International Journal of Computer Applications (0975 – 8887) Volume 16– No.7, February 2011 47 Performance Analysis of M*N Equalizer based Minimum Mean Square Error (MMSE) Receiver for MIMO Wireless Channel N.Sathish Kumar Department of ECE Sri Ramakrishna Engineering College, Coimbatore, TN, India -641022 Dr.K.R.Shankar Kumar Department of ECE Sri Ramakrishna Engineering College, Coimbatore, TN, India -641022 ABSTRACT The effect of fading and interference effects can be combated with equalizer. This paper analyses the performance of MMSE equalizer based receiver for MIMO wireless channel .The BER characteristics for the various transmitting and receiving antenna is simulated in mat lab tool box and many advantages and disadvantages the system is described. The simulation carried out signal processing lab show that the MMSE equalizer based receiver is a good choice for removing some ISI and minimizes the total noise power. The results show that the BER decreases as the m x n antenna configurations is increased. General Terms Equalizer, Bit error rate, Signal to noise ratio (eb/N0),transmitting antenna, receiving antenna Keywords MIMO (Multiple Input Multiple output), MMSE(Minimum Mearn Square Error) ,ISI(Inter Symbol Interference), ,SNR (Signal to Noise Ratio) 1. INTRODUCTION Wireless communication technology has shown that when multiple antennas at both transmitter and receiver are employed it provides the possibility of higher data rates compared to single antenna systems [1] [2]. The system with multiple antennas at the transmitter and receiver is commonly referred is to as multiple input multiple output (MIMO) systems. The multiple antennas are thus used to increase data rates through multiplexing or to improve performance through diversity. This method offers higher capacity to wireless systems and the capacity increases linearly with the number of antennas and link range with out additional bandwidth and power requirements. MIMO channel model [4][5] is depicted in Figure 1 with M transmitter and N receiver antennas. It can be achieved by higher spectral efficiency and link reliability or diversity (reduced fading). Figure 1 MIMO Model. 2. MMSE EQUALIZER In MIMO wireless communication, an equalizer is employed which is a network that makes an attempt to recover a signal that has suffers with an Inter symbol Interference(ISI) and proves the BER characteristics and maintains a good SNR. A Minimum Mean Square Error (MMSE) estimator is a method in which it minimizes the mean square error (MSE), which is a common measure of estimator quality. Minimum mean-square error equalizer, which does not usually eliminate ISI completely but instead, minimizes the total power of the noise and ISI components in the output. 2.1 Definition Let be an unknown random variable, and let be a known random variable. An estimator (X cap) is any function of the measurement , and its Mean square error is given mathematically given by equation 1 1 where the expectation is taken over both and .