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In this paper we investigate the possibility of multiple HAP coverage of a common cell area. In particular we study the uplink system performance since it is considered as a worst case scenario. In order to obtain further enhancement (interference mitigation) we also apply space-time diversity techniques, such as Single-Input Multiple-Output (SIMO) receive diversity or Multiple-Input Multiple-Output...
The subspace eigen-decomposition algorithms are applied to the problem of detecting ionospheric interfering signals affecting the performance of Loran-C receivers. In particular, we are interested in measuring the delay of these interfering Loran-C skywave components. The performance of these algorithms are evaluated and compared with our Fourierbased method. The simulation results show that many...
In this paper we study the depolarization effects caused weather conditions and scattering structures at ground level on the performance of a multiple satellite system employing multi-polarized compact MIMO antenna configurations. In order to reinforce the analysis, we first propose a novel multichannel simulator that produces realistic time-series of the fading process affecting signal transmission...
In this paper we address the potential gain of using compact MIMO antenna array configurations in conjunction with satellite diversity techniques in order to increase the data rates in satellite communication systems. We will also investigate the effects of separation angles between satellites and the spatial correlation and mutual coupling between the separate antenna elements on system performance...
In this paper we study the depolarization effects caused by rain and ice particles in the troposphere on the performance of a multiple HAP (high altitude platforms) system employing multi-polarized compact MIMO antenna configurations. In order to reinforce the analysis, we first propose a novel multi-channel simulator that produces realistic time-series of the fading process affecting signal transmission...
In this paper we propose a novel combination of orthogonal frequency division multiplexing (OFDM) and the orbital angular momentum (OAM) of the electromagnetic field to produce a novel orthogonal momentum division multiplexing (OMDM) technique. This OMDM technique is applied to a satellite diversity system employing three satellites. Simulation results show that the proposed OMDM-satellite diversity...
In this paper, performance of providing WiMAX from high altitude platforms (HAPs) with multiple antenna payload will be investigated as well as considering the coexistence capability with multiple-operator terrestrial deployments. A scenario of a HAP and terrestrial WiMAX base stations deployed inside a HAP coverage area with a radius at 30 km will be proposed. HAP cellular formation with different...
In this paper we assess the multipath propagation effects of a short-range wireless device operating at 2.4 GHz in an indoor office environment. The investigations are carried out using FEM simulations and measurement trials for NLOS and LOS propagation scenarios. The FEM simulations will also be used for assessing the influence on propagation when doors are opened or closed. Finally, we investigate...
In this paper we address the potential gain of using various compact MIMO antenna array configurations in conjunction with HAP (high altitude platforms) diversity techniques in order to enhance the data rates in HAP communication systems. We also investigate the effects of spatial correlation and mutual coupling between the separate antenna elements on system performance. Simulation results show that...
In this paper we investigate the possibility of multiple HAP coverage of a common cell area. In particular we study the uplink system performance since it is considered as a worst case scenario. The results show that we cannot have more than two HAPs simultaneously unless the user terminal has some form of directive antenna. The results also show that there may be a worst case elevation angle for...
Active suppression of noise and vibrations is a well established field of research with many applications in acoustic and mechanical industries. In this paper we test some of these active control methods combined with MIMO antenna system in order to assess their validity and performance when applied to electromagnetic fields. The application that we evaluated is a model of a mobile phone equipped...
Wireless sensor networks can be used for a multitude of applications but they all have in common that they need to send their collected data to some central processing node. If the sensors are located at a faraway distance from a processing node, the transmission might need the combined transmitter power of several sensors. In this paper we investigate array beamforming through cooperating sensor...
In this paper we propose a multi-channel simulator that produces a realistic time-series of the fading process affecting signal transmission in satellite systems. The proposed simulator takes into account the temporal, spatial and polarization properties affecting these processes. In addition, we determine the impact on the total capacity of an application that utilizes the spatial-polarization channels...
The evaluation of uplink performance of delivering WiMAX services from high altitude platforms (HAPs) is presented. System performance is assessed in terms of coexisting capability with terrestrial WiMAX system, employing directive antenna models and optimization techniques. Simulation results show that providing WiMAX via HAPs can effectively achieve 29 dB at the edge of the HAP coverage area with...
We investigate the possibility of multiple high altitude platform (HAP) coverage of a common cell area using a wideband code division multiple access (WCDMA) system. In particular, we study the uplink system performance of the system. The results show that depending on the traffic demand and the type of service used, there is a possibility of deploying 3–6 HAPs covering the same cell area. The results...
The performance obtained from providing worldwide interoperability for microwave access (WiMAX) from high altitude platforms (HAPs) with multiple antenna payloads is investigated, and the coexistence capability with multiple-operator terrestrial WiMAX deployments is examined. A scenario composed of a single HAP and coexisting multiple terrestrial WiMAX base stations deployed inside the HAP coverage...
We investigate the performance and coexistence techniques for worldwide interoperability for microwave access (WiMAX) delivered from high altitude platforms (HAPs) and terrestrial systems in shared 3.5 GHz frequency bands. The paper shows that it is possible to provide WiMAX services from individual HAP systems. The coexistence performance is evaluated by appropriate choice of parameters, which include...
In this paper we address the potential gain of using compact MIMO antenna array configurations in conjunction with HAP diversity techniques in order to increase the data rates in HAP communication systems. Simulation results show that the MIMO system provides superior performance as compared to the single HAP case.
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