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.     

Interference Analysis of TV-Band Whitespace

Cognitive radio (CR) has been suggested as a method for promoting more efficient spectrum usage through the principles of spectrum sensing and dynamic spectrum management. The IEEE 802.22 working group in particular is developing a wireless regional-area network (WRAN) standard that will employ unlicensed CR devices operating on a noninterfering basis in the commercial broadcast television (TV) bands. Before such TV-band CR networks can be deployed, the maximum levels of first adjacent and taboo channel interference that a digital television (DTV) receiver can tolerate must be determined. In this context, we will first provide an overview of the IEEE 802.22 WRAN system. Afterwards, we will report on an experimental study that was undertaken to characterize IEEE 802.22 WRAN interference limits into Advanced Television Systems Committee (ATSC) based DTV receivers. Lastly, we will discuss the implications of these WRAN interference limits in terms of the maximum allowable radiated power and out-of-band emission limits that are imposed on WRAN end-user devices.     

Spectral Efficiency of WRAN Spectrum Overlay in the TV White Space

In this letter, we investigate the spectral efficiency of IEEE 802.22 wireless regional area network (WRAN) spectrum overlay when it is used in TV white space. Since 2004, when the FCC published the notice of proposed rule making 04‐186 to make use of unused TV spectrum, the IEEE 802.22 working group has been standardizing specifications for WRAN operations. There have been a few papers investigating the spectral efficiency of this, but their analyses were limited to the cases for various guard distances between WRAN base stations. Since WRAN base station (BS) power for WRAN service may differ from country to country, it is important to analyze the spectral efficiency for various WRAN BS powers. In this letter, we analyze the spectral efficiency of WRAN spectrum overlay as a function of the power of WRAN BSs. The simulation results show that spectral efficiency decreases as the power of WRAN BSs and guard distances increase.     

基于灰色预测理论的频谱空洞特性分析研究

为了在认知无线电系统中提高频谱的利用率以及系统的性能,主要讨论了认知无线电技术中的频谱特性分析问题,基于IEEE802.22 WRAN规定的TV频段,通过信道建模,使用灰色理论的关联度理论分析频谱的特性,并提出了频谱可用性的概念.通过仿真验证了引入灰色预测理论的频谱特性分析能够显著提高系统性能.     

Deployment of wireless regional area network and its impact on DTV service coverage

Prediction of digital TV (DTV) coverage has not considered the potential interference originating in the IEEE 802.22 Wireless Regional Area Network (WRAN), which operates in the same TV bands. WRAN interference could affect DTV reception, resulting in DTV service outage in some areas. Spectrum sensing is a means of minimizing the interference by not operating WRAN in the TV band where DTV signal is detected to be present. However, limited sensing accuracy could lead to erroneous decision. This paper investigates the extent of which DTV service quality is affected by the operation of WRAN with limited sensing accuracy. One of the main factors that limit sensing accuracy is the variability in radio propagation channel. Depending on the characteristics of the statistical variation, radio channels are modeled as Gaussian, Rayleigh, Nakagami, and Rician channels in this paper. The probability of DTV service outage is analyzed and expressed as a function of sensing accuracy. The theoretical results presented here have been validated by the Monte Carlo simulations.     

OFDM-Based TVWS-IEEE Standards: A Survey of PHY and Cognitive Radio Features

Cognitive radio (CR) has been recognized as future prospect for efficient and dynamic allocation of bandwidth among users of which dynamic spectrum access is an important aspect focusing on identification and opportunistic utilization of vacant spectrum in television broadcasting licensed bands, known as television white spaces (TVWS). TVWS has been selected by numerous IEEE standards spanning diverse operating zones for implementing CR technology. Specifically, we focus our attention to IEEE 802.22, IEEE 802.11af and IEEE 802.15.4m standards operating in TVWS pertaining to regional, local and personal area networks respectively. The PHY layer in each of these standards is depending on orthogonal frequency division multiplexing (OFDM) for spectrum-wise efficient communication as well as dynamic frequency allocation. Pertinent OFDM design challenges corresponding to IEEE standards in TVWS are revealed. PHY layer structure and cognitive techniques employed in cognition-aware IEEE standards in TVWS are reviewed in detail. Lastly, open research issues and implementation challenges for TVWS IEEE standards are highlighted.

