Disputas: Frode Bøhagen

Prøveforelesning

Bedømmelseskomité

Professor Bernard Fleury, Institut for kommunikationsteknologi, Aalborg Universitet
Professor Ove Edfors, Institutionen för elektrovetenskap, Lund Universitet
Professor Sverre Holm, Institutt for informatikk, Universitetet i Oslo

Leder av disputas:  Dag Langmyhr

Veileder:  Pål Orten, Geir E. Øien

Sammendrag

Multiple-input multiple-output (MIMO) technology is embraced as one of the key technologies for fulfilling the demand for increased throughput and improved quality of service in future wireless applications. This technology can both be employed to increase reliability, through diversity schemes, or to increase the spectral efficiency by spatial multiplexing schemes. The performance of a wireless MIMO system is heavily dependent on the condition of the channel matrix, in the sense that the channel matrix should be of high rank for the MIMO system to achieve good performance. When the channel is such that a major part of the received power at the receiver is due to multipath, fulfilling the high rank criteria is dependent on low correlation between the different subchannels. On the other hand, if the dominant component at the receiver is the deterministic line-of-sight (LOS) component, fulfilling the high rank criteria becomes dependent on the design of the two antenna arrays employed.

In this work we derive optimal antenna array designs for pure LOS channels when any combination of uniform linear arrays and uniform planar arrays are employed at the transmitter and receiver. Moreover, we characterize the effects of the design deviating from the optimal. The pure LOS channel matrix utilized is subsequently employed in a Ricean channel model which also incorporate multipath, and performance is evaluated both analytically and numerically for different designs and multipath conditions. Furthermore, we investigate the performance of a possible future high frequency fixed wireless access system based on the optimal design principle, to see how it works in a more realistic scenario. In general, the results show that a considerable gain is achieved if a design close to the optimal is possible.

This work has been financed by Nera Networks, and carried out at Nera Satcom (now Thrane & Thrane) and the University Graduate Center (UniK) at Kjeller.

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