Capacity Analysis Of MIMO Relay Systems With Keyhole Effect

MIMO, which achieves the parallel transmission, has become the preferred technology toimprove the utilization of wireless spectrum. And now MIMO has become the core technologyof4G international standard for increasing the capacity of wireless link by20to30times. Asmore and more researches about the MIMO technology, a new wireless propagation environmentfor MIMO technology has been proposed and confirmed experimentally. It’s said that even if theantennas of transceiver and receiver of MIMO system have been placed in a rich scatteringenvironment, and each of the antennas is highly independent with the others, the channel transfermatrix also has low rank, even single rank, which is caused by the so-called Keyhole effect.The main work of this thesis is going to try to explain how relay can improve the capacityof MIMO system under the influence of Keyhole effect.The thesis begins with some brief introductions about MIMO system, relay and Keyholeeffect. Then the system model, which will be studied, is given by placing the Keyhole effectsinto the MIMO relay systems.Then, the theoretical capacity expression of the MIMO relay systems, under the influence ofKeyhole effect, is given by using Mathematical matrix operations. Finally MATLAB simulationsprove that Keyhole effect reduces the system capacity of MIMO systems significantly and therelay can greatly improve the average capacity of the system. And the article also discussed thepower allocation between the relay and the source in order to maximize the system capacity.