Adjustable Windowing for Transmit Beam forming in MIMO Wireless Rayleigh Fading Channel

Abstract

In a wireless communication channel, the signal propagates through multiple reflective paths. This gives rise to the rapid fluctuations in received signal amplitude which is known as fading. Fading degrades the communication system performance and may cause significant link failure. A communication channel that experiences fading is known as fading channel.

Multiple-Input Multiple-Output (MIMO) is an emerging wireless technology that provides an interesting solution to channel fading. However, exploiting MIMO spati all diversity is a spectrally efficient and powerful approach to combat channel fading. Recently, MIMO transmit beam forming which is one of the MIMO transmit diversity techniques has been attracted much attention. Maximum ratio transmission (MRT) and equal gain transmission (EGT) are the two MIMO transmit beam forming strategies used to achieve maximum signal-to-noise ratio at the receiver. Compared to MRT, EGT has more modest transmit antenna power amplifier requirements and achieves same spatial diversity order. In existing literature there has no known unique, simple and closed-form optimal solution for MIMO transmit beam former design.

In this thesis, we mainly discussed about the advantages of MIMO technology in wireless communications, existing MIMO transmit beam forming techniques and significance of windowing techniques in MIMO transmit beam forming. We consider the optimal MIMO transmit beam former design under uniform elemental power constraint. We propose an optimal transmit strategy, to maximize receive signal-to-noise ratio in MIMO wireless Rayleigh fading channel. But the proposed strategy results in high side lobe level. So, some of the adjustable window functions are used for the reduction of side lobe level of the radiation pattern.