Lower Bound on the Ergodic Capacity of MIMO Relay Channels in Rayleigh Fading Case

This paper analyzes the ergodic capacity in Rayeigh fading case and derives the signal-to-noise ratio (SNR) conditions for achieving the lower bound on ergodic capacity when nodes have different number of antennas, especially when the number of source antennas is larger than that of the destination\´s and the relay transmitter and receiver\´s. Then we verify it through simulations. Besides, simulation results show that with the increase of the number of the transmitter antennas, the lower bound on ergodic capacity raises linearly. Because the source node and the relay node can function as a "virtual" transmit antenna array when the relay node is located close to the source node.