无线局域网技术概述

本文论述了近年来发展迅速的无线局域网技术,并通过实际工程案例,介绍了相关的知识。     

Me and you and everyone we know: An empirical analysis of local network effects in mobile communications

This paper investigates the importance that consumers assign to local network effects, i.e. the extent to which they take account of their contacts’ mobile operators when choosing a provider for themselves. The authors identify individual characteristics that affect the importance consumers attach to local network effects. The study relies on a survey of 193 Italian students. The results show that consumers are highly heterogeneous with respect to the importance they give to the operators chosen by their friends/family members in choosing which provider to use. This heterogeneity is associated with individual innovativeness and patterns of mobile phone usage. For instance, consumers who are more interested in local network effects are typically more-aware users, who use voice services quite intensively. These consumers, who pay attention to local network effects, spend comparatively little proportional to the intensity of their mobile usage.     

The response strategies of incumbent mobile network operators on the disruptive potential of public W-LAN in Germany

This paper examines how three incumbent mobile network operators (MNOs) in Germany responded in terms of their strategy to the emergence of the wireless local area network (W-LAN) technology and how they interpreted this potentially disruptive technology in their own strategic context. Additionally, prior empirical results and forecasts on the limited disruptive potential of W-LAN for the German MNOs lacked persuasive firm-level evidence to distinguish the real reason for the presented observations and analysis. So far it was unclear whether the observations were caused by successful response strategies of incumbent MNOs or by the inherent limited disruptive potential of the W-LAN technology. For this purpose case studies of three major MNOs in Germany were performed to assess and compare their respective response strategies. Using the theoretical framework of disruptive technology, the results were evaluated in a cross-case analysis to study how these firms interpreted and reacted to the potential disruptiveness of W-LAN. The results indicate significant differences for the respective MNOs between their perception of W-LAN as a potential disruptive technology, their strategic development processes inside the organisation to understand the potential impact of W-LAN on their respective business model, and to enforce an appropriate response strategy and structural implementation. This incumbent heterogeneity depends primarily on their idiosyncratic strategic and structural context. These findings reveal that the incumbent MNOs in Germany were aware of the disruptive technology concept but did not react in a theory-conform way. However, since W-LAN had a sustaining impact on the MNOs and their response strategies followed sustaining reaction patterns, earlier studies, which show a limited disruptive potential of W-LAN for the German MNOs, are supported.     

Reducing the level of switching costs in mobile communications: The case of Mobile Number Portability

Switching costs are one of the most important economic forces that affect market competition in mobile communications. Both theoretical and empirical studies have shown that switching costs reduce market competition leading to higher prices, lower product and service quality, and lower customer welfare. Given their negative consequences, national regulatory authorities have designed policies aimed at reducing switching costs and fostering competition. One of the most important of these, in the mobile communications industry, is mobile number portability (MNP). The aim of this paper is to investigate the effect of MNP on switching costs in mobile phone services. First, a hierarchical Bayes model is proposed to measure switching costs at the customer level and to investigate the impact of MNP on them. Second, this study examines the drivers of MNP adoption by customers using a binary logit specification. The results reveal that this regulatory policy has significantly reduced the cost of switching and that MNP adoption partially depends on customer-related variables.     

行政管理局域网改造中的启示

文章以内蒙古国资委局域网为例,分析了局域网存在的问题、解决办法及改造后的应用效果。     

Consumer choice and local network effects in mobile telecommunications in Turkey

The aim of this paper is to analyze the extent of network effects in mobile telecommunications in Turkey, and to identify other determinants of consumer choice based on consumer survey data. This study shows that there are regional disparities in the adoption of network services in Turkey, the attractiveness of the different networks varies for consumers between different regions. The results show that local network effects are significant for consumer choice. This finding means that consumers are more likely to be affected by the choices of other people within their local area than by the overall size of a network. Furthermore, local network effects also outweigh macro network effects at least in Turkey.     

Regulation and competition in the European mobile communications industry: An examination of the implementation of mobile number portability

Over the past two decades, the mobile communications industry has seen a considerable drop in the consumer switching charges made by service providers in order to promote effective competition and ensure a level playing field for new market entrants. Mobile Number Portability (MNP) is an important regulatory measure taken to reduce switching costs, and it is believed to play an important role in fostering competition in the mobile market. MNP implementation has varied significantly across European Union countries, particularly with respect to porting time and customer fees, both of which are important factors when deciding whether to switch to another provider. The research examines the effects of MNP implementation on competition in the European mobile communications industry. The study findings indicate that subscriber churn rates are negatively affected by both the level of charges levied on subscribers wishing to maintain their current number (porting) when switching mobile providers and the length of time required to switch. The implications of the effectiveness of MNP regulation for competition in the mobile communications industry are discussed.     

通信局域网安全策略浅析

由于上网的数据遭到不同程度的破坏,被删除或被复制,数据的安全性和自身的利益受到严重威胁.因此,不论在局域网还是在广域网中,网络的安全措施应是能全方位地针对各种不同的威胁和脆弱性,这样才能确保网络信息的保密性、完整性和可用性.     

