Large Families of Ternary Sequences with Aperiodic Zero Correlation Zone Sequences for a Multi-Carrier DS-CDMA System

A new method for generating families of ternary spreading sequences is presented. The sequences have aperiodic zero correlation zones and large families are created for a specific sequence length. The sequences are proposed as spreading sequences to provide high capacity and cancel multipath and multiple access interference (MAI) in a single carrier (SC) or multi-carrier (MC) direct-spread code division multiple access (DS-CDMA) system. A Multi-carrier DS-CDMA system is simulated that employs the new sequences as spreading sequences in a multipath channel. Bit error rates (BER) and frame error rates (FER) for a range of Eb/No values are presented and it is demonstrated that the proposed sequences improve the BER and FER performance when used in place of masked Walsh Codes for the frequency selective fading channel evaluated, when a single correlator receiver is used on each sub-carrier

Creating and collaborating: students’ and tutors’ perceptions of an online group project

Although collaboration skills are highly valued by employers, convincing students that collaborative learning activities are worthwhile, and ensuring that the experience is both useful and enjoyable, are significant challenges for educators. This paper addresses these challenges by exploring students’ and tutors’ experiences of a group project where part-time distance learners collaborate online to create a website. Focus groups were conducted with students who had recently completed the project, and discussion forums were used to gather feedback from tutors who supported students and marked their group work. The research showed that students’ attitudes towards the group project on completion were generally favourable. Findings highlighted key aspects for successful online group projects and for motivating students to participate fully. These included: the design of authentic tasks, with skills development relevant to the workplace; careful attention to how the group work is assessed; and enabling students to develop websites they could be proud of. Frustrations for students were associated with the lack of engagement of fellow students and with limitations of the tool provided for building the website. Tutors found marking the work a time-consuming and complex process. Tutors were also unconvinced of the value and fairness of assessing students partly on a group, as opposed to an individual, basis

Using wikis for online group projects: student and tutor perspectives

This paper presents a study of the use of wikis to support online group projects in two courses at the UK Open University. The research aimed to investigate the effectiveness of a wiki in supporting (i) student collaboration and (ii) tutors’ marking of the students’ collaborative work. The paper uses the main factors previously identified by the technology acceptance model (TAM) as a starting point to examine and discuss the experiences of these two very different user groups: students and tutors. Data was gathered from students via a survey and from tutors via a range of methods. The findings suggest that, when used in tandem with an online forum, the wiki was a valuable tool for groups of students developing a shared resource. As previous studies using the TAM have shown, usefulness and ease of use were both important to students’ acceptance of the wiki. However, the use of a wiki in this context was less well-received by tutors, because it led to an increase in their workload in assessing the quality of students’ collaborative processes. It was possible to reduce the tutor workload by introducing a greater degree of structure in the students’ tasks. We conclude that when introducing collaborative technologies to support assessed group projects, the perceptions and needs of both students and tutors should be carefully considered

A schema for cryptographic keys generation using hybrid biometrics

Biometric identifiers refer to unique physical properties or behavioural attributes of individuals. Some of the well known biometric identifiers are voice, finger prints, retina or iris, facial structure etc. In our daily interaction with others directly or indirectly, we implicitly use biometrics to know, distinguish and trust people. Biometric identifiers represent the concept of "who a person is" by gathering vital characteristics that don't correspond to any other person. The human brain to some extent is able to ascertain disparities or variation in certain physical attributes and yet verify the authenticity of a person. But this is difficult to be implemented in electronic systems due to the intense requirements of artificial decision making and hard-coded logic. This paper examines the possibility of using a combination of biometric attributes to overcome common problems in having a single biometric scheme for authentication. It also investigates possible schemes and features to deal with variations in Biometric attributes. The material presented is related to ongoing research by the Computer Communications Research Group at Leeds Metropolitan University. We use this paper as a starting step and as a plan for advanced research. It offers ideas and proposition for implementing hybrid biometrics in conjunction with cryptography. This is work in progress and is in a very preliminary stage

The analysis of user behaviour of a network management training tool using a neural network

A novel method for the analysis and interpretation of data that describes the interaction between trainee network managers and a network management training tool is presented. A simulation based approach is currently being used to train network managers, through the use of a simulated network. The motivation is to provide a tool for exposing trainees to a life like situation without disrupting a live network. The data logged by this system describes the detailed interaction between trainee network manager and simulated network. The work presented here provides an analysis of this interaction data that enables an assessment of the capabilities of the trainee network manager as well as an understanding of how the network management tasks are being approached. A neural network architecture is implemented in order to perform an exploratory data analysis of the interaction data. The neural network employs a novel form of continuous self-organisation to discover key features in the data and thus provide new insights into the learning and teaching strategies employed

Does the scatterometer see wind speed or friction velocity?

Studies of radar backscatter from the sea surface are referred either to the wind speed, U, or friction velocity, u(sub *). Bragg scattering theory suggests that these variations in backscatter are directly related to the height of the capillary-gravity waves modulated by the larger waves in tilt and by straining of the short wave field. The question then arises as to what characteristic of the wind field is most probably correlated with the wave number spectrum of the capillary-gravity waves. The justification for selecting U as the appropriate meteorological parameter to be associated with backscatter from L-band to Ku-band are reviewed. Both theoretical reasons and experimental evidence are used to demonstrate that the dominant parameter is U/C(lambda) where U is the wind speed at a height of about lambda/2 for waves having a phase speed of C(lambda)