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Author:Alm, Jarno
Title:Dual Transceiver Wireless LAN Systems
Kahden lähetinvastaanottimen WLAN-järjestelmät
Publication type:Master's thesis
Publication year:2004
Pages:68      Language:   eng
Department/School:Sähkö- ja tietoliikennetekniikan osasto
Main subject:Radiotekniikka   (S-26)
Supervisor:Vainikainen, Pertti
Instructor:Tamminen, Jani
OEVS:
Electronic archive copy is available via Aalto Thesis Database.
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Location:P1 Ark S80     | Archive
Keywords:dual transceiver
MIMO
WLAN
polarization diversity
load balancing
kaksoislähetinvastaanotin
MIO
WLAN
polarisaatiodiversiteetti
kuorman tasapainottaminen
Abstract (eng):The ever growing need for higher data rates in wireless communications has led to the introduction of new standards, which support higher data capacities. This in turn contributed to the need to improve the capacity of the wireless links in wireless local area networks.

The purpose of this thesis is to study and measure the operation of a dual transceiver wireless LAN system. At first, the theory on MIMO transceiver systems is studied. Due to the dual transceiver structure of the system special emphasis in the theory study is placed on the characteristics needed to achieve MIMO like data rate improvements with the proposed system.

The performed measurements on system and the antennas revealed that the system would not operate as had been assumed. The dual transceiver mode with load balancing introduced a problem in the operation of the system. The problem was perceived as a major fluctuation in the measured data rate with the 5 GHz system and a clear decrease in the achieved data rate for the 2.4 GHz system. Only at times did the measured values for capacity correlated with the theoretical calculations and expectations set on the system. From the performed antenna measurements it could be concluded that without synchronization not enough isolation could be achieved between the antennas. The troubleshooting measurements introduced a possibility to achieve increased data rates with the dual transceiver system utilizing two separate carrier frequencies.
Abstract (fin):Alati kasvava tarve yhä nopeampaan langattomaan tiedonsiirtoon on johtanut uusien, nopeampia yhteyksiä tukevien standardien julkaisuun. Tämä on osaltaan vaikuttanut tarpeisiin kasvattaa kapasiteettia langattomien paikallisverkkojen linkkiyhteyksissä.

Tämän diplomityön tarkoituksena on tutkia ja mitata kahteen lähetinvastaanottimeen perustuvan MIMO-järjestelmän toimivuus. Aluksi selvitetään MIMO-järjestelmään liittyvä perusteoria. Järjestelmän kaksoislähetinvastaanotinluonteen vuoksi keskitytään enemmän teoriaan, jonka avulla järjestelmästä saataisiin MIMO-järjestelmän kaltainen.

Järjestelmällä antenneille suoritettujen mittausten pohjalta voidaan todeta, että järjestelmä ei tule toimimaan kuten oli odotettu. Ongelmia havaittiin yritettäessä käyttää järjestelmää kaksoislähetin-vastaanotinmoodissa. Ongelmat ilmenivät suurena vaihteluna mitatussa kapasiteetissa 5 GHz:n järjestelmässä ja selkeänä kapasiteetin laskuna 2,4 GHz:n järjestelmässä. Mitatut kapasiteettiarvot korreloivat teoreettisten laskujen ja oletusten pohjalta saatujen arvojen kanssa. Antennimittauksista voidaan todeta, että antennien välinen isolaatio ei ole riittävä järjestelmän toimiessa ilman synkronointia. Ongelmanratkaisumittauksissa ilmeni mahdollisuus saavuttaa miltei tuplakapasiteetti asettamalla lähetinvastaanottimet toimimaan eri kantotaajuuksilla.
ED:2004-04-01
INSSI record number: 25096
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