Architecture and enablers for optimized radio resource usage in heterogeneous wireless access networks: The IEEE 1900.4 Working Group

Over the past decade or so, the wireless industry has undergone many significant changes. Radio systems have moved toward forming heterogeneous wireless networks: collaborations of multiple radio access networks, which in some cases operate different radio access technologies, such as second- and third-generation cellular RATs, IEEE 802.x wireless standards, and so on. On the other hand, multimode reconfigurable user devices with the ability to choose among various supported RATs have become a reality, and devices and networks with dynamic spectrum access capabilities, allowing real-time sharing of spectrum resource usage among different systems, are expected to be a part of the future radio eco-space. As a result of these changes, there is a need to develop a standard that addresses the requirements and leverages the opportunities posed by such a versatile radio environment. To this end, IEEE 1900.4 aims to standardize the overall system architecture and information exchange between the network and mobile devices, which will allow these elements to optimally choose from available radio resources. In other words, the standard facilitates the distributed dynamic optimization of the usage of spectrum offered by the heterogeneous wireless network, relying on a collaborative information exchange between networks and mobile devices, thereby acting as a common means to improve overall composite capacity and quality of service for the served networks. This article provides a snapshot of IEEE P1900.4 in its current form, covering the scope and purpose of the standard, reference use cases for which the standard is applicable, its system and functional architectures, and finally, the information model for its main interfaces.     

Opportunistic channel allocation decision making in cognitive radio communications

The global spread of wireless devices with mobile Internet access and the increasing demand of multimedia‐based applications are fueling the need for wireless broadband networks. IEEE 802.16 and 802.20 are standards for a broadband wireless access with promising cognitive radio features to support mobile Internet access. However, because of the fast changing radio environment and the demand for dynamic spectrum allocation mechanisms, these standards must continuously readjust different radio parameters. The cognitive radio makes decisions based on its built‐in inference engine, which also in time can adapt itself to different situations through the process of learning from experience. In this paper we present an automated opportunistic decision making and learning process for cognitive radio based on uncertainty reasoning algorithms. This novel approach is well suited in fast changing wireless environments with vague, incomplete, and heterogeneous information. Theory and simulations prove that decision making and learning of the cognitive radio based on the proposed approach cope with the changes in the radio environment. In this work we use fuzzy logic for the learning and decision making of the cognitive radio. Simulation also show that our approach provides accurate and precise decisions on allocating spectrum to mobile Internet users even in fast varying radio conditions. Copyright © 2012 John Wiley & Sons, Ltd.     

DS-UWB在家庭网络中的应用

家庭网络可以在家庭区域内．融合各类数字电子设备，将业务和功能集于一体．为家庭用户打造无所不在的数字化个性空同。在IEEE1394b纂础上，家庭网络无线系统引入频谱利用率高效的超宽带（UWB）脉冲无线电技术，可提供典有灵活性和移动性的宽带无线接入。基于直扩序列超宽带（DS—UWB）直接序列无线脉冲高宽带传输技术的家庭网络能连接众多电子娱乐设备，无隙缝地扩展家庭无线通信环境，提供互操作功能和多媒体业务。     

Algorithms for Wireless Communication Systems: A Power-Efficiency Perspective

Within the last five years, there has been a cultural shift from wired landlocked connectivity to pervasive wireless information access. Most emerging mobile devices are now equipped with some form of embedded wireless radio. The expectations of high data rates and increased battery longevity have put tremendous pressure on all aspects of wireless system design.The goal of our projects at the Center for Multimedia Communication at Rice is to develop powerefficient wireless enabled mobile devices. In this paper, we will consider the control and coding issues to increase active access time of mobile communication devices. In particular, we develop scheduling algorithms which adaptively change the transmission power and rate, based on both the transmission queue backlog and the channel conditions. Thepacket level control algorithms exploit burstiness of data streams and channel variations to trade packet queuing delay with the average transmit power. The wide range of data rates dictated by the scheduler and our power efficiency objective is effectively met by a multi-antenna transceiver. We design non-coherent space-time codes for high mobile speeds, and space-time feedback strategies for low mobility applications. This paper highlights some of the proposed methods and presents some preliminary results. This revised version was published online in August 2006 with corrections to the Cover Date.     

