Ecole d'ingénieur et centre de recherche en télécommunications

Exploiting the wireless channel for communication

de Lacerda Neto, Raul Liberato

Thesis

      The development of cellular communications during the 1980s made wireless networks one of the most important areas of technology. Fueled by the advances in wireless computer networks, high data rate connections have recently become the focus of research in the communication domain. The growth of the Internet and the introduction of a multitude of applications culminated in a new era of communications in which wireless networks play a very important role. However, the wireless environment still offers some challenges that need to be addressed before reaching the prerequisites of future wireless networks. Due to imprecise channel characterization, much of the potential of the wireless environment is wasted. Furthermore, the requirements caused by multiple connections lead to the use of multiple access schemes that were not designed to cope with some of the wireless environment phenomenons. These two points are treated in this thesis. The first part of this thesis is dedicated to the use of probability theory tools that enable the creation of models based only on partial knowledge of the environment. Using Jaynes' maximum entropy principle, we present a framework that allows us to infer on the channel characteristics by choosing probability distributions that maximize entropy under the constraints that represent our state of knowledge. This technique is considered as the most reliable method to perform inferences. Models for two different types of environment are derived: wideband channels and multiple-input multiple-output (MIMO) channels. In the second part, the multiple access problem for ultra wideband (UWB) systems is assessed. Despite the large amount of work conducted during recent years on UWB technology, no scheme can cope with the high dispersion of UWB channels and still offer reasonable spectral efficiency. An innovative scheme that exploits the users' channels to guarantee multiple access is introduced, entitled Channel Division Multiple Access (ChDMA). This scheme provides a very simple solution and achieves high spectral efficiency.

Document Bibtex

Type:Thèse
Langue:English
Ville:
Date:
Département:Communications Mobiles
Eurecom ref:2703
Copyright: © Université de Nice. Personal use of this material is permitted. The definitive version of this paper was published in Thesis and is available at :
Bibtex: @phdthesis{EURECOM+2703, year = {2008}, title = {{E}xploiting the wireless channel for communication}, author = {de {L}acerda {N}eto, {R}aul {L}iberato}, school = {{T}hesis}, month = {12}, url = {http://www.eurecom.fr/publication/2703} }