Implementation of Filter Bank–Based RF Transceiver for TV White Space

This paper presents a general‐purpose design scheme of a filter bank (FB)–based radio frequency (RF) transceiver that operates across the entire ultra‐high frequency (UHF) TV band from 470 MHz to 698 MHz and complies with the TV white space (TVWS) regulatory requirements. To this end, an intermediate frequency (IF) band‐pass filter (BPF) with a sharp skirt characteristic is considered as a solution for handling the incoming signals from a baseband modem. Specifically, an FB‐based BPF structure with four ceramic resonator filters that effectively rejects unwanted signals is proposed to extract a desired signal in the TV band. Achievable data rates of a cognitive radio system (CRS) employing the proposed FB‐based RF transceiver at the application layer are investigated in both wired and wireless environments. The service coverage of the CRS network is measured according to several modulation and coding schemes (MCSs) of the CRS. The results show that the coverage of a wireless network in a nearly open area can be extended by more than 9.3 km in the TVWS. Experimental results also confirm that the proposed FB‐based RF transceiver is adequate for utilization in TVWS applications.     

Survey of outdoor and indoor architecture design in TVWS networks

To understand the utilizability of TV white spaces (TVWS), a comprehensive overview of the outdoor and indoor network design over TVWS is given. The related challenges are analyzed. The potential approaches to overcoming these challenges are discussed. The open research issues are investigated. The result shows that: in the indoor scenario, the white space ratio is on average 18.4% higher than that in the outdoor scenario, which corresponds to 7.7 vacant TV channels. Both network design includes 7 key components: TV spectrum identification, access point (AP) discovery, AP association, spectrum allocation, band width adaptation, interface control and disruption handling. Due to building penetration loss, the indoor TVWS identification and AP placement should be carefully considered in the indoor scenario.     

Capacity maximization in spectrum sensing for Cognitive Radio Networks thru Outage Probability

With today's increase in the usage of wireless devices and the consequent spectrum allocation, radio spectrum is becoming scarce. In practice most of the allotted spectrum is not used for large periods of time. Cognitive radio has been proposed to exploit the presence of these unused spectrum band (called as spectrum hole). Cognitive radios perform radio environment analysis, identify the spectrum holes and operate in those holes. Several factors like fading and shadowing affects the ability of the cognitive radio to detect the primary user. The current research shows that cooperation among the cognitive users can increase the detection probability for a given probability of false alarm. We proposed the system that to have maximized the capacity in spectrum sensing for Cognitive Radio Networks thru Outage Probability for Rayleigh fading channel.     

数据驱动的开放动态频谱接入系统构建方法

在认知无线电(CR)背景下,动态频谱接入已成为提高无线网络频谱利用率的重要途径。基于全球移动通信系统-铁路(GSM-R)系统中采集的细粒度频谱监测数据,提出一种数据驱动的深度学习方法,建模频谱模式,并建立一套动态频谱接入访问框架。采用一种深度频谱生成模型指导频谱分配;设计一种综合递归序列表征与场景特征嵌入的深度网络,建模和预测短时频谱占用情况,并由此提出一种动态信道接入策略。进一步,利用软件无线电(SDR)平台实现一套跳频系统,并将其与动态频谱接入策略进行集成。使用真实的历史频谱数据评估该系统的数据吞吐能力,测试结果表明,所提方法及构建的跳频系统能有效提高机会通信能力,高效利用频谱资源。该频谱接入框架及SDR系统实现具有较强的通用性,易于集成到不同场景和频段的系统中。     

Coexistence of DTV and TV white space systems

It is foreseeable that in near future, heterogeneous TV white space (TVWS) systems will operate in underused TV bands. Potential interference between TVWS systems and digital TV (DTV) broadcast system is a major concern. These TVWS systems need to maintain from the DTV service boundary some keep‐out distances d _k, which vary depending on circumstances. This work provides a comprehensive analysis on d _k for different TVWS devices that operate on co‐ and adjacent channels, based on 2 different protection criteria for DTV service, using 4 different propagation models (each suits different propagation environment) for estimating d _k. In brief, this article contributes to the mathematical technique of determining d _k under different circumstances. On the basis of the conditions chosen for the analysis, we come up with some recommendations for d _k. Moreover, we share our opinions on some regulatory requirements for d _k. The strictness of the regulatory requirement in this matter is important because when it is appropriately set, it can actually promote further development and expansion of TVWS technologies.     