     

基于WRAN技术的调制解调器及其应用研究

首先,较详细地介绍了IEEE 802.22协议的主要技术原理,并提出了基于WRAN技术的调制解调器的模型,对该类调制解调器的功能原理进行了描述,对其在不同场景中的应用进行了较深入地分析。最后,对该调制解调器的市场应用前景进行了展望。     

认知无线电中干扰规避方案的研究

虽然新技术的研发可以提升频谱利用率,但是很多授权频段的频谱利用率却非常低,尤其是信号传播特性好的低频段。认知无线电技术是一种智能的频谱共享技术,可以有效地提高授权频段利用率。文章介绍了认知无线电的关键技术和IEEE 802.22 WRAN标准,通过具体分析无线区域网(WRAN)对数字电视(DTV)接收机造成的干扰,建立了相应的场景模型,提出了有效的干扰规避方案。     

A proposed enhanced scheme for the dynamic frequency hopping performance in the IEEE 802.22 standard

This paper presents an integrated scheme for the dynamic‐frequency‐hopping (DFH) technique provided in literature for the IEEE 802.22 standard supporting wireless regional area networks (WRANs). The performance of DFH is analyzed thoroughly for various channel models and for a multiple‐input multiple‐output systems. The core of this research is based on the coexistence of digital terrestrial TV broadcasting and the WRANs in the TV white space. The proposed technique aims at protecting the incumbent users from interfering with the cognitive broadband access in the TV spectrum. In order to achieve this, spectrum sensing is performed in the intended working channel in DFH while spectrum monitoring with an energy‐ratio (ER) algorithm is applied during the WRAN data transmission in the working channel. Hence, in the DFH‐ER algorithm, the reappearance of a digital terrestrial TV signal in a band occupied by the WRANs would be detected immediately. This will provide interference free performance for the licensed signal as well as reliable data transmission for the unlicensed ones. Both analyses and simulation results of the proposed DFH‐ER technique compared with the conventional DFH scenario exemplify the enhancement of the WRAN data transmission while protecting the digital terrestrial TV users. Copyright © 2016 John Wiley & Sons, Ltd.     

认知无线电网络架构与协议体系

认知无线电网络具有动态、灵活、智能地使用频谱资源,提高频谱利用率的特点,其网络结构和协议体系的设计是实现上述网络功能的关键。现有基于认知无线电技术的网络架构主要有美国的CORVUS系统,基于IEEE 802.22的无线局域网(WRAN)和支持多信道多接口的无线Mesh网络;协议体系有CORVUS协议体系,军用的XG系统协议及WRAN协议等。     

Utility Function Selection for Streaming Videos with a Cognitive Engine Testbed

Cognitive Radio (CR) is a new wireless communication and networking paradigm that is enabled by the Software Defined Radio (SDR) technology and the recent change in spectrum regulation policy. As the first commercial application of CR technology, IEEE 802.22 wireless regional area networks (WRAN) aim to offer broadband wireless access by efficiently utilizing the unoccupied TV channels. In this paper, we investigate the problem of utility function selection and its impact on streaming video quality through an IEEE 802.22 WRAN base station (BS) cognitive engine (CE) testbed developed at Wireless@Virginia Tech. We find that significant improvement on received video quality can be achieved when CE adopts a dynamic, content-aware, video-specific utility function rather than a static, predefined, general purpose utility function. This work indicates the importance of video distortion modeling and cross-layer design, and the need for employing dynamic content-aware utility functions at the CE for cognitive streaming video communication networks.     

Game‐based cross‐layer channel allocation with SVC‐encoded multimedia streams in cognitive radio networks

The available unlicensed spectrum is increasingly being used by new wireless technologies, but past measurements show that the licensed spectrum is extremely underutilized. To address this issue, the IEEE 802.22 Working Group is developing a novel wireless air interface standard based on cognitive radios (CRs), i.e. IEEE 802.22 wireless regional area networks (WRANs). Moreover, over the last decade wireless multimedia applications have developed rapidly, raising significant concerns about the quality of service (QoS) of multimedia stream transmissions. In particular, the Joint Video Team (JVT) and ITU‐T Video Coding Experts Group (VCEG) jointly proposed Scalable Video Coding (SVC) as the next‐generation multimedia compression standard. However, the current IEEE 802.22 WRAN draft does not specify QoS mechanisms for SVC‐encoded multimedia stream transmission in CR networks. To resolve this problem, we developed a cross‐layer channel allocation algorithm (CLCAA) and a novel media access control (MAC) protocol to work with the algorithm. The CLCAA adapts to the characteristics of multimedia traffic and variations of wireless channels by determining the weighting of source–destination pair, which is determined by the deadlines of SVC‐encoded multimedia streams, the queuing delay and channel conditions. The CLCAA then allocates transmission opportunities to source–destination pairs based on their weightings and game theory. We also conducted extensive simulations to demonstrate the efficiency of the CLCAA scheme. The simulation results show that the CLCAA scheme not only guarantees QoS for multimedia traffic but also achieves fairness across different streams. Copyright © 2012 John Wiley & Sons, Ltd.     

