一种基于信誉值拍卖的区块链下的感知收益分配机制

实现频谱共享,需要以实时准确地掌握主用户的频谱占用情况以及频谱交易信息为前提.为此,在利用群智感知以及区块链的前提下,提出了三层式的基于区块链的认知无线电系统,即物理层、传输层以及应用层.其中区块链网络位于传输层,用以记录交易信息,并利用区块链的去中心化以及去信任化特性以保证交易的安全性与可靠性.特别地,为了激励系统中...     

一种基于对等协作的动态频谱分配算法

随着无线多媒体技术的发展,优质频谱资源越来越稀缺.针对频谱稀缺和频谱共享问题,提出了一种基于对等协作的动态频谱共享算法.运营商将自己的授权频谱资源部分或全部放入共享频谱池,并根据节点感知到的频谱的使用状况,平等分配该频谱池中的所有资源.仿真结果表明,所提的对等协作方案在运营商间没有信息交互的情况下,网络性能明显优于静态频谱分配方案,并且非常接近运营商间完全信息交互的频谱共享方案.     

基于分布式中继选择的自适应协作传输方案

协作分集通过使网络用户共享彼此天线以形成虚拟多天线阵列,可以显著提高网络容量,然而针对网络拓扑的动态变化与无线传输的时变特性,仅靠协作分集并不能十分有效地解决这些问题,必须结合考虑相应的自适应传输策略.本文提出动态网络环境中协作中继的最佳选择准则,在此基础上给出最佳协作中继的分布式选择协议.根据协作中继与源节点间的无线信道质量,进一步提出一种自适应协作传输方案,以有效抵抗多用户网络环境中的无线衰落.此外,对自适应协作传输方案的误码性能,在瑞利衰落信道下进行相应的理论分析,得到了系统误比特率的解析表达式,据此给出数值仿真实验以进行性能比较.结果表明:相对于传统协作分集而言,本文提出的自适应协作传输方案获得了进一步的性能增益,误比特率显著下降.     

异步区块链支持的安全频谱共享

针对目前频谱稀缺的困境,一个经济有效的解决方案是将未充分利用的授权频谱以机会的方式分配给未授权用户。然而,实现大规模频谱共享面临激励缺失、隐私泄露、安全威胁和时延过大等挑战。利用区块联盟链技术的安全机制,设计了由频谱接入层、区块链网络层、区块链共识层构成的区块链动态频谱接入系统。该系统采用异步实时拜占庭容错(Practical Byzantine Fault Tolerance,PBFT)改善共识延时,设计基于最优匹配算法的匹配方案,提高频谱复用率。经仿真验证,该方案频谱复用率提升近6%。相比于实时拜占庭机制,所提方案减少了系统延时,提升吞吐量近129%。     

基于认知无线电系统的协作中继分布式功率分配算法

协作通信与直接通信相比能够显著地提高系统性能。协作通信中的一个关键问题是管理中继节点及有效地进行功率分配。尤其对于频谱共享的认知无线电(Cognitive Radio,CR)系统,协作方案的设计不仅要最大限度地提高认知网络协作的功率效率,而且需要最小化对主系统的干扰。该文针对认知无线电系统的协作通信问题,在多个中继节点与源节点协同通信的场景下,提出了一种基于放大转发(Amplify and Forward,AF)模式下的功率分配及联合优化算法,在保证主系统传输性能不受影响的前提下,提高认知系统的传输速率。仿真结果表明该文提出的自适应协作传输方案,和直接传输及等功率传输方案相比获得了进一步的性能增益,中断概率显著下降。     

能效与资源优化的超蜂窝移动通信系统基础研究

移动通信网的发展正面临以受限的频谱与能量大幅度提高网络容量的严峻挑战,需要从系统和网络的角度探索频谱与能量的高效利用机理与方法.提出一种全新的超蜂窝体系架构,将网络中的控制信令与业务数据传输在覆盖上进行适度分离,实现资源与业务的弹性匹配,联合优化频谱和能量效率,满足未来移动通信网大容量和低能耗的双重需求.分别介绍了超蜂窝体系架构下的网络能效理论、高能效的传输与网络协作、业务建模与高能效服务,最后给出了超蜂窝系统的演示验证平台.     

基于交易构造和转发机制的区块链网络隐蔽通信方法

针对现有存储型区块链网络隐蔽通信方案存在含密交易多副本、永久存储的问题,以及现有时间型方案隐藏容量低的问题,提出了一种基于交易构造和转发机制的区块链网络隐蔽通信方法。首先发送方借助交易构造机制创建无效交易,并将秘密信息嵌入其中,再利用交易转发机制向邻居节点发送无效交易,形成隐蔽通信信道模型,使含密交易在节点间传播且不存于区块链账本中,达到信息隐蔽安全传输的目的。实验结果表明,传输容量高于现有方案,单次通信时间减少至2.5 s。     