认知无线电技术在广电中的应用

介绍了认知无线电技术的发展背景和当前的研究状况,论述了发展认知无线电的重要性,讨论了认知无线电领域的几种关键技术,论述了认知无线电在广电领域的应用范围和发展前景。举例说明了广电运营商可通过认知无线电系统接入除传统电视业务之外的多种业务。     

Protection of Incumbent Services and Its Impact on Coverage of TV Band Device Networks in TV White Space

This paper presents a set of candidate regulatory requirements for TV band devices (TVBDs) in the Rep. of Korea. To guarantee the protection of incumbent services, especially digital TV (DTV) and wireless microphones, in TV frequency bands, we suggest minimum separation distances of TVBDs from the noise‐limited contour according to incumbent users and TVBD types. This paper also deals with multiple sets of separation distances of a co‐channel TVBD network from a DTV protected contour on the basis of the radio propagation characteristics of different geographic areas to make good use of TV white space (TVWS) and safely protect the DTV service. We present a low‐power transmission mode of TVBDs and the relevant separation distances for small‐cell deployment. The service coverage reduction ratio of a TVBD network is investigated in the presence of DTV interference in four geographic areas. The TVWS field verification results, conducted on the island of Jeju (Rep. of Korea), show that incumbent services operate well without harmful interference from neighboring TVBDs with the proposed separation distances.     

An integrated low power system architecture for spectrum sensing enabled cognitive radios

Continuous rise in the number of users as well as the increased requirement of bandwidth per user has created a need to use the spectrum efficiently. Cognitive radios are solutions proposed to address the problem of using the spectrum efficiently. Regulatory bodies around the world, FCC included, have introduced specifications intended for cognitive radio applications. TV White Space devices, which operate in the spectrum holes caused by transition from analog to digital transmission, were the first targeted applications for cognitive radio specifications (IEEE 802.22, ECMA-392). However, to maximize the potential of the idea of cognitive radios it is desirable to be able to sense the spectrum across a wide band and accordingly transmit ??smartly??. This paper presents a possible transceiver architecture meant for integrated solutions while providing tentative block level specifications for the proposed architecture. Existing spectrum sensing techniques are discussed and an integrated low power system architecture at the PHY level suitable for waveform-based spectrum sensing technique that utilizes co-operative spectrum sensing methods is proposed.     

An IEEE 802.22 transceiver framework and its performance analysis on software defined radio for TV white space

With rapid increase in new applications and services, there is huge demand for internet bandwidth. Several researchers around the world have found that, majority of licensed bands (mostly terrestrial TV band) are either unused or underused. These underutilized bands allocated for TV transmission are known as TV white space (TVWS). For effective utilization of TVWS, the IEEE 802.22 is proposed. The IEEE 802.22 wireless regional area network (WRAN) is the latest standard for effective utilization of TV bands. This standard is based on orthogonal frequency division multiplexing with various modulation techniques to provide different data rates. In this paper, an implementation framework for physical layer of IEEE 802.22 WRAN standard for normal mode is demonstrated and analyzed. This transceiver is implemented using the National Instruments Laboratory Virtual Instrument Engineering Workbench programming software on the National Instruments universal software radio peripheral 2952R. We have also analyzed different blocks of IEEE 802.22 based on their execution time, and identify the critical blocks of IEEE 802.22 that should be optimized for real-time applications for commercial product development and field deployments. We have also highlighted the difference between theoretical and practical performance of the considered error control codes for IEEE 802.22 specified block size. Additionally, various covariance based spectrum sensing methods are also analyzed for real-world environment.     