Diversification strategies in network-based services: The case of mobile virtual network operators

This paper aims at discussing the entry process and competitive strategies of MVNOs in Italy and France. It illustrates the features of competition in a sector – the mobile telecom service industry – which is characterized by market saturation and demand heterogeneity. In doing so, it looks at the characteristics of the two countries in terms of competition and entry of new operators, at the motivations behind the entry of MVNOs, and at the performance of different companies. Results show that the most successful MVNOs are those characterized by the ability to find a perfect match between their core competencies (large network management, strong brand reputation) and the needs of specific segments of demand that had not been previously fulfilled. In this context, companies with ICT network management skills, whether coming from the telecom sector or from other network-based service industries such as postal operators, have been particularly successful in the market. From a policy perspective, despite the failure of some MVNOs, customers have benefited from the increased competition between MNOs and MVNOs in terms of range of service offerings and prices.     

Marking high-technology market evolution through the foci of market stories: the case of local area networks

Previous research suggests that changing consumer and producer knowledge structures play a role in market evolution and that the sociocognitive processes of product markets are revealed in the sensemaking stories of market actors that are rebroadcasted in commercial publications. In this article, the authors lend further support to the story-based nature of market sensemaking and the use of the sociocognitive approach in explaining the evolution of high-technology markets. They examine the content (i.e., subject matter or topic) and volume (i.e., the number) of market stories and the extent to which content and volume of market stories evolve as a technology emerges. Data were obtained from a content analysis of 10,412 article abstracts, published in key trade journals, pertaining to Local Area Network (LAN) technologies and spanning the period 1981 to 2000. Hypotheses concerning the evolving nature (content and volume) of market stories in technology evolution are tested. The analysis identified four categories of market stories—technical, product availability, product adoption, and product discontinuation. The findings show that the emerging technology passes initially through a 'technical-intensive' phase whereby technology related stories dominate, through a 'supply-push' phase, in which stories presenting products embracing the technology tend to exceed technical stories while there is a rise in the number of product adoption reference stories, to a 'product-focus' phase, with stories predominantly focusing on product availability. Overall story volume declines when a technology matures as the need for sensemaking reduces. When stories about product discontinuation surface, these signal the decline of current technology. New technologies that fail to maintain the 'product-focus' stage also reflect limited market acceptance. The article also discusses the theoretical and managerial implications of the study's findings.     

Business ecosystem strategies of mobile network operators in the 3G era: The case of China Mobile

In order to define the mobile network operators' strategies of building value network in the 3G era, this paper applies the ecosystem principles to the mobile industry through a China Mobile case study. Based on an analytical framework of such principles, this paper reviews China Mobile's ecosystem, and identifies its success factors and problems. The results indicate that a complete ecosystem, where mobile network operators collaborate closely with value-added service providers, content/application providers, equipment and device manufacturers, and other involved organizations, can promote the development of mobile data services substantially. Therefore, mobile network operators should play a central role in the ecosystem by managing the entire value-chain and setting up proper value-sharing mechanisms. However, while doing so, problems may arise because of regulatory issues and information asymmetry. High-value common assets, a centralized management system, partner selection schemes and continuous innovations are important success factors.     

Management principles for evaluating and introducing disruptive technologies: the case of nanotechnology in Switzerland

In this paper we address the issue of evaluating and introducing disruptive technologies. The empirical data was compiled in an interview–based survey of 20 Swiss organizations of different sizes and from different industries. All of them have been facing the issue of evaluating nanotechnology, and most of them are currently dealing with the introduction of nanotechnology in their products and processes. The underlying framework was elaborated using approaches mainly found in the following streams of technology management literature: technology intelligence, technological decision–making, and technological capability building. The aim of our project was not to advance new management concepts, but to elaborate management principles allowing the organizations to master the challenges during evaluation and introduction of disruptive technologies. We defined these principles through identifying success factors as well as possible pitfalls, and by distilling best management practices in evaluating and introducing nanotechnology.     

Technological sovereignty of the EU in advanced 5G mobile communications: An empirical approach

Two key issues within the debate around ‘technological sovereignty’ in the European Union are (i) access by countries and firms to enabling and emerging technologies and (ii) how strategic dependencies can be managed in order to preserve competitive positions in global value chains. In this paper, we present and discuss a multidimensional synthetic metric – the Technological Sovereignty Index (TSI) – to provide a global measure that captures the degree of exposure to specific technologies by a country (or group of countries) as well as the vulnerabilities that may be present. The paper validates the TSI by examining the EU's position (until 2021) within the global value chain of advanced 5G mobile communications, focusing on the hardware and component segments. Our findings reveal a weak degree of technological sovereignty due to (i) the shortage of specialized human capital in the EU and (ii) outsourcing trends in the relevant segments; however, untapped capabilities may exist that could partially offset strategic shortcomings.     

