An implementation of collaborative adaptation of cognitive radio parameters using an ontology and policy based approach

The main objective of this paper is to demonstrate the feasibility of the ontology and policy based approach to realize collaborative, automatic adaptation of cognitive radio parameters in the transmitter and receiver. The ontology and policy based approach features the following three aspects. First, all the internal and external information of the radio is represented in the Web Ontology Language (OWL). The transmitter and receiver share the same core ontology and thus can communicate with each other using this common language. Second, the policy rules are written in a declarative form and interpreted by a reasoner. Third, in order to exchange the OWL represented information between the radios, we adopt a more flexible signaling plan, which is different than the conventional protocol-predefined signaling plan, i.e. the control messages are added to an extendable payload, rather than embedded in the predefined protocol-dependent header or trailer. The paper discusses the implementation and shows some examples of radio behaviors resulting from the execution of the policies.     

入侵检测系统攻击描述语言研究与分析

为了更好的利用攻击描述语言描述网络攻击行为并设计出一种较为完善的语言,对几种比较典型的语言进行了研究,分析了它们各自的设计特点,并通过一个具体的网络攻击实例进行对比分析,从中分析其优缺点,最后总结了完善的描述语言应该具备的特点和功能,讨论了描述语言的发展过程和方向。     

TDOA定位系统的无线电监测网工程应用探讨

随着无线电监测事业的发展,在如何扩大无线电监测网的覆盖范围,提升监测能力等方面越来越得到无线电监测人员的重视,文中主要探讨了TDOA无源定位方法在无线电监测网中的应用问题。本文首先从TDOA定位原理入手,介绍了到达时间差估计的相关函数获取法,比较了双曲线方程组的两种求解算法,由此分析TDOA定位的关键技术与定位优点。文中还以云南省无线电监测网为例,从定位流程出发,进行系统设计,探讨TDOA定位系统的工程应用,进而提出能全面提升监测网监测能力的TDOA定位方案。     

An executable meta-model of a hierarchical and distributed architecture management for cognitive radio equipments

A cognitive radio (CR) equipment is a radio device that supports the smart facilities offered by future cognitive networks. Even if several categories of equipments exist (terminal, base station, smart PDA, etc.), with their different processing capabilities (and associated cost or power consumption), this means that apart from the usual radio signal processing elements, these equipments have to integrate also a set of new capabilities for the CR support; this implies not only radio adaptation and sensing capabilities. We assert that it is necessary to add some management facilities for that, and we propose here an architecture management to be inserted inside CR equipments named thereafter Hierarchical and Distributed Cognitive Architecture Management (HDCRAM). This approach is based upon a Hierarchical and Distributed Reconfiguration Management (HDReM), which is derived from our previous research on software-defined radio. The HDCRAM extends the HDReM towards CR while adding new management features, in order to support sensing and decision-making facilities. It consists in the combination of one Cognitive Radio Management Unit (CRMU) with each reconfiguration management unit distributed in the equipment. Each of these CRMU is in charge of the capture, the interpretation, and the decision making according to its own goals. In this cognitive radio context, the term “decision” refers to the adaptation of the radio parameters to the equipment environment. This paper details the management functionality and structure of the HDCRAM. Moreover, this architecture has also been modeled with a meta-programming language based on UML. The first goal is to propose a comprehensive specification of the CR management of future CR equipments. Beyond this objective, we have also derived a simulator from the obtained meta-model, which gives the opportunity to specify CR needs and play a wide variety of scenarios in order to validate the CR design. The example of a Blind Standard Recognition CR scenario illustrates the relevance of this approach.     

基于循环平稳特征的频谱感知算法概述

传统的静态频谱资源分配分配政策导致频谱利用率低下,为解决这一问题,人们提出利用认知无线电技术实现动态频谱接入.频谱感知是认知无线电的关键技术,循环平稳特征检测算法是3种常见频谱检测算法之一,但是该算法存在各种不足.首先简要介绍认知无线电的背景和概念,然后详细介绍了循环平稳特征检测算法,以及目前提出的各种基于循环平稳特征检测的增强算法,分析了各自的原理及其优缺点.     

无线单片机汇编与C语言比较和全速软件断点

无线单片机C语言和汇编语言各有所长。无线单片机内存容量极小，而且不同型无线单片机收／发硬件结构各不相同，因此C语言时常表现出很多不足之处（如C语言良好的可移植性在不同无线单片机间并不存在）。首先对无线单片机的汇编语言和C语言进行比较，说明汇编语言具有相当大的优势。接着提出改进汇编语言可交叠式模块编程方法。最后考虑至今软件断点都是极慢速的（慢100倍）；现有的硬件断点方法需要很贵的硬件来支持，成本很高，为此提出低成本和高速的全速软件断点方法。采用CPLD芯片实现的nRF24E1外围电路，完成键盘扫描，显示，收发控制和信息存储。多次并以nRF24E1收发的实验和调试验证了上述方法的正确性。     

Cyclostationary Signatures in Practical Cognitive Radio Applications

We define a cyclostationary signature as a feature which may be intentionally embedded in a digital communications signal, detected through cyclostationary analysis and used as a unique identifier. The purpose of this paper is to demonstrate how cyclostationary signatures can be exploited to overcome a number of the challenges associated with network coordination in emerging cognitive radio applications and spectrum sharing regimes. In particular we show their uses for signal detection, network identification and rendezvous and discuss these in the context of dynamic spectrum access. We present a theoretical discussion followed by application-oriented examples of the cyclostationary signatures used in practical cognitive radio and dynamic spectrum usage scenarios. We focus on orthogonal frequency division multiplexing (OFDM) based systems and present an analysis of a transceiver implementation employing these techniques developed on a cognitive radio test platform.     

