M. S. M. Isa

Simulation of virtual MIMO base stations for mobile location in IMT-Advanced networks

The conventional Location and Positioning (L&P) methods rely on availability of base station (BS) locations as well as mitigation of propagation effects. It is known that the location estimation accuracy suffers from poor geometric dilution of precision (GDOP) caused by BS location as the conventional location algorithms which result in large GDOP values correspond to poor geometrical topology. In addition, NLOS effects cause a large error in time of arrival (TOA) reading; thus affecting mobile station (MS) estimation accuracy. In this paper a novel concept of virtual BS (VirBS) utilizing multiple input multiple output (MIMO) technology has been introduced and applied for improving L&P accuracy. The performance of the proposed algorithm has been evaluated via computer simulations. The simulation results demonstrate that the proposed algorithm allows up to 30 percent improvement in L&P accuracy without additional expenditure on network architecture.

Transformation of generalized chebyshev lowpass filter prototype to Suspended Stripline Structure highpass filter for wideband communication systems

This paper presents the transformation of generalized Chebyshev lowpass filter prototype to highpass filter using Suspended Stripline Structure (SSS) technology. The study involves circuit analysis to determine generalized Chebyshev responses with a transmission zero at finite frequency. The transformation of the highpass filter from the lowpass filter prototype provides a cutoff frequency of 3.1 GHz with a return loss better than -20 dB. The design is simulated on a Roger Duroid RO4350 with a dielectric constant, εr of 3.48 and a thickness of 0.168 mm. The simulation performance results show promising results that could be further examined during the experimental works. This class of generalized Chebyshev highpass filter with finite transmission zero would be useful in any RF/ microwave communication systems particularly in wideband applications where the reduction of overall physical volume and weight as well as cost very important, while maintaining its excellent performance.

Utilising MIMO for positioning in mobile WiMAX systems

Worldwide interoperability for microwave access (WiMAX) brings additional features that can be utilized for enhancing positioning accuracy. This paper deals with WiMAX positioning scheme based on the first arrival path (FAP) of the time of arrival (TOA) technique by utilising one of WiMAX offered features i.e multiple input multiple output (MIMO) system. Simulation results show that the performance of system in term of the positioning accuracy adheres to the Federal Communications Commission (FCC) requirements.

A novel technique of controlling signal propagation within array elements using switchable miniaturized electromagnetic band gap

In this paper, a novel miniaturized capacitive loaded electromagnetic band gap (EBG) has been developed with the patch size of approximately)./36. The dimension is controllable using the lumped capacitive elements values. The surface impedance characteristic of the EBG structure is switchable as pin vias have been inserted and removed within the EBG center and the ground plane. Switching the EBG surface impedance characteristic within the array elements has demonstrated the novel application of miniaturized EBG to control the signal propagation within the array elements. Radiation pattern for the middle antenna is enhanced toward the antenna which connected with low surface impedance EBG structure resulting approximately 12dB improvement in gain. The propagation characteristics and gain of the array have been analyzed using CST Microwave Studio (CST MWS). The new application of the EBG can be very useful to realize the controlling and channeling the signal within the array elements.