MicroBusiness - Cellular Industry Competes for Broadband Business

Our previous column on WiMAX business prospects included a graph of the mobile WiMAX competitive environment. Many different versions of such graphs exist. What these graphs have in common is that they are all populated by a progression of cellular systems toward ever-higher broadband capabilities. The 4G target peak data rates agreed upon in ITU-R Working Party 8F for "Systems Beyond IMT-2000" (renamed "IMT-Advanced") are "up to approximately 100 Mb/s for high mobility such as mobile access and up to approximately 1 Gb/s for low mobility such as nomadic wireless access". The cellular industry is pursuing mobile broadband development toward these objectives along two distinct 3G/4G branches, one evolving from WCDMA and the other from CDMA2000. The former is spearheaded by the 3rd Generation Partnership Project (3GPP), and the latter by 3GPP2.     

3G无线宽带专网在配电网自动化中的应用

目前,电力系统配电自动化接入网主要有光纤网络、电力载波通信、230MHz数传设备电台、公网2G/3G等方式,光通道则为一种占有主导地位的通信方式。但针对地形复杂、高楼林立的繁华城区,光纤难以联接到户,采用3G无线宽带专网作为接入网解决最后一公里的问题成为一种既经济又便捷的手段。无线宽带专网具有接入灵活、安全性高、业务支撑能力强、投资成本相对节省等特点,它在配网自动化(DA)或用电信息采集(AMI)中作为通信通道已经成为国际电力界公认的技术趋势。文中介绍了3G无线宽带专网作为配电自动化接入网的使用实例;探讨了3G无线宽带专网与配电自动化的融合、网络建设特点及网络运行管理模式等问题。     

Beyond 3G

Beyond 3G is the official IEEE designation for the next stage of wireless technology that some people call 4G or fourth-generation radio. Over the years, every conceptual shift in wireless technology has been characterized as a generational change. Third generation includes wideband mobile multimedia networks and broadband mixed wireless systems. The mobile systems support variable data rates depending on demand and the level of mobility. Typically 144 kb/s is supported for full vehicular mobility and higher bandwidths for pedestrian levels of mobility. Switched packet radio techniques and wideband CDMA-like systems (as the physical channel is) rather than assigned physical channel schemes (referred to as circuit switched) are required to support this bandwidth-on-demand environment. There are two essential concepts beyond 3G. One of these is the provision of data transmission at rates of 100 Mb/s while mobile and 1 Gb/s while stationary. The other concept is that of pervasive networks where a handset supports many access technologies (e.g., cellular, UMTS, and WiFi) perhaps simultaneously and smoothly transitions between them     

3G和4G无线通信技术在ICT网络模式中的应用

介绍了ICT对电力通信系统研究的重要意义,在分析3G/4G移动通信系统的发展现状及应用的基础上,介绍了3G/4G移动通信技术在电力系统通信的应急通信、配电自动化、无线视频接入和智能电网等几种重要场景中的应用,论述了无线通信技术在ICT网络中应用时所面临的安全问题。     

Beyond 3G [cellular communications]

3G wireless systems are still in the early stages of development. In fact, it may be another five to 10 years before we know their full market impact. However, there are already limitations and problems. Some of these problems are technical in nature, while others are business-related. Getting different access networks to interoperate in a seamless manner without a fixed infrastructure still holds many challenges. High data rates and adequate bandwidth to handle multimedia applications like full-motion video and wireless teleconferencing still need work.     

Propagation characteristics in an underground shopping area for 5‐GHz‐band wireless access systems

5‐GHz‐band wireless access systems, such as the RLAN (Radio Local Area Network) system of IEEE 802.11a, HiperLAN/2, HiSWANa, and AWA, are deployed for indoor use at transmission rates over 20 Mbps. These 5‐GHz access systems are expected to extend service areas from the office to the so‐called “hot spots” in public areas. Underground shopping malls are one type of service area where the application of such nomadic wireless access service can be expected. In order to design radio zone configurations, it is necessary to know broadband propagation characteristics of an underground mall environment even if results obtained by previous measurements in the narrow band are available. This paper presents results of an experimental study on the propagation characteristics for broadband wireless access systems in an underground mall environment. First, broadband propagation path losses are measured and formulated considering the shadowing by human body. A ray trace simulation is used to clarify the basic propagation mechanism in such a closed environment. Next, it was determined that values of the delay spread at different distances during rush hour periods did not exceed 65 ns, which is lower than the permitted maximum value of the present 5‐GHz systems. The final conclusion is that the above propagation characteristics corroborate results of transmission tests carried out by using the AWA equipment. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 152(3): 55–64, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20059     