LTE‐Based Passive Bistatic Radar System for Detection of Ground‐Moving Targets

Use of a passive bistatic radar (PBR) system in the surveillance or monitoring of an area has its advantages. For example, a PBR system is able to utilize any available signal of opportunity (for example, broadcasting, communication, or radio navigation signals) for the purposes of surveillance. With this in mind, there are potentially many research areas to be explored; in particular, the capability of signals from existing and future communication systems, such as 4G and 5G. Long‐Term Evolution (LTE) is the world's most current communication system. Given this fact, this paper presents the latest feasibility studies and experimental results from using LTE signals in PBR applications. Details are provided about aspects such as signal characteristics, experimental configurations, and SNR studies. Six experimental scenarios are carried out to investigate the detection performance of our proposed system on ground‐moving targets. The ability to detect is demonstrated through use of the cross‐ambiguity function. The detection results suggest that LTE signals are suitable as a source signal for PBR.     

Diffusing-CRN k-means: an improved k-means clustering algorithm applied in cognitive radio ad hoc networks

With increasing demand of new wireless applications and increasing number of wireless user’s, problem of spectrum scarcity arises. In this context, cognitive radio supports dynamic spectrum access to address spectrum scarcity problem. Cognitive radio defined the cognitive radio nodes by their ability to intelligently adapt the environment to achieve specific objectives through advanced techniques. The variance of channel availability for cognitive radio nodes degrades connectivity and robustness of this type of network; in this case the use of clustering is an effective approach to meet this challenge. Indeed, the geographical areas are homogeneous in terms of type of radio spectrum, radio resources are better allocated by grouping cognitive radio nodes per cluster. Clustering is interesting to effectively manage the spectrum or routing in cognitive radio ad hoc networks. In this paper, we aim to improve connectivity and cooperativeness of cognitive radio nodes based on the improvement of the k-means algorithm. Our proposed algorithm is applied in cognitive radio ad hoc networks. The obtained results in terms of exchange messages and execution time show the feasibility of our algorithm to form clusters in order to improve connectivity and cooperativeness of cognitive radio nodes in the context of cognitive radio ad hoc networks.     

基于人工神经网络的认知无线电频谱感知研究

认知无线电是一种新的智能无线通信技术,通过感知周围环境特征,并采用构建理解的方法进行学习。频谱感知技术是认知无线电系统设计的重要组成部分,本文提出了基于人工神经网络（ANN）算法的认知无线电感知技术。由于单用户检测存在检测精度不高的问题,本文通过采用ANN的自主学习能力设计频谱检测分类器,对以往分类器所收集的环境信息进行学习和储存,从而对以后感知新的环境时起到先验信息的作用,能快速准确地判决出主用户的存在与否。通过与能量检测和循环平稳检测对不同调制方式信号进行信号识别仿真实验可以看出,相比原有的单用户频谱检测技术,ANN具有更高的有效性和可靠性。     

射电望远镜天线的指向精度测量系统设计

指向精度是衡量大口径射电望远镜天线电轴指向准确度的重要指标,如何准确地测量出天线的指向精度对使用者而言尤为重要。针对射电天文望远镜的工作特点,提出了采用射电星作为发射源进行天线指向精度测量的方法,以方位轴为例介绍了测量基本原理,根据测量需要对系统软硬件进行了设计,对实际测量和处理过程进行了描述,给出了测量结果和分析。结果表明该方法可以快捷、准确地测出天线在全天区的指向精度。     

Dynamic spectrum access — concepts and future architectures

New trends and developments in radio technology are enhancing the future capabilities of devices to access electromagnetic spectrum using the full range of dimensions associated with the spectrum. This increased capability, together with current developments towards liberalisation of spectrum management regulations, are opening up opportunities to exploit an emerging paradigm in wireless communications and networking known as dynamic spectrum access (DSA). The key characteristic of DSA networks is their ability to exploit knowledge of their electromagnetic environment to adapt their operation and access to spectrum. Their key promise is that they open the possibility of highly efficient (re)use of spectrum. This paper introduces the main concepts behind DSA, reviews the proposed architectures for future DSA systems, and outlines some of the key research challenges associated with this new paradigm. Particular emphasis will be given to autonomous cognitive radio DSA.     

