A novel spectrum sharing scheme for cognitive radios

A novel approach, which combines spectrum adaptation and orthogonal frequency division multiplexing (OFDM), is proposed to share the licensed spectrum dynamically for cognitive radio systems. Given spectrum sensing and channel estimation information by the receiver, an improved model due to signal power thresholds is adopted to achieve spectrum adaptation for unlicensed users. In order to efficiently allocate the unlicensed signal power, a dynamic power allocation algorithm is also proposed. Simulation results indicate that the propositional scheme solves the partial interference problem of interference temperature model (ITM) and improves the spectrum utilization.     

基于拍卖理论和补偿激励的频谱共享新算法

针对认知无线电系统中主次用户频谱共享问题,提出了一种基于拍卖理论和补偿激励的频谱共享新算法,该算法基于简化的VCG(vickrey-clarke-groves)拍卖模型,引入次用户间的合作关系,并运用货币补偿激励原则,建立了相应的合作型竞争的频谱博弈模型。该博弈模型不仅具有非合作博弈模型可自动实施的决策模式特点,还兼有寡头联合模型的公平性的特点。理论分析和仿真结果证明了所提出算法的正确性和公平性。     

我国频谱共享的可行性研究与推进建议

目前,我国工业和信息化领域一系列战略稳步推进,5G、移动互联网等信息技术快速发展,无线电频谱资源的稀缺性再次凸显。频谱共享为解决频谱资源的稀缺问题提供了解决方案,并被国际主流国家积极推行。在分析国内外频谱共享研究与应用现状的基础之上,进一步讨论了我国推行频谱共享的意义和挑战,给出了频谱共享可行性评估和分析框架,并提出了频谱共享的推进建议。     

A game approach for cooperative spectrum sharing in cognitive radio networks

We consider the problem of cooperative spectrum sharing among primary users (PUs) and secondary users (SUs) in cognitive radio networks. In our system, each PU selects a proper set of SUs to serve as the cooperative relays for its transmission and in return, leases portion of channel access time to the selected SUs for their own transmission. PU decides how to select SUs and how much time it would lease to SUs, and the cooperative SUs decide their respective power levels in helping PU's transmission, which are proportional to their access times. We assume that both PUs and SUs are rational and selfish. In single‐PU scenario, we formulate the problem as a noncooperative game and prove that it converges to a unique Stackelberg equilibrium. We also propose an iterative algorithm to achieve the unique equilibrium point. We then extend the proposed cooperative mechanism to a multiple‐PU scenario and develop a heuristic algorithm to assign proper SUs to each PU considering both performance and fairness. The simulation results show that when the competition among SUs is fierce, the performance gap between our heuristic algorithm and the optimal one is smaller than 3%. Copyright © 2013 John Wiley & Sons, Ltd.     

Dual-target WOA spectrum sharing algorithm based on Stackelberg game

In order to solve the complex spectrum allocation problem,a dual-target whale optimization algorithm (WOA) with strong parallel computing capabilities was introduced,and a Stackelberg game model was proposed that could effectively reflect the actual spectrum requirements,and a dual-target WOA optimized distributed antenna system (DAS) spectrum sharing scheduling algorithm was designed.Simulation results show that performance comparison is performed from multiple indicators such as optimal pricing and user benefits.The proposed algorithm has a good spectrum sharing allocation effect,can achieve fair and effective spectrum allocation,and provides an important reference for the future communication network spectrum sharing mode.     

改进的认知无线电频谱共享博弈模型

提出了一种改进的认知无线电频谱共享模型.该模型综合考虑了主用户的收益受到所有次用户请求带宽的影响,以及每个次用户的收益受到其他次用户请求带宽的影响;同时,与次用户竞争的主用户能够通过选择最佳带宽定价来获得最大的收益,相互竞争或合作的次用户通过从有限的频谱中改变请求频谱带宽来获得最大收益.对改进模型的静态博弈、动态博弈及其稳定性、帕累托最优等特性的仿真结果证明该模型适应实际情况.     