无线接入性指标优化及分析

本文从无线接入性计算公式、提升无线接入性的计算方法、参数调整的验证等几个方面来提升优化无线接入性,为用户提高更高质量的网络服务。     

Fixed wireless access: An overview

This paper is intended to provide an overview of wireless local loop (wll) today, i.e. the access to final customers through radio systems; this domain covers a wide range of applications, from telephony in rural areas or in developing countries to broadband access offered by alternate carriers in developed countries. A number of technical concepts are common to all these applications (radio transmission, radio access control, management of active devices in the distribution network, propagation, spectrum issues), but actual products and services are very different - from cheap, well-proven DECT equipment for basic telephony to expensive broadband LMDS prototypes for 2 Mbit/s (or ? ? 64 kbit/s) services and fast internet access.     

DCR‐MAC: distributed cognitive radio MAC protocol for wireless ad hoc networks

The MAC protocol for a cognitive radio network should allow access to unused spectrum holes without (or with minimal) interference to incumbent system devices. To achieve this main goal, in this paper a distributed cognitive radio MAC (DCR‐MAC) protocol is proposed for wireless ad hoc networks that provides for the detection and protection of incumbent systems around the communication pair. DCR‐MAC operates over a separate common control channel and multiple data channels; hence, it is able to deal with dynamics of resource availability effectively in cognitive networks. A new type of hidden node problem is introduced that focuses on possible signal collisions between incumbent devices and cognitive radio ad hoc devices. To this end, a simple and efficient sensing information exchange mechanism between neighbor nodes with little overhead is proposed. In DCR‐MAC, each ad hoc node maintains a channel status table with explicit and implicit channel sensing methods. Before a data transmission, to select an optimal data channel, a reactive neighbor information exchange is carried out. Simulation results show that the proposed distributed cognitive radio MAC protocol can greatly reduce interference to the neighbor incumbent devices. A higher number of neighbor nodes leads to better protection of incumbent devices. Copyright © 2008 John Wiley & Sons, Ltd.     

OS-MAC: An Efficient MAC Protocol for Spectrum-Agile Wireless Networks

Wireless networks and devices have been rapidly gaining popularity over their wired counterparts. This popularity, in turn, has been generating an explosive and ever-increasing demand for, and hence creating a shortage of, the radio spectrum. Existing studies indicate that this foreseen spectrum shortage is not so much due to the scarcity of the radio spectrum, but due to the inefficiency of current spectrum access methods, thus leaving spectrum opportunities along both the time and the frequency dimensions that wireless devices can exploit. Fortunately, recent technological advances have made it possible to build software-defined radios (SDRs) which, unlike traditional radios, can switch from one frequency band to another at little or no cost. We propose a MAC protocol, called Opportunistic Spectrum MAC (OS-MAC), for wireless networks equipped with cognitive radios like SDRs. OS-MAC (1) adaptively and dynamically seeks and exploits opportunities in both licensed and unlicensed spectra and along both the time and the frequency dimensions; (2) accesses and shares spectrum among different unlicensed and licensed users; and (3) coordinates with other unlicensed users for better spectrum utilization. Using extensive simulation, OS-MAC is shown to be far more effective than current access protocols from both the network's and the user's perspectives. By comparing its performance with an Ideal-MAC protocol, OS-MAC is also shown to not only outperform current access protocols, but also achieve performance very close to that obtainable under the Ideal-MAC protocol.     

Cognitive Wireless Communication Networks (Hossian, E. and Bhargava, V.; 2007) [Book Review]

?Cognitive radio? is emerging as a promising technology to cope with the spectrum scarcity as well as the spectrum underutilization problem in the next generation wireless communications systems. This book, Cognitive Wireless Communication Networks, edited by Ekram Hossain and Vijay Bhargava, puts together a rich set of research articles featuring recent advances in theory, design, and analysis of cognitive wireless communication networks. The book consists of 15 invited articles from distinguished researchers in this area, which cover a wide range of topics related to the cognitive radio technology. In particular, the topics covered in this book include fundamental challenges and issues in designing cognitive radio systems, information-theoretic analysis of cognitive radio systems, spectrum sensing and co-existence issues, adaptive physical layer protocols and link adaptation techniques for cognitive radio, orthogonal frequency division multiple access (OFDM) and ultra wide band (UWB)- based cognitive radio, different techniques for spectrum access by distributed cognitive radio, cognitive medium access control (MAC) protocols, decentralized learning-based dynamic spectrum access methods, and microeconomic models for spectrum management in cognitive radio.     

