Small aircraft cockpit electromagnetic interference due to UMTS signal propagation

This paper implemented a ray-tracing based algorithm to calculate the EMI generated inside an aircraft cabin with particular emphasis on flight critical equipment such as the cockpit avionics panel. The interference level caused by the deployment of a UMTS Node B antenna for the provision of passenger communication was computed. The model was employed to study the effects of the multipath electromagnetic propagation attained from positioning a Node B antenna in different locations inside a relatively small tunnel shaped fuselage with dense furnishings. The proposed framework is also able to provide an all-encompassing understanding of the generated EMI, whilst offering support for the development of conscientious network design in aircraft.peer-reviewe

In Defense of Wireless Carrier Sense

Carrier sense is often used to regulate concurrency in wireless medium access control (MAC) protocols, balancing interference protection and spatial reuse. Carrier sense is known to be imperfect, and many improved techniques have been proposed. Is the search for a replacement justified? This paper presents a theoretical model for average case two-sender carrier sense based on radio propagation theory and Shannon capacity. Analysis using the model shows that carrier sense performance is surprisingly close to optimal for radios with adaptive bitrate. The model suggests that hidden and exposed terminals usually cause modest reductions in throughput rather than dramatic decreases. Finally, it is possible to choose a fixed sense threshold which performs well across a wide range of scenarios, in large part due to the role of the noise floor. Experimental results from an indoor 802.11 testbed support these claims

Forward focus: using routing information to improve medium access control in ad hoc networks

Summary Multihop packet forwarding is a vital process in an ad hoc network. All ad hoc networking protocols, but particularly routing and medium access control protocols, must work together in order for the network to be successful. However, current MAC protocols such as IEEE 802.11 do not consider this multihop nature at all. This work develops a modification to 802.11 that focuses on forwarding packets. Routing information is utilized to streamline the sharing of the medium, by allowing forwarding nodes to reuse an already-acquired channel. Using forward focus (FF), nodes are encouraged to participate in the forwarding process and are rewarded for doing so. Simulation-generated performance evaluations reveal that the result is a MAC protocol with improved efficiency and effectiveness

Preventing phone theft and robbery: the need for government action and international coordination

The banning of stolen handsets from networks has been around for 20 years, but remains little used internationally. Where used, its effectiveness is hindered by implementation problems, reprogramming, easy fencing opportunities, and international trafficking. Kill-switches where the user remotely disables a handset and deletes data have potential but, if non-permanent, are likely to experience similar limitations. This study proposes a set of responses to be adopted by national governments with international coordination

Hello message scheme enhancement in CRMANET

© 2016 IEEE. All these years, a lot of efforts have been put upon how to reduce the broadcast overhead consumption in Cognitive Radio enabled Mobile Ad hoc Network (CRMANET). In this work, we propose an improved hello message scheme named Adaptive Classified Hello Scheme (ACHS) adopting classification method in CRMANET. Different from fixed hello interval and content form in frequently used Periodic Hello Message Scheme (PHMS), ACHS categorizes nodes into different classes based on node mobility. Each class in ACHS will be configured with different hello intervals and content format. Given each nodes real-time function performing in CRMANET (on the route or off the route), ACHS employs different strategies. For instance, when nodes are performing data transmission, instead of sending dedicate hello messages, their hello information will be attached into the data message to further reduce the control overhead. Compared with Periodic Hello Message Scheme (PHMS) and Reactive Hello Protocol (RHMS) in simulation, ACHS has improved hello efficiency around 50%

A Java Based Network Security on Wireless Network communication

Now a day a Wireless networking provides many advantages, but it also integrated with new security threats and alters the organizations overall information security risk profile. Security of data and privacy issu es are important to individuals and organizations especially where exchange of data is done through computer networks. Organizations invest time and resources to reduce the threat and occurrence of data insecurity. Encryption is one of the many methods adopted because of its adaptability to electronic communication channels we are encrypting and decrypting a message from a server to a client, in which the message is encrypted on the server side and decrypt on the client side for some security purposes. Th ough there are many methods to handle such situations like data security encryption plays a vital role. We all see how DES works for countering those threats, when a data is transfer from server to client

Sustainable–Smart–Resilient–Low Carbon–Eco–Knowledge Cities; Making sense of a multitude of concepts promoting sustainable urbanization

Over the last couple of decades, metropolitan areas around the world have been engaged in a multitude of initiatives aimed at upgrading urban infrastructure and services, with a view to creating better environmental, social and economic conditions and enhancing cities' attractiveness and competitiveness. Reflecting these developments, many new categories of 'cities' have entered the policy discourse: 'sustainable cities'; 'green cities'; 'digital cities'; 'smart cities'; intelligent cities'; 'information cities'; 'knowledge cities'; 'resilient cities'; 'eco-cities'; 'low carbon cities'; 'liveable cities'; and even combinations, such as 'low carbon eco-cities' and 'ubiquitous eco-cities’. In practice, these terms often appear to be used interchangeably by policy makers, planners and developers. However, the question arises whether these categories nevertheless each embody distinct conceptual perspectives, which would have implications for how they are understood theoretically and applied in policy. In response, this article investigates, through a comprehensive bibliometric analysis, how the twelve most frequent city categories are conceptualised individually and in relation to one another in the academic literature. We hypothesize that, notwithstanding some degree of overlap and cross-fertilization, in their essence the observed categories each harbour particular conceptual perspectives that render them distinctive. This is borne out by the findings, which demonstrate robustly for the first time the conceptual differences and interrelationships among twelve dominant city categories. The 'sustainable city' is the most frequently occurring category and, in a map of keyword co-occurrences, by far the largest and most interconnected node, linked closely to the 'eco-city' and 'green city' concepts. Recently, the more narrow concepts of 'low carbon city' and 'smart city' have been on the rise, judging by their frequency of occurrence in academic journals; the latter in particular appears to have become an increasingly dominant category of urban modernization policy. On their part, ‘resilient city’ and ‘knowledge city’ represent distinct concepts, albeit with comparatively low frequency. Overall, the findings point to the need for rigor and nuance in the use of these terms, not least if one wishes to comprehend their implications for urban development and regeneration policy and practice