超宽带时代来临

流视频对消费产品在技术上提出了挑战，而超高速HY技术对此挑战提供通过无线网络的可行解决方案。     

A Context-Aware User Interface for Wireless Personal-Area Network Assistive Environments

The daily life of people with severe motor system impairments is challenging and thus often subordinated to extensive external help; increasing their level of self-support is thus highly desirable. Recent advances in wireless communications, in particular in wireless personal-area networks, serve as technological enablers well suited for implementing smart and convenient assistive environments which can increase self-support. This paper presents the design and prototyping of a versatile interface for such wireless assistive environments. We propose a modular framework that can accommodate several wireless personal-area network standards. The interface is built upon this framework and is designed in such a way that it can be controlled by various types of input devices such as a touch screen or a tongue-control unit. The interface can automatically discover consumer appliances (e.g. Zigbee and Bluetooth enabled lights and computers) in the user’s environment and display the services supported by these devices on a user-friendly graphical user interface. A demonstrator is prototyped and experimental results show that the proposed interface is context-aware, i.e. it successfully detects available appliances, adapts itself to the changes that occur in the user’s environment, and automatically informs the user about these changes. The results also show that the proposed interface is versatile and easy to use, i.e. the user can easily control multiple devices by means of a browser menu. Hence, the proposed work illustrates how assistive technology based on wireless personal-area networks can contribute to improving the quality of life of motor system impaired persons.     

RF-MEMS for Wireless Communications [Topics in Design and Implementation]

This article presents an introduction and overview of MEMS technology with a focus on RF applications of MEMS in the design of cellular handsets. A novel, integrated, high-Q tunable digital capacitor is discussed to demonstrate how RF-MEMS technology can be utilized to make high frequency components whose RF characteristics can be adjusted during operation, allowing for the first time reconfiguration of radio hardware under software control. It is concluded that as the consumer wireless market continues to grow and evolve, product designers will remain under ever increasing pressure to develop smaller, lighter, thinner products that are more functional, energy-efficient, and intuitive, and to do so faster and at lower cost. Although issues and challenges persist, opportunities abound, and RF-MEMS technology holds the promise of being a key enabler of future generations of more highly converged, cognitive, and flexible consumer wireless products.     

A review of industrial wireless networks in the context of Industry 4.0

There have been many recent advances in wireless communication technologies, particularly in the area of wireless sensor networks, which have undergone rapid development and been successfully applied in the consumer electronics market. Therefore, wireless networks (WNs) have been attracting more attention from academic communities and other domains. From an industrial perspective, WNs present many advantages including flexibility, low cost, easy deployment and so on. Therefore, WNs can play a vital role in the Industry 4.0 framework, and can be used for smart factories and intelligent manufacturing systems. In this paper, we present an overview of industrial WNs (IWNs), discuss IWN features and related techniques, and then provide a new architecture based on quality of service and quality of data for IWNs. We also propose some applications for IWNs and IWN standards. Then, we will use a case from our previous achievements to explain how to design an IWN under Industry 4.0. Finally, we highlight some of the design challenges and open issues that still need to be addressed to make IWNs truly ubiquitous for a wide range of applications.     

A spatial statistics approach to characterizing and modeling the structure of cognitive wireless networks

The performance of cognitive wireless networks (CWNs) depends heavily on their spatial structure. However, highly simplified models are still routinely used for performance evaluation of CWNs and other wireless networks, with node locations often being assumed to be uniformly and randomly distributed in a given region. In this paper we apply techniques from spatial statistics literature to show that this assumption is not valid for a wide variety of existing networks, and neither can it be expected to hold for future cognitive wireless networks. We also develop improved models of the spatial structure of the network for a variety of wireless network types. In particular, we construct models of television and radio transmitter distributions as well as different types of cellular and Wi-Fi networks that have direct applications in cognitive wireless networks research. We use a stochastic approach based on fitting parametric location models to empirical data. Our results strongly indicate that the so-called Geyer saturation model can accurately reproduce the spatial structure of a large variety of wireless network types, arising from both planned or chaotic deployments. The resulting models can be used in simulations or as basis of analytical calculations to study different network properties. They can be also used within CWNs for on-line reasoning about the surrounding radio environment.     

Network-coding-based scheduling and routing schemes for service-oriented wireless mesh networks - [Service-oriented broadband wireless network architecture]

Service-oriented wireless mesh networks have recently been receiving intensive attention as a pivotal component to implement the concept of ubiquitous computing due to their easy and cost-effective deployment. To deliver a variety of services to subscriber stations, a large volume of traffic is exchanged via mesh routers in the mesh backbone network. One of the critical problems in service-oriented wireless mesh networks is to improve the network throughput. Wireless network coding is a key technology to improve network throughput in multihop wireless networks since it can exploit not only the broadcast nature of the wireless channel, but also the native physical-layer coding ability by mixing simultaneously arriving radio waves at relay nodes. We first analyze the throughput improvement obtained by wireless network coding schemes in wireless mesh networks. Then we develop a heuristic joint link scheduling, channel assignment, and routing algorithm that can improve the network throughput for service-oriented wireless mesh networks. Our extensive simulations show that wireless network coding schemes can improve network throughput by 34 percent.     