McWiLL无线宽带接入系统在智能电网通信中的应用

McWiLL无线宽带接入系统作为现代电力通信的有益补充。具有覆盖范围广、传输距离远、容量大、抗干扰等优点,商河县供电公司以此为基础建立了智能电网通信平台。文章重点介绍了利用该平台完成远程抄表、配变监测、调度自动化、移动视频等业务的无线传输。确保智能电网电力通信系统的安全性、可靠性和先进性。     

5G通信测试技术挑战

第5代移动通信（5G）采用的大规模天线阵列、新型多址技术、全频谱接入、超密集组网、新型网络架构等关键技术给测试带来了巨大的挑战，为便于进一步的开展具体测试方案研究，本文从测试的角度提出了第5代移动通信测试技术体系结构，结合5G通信新的网络架构、新的空口要求，重点对5G通信的无线信道模拟与评估测试、Massive MIMO系统测试、新波形和多址方案测试、业务和系统级集中测试等测试技术的难点和挑战进行了论述。     

User mobility support in an urban CDMA-based wireless network

A salient feature of wireless networks is the ability to support user roaming. However, user mobility has a profound effect on grade of service (GoS) and quality of service (QoS) provisioning. Code division multiple access (CDMA) is the multiple access technology for the third-generation wireless standard (3G) and is envisioned to be the multiple access technology beyond 3G. CDMA is interference-limited. The signal-to-interference (SIR) ratio, expressible in the form of Eb/I0, is an important parameter in CDMA systems and has a profound effect on the system capacity. The system capacity in turn affects the call-level GoS of the network layer in terms of new call blocking probability and forced termination probability. The effect of user mobility on (i) degradation in utilization and (ii) excess capacity needed to satisfy the QoS/GoS requirements, in an urban environment, is examined and quantified. A relationship between the link-layer Eb/I0 specification and the call-level GoS parameters in the presence of user mobility is also established. Numerical results which display the linkages between the link-layer QoS and call-level GoS parameters are presented and discussed. This coupling gives a quantification of the link-layer requirement to provision the call-level GoS, in the presence of user mobility.     

Size matters: next generation wireless networks[industry forum]

Broadband wireless deployments, so-called fourth generation (4G) networks, are now considered the holy grail for most operators primarily to maintain their revenue growth and, of course, subscriber base. The rapid build-out of wireless fidelity (WiFi) hotspots and planned municipal WiFi networks around the world has further fueled consumer expectations. However, there are problems: broadband wireless is restricted in range and consequently requires a significant number of access points (APs) to make the coverage ubiquitous and reliable. Furthermore, the installation costs of such a large number of wired APs to build a broadband network can make it very unprofitable for Internet providers.     

基于信息年龄的变电站业务无线接入选择算法

为更好满足变电站中大规模设备接入和高可靠低时延业务传输需求,提出了一种适用于变电站业务的多频异构无线通信网络接入选择算法。首先构造了一个异构无线网络覆盖下的变电站场景模型,综合考虑变电站业务对于可靠性和有效性的需求。其次为有效提升接收到信息的新鲜程度,以平均信息年龄（Average Age of Information,AAoI）作为无线网络接入选择的优化目标函数,提出了基于信息年龄的变电站业务接入选择优化问题。最后利用深度Q学习（Deep Q-Learning,DQN）方法求解该问题,以获得最佳的接入选择方案。通过对应用实例与试验数据的分析可以看出,所提出的接入选择优化理论和算法,可以降低业务传输时的平均信息年龄,提升数据的新鲜程度。     

多载波CDMA在宽带电力线通信中的应用探讨

目前,电力线载波通信作为家庭/办公室的宽带接入网络,面临着诸如信道时变衰落、信道频率选择性多径衰落、多址干扰以及背景噪声大等方面的挑战。作为后3G(4G)通信技术之一的多载波CDMA(MC-CDMA)技术有望成为应对这些挑战提供新的思路。文章探讨了MC-CDMA在宽带电力线中的应用,详细介绍了系统模型;从实际应用出发,进一步归纳和阐述了系统同步和多用户检测的实现方法;最后展望了本项研究的应用前景。     

电力无线虚拟专网应用分析及网络设计

随着智能电网建设的飞速发展,智能电网业务中依托运营商2G／3G无线网络的通信方式规模不断扩大。文章首先深入研究了电力无线业务应用、通信需求和网络现状,指出现有电力无线业务中存在安全接入的风险与无法管控的缺陷。其次,创新性地提出了建设电力无线虚拟专网的目标,实现电力无线业务的安全高效承载、集约化运营和规模化发展。最后,对电力无线虚拟专网网络设计以及安全接入平台、运行支撑平台设计进行了详尽分析阐述。     

Implementation of Handheld, RF Test Equipment in the Classroom and the Field

The utilization of handheld, radio frequency (RF) equipment (spectrum analyzers and signal generators) for both classroom demonstrations and for student exercises conducted in the field is discussed. Demonstrations employ real-world, wireless systems to illustrate undergraduate concepts, such as channel access, modulation methods, and transmission bandwidth. The equipment has also been used to illustrate antenna concepts, such as gain, beamwidth, and polarization. Finally, the portability and robustness of the equipment has enabled students to collect field data for the purpose of characterizing both large- and small-scale propagation effects in a variety of environments.     

