联合波束形成和功率分配算法。与已有算法相比,该算法可以在保证最优的均衡信干噪比水平的同时,大幅度降低矩阵求逆和矩阵特征值分解的次数,特别是当处于通信状态的主用户和认知用户数目很多时。本文理论证明了所提算法的收敛性和最优性,并进行了详细的复杂度分析。理论分析和仿真结果均表明在多用户的认知无线网络中,本文所提算法可以将已有算法的平均运算复杂度降低50%以上。 相似文献
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基于Q-Learning的认知无线电系统感知管理算法 总被引:2,自引:0,他引:2
认知无线电系统不仅是一个自适应系统,更应该是一个智能系统。该文将智能控制中的Q-Learning思想引入到认知无线电系统中,用于解决感知任务在认知用户之间的分配问题,给出了一种基于Q-Learning的感知管理算法。该算法在不知道信道状态信息以及不需要对主用户业务进行估计的假设下通过不断地与环境进行交互和学习来给认知用户分配感知任务。仿真表明,该算法能够提高感知效率,并且收敛速度较快,可作为未来认知无线电系统走向智能化的一种尝试。 相似文献
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本文将认知无线电技术应用于车载通信,车载用户被看作是未授权用户(次用户),并且能够机会主义地动态感知、分析和访问频谱。在车载用户频谱感知过程中提出一种三态模型,频谱占用状态分为空闲时,被主用户占用时以及被车载用户占用时三种。仿真结果表明,认知车载网络中基于三态模型的频谱感知策略可以显著提升车载用户信道利用率和传输公平性。 相似文献
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复数Chebyshev神经网络在信道均衡中的应用 总被引:2,自引:0,他引:2
首次把Chebyshev神经网络成功地应用在通信系统的信道均衡研究中,并且提出了适合于正交幅度调制(QAM)通信系统的复数Chebyshev神经网络均衡算法.计算机仿真表明,该算法在QAM通信系统的信道均衡中表现出了优良的性能. 相似文献
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本文针对由一条授权通信链路和多条次用户干扰信道组成的认知多输入多输出(Multiple Input Multiple Output,MIMO)系统,首先提出了基于信号子空间的认知干扰对齐迭代优化算法,并且利用单调有界理论证明了该算法可以收敛到稳定点。为了进一步提升系统的和速率性能,提出了一种联合信号子空间和功率分配的增强认知干扰对齐算法。该算法通过在每个次用户的多个数据流之间进行自适应功率分配,解决了次用户的有用信号空间中总是有残余的干扰信号的问题。数值仿真结果表明,相对于传统的认知干扰对齐算法,所提的算法能够获得较为明显的性能提升。 相似文献
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Lin Chen Stefano Iellamo Marceau Coupechoux Philippe Godlewski 《Wireless Networks》2011,17(5):1355-1371
Extensive research in recent years has shown the benefits of cognitive radio technologies to improve the flexibility and efficiency of spectrum utilization. This new communication paradigm, however,
requires a well-designed spectrum allocation mechanism. In this paper, we propose an auction framework for cognitive radio
networks to allow unlicensed secondary users (SUs) to share the available spectrum of licensed primary users (PUs) fairly
and efficiently, subject to the interference temperature constraint at each PU. To study the competition among SUs, we formulate
a non-cooperative multiple-PU multiple-SU auction game and study the structure of the resulting equilibrium by solving a non-continuous
two-dimensional optimization problem, including the existence, uniqueness of the equilibrium and the convergence to the equilibrium
in the two auctions. A distributed algorithm is developed in which each SU updates its strategy based on local information
to converge to the equilibrium. We also analyze the revenue allocation among PUs and propose an algorithm to set the prices
under the guideline that the revenue of each PU should be proportional to its resource. We then extend the proposed auction
framework to the more challenging scenario with free spectrum bands. We develop an algorithm based on the no-regret learning
to reach a correlated equilibrium of the auction game. The proposed algorithm, which can be implemented distributedly based
on local observation, is especially suited in decentralized adaptive learning environments as cognitive radio networks. Finally,
through numerical experiments, we demonstrate the effectiveness of the proposed auction framework in achieving high efficiency
and fairness in spectrum allocation. 相似文献
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针对全负载蜂窝网络中D2D通信的功率分配问题,该文提出了一种基于非合作完全信息博弈纳什均衡解的多复用D2D通信功率分配算法。以优先保证蜂窝用户通信质量与D2D用户接入率为前提,设置D2D通信系统上行链路帧结构,之后建立非合作完全信息博弈系统模型,引入定价机制到功率分配博弈模型中并分析纳什均衡解的存在性与唯一性,最后给出该模型的分布式迭代求解算法。仿真结果表明,随着D2D用户复用数量的增加,该算法在提升系统吞吐量的同时,能有效地控制系统内部干扰,大幅度降低系统总能耗。 相似文献
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认知无线电网络在提高频谱利用率的同时,带来了通信能耗增大的问题。在满足用户体验质量的前提下,引入绿色通信的理念,面向基站提出一种新型节能策略。通过构建具有抢占式优先服务和单重工作休假机制的二维离散时间马尔可夫随机模型,运用矩阵几何解方法,从系统节能率、信道利用率、认知用户平均延迟及认知用户中断率等方面评估节能策略的系统性能,并综合理论分析结果和仿真统计结果,验证节能策略的有效性。从经济学角度出发,构造收益函数,设计非线性智能优化算法,研究认知用户数据分组的纳什均衡与社会最优行为,面向认知用户制定授权频谱的定价方案。针对不同的系统参数,进行系统实验,验证定价方案的合理性。 相似文献
