RF communication between surface and underwater robotic swarms

In order for underwater robots to communicate with land and air based robots on an equal basis, high speed communications is required. If the robots are not to be tethered then wireless communications is the only possibility. Sonar communications is too slow. Unfortunately radio waves are rapidly attenuated under water due to phenomena such as skin depth. These experiments attempt to extend the range of underwater radio communications.

A distributed directory scheme for information access in mobile computers

In this paper, we discuss the design aspects of a dynamic distributed directory scheme (DDS) to facilitate efficient and transparent access to information files in mobile environments. The proposed directory interface enables users of mobile computers to view a distributed file system on a network of computers as a globally shared file system. In order to counter some of the limitations of wireless communications, we propose improvised invalidation schemes that avoid false sharing and ensure uninterrupted usage under disconnected and low bandwidth conditions.

Cloud-linked and campus-linked students’ perceptions of collaborative learning and design based learning in engineering

The aim of this paper is to analyse and present cloud- link as well as campus-linked students’ perceptions of collaborative learning and design based learning in engineering. Project oriented design based learning (PODBL) is a learning and teaching approach, where students learn through design activities while being driven by project(s). PODBL enhances cloud-linked and campus-linked students’ ability to acquire career essential skills that fulfill future industry needs. A paper-based survey is used to recognise a cohort of students' experience of collaborative learning and design based learning in engineering. The paper-based survey was given to 30 students from an engineering discipline. The quantitative analysis of the survey results shows that more than 50% of the students view collaborative learning to have a large benefit in design-based learning.

Multicast lifetime maximization using network coding in lossy wireless ad-hoc networks

In traditional stop-and-wait strategy for reliable communications, such as ARQ, retransmission for the packet loss problem would incur a great number of packet transmissions in lossy wireless ad-hoc networks. We study the reliable multicast lifetime maximization problem by alternatively exploring the random linear network coding in this paper. We formulate such problem as a min-max problem and propose a heuristic algorithm, called maximum lifetime tree (MLT), to build a multicast tree that maximizes the network lifetime. Simulation results show that the proposed algorithms can significantly increase the network lifetime when compared with the traditional algorithms under various distributions of error probability on lossy wireless links.

Emerging wireless personal area networks(WPANs) : - An analysis of techniques, tools and threats

Wireless Personal Area Networks provide a pivotal role in local area network technology complementing traditional Wireless Local Area Network technologies. Bluetooth, ZigBee and NFC (Near Field Communications) have emerged as key WPAN technologies with UWB (Ultra Wide Band) standards currently evolving. They are however subject to the usual range of security vulnerabilities found in wireless LANs such as spoofing, snooping, man-in-the-middle, denial of service and other attacks. However security in WPANs is not as mature as it is in Wireless LANs and further work is needed in order to provide comparable protection. This paper examines a range of WPAN technologies and security issues and proposes protection mechanisms that can mitigate risk in each case. © 2012 IEEE.

ChainCluster : engineering a cooperative content distribution framework for highway vehicular communications

The recent advances in wireless communication techniques have made it possible for fast-moving vehicles to download data from the roadside communications infrastructure [e.g., IEEE 802.11b Access Point (AP)], namely, Drive-thru Internet. However, due to the high mobility, harsh, and intermittent wireless channels, the data download volume of individual vehicle per drive-thru is quite limited, as observed in real-world tests. This would severely restrict the service quality of upper layer applications, such as file download and video streaming. On addressing this issue, in this paper, we propose ChainCluster, a cooperative Drive-thru Internet scheme. ChainCluster selects appropriate vehicles to form a linear cluster on the highway. The cluster members then cooperatively download the same content file, with each member retrieving one portion of the file, from the roadside infrastructure. With cluster members consecutively driving through the roadside infrastructure, the download of a single vehicle is virtually extended to that of a tandem of vehicles, which accordingly enhances the probability of successful file download significantly. With a delicate linear cluster formation scheme proposed and applied, in this paper, we first develop an analytical framework to evaluate the data volume that can be downloaded using cooperative drive-thru. Using simulations, we then verify the performance of ChainCluster and show that our analysis can match the simulations well. Finally, we show that ChainCluster can outperform the typical studied clustering schemes and provide general guidance for cooperative content distribution in highway vehicular communications.

A cross-layer key establishment scheme in wireless mesh networks

Cryptographic keys are necessary to secure communications among mesh clients in wireless mesh networks. Traditional key establishment schemes are implemented at higher layers, and the security of most such designs relies on the complexity of computational problems. Extracting cryptographic keys at the physical layer is a promising approach with information-theoretical security. But due to the nature of communications at the physical layer, none of the existing designs supports key establishment if communicating parties are out of each other's radio range, and all schemes are insecure against man-in-the-middle attacks. This paper presents a cross-layer key establishment scheme where the established key is determined by two partial keys: one extracted at the physical layer and the other generated at higher layers. The analysis shows that the proposed cross-layer key establishment scheme not only eliminates the aforementioned shortcomings of key establishment at each layer but also provides a flexible solution to the key generation rate problem. © 2014 Springer International Publishing Switzerland.