Throughput-based rate adaptation algorithm for IEEE 802.11 vehicle networks

A key problem with IEEE 802.11 technology is adaptation of the transmission rates to the changing channel conditions, which is more challenging in vehicular networks. Although rate adaptation problem has been extensively studied for static residential and enterprise network scenarios, there is little work dedicated to the IEEE 802.11 rate adaptation in vehicular networks. Here, the authors are motivated to study the IEEE 802.11 rate adaptation problem in infrastructure-based vehicular networks. First of all, the performances of several existing rate adaptation algorithms under vehicle network scenarios, which have been widely used for static network scenarios, are evaluated. Then, a new rate adaptation algorithm is proposed to improve the network performance. In the new rate adaptation algorithm, the technique of sampling candidate transmission modes is used, and the effective throughput associated with a transmission mode is the metric used to choose among the possible transmission modes. The proposed algorithm is compared to several existing rate adaptation algorithms by simulations, which shows significant performance improvement under various system and channel configurations. An ideal signal-to-noise ratio (SNR)-based rate adaptation algorithm in which accurate channel SNR is assumed to be always available is also implemented for benchmark performance comparison.

Structured engagement in the extended enterprise

Discusses the necessity for the conscious recognition of the phenomenon known as the extended enterprise; this demands that product, process and supply chain design are all considered simultaneously. Structure must be given to the extended enterprise in order to understand and manage it efficaciously. The authors discuss multiple perspectives for doing this, and employ the notions of “3-dimensional concurrent engineering” and “holonic thinking” for conceiving what the structure may look like. Describes a current “action research” project that is investigating potential lead-time reductions within an extended enterprise’s product introduction process. This aims to produce process visualisations, a framework for structuring and sychronising phases and stage-gates within the extended enterprise, and a new simulation tool which will provide a synthetic distributed hypermedia network. These deliverables will be used to play strategic “games” to explore problem issues within the product introduction process that belongs to the extended enterprise, develop teamwork across autonomous companies, and ultimately, contribute to the design of future extended enterprise supply chains.

Developing a framework to evaluate business networks:the case of Ireland's industry-led network initiative

Business networks have been described as cooperative arrangements between independent business organisations that vary from contractual joint ventures to informal exchanges of information. This collaboration has become recognised as an innovative and efficient tool for organising interdependent activities, with benefits accruing to both firms and the local economy. For a number of years, resources have been devoted to supporting Irish networking policies. One recent example of such support is the Irish government's target of €20 million per annum for five years to support the creation of enterprise-led networks. It is imperative that a clear rationale for such interventions is established, as the opportunity cost of public funds is high. This article, therefore, develops an evaluation framework for such networking interventions. This framework will facilitate effective programme planning, implementation and evaluation. It will potentially show how a chain of cause-and-effect at both micro and macro-levels for networking interventions can be established.

Enterprise networking:multilayer switching and applications

Primarily targeted toward the network or MIS manager who wants to stay abreast of the latest networking technology, Enterprise Networking: Multilayer Switching and Applications offers up to date information relevant for the design of modern corporate networks and for the evaluation of new networking equipment. The book describes the architectures and standards of switching across the various protocol layers and will also address issues such as multicast quality of service, high-availability and network policies that are requirements of modern switched networks.

Minority enterprise in the clothing industry: an analysis of Asian jeans manufacturers in Birmingham

This thesis discusses and assesses the resources available to Asian entrepreneurs in the West Midlands' clothing industry and how they are used by these small businessmen in order to address opportunities in the market economy within the constraints imposed. The fashion industry is volatile and is dependent upon flexible firms which can respond quickly to shortrun production schedules. Small firms are best able to respond to this market environment. Production of jeans presents an interesting departure from the mainstream fashion industry. It is traditionally gared towards longrun production schedules where multinational enterprises have artificially diversified the market, promoting the 'right' brand name and have established control of the upper end of the market, whilst imports from Newly Developing Countries have catered for cheap copies at the lower end of the market. In recent years, a fashion element to jeans has emerged, thus opening a market gap for U.K. manufacturers to respond in the same way as for other fashion articles. A large immigrant population, previously serving the now declining factories and foundries of the West Midlands but, through redundancy, no longer a part of this employment sector, has ~5ponded to economic constraints and market opportunities by drawing on ethnic network resources for competitive access to labour, finance and contacts, to attack the emergent market gap. Two models of these Asian entrepreneurs are developed. One being somecne who has professionally and actively tackled the market gap and become established. These entrepreneurs are usually educated and have personal experience in business and were amongst the first to perceive opportunities to enter the industry, actively utilising their ethnicity as a resource upon which to draw for favorable access to cheap, flexible labour and capital. The second model is composed of later entrants to jeans manufacturing. They have less formal education and experience and have been pushed into self-employment by constraints of unemployment. Their ethnicity is passively used as a resource. They are more likely confined to the marginal activity of 'cut make and trim' and have little opportunity to increase profit margins, become estalished or expand.

