Albert Helberg

On multiple insertion/deletion correcting codes

We investigate binary, number-theoretic, bit insertion/deletion correcting codes as pioneered by Levenshtein (1965, 1966, 1989). The weight spectra and Hamming distance properties of single insertion/deletion error-correcting codes are analyzed. These relationships are then extended to investigate codes that can correct multiple random insertions and deletions. From these relationships, new bounds are derived and a general construction for multiple insertion/deletion correcting codes is proposed and evaluated.

An approach to Improve the Match-on-Card Fingerprint Authentication System security

The combination of smart cards and biometrics results in a strong 2-factor authentication. It facilitates a trusted credential for authenticating an individuals identity through one-to-one biometric verification using the smart card token. Fingerprint Authentication Systems (FASs) embedded in smart cards are gaining massive acceptance as it offers a superior level of security when compared to the conventional Match-on-Device (MOD) and Match-on-Server (MOS) technologies. The fundamental difference between the conventional FAS authentication process and FAS using smart card process is all about the authentication location. FAS authentication using smart card token is possible through four authentication approaches. They are the Template-on-Card (TOC), Match-on-Card (MOC), Work-Sharing On-Card (WSOC), and System-on-Card (SOC). Out of these four approaches, the SOC is considered as the most secure and expensive, whereas the TOC is considered as the least secure and least expensive. The MOC scheme offers a higher level of security than the TOC scheme at an affordable cost when comparing to SOC and is thus the most practical solution available today. Although this is the case, the MOC scheme is also susceptible to the inherent security vulnerabilities associated with biometric modalities in general. The front runner of the biometric vulnerabilities being the compromise of the original finger templates. This paper focuses on this critical vulnerability aspect and conceptualizes a novel Match-on-Card Fingerprint Authentication System. The proposed system does not need to store or transfer the original fingerprint template to/from the smart card and therefore facilitates an enhanced security than the conventional MOC approach.

Intrusion detection in Bluetooth enabled mobile phones

Bluetooth plays a major role in expanding global spread of wireless technology. This predominantly happens through Bluetooth enabled mobile phones, which cover almost 60% of the Bluetooth market. Although Bluetooth mobile phones are equipped with built-in security modes and policies, intruders compromise mobile phones through existing security vulnerabilities and limitations. Information stored in mobile phones, whether it is personal or corporate, is significant to mobile phone users. Hence, the need to protect information, as well as alert mobile phone users of their incoming connections, is vital. An additional security mechanism was therefore conceptualized, at the mobile phones user level, which is essential in improving the security. Bluetooth Logging Agent (BLA) is a mechanism that has been developed for this purpose. It alleviates the current security issues by making the users aware of their incoming Bluetooth connections and gives them an option to either accept or reject these connections. Besides this, the intrusion detection and verification module uses databases and rules to authenticate and verify all connections. BLA when compared to the existing security solutions is novel and unique in that it is equipped with a Bluetooth message logging module. This logging module reduces the security risks by monitoring the Bluetooth communication between the mobile phone and the remote device.

Evaluation of the Wideband Compressive Radio Receiver for spectrum sensing

We present an empirical evaluation of the carrier detection method used in the Wideband Compressive Radio Receiver (WCRR), which is of particular interest for spectrum sensing in Cognitive Radio (CR) and Dynamic Spectrum Access (DSA). We study the effect of different combinations of the decimation factor L, and window lengths, N. We then assess the robustness of the carrier detection method to noise. We find that the WCRR should be a viable option for wideband spectrum sensing using readily available Analog to Digital Converters (ADCs).

White space and digital dividends: The case for dynamic spectrum access in South Africa

In this paper we present the current state of affairs surrounding the analog switch-off and corresponding digital dividend as pertaining to South Africa. Analog switch-off and digital dividends has enjoyed much attention lately due to the constantly increasing data requirements of wireless devices and the alarming decrease of available spectrum for deployment of new wireless technologies. An estimated 300 MHz of spectrum will be made available after analog switch-off. To this end the main contributions of this paper is to detail the state of affairs surrounding analog switch-off, the possibilities for the digital dividend and Spectrum Opportunities that exist in South Africa.

Modified Earliest Decoding for Random Network Codes

We present a practical, modified version of earliest decoding for random linear network coding networks. This decoding method has a lower complexity and decoding delay than traditional Gaussian elimination decoding schemes.

Data acquisition system for capturing dynamic transients in a control valve

This work presents the development of a data acquisition (DAQ) system to be used in conjunction with fuzzy modelling to derive a dynamic mathematical model of a control valve. Characterising the behaviour of a control valve or any other mechanical device, either requires expert knowledge of the device and its subcomponents or real-world data thereof. Capturing real-world data not necessarily requires expert device knowledge but requires some from of post-analysis with either neural networks or fuzzy logic systems to derive a mathematical model. In order to capture valve specific physical data, different tests need to be conducted with the intent of capturing transient specific data embedded within the temperatures, mass flow rate, pressures and corresponding valve opening. The dynamic mathematical model will be used in a simulator to predict the behaviour of the device within the system. An accurate DAQ system and modelling procedure needs to be in place to ensure the development of reliable mathematical models of such mechanical devices. Once all relevant data have been acquired it can be used to derive a mathematical model for the control valve which includes static, dynamic, choke and nonchoke characteristics.

The performance of feature-based classification of digital modulations under varying SNR and fading channel conditions

Feature-based classification is a method used for automatic modulation classification of communication signals. This method requires extraction of various features from a signal. One of the approaches for feature extraction is the use of instantaneous amplitude, phase and frequency. The performance of these features under different SNR conditions is well described in literature [1]-[2], but the effect of fading on the extracted features has received little investigation. In this paper we investigate the quality of the features in a static multipath Rayleigh fading channel under varying channel conditions. It was found that most feature values are distinguishable for the different digital signals in a flat fading channel. This work shows the behaviour of these features in a fading channel under deteriorating conditions and suggests ways to reduce the effect of the fading on the classification of the signals.

2D Methods for Pose Invariant Face Recognition

The ability to recognise face images under random pose is a task that is done effortlessly by human beings. However, for a computer system, recognising face images under varying poses still remains an open research area. Face recognition across pose is the ability of a face recognition technology (FRT) to recognise face images in different viewpoints, i.e. recognition of face images that are out of the image plane. In this research work, a short literature survey of 2D techniques which are used to correct pose are discussed. The classification of these techniques is based on three categories, (1) Real-view based matching, (2) Image space pose transformation and (3) Feature space pose transformation. This paper discuss the types of databases used, approaches to correct pose, the types of features extracted.

Fingerprint Matching on Smart Card: A Review

Fingerprint Match-on-Card (MoC) offers the highest degree of privacy and security to cardholders as the fingerprint never leaves the secure environment of a smart card. The level of security of a biometric system is evaluated by the location where the biometric matching takes place. However, it is challenging to implement an accurate fingerprint MoC algorithm, which can execute in a short period of time due the limited working memory and processing speed that the smart card provides. Implementing a fingerprint algorithm inside the smart card requires a small template size and a light matching algorithm. This paper reviews the existing fingerprint MoC algorithms, their shortfalls, and advantages.