Cooperative Sensing in Wireless Regional Area Network to Improve DTV Coverage Prediction

Predicting Digital TV (DTV) coverage becomes harder as a result of operating IEEE 802.22 Wireless Regional Area Network (WRAN) in the same TV bands. Interference originates in WRAN could cause DTV service outage. In this paper, the uncertainty in prediction is measured by outage probability, $P_{o}$ . With spectrum sensing capability, WRAN can avoid operating in the TV band where DTV signal is detected to be present. Nevertheless, due to limited sensing accuracy, interfering operation cannot be completely avoided. Cooperative spectrum sensing (CSS) gives better detection by means of combining multiple sensing results. This paper investigates the extent of which $P_{o}$ is reduced as a result of implementing CSS in WRAN. The investigation is conducted for two different combining techniques: Equal Gain Combining and Selection Combining, and four different types of channel variability: Gaussian, Nakagami, Rayleigh, and Rician channels. All theoretical results have been validated by Monte Carlo simulations. An arbitrarily chosen example shows that $P_{o}$ reduces by about 40 times after implementing CSS.     

WRAN系统的频谱分配算法

IEEE802.22工作组的工作范围是对工作在54～862MHz的VHF/UHFTV频带内的固定点对多点无线区域网（WRAN）制定基于认知无线电的空中接口。频谱资源分配是WRAN中的关键技术,目前对认知无线电的频谱分配算法的研究多集中在比较广义的范围,对WRAN等具体系统的频谱分配研究较少。根据WRAN的特点和OFDM的传输特性,提出一种OFDM多用户资源分配算法：多载波比例公平算法（MPF）和最大化吞吐量算法（KH）的组合算法（KH＆MPF）,该算法将最大化吞吐量算法和多载波比例公平算法进行优势互补,得到公平性和吞吐量都次优的结果,解决用户之间的公平性问题,考虑用户的Qos要求。最后对该算法进行仿真。     

WRAN系统频谱感知研究

IEEE802.22WRAN系统使用动态频谱接入.它有效提高了频谱利用率.频谱感知是WRAN系统的关键技术.文章首先对WRAN系统和频谱感知进行了简要介绍.然后,从三个方面对频谱感知进行了研究,包括频谱感知要求,频谱感知功能和频谱感知方案.     

基于认知无线电技术的802.22标准

认知无线电技术能够监测到无线电环境中已存在的用户,同时监控频谱资源的使用情况,并能动态地调整各无线用户的传输参数,从而提高频谱资源的利用率。基于认知无线电技术的802.22标准要求在不损害已有电视设备服务的前提下,使用电视频带为非授权用户提供廉价的无线接入服务。对认知无线电技术和802.22标准结构进行了深入分析,并讨论了一些重点需要解决的问题。     

COGNITIVE RADIOS FOR DYNAMIC SPECTRUM ACCESS - Dynamic Frequency Hopping Communities for Efficient IEEE 802.22 Operation

One of the key challenges of the emerging cognitive radio-based IEEE 802.22 wireless regional area networks (WRANs) is to address two apparently conflicting requirements: ensuring QoS satisfaction for WRAN services while providing reliable spectrum sensing for guaranteeing licensed user protection. To perform reliable sensing, in the basic operation mode on a single frequency band (non-hopping mode), one must allocate quiet times, that is, periodically interrupt data transmission that could impair the QoS of WRAN. This critical issue can be addressed by an alternative operation mode proposed in 802.22 called dynamic frequency hopping (DFH), where WRAN data transmission is performed in parallel with spectrum sensing without interruptions. DFH community, as described in this article, is a mechanism that coordinates multiple WRAN cells operating in the DFH mode, such that efficient frequency usage and reliable channel sensing are achieved. The key idea of DFH community is that neighboring WRAN cells form cooperating communities that coordinate their DFH operations     

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。     

Efficient topology construction and routing for IEEE 802.15.4m-based smart grid networks

IEEE 802.15.4m TVWS Multi-Channel Tree PAN (TMCTP) standard that uses the vacant TV frequency of a region is the key to provide a flexible, scalable and cost-effective AMI smart grid networks. However, the performance of the IEEE 802.15.4m based AMI network can suffer from network interruption, varying transmission reliability and energy consumption problems due to the excessive number of channels and periodic channel scanning. To resolve these issues, we presented an enhanced IEEE 802.15.4m TMCTP called TVWS Orphan channel scanning with Multi-Channel Tree PAN Routing (TOMTPR). The proposed TOMTPR framework includes pilot-channel based Multi-Channel beaconing and interleaving-based TVWS orphan channel scanning. Furthermore, a capacity-aware routing tree is constructed during the neighbor discovery procedure. The proposed protocol suite is designed to provide compatibility with the IEEE 802.15.4 family standards with lower architecture complexity. The simulation results in presence of realistic AMI traffic and AMI network model show that TOMTPR can not only satisfy delay requirements of the AMI traffic, but also outperforms IEEE 802.15.4m TMCTP with IEEE 802.15.5 layer 2 mesh routing in terms of topology construction delay, end-to-end transmission reliability, and energy efficiency.     

IEEE802.22中WRAN系统信道的探测

认知无线电技术（CR-cognitive radio）是软件无线电技术的演化,是一种新的智能无线通信技术。通过讨论IEEE802.22中WRAN系统信道的探测,分析了TDD和OFDMA WRAN系统的异步静态时间周期的算法,以及如何使用这个时间周期来探测信道。并分析了各种算法的优缺点。