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An access control engine with dynamic priority resource allocation (ACE-DPRA) is proposed for unlicensed users to utilize free spectrum of wireless communication systems. A cognitive radio (CR) network with sensing and learning abilities is essential for unlicensed users to achieve ACE-DPRA. Three algorithms are included in ACE-DPRA to improve the spectral efficiency. While requesting to set up connection, unlicensed CR users generate excessive interferences to licensed users. The proposed ACE-DPRA with an admission control scheme allows the connection of unlicensed CR users without degrading the communication quality of licensed users. The priority algorithm for utilizing the unused spectrum is designed according to the location information of unlicensed users. A transmitted power control method is achieved by a fuzzy-learning mechanism. The spectral efficiency of wireless communication systems can be increased after adopting the proposed ACE-DPRA algorithm. Simulation results show that licensed users keep the advantages of high transmission data rate, low interference power, and low average outage probability after the connection of unlicensed CR users. 相似文献
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在基于正交频分多址(OFDMA)的认知无线电系统中,每个认知用户在实际中都是以整数比特进行传输,而以往的速率取整算法只考虑了单认知用户。针对这种情况,提出了一种新的速率取整算法,该算法在原有算法的基础上进行了改进,让每个子载波最多参与一次速率的调整,从而使其在应用于多认知用户时保证了速率取整时的公平性,同时总的传输比特率比原算法有了一定的提高。仿真结果表明,所提算法有效提高了各认知用户在速率取整时的公平性。 相似文献
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在一类典型的认知无线网络中,多个次级用户通过支付费用竞争租用主用户授权频带的子带来传输信息。该文针对此类系统通过博弈论方法联合优化次级用户的发射功率和子带分配,及主用户的定价系数,同时最大化主用户和次级用户的收益。具体而言,该文基于逆向归纳法,将博弈问题分解为功率控制、子带分配和价格调整等3个耦合的子问题,并逐一求解,从而得到整个博弈的子博弈精炼纳什均衡。最后,该文基于理论分析结果,提出一种博弈均衡求解算法。仿真结果验证了该文的理论推导结果和该算法的有效性。 相似文献
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Artificial bee colony–based spectrum handoff algorithm in wireless cognitive radio networks 下载免费PDF全文
In this work, we proposed a new artificial bee colony–based spectrum handoff algorithm for wireless cognitive radio systems. In our wireless cognitive radio system, primary users, secondary users, and related base stations exist in the same communication environment. For our artificial bee colony–based algorithm, secondary users that always struggle to discover an idle channel have a leading role. While honey bees work hard to find the best‐quality nectar source for foraging, secondary users try to find idle channels for making communication. In this way, secondary users are organized for different missions such as sensing and handoff similar to honey bees to minimize spectrum handoff delay by working together. In the spectrum handoff stage, some secondary users must sense the spectrum so that the interrupted secondary user may perform the spectrum handoff process. In our developed spectrum handoff algorithm, the spectrum availability characteristic is observed on the basis of the missions of the bees in the artificial bee colony algorithm with the aim of minimizing the spectrum handoff delay and maximizing probability of finding an idle channel. With the help of the algorithm that is developed using the artificial bee colony, spectrum handoff delay of secondary users is considerably decreased for different number of users without reducing probability of finding an available channel. 相似文献
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动态频谱分配技术是认知无线电的一项关键技术,本文针对以OFDM为传输技术的认知无线电系统,提出了固定速率认知用户和变速率认知用户并存情况下的动态频谱分配新算法。本文算法以最小化每比特发射功率为目标,运用最小最大准则与分步求解的方法,对系统目标函数予以简化,在最大公平意义上对认知小区的空闲频谱资源进行动态分配。仿真结果表明,该算法具有较好的公平性,在固定速率用户功率最小化需求和变速率用户吞吐量最大化的需求之间取得了比较好的平衡,适用于两种需求用户并存环境下的认知无线电系统。 相似文献