Measurement-Based Modeling of Wireless Propagation Channels - MIMO and UWB

Research output: ThesisDoctoral Thesis (compilation)

Abstract

Future wireless systems envision higher speeds and more reliable services but at the same time face challenges in terms of bandwidth being a limited resource. Two promising techniques that can provide an increased throughput without requiring additional bandwidth allocation are multiple-input multiple-output (MIMO) systems and ultra-wideband (UWB) systems. However, the performance of such systems is highly dependent on the properties of the wireless propagation channel, and an understanding of the channel is therefore crucial in the design of future wireless systems. Examples of such systems covered by this thesis are wireless personal area networks (papers I and II), vehicle-to-vehicle communications (paper III), board-to-board communications inside computers (paper IV) and sensor networks for industrial applications (paper V). Typically, channel models are used to evaluate the performance of different transmission and reception schemes. Channel modeling is the focus of this thesis, which contains a collection of papers that analyze and model the behavior of MIMO and UWB propagation channels.

Paper I investigates the fading characteristics of wireless personal area networks (PANs), networks that typically involve human influence close to the antenna terminals. Based on extensive channel measurements using irregular antenna arrays, typical properties of PAN propagation channels are discussed and a model for the complete fading of a single link is presented.

Paper II extends the model from paper I to a complete MIMO channel model. The paper combines the classical LOS model for MIMO with results from paper I by prescribing different fading statistics and mean power at the different antenna elements. The model is verified against measurement data and the paper also provides a parameterization for an example of a PAN scenario.

Paper III presents a geometry-based stochastic MIMO model for vehicle-to-vehicle communications. The most important propagation effects are discussed based on the results from extensive channel measurements, and the modeling approach is motivated by the non-stationary behavior of such channels. The model distinguishes between diffuse contributions and those stemming from interaction with significant objects in the propagation channel, and the observed fading characteristics of the latter are stochastically accounted for in the model.

Paper IV gives a characterization of UWB propagation channels inside desktop computer chassis. By studying measurement results from two different computers, it is concluded that the propagation channel only shows minor differences for different computers and positions within the chassis. It is also found out that the interference power produced by the computer is limited to certain subbands, suggesting that multiband UWB systems are more suitable for this type of applications.

Paper V describes a UWB channel model based on the first UWB measurements in an industrial environment. Analyzing results from two different factory halls, it is concluded that energy arrives at the receiver in clusters, which motivates the use of a classical multi-cluster model to describe the channel impulse response. Parts of the results from this paper were also used as input to the channel model in the IEEE 802.15.4a UWB standardization work.

In summary, the work within this thesis leads to an increased understanding of the behavior of wireless propagation channels for MIMO and UWB systems. By providing three detailed simulation models, two for MIMO and one for UWB, it can thus contribute to a more efficient design of the wireless communications systems of tomorrow.

Details

Authors
  • Johan Kåredal
Organisations
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Electrical Engineering, Electronic Engineering, Information Engineering

Keywords

  • personal area networks, MIMO, channel modeling, Propagation, channel measurements, vehicle-to-vehicle communicationa, ultra-wideband
Original languageEnglish
QualificationDoctor
Awarding Institution
Supervisors/Assistant supervisor
Award date2009 Feb 12
Publication statusPublished - 2009
Publication categoryResearch

Bibliographic note

Defence details Date: 2009-02-12 Time: 10:15 Place: Room E:1406, E-building, John Ericssons väg 4, Lund University, Faculty of Engineering External reviewer(s) Name: Oestges, Claude Title: Professor Affiliation: Microwave Laboratory, Université catholique de Louvain (UCL), BELGIUM ---

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Related research output

Johan Kåredal, Peter Almers, Anders J Johansson, Fredrik Tufvesson & Andreas Molisch, 2010, In : IEEE Transactions on Wireless Communications. 9, 1, p. 245-255

Research output: Contribution to journalArticle

Johan Kåredal, Fredrik Tufvesson, Nicolai Czink, Alexander Paier, Charlotte Dumard, Thomas Zemen, Christoph Mecklenbräuker & Andreas Molisch, 2009, In : IEEE Transactions on Wireless Communications. 8, 7, p. 3646-3657

Research output: Contribution to journalArticle

Johan Kåredal, Anders J Johansson, Fredrik Tufvesson & Andreas Molisch, 2008, In : IEEE Transactions on Wireless Communications. 7, 11, p. 4575-4585

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