基于软件无线电的无线设备指纹识别

无线局域网由于其开放的信道环境和传统的密钥身份验证机制,安全问题十分严峻。通过射频指纹识别技术,提取无线设备硬件特征进行身份验证,能够大大提高无线网络安全性。本文基于通用软件无线电外设(USRP)和GNU Radio开源平台,提取IEEE 802.11a/g信号载波频偏作为指纹,结合神经网络分类器进行识别。首先接收信号并提取每帧信号载波频偏,然后训练神经网络分类器,最后利用此分类器对无线设备进行识别。在办公室和体育馆2种典型室内环境进行无线设备个体识别实验,识别率均大于90%。实验结果说明,基于软件无线电提取信号载波频偏可以识别出不同的无线设备,检测出非法设备接入,能够提高无线网络安全性。     

Development of Ka-band 100-W peak power MMPM

Various types of millimeter-wave radio systems are being developed for strong broadband service demands such as fixed wireless access, local multipoint distribution service, as well as satellite communications. In each system, the higher data rate transmission requires more powerful amplification devices. This paper describes the development of a Ka-band 100-W peak power millimeter-wave power module, traveling wave tube-based millimeter-wave amplification module, used for millimeter-wave fixed wireless access base stations and Ka-band satellite Internet terminals.     

Location Estimation Based on Semi-Supervised Locally Linear Embedding (SSLLE) Approach for Indoor Wireless Networks

Location aware computing is popularized and location information use has important due to huge application of mobile computing devices and local area wireless networks. In this paper, we have proposed a method based on Semi-supervised Locally Linear Embedding for indoor wireless networks. Previous methods for location estimation in indoor wireless networks require a large amount of labeled data for learning the radio map. However, labeled instances are often difficult, expensive, or time consuming to obtain, as they require great efforts, meanwhile unlabeled data may be relatively easy to collect. So, the use of semi-supervised learning is more feasible. In the experiment 101 access points (APs) have been deployed so, the RSS vector received by the mobile station has large dimensions (i.e. 101). At first, we use Locally Linear Embedding to reduce the dimensions of data, and then we use semi-supervised learning algorithm to learn the radio map. The algorithm performs nonlinear mapping between the received signal strengths from nearby access points and the user??s location. It is shown that the proposed scheme has the advantage of robustness and scalability, and is easy in training and implementation. In addition, the scheme exhibits superior performance in the nonline-of-sight (NLOS) situation. Experimental results are presented to demonstrate the feasibility of the proposed SSLLE algorithm.     

WiMAX无线网络规划方法

随着宽带无线接入技术的发展,WiMAX无线网络的应用越来越广泛,因此WiMAX网络的规划方法和手段受到越来越多的重视.本文讨论了 WiMAX无线网络在规划中引入的新问题,介绍了WiMAX无线网络规划流程和方法,阐述了规划中需重点考虑的问题.     

Vertical Handover Solutions Over LTE-Advanced Wireless Networks: An Overview

The convergence of multitude radio access networks forming a cluster of seamless heterogeneous wireless environment has made the wireless communication industry meet the paradigm of always best connected, where various mobile devices are able to access numerous types of applications and services. However, achieving such landmarks could not be possible without difficulties which this paper tries to highlight some of the technical challenges underlying seamless vertical handover. It provides a general overview of the mobility management process including a brief on multi-homing mobility protocol and focuses on vertical handover decision making techniques, hi ghlighting some radio interface standar and analysed some handover approaches. The paper proposes fast intelligent inter-layer network selection as a new handover approach to select the best network among the candidate networks, where Quality of Service, handover delay and improved data bit rates are set to be achieved.     

Evaluation of signalling loads in a cognitive network management architecture

Future networks will need to accommodate a significantly augmented user demand, mainly stemming from the wireless and mobile domains. In general, the emerging radio landscape will comprise multiple, collaborating radio access networks (RANs) able to operate a plethora of diverse radio access technologies (RATs), variant types of mobile terminals (MTs), with the ability to choose among various supported RANs/RATs and, in addition, both devices and networks with dynamic spectrum access capabilities that allow the sharing and/or optimization of spectrum usage among different systems. The above will stress network operators for developing mechanisms to confront the challenges and to leverage the opportunities posed by such a versatile radio environment. In particular, the situation calls for adaptive and flexible management paradigms that are able to dynamically manage network elements and terminals, thus ensuring the great availability and efficient usage of spectrum and other radio resources. Framed within the above, this paper considers a cognitive network management architecture, which is destined for optimized management of future wireless networks operating in versatile radio environments, and presents a performance evaluation methodology, which was set up for measuring the signalling loads that the operation of the architecture will bring to the managed network. The methodology is analytically described, and useful results with respect to the signalling load produced for management signalling purposes in an indicative scenario are presented and analysed. Copyright © 2011 John Wiley & Sons, Ltd.     

