Study On Effect Of Receiver Locations In Indoor Wireless MIMO System

In wireless communications, spectrum is a scarce resource and hence imposes a high cost on the high data rate transmission. The emergence of multiple antenna system has provide very promising gain in capacity without increasing the use of spectrum, hence leading to a breakthrough in the data rate of wireless communication systems. Multiple antenna technologies are now being considered as a viable solution for the next generation of mobile and wireless local area networks (WLAN). The use of multiple antennas offers extended range, improved reliability and higher throughputs than conventional single antenna communication systems. Multiple Input -Multiple Output (MIMO) system has become one of the major focuses in the research community of wireless communications and information theory. The study of the performance limits with the capacity of MIMO system becomes very important since it gives a lot of insights in understanding and designing the practical MIMO systems to the wireless communication field. The multiple antennas used on indoor wireless Multiple Input-Multiple Output (MIMO) communication system, under line of sight (LOS) and non line of sight (NLOS) situations, does have effects on thechannel.In the thesis, an indoor system is modeled having the MIMO link of 2x2 antennas at both the ends. Metallic blocks are placed in between the transmitter and receiver to provide the NLOS environment. FDTD method is used for analyzing the MIMO channel. For both LOS and NLOS cases, different MIMO capacities are calculated and examined. For the better comparison, the Complementary Cumulative Distribution Function (CCDF) of MIMO channel capacity is calculated. It is found that MIMO channel capacity for LOS case is larger than that for the NLOS case and it is true because of the metallic blocks placed in between the two ends. We also found that MIMO capacity for the transmitter position at the center of room, for both the cases is high whereas for the transmitter position at the corner of room, capacity is small. The capacity is higher in LOS case and it will be due to fact the received power level is greater than NLOS case. The capacity can be increased by increasing the number of scatterers and by increasing the scatterers, multipath can be increased which favors the condition for the MIMO but in the mean time multipath also introduces the loss. From the Friis equation, increase in losses decreases the received signal which overall decreases the signal to noise ratio and hence decreases the capacity of the system.Further discussion is provided on MIMO application, large range coverage, compared with different number of antennas in transmitter and receivers and finds out that MIMO can provide better range coverage than other antenna systems. With the MIMO system, capacity can be increased by increasing the number of antennas and with the lower data rate corresponds to the lower signal to noise ratio, the larger range can also be obtained. Cost -231 propagation model is used to calculate the path loss of the system and using the Friis formula signal to noise ratio is calculated. With the simulation results we found SIMO provides better range coverage than SISO and MISO systems and MIMO provides better coverage than SIMO, MISO and SISO systems.