Analysis of QoS Provisioning in Cognitive Radio Networks: A Case Study

Dynamic Spectrum Access (DSA) is a promising solution to the problem of spectrum inefficiency. Based on Cognitive Radio (CR) technology, DSA allows a CR device to opportunistically access unused or less crowded spectrum while ensuring protection for the incumbents. Though DSA shows great potential to enhance network performance, its adverse side-effects on application QoS may limit its usefulness. QoS support in a DSA-based network is not trivial due to the fact that in addition to unfavorable characteristics of the wireless medium, the secondary devices must face additional interference and interruption from incumbents that have to be protected. In this paper, we present a case study of key DSA protocol characteristics necessary for QoS provisioning. Specifically, we consider a personal/portable CR system that supports high quality multimedia (including HDTV) streaming over UHF frequency bands. We model and evaluate the QoS-oriented CR system together with the underlying QoS-Provisioned DSA Protocol (called QPDP) through extensive simulations. The results show the effectiveness of the proposed DSA QoS provisioning approach in sustaining high levels of QoS, e.g., supporting HDTV streaming in TV bands. This outcome is significant as FCC has recently approved UHF bands for unlicensed operations in the USA, and various DSA-based CR systems are being actively designed by the wireless industry. The techniques outlined in this work can be generalized to be applicable to generic DSA design in various spectrum bands.     

广播电视台技术中心IT化转型发展的思考

党的十七届六中全会提出,“发展现代传播体系。推进电信网、广电网、互联网三网融合,建设国家新媒体集成播控平台,创新业务形态。推进文化科技创新。”本文在其他学者对于广电技术及其管理运营与发展趋势等的研究基础之上,以SMG技术运营中心为例,对于广播电视台技术中心IT化转型发展过程中所面临的矛盾问题、职能定位、组织结构等问题进行讨论,对于广播电视台技术中心IT化转型发展提出基本建议与策略。     

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.

     

White broadband power line communication: Exploiting the TVWS for indoor multimedia smart grid applications

Balancing the energy production and consumption in smart grids influences the integration of new high‐speed communication technologies, to support monitoring services. Sharing the television white space (TVWS) spectrum between licensed and unlicensed users has been recommended by the federal communications commission in 2004. Federal communications commission allows the unlicensed users to access both the very high frequency (VHF) and the ultra‐high frequency channels in TVWS. On the other hand, broadband power line communication (BPLC) has drawn the researchers' attention over the last decade as a high‐speed indoor communication technology. One application for BPLC is the multimedia service in smart grid applications. In this article, we present an overview of the standards, regulations, and channel models of the TVWS and BPLC as 2 separate technologies. We then propose the deployment of the BPLC technology in the TVWS VHF band to build up the white BPLC (WBPLC) communication systems. The WBPLC incorporates the TVWS and the BPLC technologies into multiple‐input multiple‐output communication systems in the VHF band. The simulation results show significant throughput enhancement in the WBPLC over both the TVWS and BPLC communication systems, indicating that WBPLC can be a promising technology to serve the growing needs for the multimedia services in future smart grids.     

A Cross-Layer Cognitive Radio-Based Framework and CAC Scheme in WiMAX Networks

Quality of service (QoS) provisioning is an important issue in the deployment of broadband wireless access networks with real-time and non-real-time traffic integration. The Connection Admission Control (CAC) operation is essential to guarantee the QoS requirements of connections while achieving system efficiency. Cognitive Radio is seen as a solution to the current low usage of the radio spectrum and the problem of the fixed spectrum allocation. In this paper, we propose a novel cross-layer Cognitive Radio-based QoS support framework and Cognitive Radio-based CAC scheme in WiMAX point-to-multipoint systems. By using a cross-layer approach, the proposed solution can intelligently explore unused spectrums and spread to non-active spectrums to improve the capacity of the system significantly and provide QoS guaranteed service to real-time traffic. A queueing analytical modeling for the WiAMX system has been carried out. The key system performance parameters are obtained based on the queueing analytical model theoretically. Extensive simulation experiments have been carried out to evaluate the performance of our proposal. The simulation results show that our proposed solution can expand the capacity of WiMAX systems up to two times while providing QoS guaranteed service to real-time and non-real-time traffics.     

A dynamic spectrum access network based on cognitive radio

Dynamic spectrum access technologies based on Cognitive Radio (CR) is under intensive research carried out by the wireless communication society and is expected to solve the problem of spectrum scarcity. However, most enabling technologies related to dynamic spectrum access are considered individually. In this paper, we consider these key technologies jointly and introduce a new implementation scheme for a Dynamic Spectrum Access Network Based on Cognitive Radio (DSAN-BCR). We start with a flexible hardware platform for DSAN-BCR, as well as a flexible protocol structure that dominates the operation of DSAN-BCR. We then focus on the state of the art of key technologies such as spectrum sensing, spectrum resources management, dynamic spectrum access, and routing that are below the network layer in DSAN-BCR, as well as the development of technologies related to higher layers. Last but not the least, we analyze the challenges confronted by these mentioned technologies in DSAN-BCR, and give the perspectives on the future development of these technologies. The DSAN-BCR introduced is expected to provide a system level guidance to alleviate the problem of spectrum scarcity.     