Improving Spatial Reuse in Multihop Wireless Networks - A Survey

In multihop wireless ad-hoc networks, the medium access control (MAC) protocol plays a key role in coordinating the access to the shared medium among wireless nodes. Currently, the distributed coordination function (DCF) of the IEEE 802.11 is the dominant MAC protocol for both wireless LANs and wireless multihop ad hoc environment due to its simple implementation and distributed nature. The current access method of the IEEE 802.11 does not make efficient use of the shared channel due to its conservative approach in assessing the level of interference; this in turn affects the spatial reuse of the limited radio resources and highly affect the achieved throughput of a multihop wireless network. This paper surveys various methods that have been proposed in order to enhance the channel utilization by improving the spatial reuse.     

Radio Network Aggregation for 5G Mobile Terminals in Heterogeneous Wireless and Mobile Networks

This paper provides a novel design concept for advanced mobile multi interface terminals with radio network aggregation capability and enhanced quality of service (QoS) provisioning for multimedia services (voice, video and data) in heterogeneous wireless and mobile networks. A new module is established which provides the best QoS and lowest cost for any given multimedia service by using simultaneously all available wireless and mobile access networks for a given traffic flow. This novel adaptive QoS module with adaptive QoS routing algorithm is called advanced QoS routing algorithm (AQoSRA), which is defined independently from any existing and future radio access technology. The performance of our proposal is evaluated using simulations and analysis with multi-interface mobile stations with AQoSRA within, carrying multimedia traffic in heterogeneous mobile and wireless environment with coexistence of multiple Radio Access Technologies, such as 3G, 4G as well as future 5G radio access networks. The analysis of the proposed framework for radio networks aggregation in advanced mobile terminals has shown overall better performances regarding the achievable throughput and multimedia access probability in heterogeneous wireless and mobile environment.     

Always-best-served music distribution for nomadic users over heterogeneous networks

The distribution of online music has played a key role in driving the digital multimedia entertainment business to the pervasive extent we know today. The digital music revolution was substantially fueled by the invention of new online distribution models, such as P2P file sharing and online music libraries containing over one million songs in a pay-per-listen fashion. In this context, a new generation of devices that seamlessly integrate multiple radio access technologies is quickly emerging into a market for handheld devices. These devices contributes to the spread of ubiquitous multimedia for everywhere entertainment, and also strongly influence music consumer habits. New music distribution models be implemented to offer the user mobile services based on integrated wired/wireless infrastructures. Novel services allows users to establish or negotiate a music download considering a complex set of access selection criteria, thereby accessing music in the best possible way. The user, moving from a music shower that distributes digital music contents to a 3G wireless entry point, could also decide to nomadically change the download and playout device. An individual who is entering a car while downloading through a cell phone continues the download using the car radio, and finally end the file transfer on a home theatre. In this article we investigate the architectural requirements to effectively support a ubiquitous and nomadic multimedia entertainment service, and propose a music distribution system that offers a seamless and wandering music delivery service. We present experimental results that show the functionalities and performances of our proposed approach in terms of reliability and effectiveness.     

Technologies and performance for non-line-of-sight broadbandwireless access networks

This article presents emerging technologies for upcoming non-line-of-sight fixed or stationary broadband wireless access systems. We describe design trade-offs for overall maximization of the radio capacity and coverage of fixed wireless access (FWA) in multicell interference- and fading-prone environments. We characterize quantitatively the impact of key emerging radio technologies on the overall performance     

Radio software download for commercial wireless reconfigurable devices

Commercial wireless end user terminals are becoming increasingly complex in order to integrate in a common package distinct separate capabilities formerly implemented in multiple single-function, single-band devices. Software is an increasingly important aspect of these complex terminals. The increased amount of software installed in wireless devices includes both application software and operational software, such as radio software used to implement software-defined radio capabilities. A resulting need is to be able to upgrade these wireless devices through software download in order to incorporate new capabilities and fix software deficiencies.