一种新的智能无线技术——认知无线电技术

认知无线电技术(CR——cognitiveradio)是软件无线电技术的演化,是一种新的智能无线通信技术。它可以感知到无线电传输的环境特征,通过无线电知识描述语言与通信网络进行智能交流,来调整其传输参数,使系统的无线规则满足用户通信最佳性能的需求。文章对认知无线电技术进行了较详细介绍,包括其概念、通信特点、工作过程和部分关键技术等,最后指出了未来认知无线电技术的若干重要发展方向。     

A Software Radio Implementation of Centralized MAC Protocol for Cognitive Radio Networks

In the past decade the cognitive radio paradigm has received great attention from academia and industry as a promising approach to solve the spectrum shortage problem. In spite of the intense research activity in the field of cognitive radio, we still register a limited number of network implementations based upon the cognitive radio principles. In this work we present the design and implementation of a proprietary medium access control protocol that we have conjectured using ECMA-392 standard as reference. In the proposed design, the network uses an out-of-band cognitive control channel (CCC) for network management operations. The main contributions of this paper are: (1) a working prototype of a centralized cognitive network implemented in the platform provided by the universal software radio peripheral and GNU Radio software; (2) the presentation of significant data acquired during the field test of our prototype such as average network reconfiguration delay when the CCC is jammed by the primary user and the capability of the cognitive network to reconstruct channel occupancy/vacancy by means of distributed spectrum sensing. The prototype has been designed to operate in the 375–445 MHz frequency bands for a potential application in public safety ad-hoc networks.     

A survey of spectrum sensing algorithms for cognitive radio applications

The spectrum sensing problem has gained new aspects with cognitive radio and opportunistic spectrum access concepts. It is one of the most challenging issues in cognitive radio systems. In this paper, a survey of spectrum sensing methodologies for cognitive radio is presented. Various aspects of spectrum sensing problem are studied from a cognitive radio perspective and multi-dimensional spectrum sensing concept is introduced. Challenges associated with spectrum sensing are given and enabling spectrum sensing methods are reviewed. The paper explains the cooperative sensing concept and its various forms. External sensing algorithms and other alternative sensing methods are discussed. Furthermore, statistical modeling of network traffic and utilization of these models for prediction of primary user behavior is studied. Finally, sensing features of some current wireless standards are given.     

Adaptability and Configurability in Cognitive Radio Design on Small Form Factor Software Radio Platform

The recent advances in cognitive radio technology based on software defined radio platforms have extended the capabilities of wireless communication systems. The unique ability of cognitive radios to alter their communication protocols to meet changing system demands make them great candidates for wireless applications that are difficult to implement using conventional wireless terminals. Small form factor platforms make cognitive radio portable and easy to deploy. This paper discusses the design and implementation methodology to build a cognitive radio on small form factor platform with heterogeneous processing architecture. The result of this discussion is a configurable wireless transceiver that features two important concepts of cognitive radio, namely configurability and adaptability.     

一种支持变化性的构件模型JBCOM/E

在基于构件的软件开发中,构件模型是基础,领域变化性是关键因素之一.为此,本文在原有构件模型的基础上,提出了抽象构件的概念,使之能对一族具有领域共性和变化性的构件进行定义与描述.文中就抽象构件的定义、规约语言描述以及相应的构件组装和构件管理等问题进行了讨论,定义了一种支持变化性的构件模型JBCOM/E,并给出了一个应用实例-青鸟POS领域平台.     

频谱空穴检测及其仿真

感知无线电接收机为了感知其周围的无线电环境,首要的工作就是对其周围存在的信号进行检测。本文针对感知无线电系统中最为关键的频谱空穴检测技术进行了研究。通过对3种信号检测技术的比较,选择循环平稳特征检测法作为感知无线频谱的方法并对该方法进行了仿真。此外．对控制实体根据频谱感知的结果、从频谱中检测出频谱空穴区域的功能、以及感知无线电接收机与感知无线电发射机进行协调的功能也进行了仿真。     

Spectrum sensing in cognitive radio networks: requirements, challenges and design trade-offs [cognitive radio communications]

Opportunistic unlicensed access to the (temporarily) unused frequency bands across the licensed radio spectrum is currently being investigated as a means to increase the efficiency of spectrum usage. Such opportunistic access calls for implementation of safeguards so that ongoing licensed operations are not compromised. Among different candidates, sensing-based access, where the unlicensed users transmit if they sense the licensed band to be free, is particularly appealing due to its low deployment cost and its compatibility with the legacy licensed systems. The ability to reliably and autonomously identify unused frequency bands is envisaged as one of the main functionalities of cognitive radios. In this article we provide an overview of the regulatory requirements and major challenges associated with the practical implementation of spectrum sensing functionality in cognitive radio systems. Furthermore, we outline different design trade-offs that have to be made in order to enhance various aspects of the system's performance.     

基于认知无线电技术的导航定位系统设计

认知无线电技术是认知科学和信息科学相结合形成的一个崭新的学科,是一种具有频谱感知和智能决策能力的软件无线电。本文对传统导航定位系统的接收结构进行了分析,阐述了基于认知无线电技术进行导航信号识别的理论基础,构建了一种认知导航定位系统接收结构。