On Detecting Spectrum Opportunities for Cognitive Vehicular Networks in the TV White Space

We overview the challenges related to spectrum awareness in the vehicular environment, with emphasis on awareness in the TV licensed band. In the vehicular environment the cognitive radio can help to: 1) satisfy capacity demand for Intelligent Transportation Systems (ITS) applications; and 2) offload time insensitive applications from the ITS dedicated spectrum. However, using simple propagation models we show that neither sensing, nor geolocation database lookup alone can provide sufficient incumbent protection. Collaboration among the sensors to take advantage of spatial diversity is difficult due to the rapidly changing network topology. Nevertheless, mobility provides the opportunity to use time diversity at each sensor. We also discuss the influence of sensing subsystem design on the vehicular cognitive network medium access (MAC) sublayer. Whenever appropriate, we evaluate applicability of the requirements imposed by the Federal Communications Commission (FCC) and the IEEE 802.22 standard to the cognitive vehicular networks.     

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.     

认知电力物联网电视频谱感知方法

基于认知无线电(CR)技术的电力物联网(IOTIPS)通过频谱感知实现对空闲授权频段的接入,可以有效提高频谱利用率,由于电力物联网的通信环境复杂,载波频偏无法避免,提出一种适用于电视频段授权用户数字地面多媒体广播(DT-MB)的复合相关检测算法,可以在大载波频偏条件下保持对DTMB信号稳定的检测性能,提升了通信网络的可靠性.同时基于复合相关检测的协作频谱感知,可以有效降低隐藏终端对感知性能的不利影响,提高认知电力物联网的通信效率.     

Towards trustworthy collaboration in spectrum sensing for ad hoc cognitive radio networks

Cognitive radio networks (CRN) make use of dynamic spectrum access to communicate opportunistically in frequency bands otherwise licensed to incumbent primary users such as TV broadcast. To prevent interference to primary users it is vital for secondary users in CRNs to conduct accurate spectrum sensing, which is especially challenging when the transmission range of primary users is shorter compared to the size of the CRN. This task becomes even more challenging in the presence of malicious secondary users that launch spectrum sensing data falsification (SSDF) attacks by providing false spectrum reports. Existing solutions to detect such malicious behaviors cannot be utilized in scenarios where the transmission range of primary users is limited within a small sub-region of the CRN. In this paper, we present a framework for trustworthy collaboration in spectrum sensing for ad hoc CRNs. This framework incorporates a semi-supervised spatio-spectral anomaly/outlier detection system and a reputation system, both designed to detect byzantine attacks in the form of SSDF from malicious nodes within the CRN. The framework guarantees protection of incumbent primary users’ communication rights while at the same time making optimal use of the spectrum when it is not used by primary users. Simulation carried out under typical network conditions and attack scenarios shows that our proposed framework can achieve spectrum decision accuracy up to 99.3 % and detect malicious nodes up to 98 % of the time.     

Integrating dynamic spectrum access and device‐to‐device via cloud radio access networks and cognitive radio

Dynamic Spectrum Access (DSA) can be integrated with Device‐to‐Device (D2D) communications to enable the exploitation of unused spectrum portions and to address the spectrum scarcity problem. Spectrum management mechanisms integrated into DSA and D2D allow low‐power communications between User Equipments without interfering with licensed primary users. However, these mechanisms tend to be energy and processing intensive, being unfeasible to implement in User Equipments with strict battery and processing limitations. On the other hand, Cloud Radio Access Networks already leverage the virtually unlimited computing capacity of clouds for baseband processing functions. Thus, in this article, we propose the Cognitive Radio Device‐to‐Device (CRD2D) approach aiming to offload spectrum management functionality to the cloud taking advantage of Cloud Radio Access Networks architecture to support the integration of DSA and D2D.