New coalition formation game for spectrum sharing in cognitive radio networks

In cognitive radio networks, Secondary Users (SUs) can access the spectrum simultaneously with the Primary Users (PUs) in underlay mode. In this case, interference caused to the licensed users has to be effectively controlled. The SUs have to make spectrum access decisions in order to enhance their quality of service, but without causing harmful interference to the coexisting PUs. In this paper, we propose a cooperative spectrum decision, which enables the SUs to share the spectrum with the PUs more efficiently. Our approach is based on a new coalitional game in which the coalition value is a function of the SUs' spectral efficiencies, the inter‐SUs interference, and the interference caused to the PUs. By applying new Enter and Leave rules, we obtain a stable coalition structure. Simulation results show that the SUs' spectral efficiencies are considerably increased and that the interference caused to the coexisting PU is reduced by about 7.5% as compared to an opportunistic spectrum access scheme. Moreover, the proposed coalitional game results in a more balanced spectrum sharing in the network. Copyright © 2014 John Wiley & Sons, Ltd.     

Cooperative spectrum sharing of multiple primary users and multiple secondary users

This paper proposes a multiple-input multiple-output (MIMO) based cooperative dynamic spectrum access (DSA) framework that enables multiple primary users (PUs) and multiple secondary users (SUs) to cooperate in spectrum sharing. By exploiting MIMO in cooperative DSA, SUs can relay the primary traffic and send their own data at the same time, which greatly improves the performance of both PUs and SUs when compared to the non-MIMO time-division spectrum sharing schemes. Especially, we focus on the relay selection optimization problem among multiple PUs and multiple SUs. The network-wide cooperation and competition are formulated as a bargaining game, and an algorithm is developed to derive the optimal PU-SU relay assignment and resource allocation. Evaluation results show that both primary and secondary users achieve significant utility gains with the proposed framework, which gives all of them incentive for cooperation.     

Cross‐layer design of partial spectrum sharing for two licensed networks using cognitive radios

To utilize spectrum resources more efficiently, dynamic spectrum access attempts to allocate the spectrum to users in an intelligent manner. Uncoordinated sharing with cognitive radio (CR) users is a promising approach for dynamic spectrum access. In the uncoordinated sharing model, CR is an enabling technology that allows the unlicensed or secondary users to opportunistically access the licensed spectrum bands (belonging to the so‐called primary users), without any modifications or updates for the licensed systems. However, because of the limited resources for making spectrum observations, spectrum sensing for CR is bound to have errors and will degrade the grade‐of‐service performance of both primary and secondary users. In this paper, we first propose a new partial spectrum sharing policy, which achieves efficient spectrum sharing between two licensed networks. Then, a Markov chain model is devised to analyze the proposed policy considering the effects of sensing errors. We also construct a cross‐layer design framework, in which the parameters of spectrum sharing policy at the multiple‐access control layer and the spectrum sensing parameters at the physical layer are simultaneously coordinated to maximize the overall throughput of the networks, while satisfying the grade‐of‐service constraints of the users. Numerical results show that the proposed spectrum sharing policy and the cross‐layer design strategy achieve a much higher overall throughput for the two networks. Copyright © 2013 John Wiley & Sons, Ltd.     

动态频谱共享研究现状及展望

动态频谱共享作为解决频谱供需矛盾的有效方式之一,在国际上受到了广泛关注.首先,对动态频谱共享的发展情况进行了概述.然后,对国际上动态频谱共享的政策制定、标准化及应用情况等进行了梳理.最后,结合无线电管理现状,分析了实施动态频谱共享在频率管理、台站管理及无线电监测等方面的影响及挑战.     

