A. S. Hussaini

Evaluation of the angle of arrival based techniques

In this work we present the angle of arrival estimation techniques and their comparison at different values of SNR using a 5 element UCA. The techniques that have been considered include phase interferometry, Multiple Signal Classification and covariance. The results show that for very low values of SNR the performance of the covariance matrix based algorithm is the best but for slightly higher values of SNR, MUSIC algorithm outperforms covariance.

A load-pull approach to design an optimum load impedance and matching network for class-F RF power amplifier

This paper presents a Load-pull approach to design a fundamental load impedance and independent matching for class-F RF power amplifier high efficiency operation. The output used a transmitting type active integrated antenna. Power amplifier was design and simulated using Cree GaN FET CGH40010F transistor device at 2.62-GHz operating frequency. The performance of the network has improved by 78% power added efficiency at 30dBm output power.

Current technologies and location based services

This paper examines the benefits and drawbacks of these services, reviewing differences in infrastructure, power requirements, sensing devices, and other factors. Technologies covered include Radio Frequency Identification, GSM, GPS, A-GPS, Smart Antennas, Distributed Antenna Systems, Localization by Cell-ID, Localization by Prediction (Dead Reckoning method), Angle of Arrival (AOA), Localization by Finger Printing, Localization by Time of Arrival (TOA), Localization by Observed Time Difference of Arrival (TDOA), and Hybrid Localization-based AOA-TOA.

A 2.62-GHz class-F power amplifier with lumped-element and transmission line network design

A 2.62-GHz class-F power amplifier with independent analogous method, lumped-element network design is presented. The amplifier is designed using CGH40010 GaN HEMT transistor device with 5th order low pass structure at the lumped-element output network. A transmission line networks has been used in transformation of both input and output of the amplifier. Optimum fundamental impedance matching networks and optimization are applied at the frequencies of interest to controlling the even and odd harmonics, to allow fundamental frequency deliver to the load. The power amplifier achieves 81.5% peak efficiency at 18.1dBm output power.

Africa: cyber-security and its mutual impacts with computerisation, miniaturisation and location-based authentication

The state of insecurity occasioned by fraudulent practices in Africa has been of concern economically, both at home and abroad. In this paper, we propose ways to mitigate this problem, using Nigeria as a case study. Based on surveys in West Africa, the paper examines the security situation in the continent and its mutual impacts with computerisation, miniaturisation and Location-Based Authentication (LBA). It was discovered that computerisation and miniaturisation had negative effects on cyber-security, as these were being exploited by fraudsters, using advance fee fraud; called 419. As a countermeasure, the paper examines the possibility of using LBA and digitisation of the GSM Mobile country codes down to city/area codes along with GSM/GPS authentications. These could also be combined with the use of a web-based Secret Sharing Scheme for services with very high security demands. The challenges of roaming were also examined and considered to be of negligible impact.

The computation of complex resonance of microstrip antenna using method of moment and firefly algorithms

In this paper, the hybrid optimisation process to predict the resonance frequencies of printed patch antennas is presented. The firefly method is used for optimisation whereas the spectral moment of method is used for modelling the antenna structure. The Fourier transform is applied to the equilateral triangle shape patch antenna with appropriate choice of basis to determine the Eigen solution to compute the antenna resonances. Several results were demonstrated to prove the concept.

A 15.5 W Si-LDMOS Balanced Power Amplifier with 53% Ultimate PAE for High Speed LTE

In this paper, a 15.5 W Si-LDMOS balanced power amplifier (PA) technique operating in the 2.620–2.690 GHz frequency band for LTE systems is presented. The amplifier was designed using large signal Si-LDMOS models, which demonstrated saturation P1dB of 41 dBm and 53% PAE. The AM-AM and AM-PM measured data of the balanced amplifier is extracted and embedded in the device under test (DUT) based on IEEE 802.16 OFDM WLAN Transceiver system. A simple linear model was design for behavioral modelling of memory-less baseband digital pre-distorter. The nonlinearity of the balanced amplifier has been compensated using the Simulink version R2011a.

Nigeria: Cyber Space Security vis a vis Computerisation, Miniaturisation and Location-Based Authentication

The degree of insecurity occasioned by fraudulent practices in Nigeria has been of great concern economically, especially as it relates to overseas transactions. This paper was designed to mitigate this problem for Nigeria and countries with similar dispositions. Based on a survey involving field trip to Nigeria, the paper examines the general security situation in Nigeria and its mutual impacts with computerisation, miniaturisation and Location-Based Authentication (LBA). It was discovered that both computerisation and miniaturisation had some negative effects on cyber-security, as these were being exploited by fraudsters, especially using ‘advance fee fraud;’ popularly called 419. As a countermeasure, the research examined the possibility of using LBA and further digitisation of the GSM Mobile country codes down to City/Area codes along with GSM Mobile/Global Positioning System (GPS) authentications. Where necessary, these could be combined with the use of a web-based Secret Sharing Scheme for services with very high security demands. The anticipated challenges were also examined and considered to be of negligible impacts; especially roaming.

Performance of different wavelet families using DWT and DWPT-channel equalization using ZF and MMSE

We have studied the performance of multidimensional signaling techniques using wavelets based modulation within an orthogonally multiplexed communication system. The discrete wavelets transform and wavelet packet modulation techniques have been studied using Daubechies 2 and 8, Biothogonal1.5 and 3.1 and reverse Biorthognal 1.5 and 3.1 wavelets in the presence of Rayleigh multipath fading channels with AWGN. Results showed that DWT based systems outperform WPM systems both in terms of BER vs. SNR performance as well as processing. The performances of two different equalizations techniques, namely zero forcing (ZF) and minimum mean square error (MMSE), were also compared using DWT. When the channel is modeled using Rayleigh multipath fading, AWGN and ISI both techniques yield similar performance.