Unified Mobility Manager: enabling efficient SIP/UMTS mobile network control

Internet telephony is viewed as an emerging technology not only for wireline networks, but also for third-generation wireless networks. Although IP end to end is considered the ultimate approach to future wireless voice services, there is still a long way to go before IP voice packets can be effectively transported over the air. Therefore, Internet telephony and today's circuit-switched wireless network will coexist for years to come, and it is essential to effectively perform interworking between these networks. This article proposes the Unified Mobility Manager (UMM) that achieves efficient interworking between traditional wireless networks and Internet telephony networks. The main characteristic of the UMM is that it combines UMTS HLR and SIP proxy functionality in one logical entity, which helps eliminate the performance degradation due to interworking between SIP and UMTS. This article identifies seven potential network architectures with and without the UMM and with varying degrees of IP penetration in the wireless core networks, and performs comparative analysis in terms of their call setup signaling latency. Our performance results show that for SIP originated calls, the architecture with the UMM can achieve better performance than existing UMTS networks without the UMM. Our results further show that when the backbone network is fully IP-enabled, dramatic performance gains can be accomplished with the UMM for PSTN originated calls as well as for SIP originated calls. The article also demonstrates that the UMM allows graceful migration from today's circuit-switched wireless networks to hybrid SIP/circuit-switched wireless networks, and toward the IMS architecture for all-IP UMTS networks in the future.     

Local-area networks go wireless

As standards emerge, data rates rise, and laptops seek connectivity, wireless LANs are finding a market niche as extensions to wired networks. Wireless LANs have found homes in buildings where installing wires would expose asbestos or destroy historic architecture. They have also proved valuable to companies that often relocate and want networks they can take with them. Another common use is for connecting wired LANs that are physically separated. The growth has been fueled by the desire to add wireless adjuncts to wired LANs, so that mobile workers can keep in constant contact with corporate networks over short distances. The author discusses the befits of wireless LANs. The radio based wireless LAN is discussed including multipath interference and data bottlenecks. The infrared based wireless LAN is also discussed and an inset discusses standards for wireless LANs     

IEEE 802.11s: WLAN mesh standardization and high performance extensions

In recent years, remarkable market competition and economy of scale has resulted in the price erosion of wireless devices for consumer electronics. Especially for wireless data networks, IEEE project 802 provides the standards for mass markets. With ever-growing usage, the demand for ubiquitous wireless networks increases. However, the achievable data rates decrease with the increasing distance of client devices from the infrastructure, and a sufficiently dense deployment of infrastructure devices is required to fulfill the customers' demand for broadband access. Today, these infrastructure devices rely on a wired backbone for background services; however, to reduce their costly deployment, they should interconnect wirelessly. In this case, devices mutually serve as wireless relays that forward and route packets over multiple wireless hops, and wireless mesh networks come into existence. In this article we provide an overview of wireless mesh networking and provide insights into the related standardization efforts in IEEE 802. For a more in-depth analysis, we focus on the draft WLAN mesh standard IEEE 802.11s and identify challenges for medium access control in multihop communication. Derived from our proposal to 802.1 Is, the current draft incorporates an optional medium access scheme that circumvents a performance gap. By means of simulations, we compare the performance of both solutions and provide an outlook for future 802 wireless systems that will be more reliable.     

Managing end‐to‐end quality of service in multiple heterogeneous wireless networks

Supporting quality of service (QoS) in wireless networks has been a very rich and interesting area of research. Many significant advances have been made in supporting QoS in single wireless networks. However, the support for QoS across multiple heterogeneous wireless networks will be required in future wireless networks. In connections spanning multiple wireless networks, end‐to‐end QoS will depend on several factors such as mobility patterns, connection patterns, and the QoS policies in each of the networks. In this paper, we present an architecture for multiple heterogeneous wireless networks, several QoS schemes, a simulation model and several interesting results. The simulation model can evaluate the QoS performance under a variety of network configurations, user and mobility types, and network resources. Our results show that end‐to‐end QoS depends on several factors, including system utilization, mobility levels, and the individual QoS schemes implemented in individual networks. We also show how the QoS ideas presented in this paper can be used by wireless carriers for improved QoS support and management. Copyright © 2006 John Wiley & Sons, Ltd.     

