International Journal of Wireless & Mobile Networks (IJWMN) Vol. 5, No. 1, February 2013 DOI : 10.5121/ijwmn.2013.5106 73             !  Navjot Kaur and Lavish Kansal Lovely Professional University, Phagwara, E-mails: er.navjot21@gmail.com, lavish.15911@lpu.co.in Abstract Multiple-Input Multiple-Output (MIMO) systems have been emerged as a technical breakthrough for high-data-rate wireless transmission. The performance of MIMO system can be improved by using different antenna selection so as to provide spatial diversity. In this paper, the performance of MIMO system over AWGN (Additive White Gaussian Noise) and Rician fading channels with ZF receiver is analyzed using different antenna configurations. The bit error rate performance characteristics of Zero- Forcing (ZF) receiver is studied for M-PSK (M-ary Phase Shift Keying) modulation technique using AWGN and Rician channels for the analysis purpose and their effect on BER (Bit Error Rate) have been presented. Keywords – MIMO, spatial diversity, AWGN, Rician, fading, ZF, antenna, BER, M-PSK. I. INTRODUCTION MIMO systems make use of multiple antennas at the transmitter and receiver so as to increase the data rates by means of spatial diversity. So MIMO systems are well-known in wireless communications for high data rates. [1] The capacity of wireless systems can be increased by varying the number of antennas. The two primary reasons for using wireless communication over wired communication: • First is multi-path fading i.e. the variation of the signal strengths due to the various obstacles like buildings, path loss due to attenuation and shadowing [2]. • Second, for the wireless users, the transmission media is air as compared to the wired communication where each transmitter–receiver pair is considered as an isolated point-to- point link. MIMO system utilizes the feature of spatial diversity by using spatial antennas in a dense multipath fading environment which are separated by some distance [3]. MIMO systems are implemented to obtain diversity gain or capacity gain to avoid signal fading. The idea to improve the link quality (BER) or data rate (bps) is the basic consideration behind the development of MIMO systems by using multiple TX/RX antennas [4]. The core scheme of MIMO is space-time coding (STC). The two main functions of STC: diversity & multiplexing. The maximum performance needs tradeoffs between diversity and multiplexing.