Moniantennijärjestelmät autoympäristössä

MIMO systems have emerged in the last few years as a means to improve the quality of service and spectral efficiency of wireless communication systems. This thesis examines the use of multi-antenna systems on vehicles. The main objectives of this thesis are to develop a procedure for the design of multi-antenna systems, compare the benefits of different multi-antenna systems in automotive environment, study the suitability of the chosen electromagnetic simulation method to modelling and simulation of automotive antennas, and also to give ample references for the reader, in case a more in-depth understanding in the areas of multi-antenna techniques and automotive antennas is needed. The electromagnetic simulation of the antenna systems are based on the finite integration technique with commercial software, while link level performance simulation is performed on a MATLAB implementation of the SCME radio channel model. The finite integration technique is found to provide accurate radiation pattern results, and it can be recommended for the purpose of simulation of automotive antenna systems at the 700 MHz carrier frequency. On link level simulations the focus is on simulating 2×2 multiantenna systems. These simulations imply a noticeably improved BER when a BF MIMO system is employed, compared to the traditional MIMO system. The BF MIMO is a new concept that combines the best sides of beamforming and MIMO. This is the first study where the BF MIMO concept is applied to antennas in automotive environment. The results for the different antenna array configurations were indeterminate. In general, it can be said that the radio channel (or channel model) is one of the most significant factors in determining the performance of a multi-antenna systems, and it is highly unlikely that any single array configuration can provide optimal performance in every channel conditions. The first part of this thesis, Chapters 2 and 3, provides background of multi-antenna systems. Theoretical concepts of multi-antenna systems are introduced in Chapter 2 to enable the analysis of such systems. In the third chapter, a literature survey is presented as a summary of related studies on the areas of automotive antennas, multi-antenna systems, related information theory and electromagnetic simulation methods of antennas. In the latter part of this thesis, Chapter 4 describes the electromagnetic and link level simulation software packages and the simulation of the antennas. The results are presented in Chapter 5, and conclusions are drawn in Chapter 6. /Kir1