基于全频谱共享的三维轨迹和功率优化方法

当前蜂窝系统频谱资源极度短缺,免授权频谱因而被建议在蜂窝系统中使用。无人机(UAV)的飞行轨迹和功率控制对频谱利用效率有重大影响。然而,基于频谱共享的3维轨迹和功率优化方法却鲜少研究。为此,该文首先提出一种全频谱共享方法,即无人机通过控制上行蜂窝用户和设备到设备(D2D)用户的发射功率,在不影响WiFi设备正常传输的前提下使用免授权频谱;同时无人机也能够在不影响其他下行蜂窝用户的前提下使用授权频谱。然后基于提出的全频谱共享方法,该文构建了无人机电池能量约束下的3维飞行轨迹和发射功率的联合优化问题。为了求解提出的复杂多变量耦合的非凸优化问题,该文采用块坐标下降和连续凸逼近方法将原问题转化为3维轨迹优化和功率控制两个凸优化子问题并迭代求解。大量仿真结果证明提出的基于3维轨迹和功率优化的全频谱共享方法能够显著提高频谱利用效率。     

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。     

多跳认知无线Mesh网络中频谱决策与路由的跨层设计

灵活高效的频谱共享技术能够实现频谱资源的最大化利用,有效地缓解了无线频谱紧缺的现状。在一个与TDMA/FDMA蜂窝网络共存的多跳认知无线Mesh网络环境下,基于覆盖式（Underlay）与机会式（Overlay）相结合的频谱共享机制,提出了一种有效的链路层频谱决策与网络层路由的跨层设计方案。仿真结果表明,该方案比基于最小跳数的随机信道选择算法在网络端到端传输性能上有显著的优势。     

Incentive mechanism based on auction model for mobile crowd sensing network

The selfishness and uncertainty of user behaviors in the mobile crowd sensing network make them unwilling to participate in sensing activities,which may result to a lower sensing task completion rate.To deal with these problems,an incentive mechanism based on auction model was proposed.In order to maximize the utility of each user,the proposed incentive method based on reverse auction (IMRA) leveraged a task-centric method to choose winners,and payed them according to a critical-price strategy.Furthermore,the proposed user-bidirectional interaction incentive mechanism (UBIM) helped drop-out users (buyers) to transfer their unfinished tasks to new users.Simulation results show that,compared with TRAC and IMC-SS,IMRA can achieve a better performance in terms of average user utility and tasks coverage ratio,and the task completion ratio can also be improved by UBIM.     

基于单频段多赢家拍卖的动态频谱分配

针对传统拍卖方法在认知无线网络动态频谱分配中的低效问题,提出了一种基于单频段多赢家拍卖的动态频谱分配算法。该算法在原始贪婪算法的基础上增加了多重贪婪策略,以较低的计算复杂度获得了较优的解;改进了VCG(vickery-clarke-groves)机制,在保留占优策略激励兼容特性的基础上,提高了卖家的收益,有效抑制共谋的发生。仿真结果表明,该算法的频谱分配效率接近最优分配效率,同时提高了拍卖的经济收益。     

Spectrum Sharing between Cellular and Mobile Ad Hoc Networks: Transmission-Capacity Trade-Off

Spectrum sharing between wireless networks improves the efficiency of spectrum usage, and thereby alleviates spectrum scarcity due to growing demands for wireless broadband access. To improve the usual underutilization of the cellular uplink spectrum, this paper addresses spectrum sharing between a cellular uplink and a mobile ad hoc networks. These networks access either all frequency subchannels or their disjoint subsets, called spectrum underlay and spectrum overlay, respectively. Given these spectrum sharing methods, the capacity trade-off between the coexisting networks is analyzed based on the transmission capacity of a network with Poisson distributed transmitters. This metric is defined as the maximum density of transmitters subject to an outage constraint for a given signal-to-interference ratio (SIR). Using tools from stochastic geometry, the transmissioncapacity trade-off between the coexisting networks is analyzed, where both spectrum overlay and underlay as well as successive interference cancelation (SIC) are considered. In particular, for small target outage probability, the transmission capacities of the coexisting networks are proved to satisfy a linear equation, whose coefficients depend on the spectrum sharing method and whether SIC is applied. This linear equation shows that spectrum overlay is more efficient than spectrum underlay. Furthermore, this result also provides insight into the effects of network parameters on transmission capacities, including link diversity gains, transmission distances, and the base station density. In particular, SIC is shown to increase the transmission capacities of both coexisting networks by a linear factor, which depends on the interference-power threshold for qualifying canceled interferers.     

UNIFORM—PRICE AUCTION FOR BANDWIDTH ALLOCATION IN THE INTERNET

It has been widely accepted that auctioning which is the pricing approach with minimal information requirement is a proper tool to manage scare network resources.Previous works focus on vickrey auction which is incentive compatible in classic auction theory.In the beginning of this letter,the faults of the most representative auction-based mechanisms are discussed.And then a new method called Uniform-Price Auction(UPA),which has the simplest auctiopn rule is proposed and its incentive compatibility in the network environment is also proved.Finally,the basic mode is extended to support applications which require minimum bandwidth guarantees for a given time period by introducing derivative market.and a market mechanism for network resource allocation which is predictable,riskless,and simple for eng-users is completed.     