A Multi-channel Scheduling Scheme for Collision-Free High-Rate WPANs

Ultra wide-band (UWB) technologies are being feverishly developed in the technical community. UWB devices are expected to operate at rates of up to 0.5 Gb/s and communicate with other devices at a range of up to 10 m. Thus, UWB technologies are being developed as core technology for high-speed wireless personal area networks. The salient features of UWB networks—high-rate communications, low interference with other radio systems, and low power consumption—bring many benefits to users. Thus, they enable consumers to experience new applications such as wireless universal serial bus for connecting personal computers to their peripherals and the consumer–electronics in people’s living rooms. However, if multiple WiMedia logical link protocol Service Sets (WSSs) coexist in an adjacent area, various conflicts among independent WSSs can occur frequently. In order to solve this problem, we propose a multi-channel scheduling scheme (MCS) for the coexistence of adjacent WSSs. The proposed MCS scheme can scan new idle channel and detect its time offset where a WSS device can transmit a new beacon frame and data frames without conflicts. We also evaluate the performance of the proposed MCS scheme through various simulations in terms of several metrics. Simulation results demonstrate that the MCS scheme can minimize the possibility of data frame collisions by efficiently managing the multiple available channels in a hybrid manner combining proactive and reactive methods.     

MPEG-21 Rights Expression Language: enabling interoperable digital rights management

The Internet has spawned a revolution in the way people distribute content and access services. At the same time, the availability of broadband and wireless networks has increased, as have the capability and portability of computing and consumer electronic devices. These factors have fueled the development of new technologies to automate, manage, and secure content flow and service access over the Internet. This paper deals with the recently approved ISO standard, MPEG-21 Rights Expression Language (REL). This language is precise, flexible, extensible, and rich in expressing rights. Thus, it can support reliable, flexible, and cost-effective interoperable digital rights management (DRM) systems and applications for electronic commerce and enterprise management of content and services. It is an international standard for expressing and interpreting rights for using and distributing content, resources, and arid services. As an enabling technology for interoperable DRM, its' adoption by industry and incorporation into products certainly takes time. The challenge is to proliferate the REL's adaptation across many different DRM systems as well as conditional access and authorization systems. Moreover, the REL must pervade not only entertainment but also many other applications, such as enterprise, medical information, and even privacy protection.     

Cross‐layer perspective for channel assignment in cognitive radio networks: A survey

With the advent of various emerging wireless products, the usage of limited spectrum has grown exponentially in the recent years. In the next few years, that mobile data traffic globally is expected to grow up to 50 EB/month, which is nearly a five times increase over year 2018. Therefore, it will become extremely difficult to satisfy the ever increasing demand through the current fixed spectrum assignment policy in which spectrum band is exclusively used for the particular applications, and it has also led to underutilization of a significant portion of the spectrum (like TV bands). Cognitive radio networks has emerged as a possible solution for the problem which makes dynamic spectrum access possible for unlicensed user when licensed user is not active. Among various operations of cognitive radio, channel assignment to the unlicensed user is very important. Further, wireless regional area network is one of the most important application of cognitive radio, which provides wireless broadband to the rural area using vacant TV channels. This paper discusses channel assignment techniques considering various functionalities for cognitive radio networks in respect of wireless regional area network in the existing literature. Initially, a comprehensive introduction to both cognitive radio networks and wireless regional area networks is provided, and in the end, the paper summarizes the various issues and research challenges in the channel assignment for wireless regional area networks.     

A Survey of Energy Efficient Network Protocols for Wireless Networks

Wireless networking has witnessed an explosion of interest from consumers in recent years for its applications in mobile and personal communications. As wireless networks become an integral component of the modern communication infrastructure, energy efficiency will be an important design consideration due to the limited battery life of mobile terminals. Power conservation techniques are commonly used in the hardware design of such systems. Since the network interface is a significant consumer of power, considerable research has been devoted to low-power design of the entire network protocol stack of wireless networks in an effort to enhance energy efficiency. This paper presents a comprehensive summary of recent work addressing energy efficient and low-power design within all layers of the wireless network protocol stack.     

A high-performance MIMO OFDM wireless LAN

Tremendous consumer interest in multimedia applications is fueling the need for successively higher data rates in wireless networks. Data rates in wireless wide area networks are limited by the need to address wide coverage, vehicular mobility, and the limitations of licensed spectrum. Thus, data rates in WWANs continue to lag advances in wireless local area networks by orders of magnitude. There are valuable lessons to be learned from the design of WLANs that provide data rates in excess of hundreds of megabits per second. Several technologies are instrumental in enabling the future of high-performance WWANs, including multiple transmit and receive antennas, OFDM, closed loop transmission control, and low-latency MAC operation. We describe a MIMO WLAN design and prototype that exploits these attributes to provide data rates in excess of 200 Mb/s above the MAC     