A QoS control scheme using dynamic window size control for wide area ubiquitous wireless network

This paper describes a quality‐of‐service (QoS) control scheme for a wide‐area ubiquitous wireless network which is designed to accommodate many wireless terminals (WTs), such as sensors and actuators, in a large cell area. The purpose of this paper is to establish a QoS control scheme in a medium access control (MAC) layer that can hold the transmission delay of high‐priority class traffic within a predefined value regardless of how much low‐priority class traffic there is. Several QoS control schemes for wireless communication use have been proposed. However, in the wide‐area ubiquitous wireless network, an access point (AP) accommodates many WTs and the AP traffic volume often drastically changes. Therefore, conventional schemes sometimes cannot control the QoS of high‐priority traffic. To solve this problem, we propose a QoS control scheme that calculates a suitable initial back‐off window size of random access for each QoS class by using equations derived from a Markov chain behavior model. The proposed scheme adjusts the window size so as to prevent increased transmission delay of high‐priority traffic. The scheme's performance is clarified by computer simulation. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Cell searching in WCDMA

In Europe, the digital second generation (2G) systems, IS-136 and the Global System for Mobile communications (GSM), developed were based on time division multiple access (TDMA) and in the US, the IS-95 system developed was based on code division multiple access (CDMA). The 2G technologies developed both in Europe and US suffered from a number of limitations that included: low bit rate for 2G systems and non-interoperability between the standards. The low bit rate for 2G systems could not meet subscriber demands for new and faster non-voice services while on the move. Hence, the third generation (3G) systems were developed with the aim to solve these problems by promising global roaming across 3G standards, as well as support for multimedia applications. These 3G services are based on CDMA.     

基于4G通信技术的无线网络安全通信分析

随着计算机技术和无线通信技术的不断融合、发展。无线网络通信技术从WPAN／WLAN／WMAN、GSM／GPRS、3G逐步向4G方向发展。无线网络安全通信问题日益突出,亟待解决。文章通过分析无线网络通信技术发展历程、4G通信的接入系统及移动终端需求,发现4G通信的安全风险和问题,并提出相应的安全策略和安全措施,可为4G通信技术的无线网络安全防护研究提供参考。     

A Novel Dimension of Cooperation in 4G

The Fourth Generation (4G) of wireless networks is no longer a dream; it is knocking now at the doors of our information village. 4G promises to offer a vast range and diversity of converged devices, services, and networks and to revolutionize the way we communicate. 4G would influence today's networking architecture where the inter-user communication is realized with the help of third-party communication infrastructure. In 4G, the centralized third-party controlled networking architecture can emerge into a hybrid model, where a part of user-to-user interaction would be envisaged by short/medium range wireless communication systems.     

Reputation Systems for Self-Organized Networks

Self-organized networks such as mobile ad-hoc, Internet-based peer-to-peer, wireless mesh and Fourth generation (4G) wireless networks depend on cooperation of nodes. Reputation systems help nodes decide with whom to cooperate and which nodes to avoid. They have been studied and applied almost separately in diverse disciplines such as economics, computer science, and social science, resulting in effort duplication and inconsistent terminology. We aim to bring together these efforts by outlining features and fundamental questions common to reputation systems in general. We derive methodologies to address these questions for both reputation system design and research from our own experiences and evaluations by simulation and analytical modeling. We argue for using deviation tests, discounting, passing on only first-hand information, introducing secondary response, and stressing the importance of identity.     

Identity management systems

Most organizations have difficulty keeping track of and controlling all the user identifiers and passwords across their systems. In particular, with people leaving the organization and constantly changing roles, it is more difficult to make sure every user has appropriate access to the systems. In our case at a university, we constantly have new students arriving and former students leaving. New students need access to our systems to register for classes and use e-mail, library resources, and the computing labs. Former students should no longer have access to systems we don't have permission to provide (such as some library resources) or don't have the capacity to continue to provide. At companies, similar problems exist with new and former employees, as well as the need to meet requirements from laws such as Sarbanes-Oxley regarding who is permitted access. Identity management (IdM) systems are designed to help manage user identifiers across multiple systems as well as providing a way to manage user access over their lifecycle of roles in the organization. They are tightly integrated with other systems such as those that provide a single sign-on mechanism and the checking of their credentials. As such, these IdM systems have become extremely common in information technology infrastructure.