Cooperative caching game based on social trust for D2D communication networks

Content sharing via device‐to‐device (D2D) communications has become a promising method to increase system throughput and reduce traffic load. Due to the characteristic of spectrum sharing in D2D network, confidentiality is becoming a key issue in content transmission. Secure communication in D2D networks is generally guaranteed by a physical‐layer security mechanism. However, this method sacrifices the system transmission rate while ensuring security. Since mobile devices are carried by humans, we can leverage their trust relations to enhance the security of communications. As much, considering the psychology structure and social attributes of mobile users, we build a multidimensional trust evaluation mechanism to evaluate the trust relationship between users, and we pick out the trusted users based on the decision‐theoretic rough sets. By sharing content only between trust users, we can enhance the security of content transmissions without relying on physical‐layer security measures. Meanwhile, content caching is now widely used to improve accessing efficiency and reduce traffic load on cellular networks. However, caching content for other users incurs additional cost, which results in selfish and noncooperative behavior in users. Considering such selfishness, we introduce a cooperative caching game based on multidimensional trust relations to motivate users to cache contents for other devices. In this game, the trust relations and physical distance between two users are considered to formulate the cost function. Furthermore, we introduce an incentive caching algorithm based on social trust to minimize the total cost in the D2D network.     

Online combinatorial based mechanism for MEC network resource allocation

In this paper, the resource allocation problem for mobile edge computing (MEC) network is discussed. We focus on the design of online resource allocation strategy by considering the time‐varying demands of the combinatorial resources for the mobile users. To handle this issue, at first, a time splitting‐based online allocation mechanism is introduced. Then, for a given resource allocation period of the time splitting, a combinatorial auction mechanism for the combination resources allocation is proposed. We further prove that the proposed combinatorial auction is both individual rational and incentive‐compatible, and which can bring a higher revenue to the service provider. In order to verify the performance of the proposed mechanism, a variable‐relaxed‐based performance‐bound algorithm and a greedy optimization‐based suboptimal algorithm are presented for comparison purpose. Finally, the performance of these proposed algorithms are testified by numerical simulations, which confirm the analysis results.     

Behavior modeling for spectrum sharing in wireless cognitive networks

Cognitive networks are designed based on the concept of dynamic and intelligent network management, characterizing the feature of self-sensing, self-configuration, self-learning, self-consciousness etc. In this paper, focusing on the spectrum sharing and competition, we propose a novel OODA (Orient-Observe-Decide-Act) based behavior modeling methodology to illustrate spectrum access problem in the heterogenous cognitive network which consists of multiple primary networks (PN, i.e. licensed networks) and multiple secondary networks (SN, i.e. unlicensed networks). Two different utility functions are designed for primary users and secondary users respectively based on marketing mechanism to formulate the decide module mathematically. Also, we adopt expectation and learning process in the utility design which considers the variance of channels, transmission forecasting, afore trading histories and etc. A double auction based spectrum trading scheme is established and implemented in two scenarios assorted from the supply-and-demand relationship i.e. LPMS (Less PNs and More SNs) and MPLS (More PNs and Less SNs). After the discussion of the Bayesian Nash Equilibrium, numerical results with four bidding strategies of SNs are presented to reinforce the effectiveness of the proposed utility evaluation based decision modules under two scenarios. Besides, we prove that the proposed behavior model based spectrum access method maintains frequency efficiency comparable with traditional centralized cognitive access approaches and reduces the network deployment cost.     

An auction-based approach for spectrum leasing in cooperative cognitive radio networks: when to lease and how much to be leased

The problem of resource allocation in a spectrum leasing scenario in cooperative cognitive radio networks is addressed. The system model consists of a number of primary user (PU) pairs and a secondary user (SU) pair. The SU pair allocates the whole its transmission power in a portion of transmission frame to relay the primary signals. In return, the PU pairs lease their unused portion of transmission frame to the SU pair. In this way, the PU pairs take advantage of their unused portion of time to gain savings in their transmission power. However, a few important questions must be answered: When to lease and how much to be leased. We determine when is beneficial for PUs to lease their unused spectrum portion to the SU and how much of PUs’ resources is optimum to be leased. An efficient auction mechanism is proposed and the existence and uniqueness of the Nash Equilibrium (NE) for the proposed auction game is proved. Since the NE is the solution of a set of fixed point problems, two iterative algorithms, synchronous and asynchronous schemes, are proposed to reach the NE in an iterative manner and their convergence to the fixed point is also proved. Finally, the proposed auction is extended to a network with multiple secondary user pairs. Simulation results acknowledge the more efficient utilization of resources as a result of implementing the proposed auction based resource allocation.     

IEEE802．22 WRAN网络中基于拍卖的频谱租借算法

在IEEE802．22WRAN网络中,基站间的频谱共享是一个重要的研究方向。若每个WRAN基站伺机占用信道,将带来信道分配不均的问题。利用拍卖理论激励基站间平衡信道分配,提出一种动态的频谱租借算法。该算法将频谱共享情况建模为一个拍卖基站和多个竞拍基站的拍卖模型,同时考虑竞拍基站间的信道需求和拍卖基站的收益,建立频谱共享的数学优化模型。仿真结果表明,与已有的频谱拍卖机制相比,该算法能获得较高的拍卖收益。