Expanding mobile wireless capacity: The challenges presented by technology and economics

As demand for mobile broadband services continues to explode, mobile wireless networks must expand greatly their capacities. This paper describes and quantifies the economic and technical challenges associated with deepening wireless networks to meet this growing demand. Methods of capacity expansion divide into three general categories: the deployment of more radio spectrum; more intensive geographic reuse of spectrum; and increasing the throughput capacity of each MHz of spectrum within a given geographic area. The paper describes these several basic methods to deepen mobile wireless capacity. It goes on to measure the contribution of each of these methods to historical capacity growth within U.S. networks. The paper then describes the capabilities of 4G LTE wireless technology, and further innovations off of it, to further improve network capacity. These capacity expansion capabilities of LTE-Advanced along with traditional spectrum reuse are quantified and compared to forecasts of future demand to evaluate the ability of U.S. networks to match future demand. Without significantly increasing current spectrum allocations by 560 MHz over the 2014–2022 period, the presented model suggests that U.S. wireless capacity expansion will be inadequate to accommodate expected demand growth. This conclusion is in contrast to claims that the U.S. faces no spectrum shortage.     

An institutional analysis of environmental management in the Korean mobile communications industry

Environmental sustainability in the mobile communications industry can affect corporations not only in the sector but also in other industries by providing solutions to cope with environmental issues. However, despite the significance of environmental sustainability in the industry, there has been a lack of academic attention. This study investigated the environmental issues in the mobile communications industry by adopting an integrated and holistic approach to corporate sustainable management. In addition, the environmental management of mobile network operators was analyzed using the framework of institutional theory. To investigate the environmental management of mobile network operators, we carried out a case study on three Korean mobile network operators including SK Telecom, KT, and LG Uplus. The results demonstrated that economic and environmental issues were mostly found in the mobile communications industry, and the mobile network operators have actively coped with these issues. Their environmental management was relatively active, and regulatory, mimetic and normative mechanisms were working simultaneously. This study provides some meaningful implications for practitioners and policymakers.     

The emerging value network in the mobile phone industry: The case of Japan and its implications for the rest of the world

This paper considers how the mobile phone industry is changing from a value chain to a value network using the Japanese market as an example. Value networks involve a larger number of firms, a more complex set of relationships between them, and agreements on a greater number of interface standards than do value chains. Building from this concept of a value network, the paper shows how: (1) agreements on many of these interface standards are enabling connections to be made between the mobile phone and other industries; (2) the resulting products and services often reflect the technological capability of phones and the existing products and services in these “other” industries; (3) each new interface standard requires a new critical mass of users; and (4) a critical mass of users for a new interface standard partly builds from previously created critical masses of users. On a practical level, this paper's analysis adds to a growing list of evidence that the growth in Western mobile Internet markets is nowhere near its potential and that the change from a value chain to a value network requires a different form of standard setting, policy making, and management than are currently used in the mobile phone industry.     

Opportunity cost of spectrum for mobile communications: Evaluation of spectrum prices in Bangladesh

The purpose of this study is to focus attention on the choice of the reserve price made by the telecom regulator to explain the under-performance of spectrum auctions in Bangladesh. The overestimation of the reserve prices for several auctions in Bangladesh including the auction of the 3G – 2100 MHz band in 2013, the 2G - 1800 MHz band in 2015, and the 4G – 1800 and 2100 MHz bands in 2018 is established by comparing the reserve prices to the economic value of spectrum, determined by using the engineering valuation and production function approaches. Possible reasons for the inflation of the reserve price are discussed.     

The evolution of mobile communications in Europe: The transition from the second to the third generation

This paper analyses the evolution of the mobile communications industry in the European Union. The research focuses its interest on the different roles played by the regulator in Europe and in other regions of the world (mainly the US). The diffusion of GSM was extraordinarily fast in Europe, mainly due to the adoption of a unified standard from inception. This rapid diffusion has resulted in an important competitive advantage for European operators. Interestingly, while the regulator acted similarly in the case of UMTS, the development of the latter has faced many problems and, presently, its diffusion is still low (about 5% in the EU). The paper also offers basic information on market structure that may be useful for extracting some preliminary conclusions about the degree of rivalry within the industry and the differences that can be observed between European countries.     

The disruptive potential of PWLAN at the country-level: The cases of Germany,the UK,and the USA

This paper analyzes the impact of WLAN technologies for incumbent MNOs based on an empirical cross-country study of the players in the public WLAN-hotspot market using the theory of disruptive innovation and theoretical extensions for the industry- and country-level. The main research question to be analyzed is whether and why PWLAN has shown a disruptive or sustaining impact trend for incumbent MNOs in the hotspot markets of Germany, the UK, and the USA in recent years. The results imply that incumbent MNOs and new entrants have taken advantage of the opportunity provided by PWLAN, but the market success of both types of players varies between the countries analyzed. Incumbent MNOs dominate in Germany but not in the UK and the USA. The reasons for these country-specific differences were further investigated, and the results suggest that the analysis of disruptive potential in telecommunications needs to include country- and firm-specific factors, which are, again, largely influenced by the local regulation.     

JAVA语言在网络通信程序中的实际应用

JAVA语言具有简单、面向对象、多线程、分布性、体系结构中立、安全高效等广泛而强大的功能.本文介绍了使用JAVA编程语言对基于客户/服务器模式的应用编写网络通信程序,讨论了SOCKET机制、输入输出流及程序实现代码,并给出了具体实现中的一些关键技术.