Asymmetric active cooperation strategy in spectrum sharing game with imperfect information

In this paper, we study the spectrum sharing problem in the cognitive network where two secondary users coexist and interfere with each other in an unlicensed channel. Each user in our scenario is independent and is unaware of the characteristic of its rival but its statistics (imperfect information). An important issue is the interaction among selfish independent wireless communication systems (secondary users) who aim to maximize their own current utility. We provide a self‐enforcing spectrum sharing framework, which has the advantage of not requiring a control center or communicating between two users. The short‐term profits of users gained before cooperation being builded are asymmetrical. The long‐term profit is used as the user's utility. Users improve their long‐term profits by creating mutual cooperation actively. The historical action of the user is used by its rival to evaluate/update the current action. The action updating algorithm is provided. Moreover, we investigate the stability of the cooperation. As demonstrated, the proposed scheme can build mutual cooperation through extensive simulations. The existence of equilibrium is confirmed by the repeated game. And our scheme can achieve a good trade‐off between short‐term profits and long‐term profits. Copyright © 2013 John Wiley & Sons, Ltd.     

基于射频前端的动态频谱共享无线通信系统工作信道选择分析

由于有主用户信号的存在和部分射频器件具有不可消除的非线性特性,将在射频接收机前端中产生三阶交调等干扰信号。为了减小干扰信号的影响,从射频接收机前端的角度分析了主用户信号对动态频谱共享无线通信系统的干扰特性,得出了频谱共享无线通信系统工作信道的选择约束条件,遵循此约束条件可以降低干扰信号带来的负面影响,保障频谱共享无线通信系统的通信质量。最后,在UHF频段动态频谱共享无线通信系统中,实验验证了工作信道选择约束条件的有效性。     

基于可靠度和信息共享的分布式频谱检测算法

目前基于可靠度的频谱检测方案主要针对集中式频谱检测。基于已有文献的优点,以信噪比作为可靠度,给出了一种新的基于信息共享的分布式频谱检测算法。在该算法中,认知用户共享本地检测的判决结果和可靠度,可靠度低的用户用比他可靠度高的用户的判决结果来更新自己的判决,需要进行数据传输的两个认知用户的判决结果只要都不存在主用户就可以进行通信,这样便于快速建立连接。通过ROC曲线的仿真结果,检测性能有较好的改进。     

OFDMA认知无线电网络中面向需求的频谱共享

从满足次网络通信需求的角度,设计一个两阶段模型,求解OFDMA 认知无线电网络中频谱租赁与分配问题。模型第1阶段,次基站收集次网络通信需求,向多个主基站租用频谱资源。运用Bertrand博弈对主、次基站的交易行为进行建模,并将纳什均衡作为最终定价方案。第2阶段,基于纳什议价方案,将次基站子载波和功率分配问题定义成非线性规划问题,并通过拉格朗日乘数法进行求解。仿真实验表明,相对于其他频谱共享方案,所提方案高效地满足每个次用户的通信需求。     

Joint power control and spectrum sensing for capacity maximisation in spectrum sharing systems

We study the problem of joint power control and spectrum sensing for maximising the capacity at the secondary user while protecting the primary user's transmissions in spectrum sharing cognitive radio systems. Power control regulates the transmission power of the secondary user and spectrum sensing regulates the sensing time and the sensing threshold that care for the primary user's protection. This problem is a capacity maximisation problem that we formulate and solve using an iterative greedy algorithm due to its complex form. The solution of the proposed algorithm leads to the global optimal solution that represents the optimal triplet values of transmission power, sensing time and threshold. The obtained results show the potential capacity maximisation that is achieved by the proposed joint design as long as the primary user's protection is provided. Finally the convergence behaviour of the proposed algorithm is assessed in terms of the needed iterations for enhancing the capacity of spectrum sharing systems.     