Understanding enterprise behaviour:a feasibility study

This paper describes work conducted as a joint collaboration between the Virtual Design Team (VDT) research group at Stanford University (USA) , the Systems Engineering Group (SEG) at De Montfort University (UK) and Elipsis Ltd . We describe a new docking methodology in which we combine the use of two radically different types of organizational simulation tool. The VDT simulation tool operates on a standalone computer, and employs computational agents during simulated execution of a pre-defined process model (Kunz, 1998). The other software tool, DREAMS , operates over a standard TCP/IP network, and employs human agents (real people) during a simulated execution of a pre-defined process model (Clegg, 2000).

Knowledge management and enterprise risk management implementation in financial services

This paper starts from the viewpoint that enterprise risk management is a specific application of knowledge in order to control deviations from strategic objectives, shareholders’ values and stakeholders’ relationships. This study is looking for insights into how the application of knowledge management processes can improve the implementation of enterprise risk management. This article presents the preliminary results of a survey on this topic carried out in the financial services sector, extending a previous pilot study that was in retail banking only. Five hypotheses about the relationship of knowledge management variables to the perceived value of ERM implementation were considered. The survey results show that the two people-related variables, perceived quality of communication among groups and perceived quality of knowledge sharing were positively associated with the perceived value of ERM implementation. However, the results did not support a positive association for the three variables more related to technology, namely network capacity for connecting people (which was marginally significant), risk management information system functionality and perceived integration of the information systems. Perceived quality of communication among groups appeared to be clearly the most significant of these five factors in affecting the perceived value of ERM implementation.

Exploring chain, network and cluster collaborative practices:implications for SMEs

Collaboration among enterprises has been rendered as one of the most important issues in the business agenda, either as a result of the globalisation and deregulation of markets or as a result of the Information and Communication Technology (ICT) revolution. Both factors have created a business reality where success in the collaboration practices followed, may result in improvements in the competitive position of enterprises. This paper starts from the basic business activity of the individual enterprise, looks into the chain, network and cluster collaborative practices and analyses their characteristics and the implications for Small-Medium Enterprises (SMEs). In addition, it provides insights regarding the opportunities, benefits, requirements and risks related to each collaborative practice. This paper finally argues that different collaboration practices are required, as enterprises and the industrial sectors where they operate, present distinctive characteristics.

Impact of denial of service solutions on network quality of service

The Internet has become a universal communication network tool. It has evolved from a platform that supports best-effort traffic to one that now carries different traffic types including those involving continuous media with quality of service (QoS) requirements. As more services are delivered over the Internet, we face increasing risk to their availability given that malicious attacks on those Internet services continue to increase. Several networks have witnessed denial of service (DoS) and distributed denial of service (DDoS) attacks over the past few years which have disrupted QoS of network services, thereby violating the Service Level Agreement (SLA) between the client and the Internet Service Provider (ISP). Hence DoS or DDoS attacks are major threats to network QoS. In this paper we survey techniques and solutions that have been deployed to thwart DoS and DDoS attacks and we evaluate them in terms of their impact on network QoS for Internet services. We also present vulnerabilities that can be exploited for QoS protocols and also affect QoS if exploited. In addition, we also highlight challenges that still need to be addressed to achieve end-to-end QoS with recently proposed DoS/DDoS solutions. © 2010 John Wiley & Sons, Ltd.

Verification of the indoor gps system by comparison with points calibrated using a network of laser tracker measurements

This paper details a method of determining the uncertainty of dimensional measurement for a three dimensional coordinate measurement machine. An experimental procedure was developed to compare three dimensional coordinate measurements with calibrated reference points. The reference standard used to calibrate these reference points was a fringe counting interferometer with the multilateration technique employed to establish three dimensional coordinates. This is an extension of the established technique of comparing measured lengths with calibrated lengths. Specifically a distributed coordinate measurement device was tested which consisted of a network of Rotary-Laser Automatic Theodolites (R-LATs), this system is known commercially as indoor GPS (iGPS). The method was found to be practical and able to establish that the expanded uncertainty of the basic iGPS system was approximately 1 mm at a 95% confidence level. © Springer-Verlag Berlin Heidelberg 2010.