Comparison of Different Modulation Techniques Using V- Blast Mimo System in Rayleigh Channel

Multiple Input Multiple Output (MIMO) systems have been extensively studied in context of wireless communication system, which promising the both increased capacity and link level reliability. In this paper we will present an analysis of the Vertical Bell Laboratories Layered Space-Time (V-BLAST) system at high signalto noise ratio (SNR) region using BPSK, QPSK and 16-QAM modulation technique by using various decoding techniques. We will consider a point-to-point MIMO communications over an independent, identically distributed (i.i.d) Rayleigh flat fading channel with ̳N‘ transmitting antennas and ̳M‘ (M≥N) receiving antennas. We will analyze the zero-forcing V-BLAST (ZF-V-BLAST), minimum mean-squared-error (MMSE-V-BLAST), zeroforcing + Ordered Serial Interference Cancellation V-BLAST (ZF+OSIC V-BLAST), minimum mean-squarederror + Ordered Serial Interference Cancellation V-BLAST (MMSE+OSIC V-BLAST) and Maximum Likelihood V-BLAST (ML-V-BLAST) decoding techniques with respect to their BER performances. V-BLAST system is compared with different modulation technique and system gets better result in BPSK modulation. Finally we will conclude that ML-VBLAST decoding technique gives the better performance than other decoding techniques using BPSK modulation. Further simulation results for BPSK modulation with only ML decoding technique using various antennas at input and output. In this we got more optimal result for 4 x 4 antennas for V-BLAST system.