Spectrum sensing scheduling for group spectrum sharing in cognitive radio networks

This paper addresses the issues on spectrum sharing in a cognitive radio network consisting of a primary user and a group of cognitive users. Each cognitive user may occupy a non‐overlapped sub‐band of the primary spectrum, but it needs to perform spectrum sensing independently before accessing the sub‐band. To reduce the complexity of spectrum sensing and thus energy consumption, this paper proposes a scheduled spectrum sensing scheme. First, we consider a single spectrum sensing scenario where only one cognitive user is elected to perform spectrum sensing, and then it broadcasts its sensing results to the other cognitive users. The scheduled spectrum sensing scheme works in both network‐centric and user‐centric ways. Next, the scheduled spectrum sensing scheme is further generalized to work in a multiple spectrum sensing scenario. The results show the effectiveness of the proposed schemes compared with the traditional schemes where all cognitive users may perform spectrum sensing at the same time. Copyright © 2010 John Wiley & Sons, Ltd.     

A Hierarchical Game Model for Computation Sharing in Smart Buildings

Recently,initiatives to integrate Internet of Things(IoT)technologies into smart buildings have attracted extensive attention for improving the performance of buildings and the comfort of occupants.However,the amount of data generated by IoT devices remains a challenge to the building management systems(BMSs)in terms of intensity and complexity.Different from cloud computing and edge computing,we propose a computation sharing architecture in smart buildings to incentivize idle computing devices(ICDs,sellers)to offload computational tasks for the BMS(buyer).In this paper,we design a hierarchical game model,consisting of a Stackelberg game and a Cournot game,to achieve a dynamic increase in computational capacity for the BMS.To guarantee the utility of BMS and ICDs,the Stackelberg game model is built to analyze the interactions between BMS and ICDs.Then,the Cournot game model is presented to formulate the internal competition among multiple ICDs.Under the premise of the subgame perfect Nash equilibrium,the BMS can quote the optimal pricing strategy,and the ICDs can share the corresponding optimal amount of computing resources.Finally,the simulation results show that the BMS’s computational capacity is enhanced on-demand,and each participant in the game obtains maximal utility.     

认知无线电网络子空间映射频谱共享

针对集中式多用户多天线认知无线电网络,分析了子空间映射能够为认知系统提供的通信机会以及理想信道条件下的空间子信道分配方案。在此基础上,提出了一种基于子空间映射的频谱共享策略。根据认知系统的感知结果,计算可以利用的空间子信道数,通过认知用户接入控制和子空间映射避免或抑制系统间干扰,从而在保证授权用户通信质量的前提下,为认知用户提供通信机会。仿真结果表明,与已有的子空间映射频谱共享方法相比,该策略不仅具有更高的认知系统可达和速率,而且能够为认知系统提供更多通信机会。     

一种可验证的基于超混沌系统的灰度图像多密钥共享算法

提出一种可验证的图像多密钥共享方案。算法中,灰度图像首先被置乱,而后划分为多个图像子块,利用图像子块的哈希值作为超混沌系统的初始值,生成多个随机网格(RG),最后利用RG和图像子块的异或生成共享的多个子密钥。提出的算法具有共享密钥空间小、能够无损恢复秘密图像,同时能够验证密钥的持有者是否对密钥进行了恶意篡改,能应用于重要领域如医学以及军事图像的保护。实验结果和对算法的比较分析,验证了算法的有效性。     

认知车载网络中基于QoS保障的频谱共享新策略

构建了基于认知无线电的新型车载网络,并提出基于安全业务服务质量(QoS)保障的两步式频谱共享策略:多认知小区间的频谱分配和单认知小区内的频谱共享。仿真结果表明,提出的GNBS(generalized nash bargaining solution)分配方案综合考虑了系统的公平性和总效用,可获得明显大于最大化最小方案的系统和速率,以及明显优于最大化和速率方案的多认知小区间的公平性;GNBS方案可以根据多小区间频谱需求的差异性来动态调节资源分配的比例,有效地实现了需求非对称的多小区间频谱资源的最优化配置;此外,单小区内的协作频谱共享机制,使得协作双方均获得了优于非协作方案的系统效用,有效地提高了系统吞吐量以及认知OBU间的公平性。