Tommy Hult

... Ericsson Research, Sweden {mikael.coldrey,patrik.c.persson}@ericsson.com † Lund University, Sweden tommy.hult@eit.lth.se Chalmers University of Technology, Sweden andreas.wolfgang@ chalmers.se ... Kolmonen, T. Riihonen, R. Wichman, P. Vainikainen, JI. ...

Abstract The properties of the single-link multiple-input-multiple-output (MIMO) propagation channels have been analyzed in many studies based on extensive propagation measurements. In this letter, we extend the measurement-based analysis to dual-link ...

... of Electrical and Information Technology, Lund University, Sweden Email: fredrik.harrysson@ ericsson.com, {tommy.hult, fredrik.tufvesson}@eit.lth.se ... For the measurements we used the MedavRUSK Lund channel sounder in the frequency band 2570–2630 MHz, and the signal ...

Analytical Multiple-Input Multiple-Output (MIMO) models are often attractive due to their low complexity when analyzing possibilities and limitations in the system. In this paper we outline a a possible dual link extension of an analytical MIMO channel model and investigate its suitability based on measurements of a dual link MIMO scenario. The extension is based on the correlation matrix distance (CMD) as a gauge to generate correlation matrices for the additional links of the multi-link scenario.

Abstract Correlation between different links is an essential characteristic for many of the forthcoming radio communication systems that utilize the multiple-input-multiple-output (MIMO) technology. This paper investigates the physical phenomena that cause the inter-...

In this paper we assess the effects of multipath propagation on the link performance of a short-range wireless device, like the Bluetooth, in an indoor office environment. Specifically, we analyze the non line of sight (NLOS) propagation scenario and confirm the theoretical statistics of the fading using real measurements and finite element method (FEM) simulations of the environment. The simulations are also used for assessing the impact of multipath propagation when doors are opened or closed. In addition, we also investigate the improvement in performance resulting from receive diversity gain of a system employing multiple receive antennas with various combining techniques.

In this paper we address the potential gain of using compact MIMO antenna array configurations in conjunction with HAP (High Altitude Platforms) diversity techniques in order to increase the data rates in HAP communication systems. We will also investigate the effects of spatial correlation and mutual coupling between the separate antenna elements on system performance. Simulation results show that although the capacity is degraded by correlation and mutual coupling, we still achieve significant capacity gain compared to the single HAP case. In addition, we evaluate the performance of the system for different separation angles between HAPs, and determine the optimal separation angle that maximizes the total capacity of the system.

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 although the capacity is degraded by correlation and mutual coupling, we still achieve significant capacity gain compared to the single HAP case. Simulations also show the existence of an optimum separation angle between HAPs that maximizes capacity.

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 HAP systems. The proposed simulator takes into account the temporal, spatial and polarization properties affecting these processes. Finally, we analyse the impact of depolarization on the total capacity of the system. Simulation results show a significant drop in performance as the cross polar discrimination decreases.

Abstract Antennas that are able to direct the transmitted and received signals' energy are of great interest for future wireless communication systems. The directivity implies reduced transmit power and interference, and hence potential for increased capacity. In this paper ...

ABSTRACT In this paper we investigate the wave propagation effects of a short‐range wireless device, like the Bluetooth, in an indoor office environment. Specifically, we investigate line of sight (LOS) and non line of sight (NLOS) propagation scenarios and verify the theoretical statistics of the fading using real measurements and finite element method (FEM) simulations of the environment. The simulations are also used for assessing the impact on propagation when doors are opened or closed. In addition, we also investigate the improvement in performance resulting from receive diversity gain of a system employing multiple receive antennas with various combining techniques. © 2006 American Institute of Physics

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.

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. Simulation results show that by exploiting the additional multiple polarization channels and satellite diversity we can achieve considerable capacity gain compared to the single satellite case.

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 reuse patterns will be established. Coexistence performance will be assessed in terms of HAP downlink signal interfered by terrestrial WiMAX deployment. This paper will show it is effective to deliver WiMAX via HAPs and can efficiently share the spectrum with terrestrial WiMAX systems.

ABSTRACT Reliable characterization of the propagation environment and channel modelling of mobile satellite communication systems is necessary in order to provide better quality of service and efficient design of these systems. In this paper, the channel impairments affecting the performance and an overview of the satellite channel models are presented. The statistical distributions of the received signal that can be used to characterize the dynamic nature of these propagation channels are also presented. The main modelling parameters are investigated and simulation results show that the bit error rate (BER) performance is predominantly affected by the shadowing factor. Finally, in order to further test the channel models and the effect of the propagation environment, we investigate a novel application of using satellite diversity in conjunction with compact MIMO (multiple‐input multiple‐output) antenna array configurations in order to enhance the capacity of satellite communication links.

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 (MIMO) diversity, to

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. Simulation results show that although the capacity is degraded by correlation and mutual coupling, we still achieve significant capacity gain compared to the single satellite case. Simulations also show the existence of an optimum separation angle between satellites that maximizes capacity.

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 a single-input multiple-output (SIMO) antenna receive diversity system utilizing different combining techniques to improve the performance over a fading radio channel in a NLOS propagation environment. Simulation results show that a substantial diversity gain would be achieved by using this system.

... Tommy Hult, Abbas Mohammed Blekinge Institute of Technology, 372 25 Ronneby Sweden Email:tommy.hult@bth.se, Email: abbas.mohammed@bth.se ABSTRACT ... 127-137, June 2001. Page 5. [6] Thornton, J., Grace, D., Spillard, C., Konefal, T. and Tozer, TC “Broadband ...

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 in order to assess their validity and performance when applied to electromagnetic fields. The application that we evaluated is a model of a mobile telephone equipped with one ordinary transmitting antenna and two actuator-antennas which purpose is to cancel out the electromagnetic field at a specific point in space (e.g. at your head).