Capacity Analysis Of Mimo (8x8) System With Or Without Csi Under Different Wireless Fading Channels

Abstract

In current time Multiple Input Multiple Output (MIMO) wireless links has emerged as one of the most significant technical breakthrough in modern communication. In this thesis, an overview of MIMO system has been discussed. After presenting brief idea of MIMO system Transmissions, the system Capacity and Bit Error Rate (Detection Techniques) of MIMO designs have been explained. Multiple antennas have been used to increase diversity to combat channel fading. Hence, a MIMO system can provide two types of gains: spatial multiplexing or capacity gain and diversity gain. However, the capacity and diversity benefits of MIMO systems depend on what kind of fading(Rayleigh and Rician) the channels undergo; whether the fades associated with different transmit and receive antennas are correlated; and whether the channel state information (CSI) is available at the transmitter or not available at transmitter. This thesis presents the progress we have made towards determining the capacity and diversity benefits of multiple antennas under different assumptions about the fading channel. In this thesis work capacity analysis of MIMO (8X8) system with or without CSI under different wireless fading MIMO system had been done. Rayleigh and Rician fading channel has been taken between (8X8) transmitter and receiver. This thesis also represent work regarding to Beamforming. Wireless relaying networks had recently been given considerable benefits over traditional communication system. The relaying terminals forward the information from the source to the destination mainly using the Amplify-Forward method. The main aim of MIMO system is to increase the diversity gain and range of system. Here, in this thesis slow and frequency non selective Rician fading channel is assumed, and the effect of Rician factor (K) on the capacity and diversity gains of correlated MIMO channels is investigated. Thesis presents the view point that the loss or gain in the capacity or diversity can be considered as an equivalent increase or decrease in the signal-to-noise power ratio (SNR). For N_t× N_R MIMO systems, as value of k increases the ergodic capacity and outage capacity decreases. If value of correlated fading parameter (r) increases, the ergodic and the outage capacity decreases. When transmitter know the CSI capacity increases as compare when transmitter does not know the CSI. When transmitter does not know the CSI at that time equal power is given to each transmitter. The bit error rate analysis of MIMO system have been analyzed using BPSK modulation scheme over Rayleigh and Rician wireless fading channels. The BER performance characteristics investigation of 8x8 antenna configuration had done by using different type of linear and non-linear equalizer techniques namely ML, ZF and MMSE for MIMO system. In the case of MIMO (4,3) when CSI is not present at transmitter then at SNR (dB) 5, 10 the capacity results for Rayleigh channels are 4(bps/Hz), 13(bps/Hz). But in case of (8x8) MIMO capacity become 13.5(bps/Hz) , 22 (bps/Hz) for taking same condition. When transmitter know the CSI then at 5(dB), 10(dB) the capacity for MIMO(8X8) become 29.5 (bps/Hz) , 41(bps/hz). So there is increase in capacity when number of transmitter and receiver increases. In case of Rician channel at 30(dB),k=0 the capacity for(8x8) is 70(bps/Hz),at k=3 the capacity is 59(bps/hz) and at k=7 capacity becomes 52(bps/Hz).As value of k increases the capacity of Rician fading channel continuously decreases. The capacity of MIMO (8x8) for k=10 (rt=0.5,rr=0.5) at 30 (dB) become 59(bps/Hz) .Increasing channel correlation (r) reduces the capacity of the system. Ergodic capacity of MIMO (8x8) when there are eight relay between transmitter and receiver at 30 (dB) is 28(bps/Hz). Ergodic capacity of MIMO(8x8) when there are four relay between transmitter and receiver at 30 (dB) is 24(bps/hz). So as number of relay between transmitter and receiver increases it increases the capacity. The BER rate of MMSE detection techniques for MIMO (8X8) is less than as compare of BER for ZF detection techniques at same SNR.