Industrial wireless sensor and actuator networks in industry 4.0: Exploring requirements,protocols, and challenges—A MAC survey

The vision to connect everyday physical objects to the Internet promises to create the Internet of Things (IoT), which is expected to integrate the diverse technologies such as sensors, actuators, radio frequency identification, communication technologies, and Internet protocols. Thus, IoT promises to transfer traditional industry to advance digital industry known as the Industry 4.0. At the core of the Industry 4.0 are the wireless sensor networks (WSNs) and wireless sensor and actuator networks (WSANs) that led to the development of industrial wireless sensor networks (IWSNs) and industrial wireless sensor and actuator networks (IWSANs). These networks play a central role of connecting machines, parts, products, and humans and create a diverse set of new applications to support intelligent and autonomous decision making. The IWSAN is a promising technology for numerous industrial applications because of their several potential benefits such as simple deployment, low cost, less complexity, and mobility support. However, despite such benefits, they impose several unique challenges at different layers of the protocol stack when deploying them for various monitoring and control applications in the Industry 4.0. In this article, we explore IWSAN, its applications, requirements, challenges, and solutions in the context of industrial control applications. Our main focus is on the medium access control (MAC) layer that can be exploited to satisfy such requirements. Our discussion presents extensive background study of the MAC schemes and it reviews the MAC protocols of the existing wireless standards and technologies. A number of application‐specific MAC protocols developed to support industrial applications, which are not part of these standards, are also elaborated. We rationalize to what extent the existing standards and protocols help in solving such requirements as laid down by the Industry 4.0. In the end, we emphasize on existing challenges and present important future directions.     

卫星通信网络和短波/超短波通信网络的互连

基于未来战争对于无线通信系统集成化、综合化的要求。通过对卫星网络、短波／超短波网络的深入研究,设计了一个新型的无线通信系统,该系统不但可以同时接入上述3种网络实现不同系统的连接,也可以单独作为某一无线网络而独立应用,对未来的军用无线系统研究有一定的参考价值。     

基于P2P的无线传感器网络应用架构研究

通过基础网络互联多个传感器网络，为用户提供大规模、大范围、多样化的信息服务成为未来无线传感器网络的应用模式之一。据此，提出了一种基于P2P（Peer-to—Peer）技术的无线传感器网络应用架构。采用P2P技术，解决了大数据量的通信瓶颈，传感器网络亦可自由加入、变更或退出，方便部署，网络可扩展性好．同时屏蔽底层网络差异及多种接入方式．为用户提供多个访问入口。     

Cross-Layer Design for QoS Support in Multihop Wireless Networks

Due to such features as low cost, ease of deployment, increased coverage, and enhanced capacity, multihop wireless networks such as ad hoc networks, mesh networks, and sensor networks that form the network in a self-organized manner without relying on fixed infrastructure is touted as the new frontier of wireless networking. Providing efficient quality of service (QoS) support is essential for such networks, as they need to deliver real-time services like video, audio, and voice over IP besides the traditional data service. Various solutions have been proposed to provide soft QoS over multihop wireless networks from different layers in the network protocol stack. However, the layered concept was primarily created for wired networks, and multihop wireless networks oppose strict layered design because of their dynamic nature, infrastructureless architecture, and time-varying unstable links and topology. The concept of cross-layer design is based on architecture where different layers can exchange information in order to improve the overall network performance. Promising results achieved by cross-layer optimizations initiated significant research activity in this area. This paper aims to review the present study on the cross-layer paradigm for QoS support in multihop wireless networks. Several examples of evolutionary and revolutionary cross-layer approaches are presented in detail. Realizing the new trends for wireless networking, such as cooperative communication and networking, opportunistic transmission, real system performance evaluation, etc., several open issues related to cross-layer design for QoS support over multihop wireless networks are also discussed in the paper.     

Software testing for wireless mobile computing

4G wireless networks make it increasingly difficult to develop and test application software for mobile terminals in comparison with 3G or earlier generations. These 4G networks incorporate wireless LAN technologies, and mobile terminals can access the services provided by LANs as well as global network services. Therefore, software running on mobile terminals may depend on not only its application logic but also on services within the LANs to which the terminals are connected. To construct correct software to run in mobile terminals for 4G wireless networks and wireless LANs, it must be tested in all the networks to which the terminal could be moved and be connected. This article presents a new approach, called flying emulator, to testing software designed to run on mobile terminals. Like existing approaches, the approach provides software-based emulators of its mobile terminals for software designed to run the terminals. It is unique because it constructs emulators as mobile agents that can travel between computers. These emulators can carry the target software to the networks to which the terminals are connected and allow it to access services provided by the networks in the same way as if it was moved with and executed on the terminals connected to the networks. This article describes the idea of the approach, its implementation, and our experience with a typical application.